The austenitic stainless steel weldment is important load-bearing structure in high-pressure hydrogen systems. The weldment long-term service in a high-pressure and high-purity hydrogen environment will cause hydrogen embrittlement such as plastic loss and accelerated fatigue crack growth rate, which leads to safety hazards in high pressure hydrogen system. Therefore, in order to ensure the safe operation of the high-pressure hydrogen system, it is necessary to study the hydrogen embrittlement of austenitic stainless steel weldments. This paper first introduced two sources of hydrogen in austenitic stainless steel weldments, and then discussed the static and dynamic experimental methods to evaluate the hydrogen embrittlement sensitivity of materials. Secondly, it summarized the current mainstream hydrogen embrittlement mechanism, and then focused on the analysis of the influence of internal and external factors on the hydrogen embrittlement sensitivity of austenitic stainless steel weldments, Finally, the effects of five typical austenitic stainless steel welding processes on the microstructure of weldments were summarized, and the hydrogen embrittlement sensitivity of corresponding weldments was further discussed. Based on the above analysis, several suggestions were put forward to provide references for the research on hydrogen embrittlement of austenitic stainless steel weldments in high pressure hydrogen environment.

Melt-blown non-woven fabric has many excellent uses in filtration, bacteria resistance, adsorption, waterproofing and so on, with the potential for a vast future market. The stretching process of polymer to produce melt-blown non-woven fabric is too complex and rapid to be observed experimentally. Therefore, a computational fluid dynamics (CFD) method is widely used in the analysis of this process including the analysis of the flow channels in the dies and the jet flow field under the spinneret. The jet flow field analysis is the most extensively examined, which provides solutions for optimizing the spinneret structures and the jet flow field. This article briefly introduced the principles and characteristics of melt- blowing, and reviewed the research progress of CFD simulations in this area. Currently, the CFD simulations of melt-blowing processes were generally based on airflows in the jet flow field without considering the effect of viscous polymer fibers on them. However, the viscous polymer fibers vibrated under conditions of high velocity and high-temperature airflows, and these effects on the jet flow field should not be neglected. The key problem in melt-blowing was to reduce the diameters of the polymer fibers and improved the quality of the melt-blown non-woven fabric. Consequently, the research should concentrate on the fibers flow field and not the airflow field. The viscous polymer fibers that flow in the melt-blowing process were effected by the high velocity and temperature of the airflows in the jet flow field as the phase was changed from liquid to solid. Although CFD simulations were widely utilized in modeling the melt-blowing process, the study of the flow field simulation of polymer fibers in a molten state had not yet been carried out. This problem remained and should be studied in the future.

As a new two-phase heat transfer technology, vapor chamber has the advantages of high thermal conductivity, good temperature uniformity, reversible heat flow direction, and so on. It overcomes the problems of traditional heat pipe, such as small contact area, large heat resistance and ununiform heat flow density, and has become one of the effective ways to solve the heat dissipation of electronic devices with high heat flow density in the future electronic industry. In this paper, the three types of wick structures, namely, grooved, sintered powder and sintered wire mesh were summarized, and the preparation methods of each capillary wicks were introduced and their advantages and disadvantages were compared. The latest research progress of heat and mass transfer theory in vapor chamber was reviewed. the boiling theory of transport model to capture the gas-liquid interface was used by researchers. The critical heat flux was confirmed. The flow and heat transfer law of working medium was analyzed in the vapor chamber. Then, the factors affecting the performance of vapor chamber, including fluid selection, liquid filling rate, heat load, inclination, et al. were analyzed. Finally, the application direction of the vapor chamber was prospected from the perspective of background environment.

Because of its mature technology, lime gypsum flue gas desulfurization has been widely used in coal-fired power plants, iron and steel metallurgy and other industries. The technology has the characteristics of high removal efficiency and easy to buy absorbent. However, there are many fuzzy uncertainties in the daily operation of desulfurization system. In order to make a better comprehensive evaluation of the system operation stability, the influencing factors were analyzed through three steps, and the final conclusion was obtained. First of all, according to the technical characteristics and operation status of the project, the investigation was carried out from six aspects of process, equipment, electrical, instrument automation, public and auxiliary and operation and maintenance, and various factors and constraints leading to the instability of the system operation were found. Secondly, the cause and effect fuzzy analytic hierarchy process was used to analyze the reasons leading to the instability of lime gypsum desulfurization system, and the fuzzy evaluation model of system operation was established. The weight calculation and fuzzy comprehensive evaluation of various influencing factors were carried out, and the weight order, comprehensive score and evaluation grade were obtained. Thirdly, combined with the case of sintering machine flue gas desulfurization, the influencing factors of project operation instability were divided into 6 categories and 24 sub items, and the evaluation level was divided into very stable, relatively stable, basically stable, less stable and unstable. Finally, through the case analysis, evaluation and comparison with the on-site detection, the following three conclusions were obtained. ①The weight order of each influencing factor was obtained as follows: electrical failure, instrument automation inaccuracy, abnormal process index, equipment failure, public and auxiliary supply instability, daily operation and maintenance management. ②The comprehensive score of the case project was 77.75, and the evaluation level was determined as level 3-basically stable. ③After comparing the comprehensive evaluation results of causal fuzzy analytic hierarchy process with the field monitoring results, it was determined that the two results were consistent, which showed that the method had good applicability for the stability evaluation of lime gypsum desulfurization system.

Liquid-bridge is an important feature of helical liquid-bridge flow structured packings. It exists in the helical channels and connects two parallel helical string. However, there are few studies on the formation and fluid flow of liquid bridge in helical channels. To investigate the influence of the different structured parameters of the helical liquid-bridge flow structured packings and liquid load on the liquid-bridge, and the flow behavior of liquid-bridge in the helical channels, the lab-scale fluid flow observation rig was built. Meanwhile, a high-definition camera and high-speed video camera equipped with a macro lens, combing with a particle tracking method, was used to observe the formation, change and flow behavior of the liquid-bridge in the helical channels. The results showed that a stable and continuous liquid-bridge could be formed in different helical channels. The diameter and width of the helical string had little effect on the formation, change and flow behavior of the liquid-bridge. The smaller the helical channels width, the larger the liquid load, the more stable the liquid bridge, but the surface area of the liquid-bridge would decrease. In addition, with the increase of the liquid load, the boundary of the liquid-bridge would change from concave to flat. It could be found by slow-motion of the image that the liquid-bridge spirally descended along the helical string in the helical channels. The present study provides insight into the setting and application of structure parameters of helical liquid-bridge flow structured packings.

For a complicated chemical process, i.e. the fluorochemical process, the simultaneous existence of the time-varying processes with different time characteristics makes regular machine learning methods unable to predict product quality precisely. In this study, a convolutional neural network with attention mechanism of input data (ACNN) was proposed to improve the prediction of the product quality. By introducing the adaptive attention mechanism on input data at different-time span, this method can simultaneously extract the characteristics of time-varying processes. Therefore, it can overcome the abovementioned drawbacks of the regular convolution neural network. This advantage allows the possibility for ACNN to accurately extract the features of strong and complicated time-varying fluorine chemical process, and to further precisely predict the quality of products to improve the performance of the industrial control system. The performance of ACNN was strongly proved by the application in quality prediction of the fluorine chemical process located in East China. The application of it in the TE (Tennessee Eastman) benchmark also proved its generalization in the applications on other chemical processes. The results showed that the accuracy of ACNN was higher for strong time-varying or long time-span fluctuations as compared to the conventional methods.

A novel multiple downcomer tray with uniform flow field and large liquid phase processing capacity was developed. The hydrodynamic performances of the novel tray were experimentally investigated with an air-water system in a plexiglass column with an inner diameter of 1219mm. The results showed that under the same gas-liquid load, compared with the segmental downcomer tray, the novel tray had the advantages of lower wet plate pressure, smaller entrainment and less weeping. At the same time, the novel tray had the merits of large liquid phase capacity of multi-downcomer (MD) tray, the highest spray density reached 80m³/(m²·h) under the condition of an empty tower kinetic energy factor of 2.4(m/s)·(kg/m³)^0.5. The characterizations of the on-tray liquid phase flow field were analyzed via computational fluid dynamic (CFD) simulation, and the results were compared with those of the conventional MD tray. It was inferred that the downcomer structure and arrangement of the novel tray led to the uniform liquid flow field and a higher tray efficiency was expected.

In order to study the principle of enhancing substrate droplet evaporation by electric field, the evaporation process of droplets on solid substrate under external electric field was numerically simulated by finite element method. The effect of electric field on the evaporation rate and internal flow of droplet and its reasons were analyzed by comparing cases of droplets with different electric conductivities. The relationship between the internal flow and heat and mass transfer of droplet was also analyzed. The results showed that the effect of electric field can significantly enhance the internal flow and promote the heat and mass transfer of droplets. In addition, the effect of electric field on droplet evaporation and internal flow was analyzed. It was found that the effect of temperature on the internal flow and evaporation of droplets is also obvious. For the pure water droplet with low conductivity, when the electric field intensity was lower than and higher than the critical value 6kV/cm, the effect of temperature on the internal flow and evaporation of electric field enhanced droplets was different, and for the HCl droplet with high conductivity, temperature has great influence on electric field enhanced droplet influx and evaporation. The current study provides a research foundation for the development of efficient electrostatic spray cooling technology.

Solvent extraction is widely used in the petrochemical industry, which is a powerful technology for the separation and purification of petroleum and petrochemical products. Ionic liquids, as a new type of separation medium, have attracted great attention in recent years, especially in oil extraction and separation due to their advantages such as designable structure, high chemical and thermal stability, and very low vapor pressure. In this paper, the properties and classification of ionic liquids are introduced firstly. Secondly, according to different separation objectives, the latest progress of ionic liquids in the fields of aromatics separation from saturated hydrocarbons, desulfurization and denitrification, separation of olefins from paraffins is summarized. The existing problems and future development directions of ionic liquids in oil separation are discussed. The chain of cationic sides and polarity are the key factors affecting the extraction efficiency of aromatic hydrocarbons. However, the separation of aromatics form saturated hydrocarbons in the real oils needs further study. Ionic liquids show a strong ability to separate heteroatomic sulfur and nitrogen compounds, but it is difficult to remove basic nitrogen and non-basic nitrogen compounds simultaneously by using the same ionic liquid. The alkalinity of hydrogen bond is a key factor affecting the separation of olefins by ionic liquids. However, most ionic liquids have low selectivity to olefins. According to different separation tasks, it is important to understand the relationship between the structure of ionic liquids and their separation performance at molecular level, and then design new ionic liquids with high separation efficiency and low environmental impact, which will maximize the utilization value of the key components in oil.

Separation is difficult due to the complex interaction of oil-water-solid three phases in heavy oil solids (such as oil sands, bituminous rocks, oil shale, heavy oil, oil sludge, etc.). This article takes Indonesian bituminous heavy oil as an example to study the structure of the interfacially active asphaltene which has the strongest interfacial activity among the heavy components and its adsorption characteristics on the surface of minerals. The structure of interfacially active asphaltene was analyzed by gel permeation chromatography, infrared spectrometer, XPS, etc., and its preliminary structure was proposed. Taking SiO₂ as the mineral solid model, using QCM-D and AFM to study the adsorption characteristics of interfacially active asphaltenes on the solid surface in a toluene solvent environment, it is found that the adsorption of this subfraction of asphaltene molecules on the SiO₂ surface is larger than that of ordinary asphaltene molecules. The difference shows the characteristics of multilayer adsorption, which is in line with the Freundlich adsorption model. The adsorption film has more high-dispersion agglomerates and greater viscoelasticity, and is easy to form a strong mechanical interface film with three-dimensional structure. The structure and interface adsorption characteristics can provide a favorable basis for revealing its mechanism in the oil-water emulsion stabilization process.

Microwave(MW)-assisted biomass conversion is a promising method for the production of value-added chemicals. Carbon materials have good chemical stability and dielectric properties, which are ideal catalyst supports and microwave absorbers in the process of MW reaction. In view of this, four carbon materials, including carbon nanotubes(CNT), carbon nanofibers(CNF), carbon black(CB) and activated carbon(AC), were used to catalyst fructose conversion under conventional heating and MW irradiation conditions. The enhancement effects of MW coupling with different supports for the reaction performance were further explored. The heating behaviors of different carbon material suspensions were measured under MW condition, and the difference in their dielectric properties was explained by structural and physical properties. The results show that the MW induced thermal effect of carbon-based catalysts can effectively improve the reaction efficiency. The catalyst with high loss tangent and conductivity tends to have a strong heating ability, which is conductive to transfer MW energy to the catalyst surface. Carbon-based catalysts with high specific surface area, high aspect ratio, low density and high graphitization degree are also beneficial to the generation of thermal effect. In addition, CNT-SA is the most suitable catalyst among the four alternatives. The yield of 5-hydroxymethylfurfural(5-HMF) reaches 96.30% in 10min at 110℃ under MW irradiation, and the catalyst has a good recyclability.

Fe₂O₃/Al₂O₃ oxygen carrier used in chemical looping process will form FeAl₂O₄, which is difficult to react with water to produce hydrogen due to thermodynamic limitations. In order to solve this problem, Mg was added to Fe/Al oxygen carrier for coal chemical looping hydrogen generation, and the action mechanism of Mg was deeply analyzed and its influence on the experimental results was explored. The XRD results show that when the Mg content increases from 1% to 26.5%, the characteristic peak of MgAl₂O₄ increases, and the characteristic peak of FeAl₂O₄ gradually disappears, indicating that Mg weakens the interaction between Fe and Al. SEM shows that the size of oxygen carrier particles decrease after adding Mg, and the sintering resistance is excellent. Based on the experiments of different coal/oxygen-carrier mass ratio, the carbon conversion and hydrogen production were the highest when the mass ratio was 0.5/15. Among the oxygen carriers with different Mg contents, Fe40Mg20Al40 has the best reaction performance, and the carbon conversion and hydrogen production are 81.75% and 1.7182L/g, which increase by 10.2% and 58.5% compared with Fe40Al60, respectively. After 10 cycles, the surface of Fe40Mg20Al40 is only slightly sintered, and the carbon conversion and hydrogen production are above 78% and 1.52L/g, respectively, showing good cycling performance. The addition of Mg can effectively inhibit the formation of FeAl₂O₄, significantly enhance the reactivity of steam oxidation process, and greatly increase the yield of hydrogen, which is very suitable for coal chemical looping hydrogen generation.

The influence of air volume on the atomization characteristics of waste oil biodiesel in swirl nozzles was studied using a combination of Fluent numerical simulation and experiment. The impact of primary and secondary air volumes on the atomization process of waste oil biodiesel was analyzed. The results show that when the total air volume in the oil burner is set to 429L/min under isothermal and isostatic conditions, the primary and secondary air volumes have a greater impact on the Sauter average diameter (D₃₂), droplet velocity, atomization cone angle and atomization penetration distance of the oil spray droplets. Specifically, with the increase of the primary air volume, the breaking time of the droplets becomes shorter, D₃₂ gradually decreases, and the speed gradually increases. While atomization penetration distance and the atomization cone angle firstly increase and then decrease, the maximum values are attained with the primary air volume of 50L/min. Meanwhile, the turbulent kinetic energy is proportional to the primary air volume. However, the D₃₂ basically tends to be stable when the primary air volume reaches 30L/min. As for the statistical analysis of the number of atomized droplets of different particle diameters, the distribution of quantity density of different particle diameters of biodiesel and the fitting empirical formula are obtained. The particle diameters are mainly concentrated between 25—75μm.

Single-atom site catalysts have received extensive attention due to their close to 100% atom utilization efficiency, and excellent activity, selectivity and stability. This review describes the latest research results of single-atom site catalysts and their applications in electrocatalysis. The preparation methods of single-atom site catalysts are introduced in detail, including the co-precipitation, electrochemical precipitation, atomic layer deposition, photochemical and atomic confinement using the “bottom-up” synthesis strategy, as well as the high-temperature atom migration trapping, high-temperature pyrolysis and hanging key trapping using the "top-down" synthesis strategy. Characterization techniques of high-angle annular dark field transmission scanning microscope and X-ray absorption spectroscopy are analyzed. Theoretical calculations by density functional theory and first principle are also analyzed. Applications in electrocatalysis, mainly including oxygen reduction reaction (ORR), nitrogen reduction reaction (NRR), CO₂ reduction reaction (CO₂RR), hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are introduced. Finally, the current problems of single-atom catalysts such as the inability to large scale production and the unclear catalytic mechanism are pointed out and relevant suggestions are given. The prospect of single-atom site catalysts is proposed. Innovative preparation of stable single-atom site catalysts to achieve their large-scale preparation and industrial application, and the use of advanced characterization techniques to further clarify the catalytic mechanism should be the directions of future development.

In recent years, the process of green diesel production by hydrothermal catalysis has attracted much attention. while heterogeneous catalysts can improve the yield and selectivity of green diesel, the regeneration of deactivated catalysts is still a challenge. First, the catalysts widely used in the hydrothermal catalysis process are introduced. Second, the deactivation mechanism of heterogeneous catalysts is discussed, including the metals and the supports. The leaching and sintering of the supported metal are responsible for the deactivation of the catalyst, and the instability of the supports is an important reason. Then, the regeneration methods for the deactivated catalysts are summarized, including calcination and washing. Finally, suggestions are made for the catalytic hydrothermal preparation of green diesel, i.e., to develop catalysts with high activity, to find efficient regeneration methods, and to select suitable reaction conditions.

Mercury is a highly toxic and useless element in coal. The prevention and control of mercury pollution in coal-fired flue gas has become a national focus and research hotspot. The titanium-based catalysts for photocatalytic mercury removal were systematically introduced, including morphology-controlled titanium, metal modified titanium, nonmetal modified titanium, semiconductor composite titanium, supported titanium. The photocatalytic mercury removal efficiency of titanium-based catalysts by different modifications was compared, and the effects of preparation method, light source, reaction temperature, flue gas composition and photocatalytic reactor on the mercury removal efficiency were discussed. Then, the reaction mechanism of photocatalytic mercury removal with titanium-based catalysts was summarized, and the potential application prospects and challenges of photocatalytic mercury removal from coal-fired flue gas were prospected, so as to provide reference for the prevention and control of the mercury pollution from coal-fired flue gas. It will be an important research and development trend to improve the catalyst modification methods and carry out pilot-scale experiments, which is also the key to realize the industrial application of photocatalytic oxidation mercury removal technology.

Methacrolein (MAL) is an important organic synthesis intermediate, which shows a broad application prospect in pharmaceuticals and pesticides, flavors and fragrances, industrial additives and cement water-reducing agent. Mannich condensation of propionaldehyde and formaldehyde to MAL could be operated under mild conditions and produce minor byproducts. In this review, the industrial application of MAL, the reaction mechanism of Mannich condensation, and in particular, the recent progress in the catalysts and the reaction process for Mannich condensation of formaldehyde and propionaldehyde are expounded. Researches have suggested that there are some problems in current homogeneous synthesis of MAL via Mannich condensation, such as the overuse and the difficult separation and recycle of the catalysts, serious pollution, high cost. On the other hand, with the application of heterogeneous catalysts, problems like separation, recycling and reusage of catalysts could be easily solved. However, the activity and selectivity of current heterogeneous catalysts remain relatively low. Therefore, future research should focus on: ①Developing new efficient homogeneous catalyst and corresponding continuous reaction process to reduce the dosage of catalyst; ②Developing high-performance heterogeneous catalysts with improved activity and selectivity.

Halogenated organic compounds (HOCs) are a class of primary pollutants. Because of their high persistence, toxicity, bioaccumulation and strong resistance to natural degradations, HOCs have aroused great concerns. Reductive dehalogenation is an effective, low-cost and feasible approach for the degradation of HOCs. Vitamin B₁₂ (VB₁₂) is a biological cofactor that can efficiently catalyze the reductive dehalogenation reaction of HOCs. In this review, we summarized the synergistic systems of mono-metal, bimetallic materials, metal mineral compounds, and semiconductor materials in combination with VB₁₂ for the catalytic reductive degradation of HOCs. The synergistic catalytic mechanism, HOCs degradation mechanism and their practical applications are discussed. Results indicated that the synergistic system of metal material and VB₁₂ has unique advantages on catalyzing the reductive dehalogenation of HOCs such as accelerating electron transfer, mediating surface catalysis and activation carbon-halogen bond, and therefore is promising for future application. Finally, based on the latest researches, challenges and future research directions were proposed including mechanism investigation, material design, practical application, and technology development.

In recent years, developing and utilizing catalysts with wide spectral response, high adsorption capacity and strong catalytic activity for photocatalytic removal of gaseous pollutants was widely concerned. In this work, the preparation and modification of perovskite-type photocatalysts were elaborated in detail, and then the research status, reaction mechanism and future research directions of perovskite-type photocatalysts for removing typical atmospheric emissions were summarized and reviewed systematically. The perovskite-type photocatalyst prepared by citric acid complexation method has the characteristics of small particle size and high photocatalytic activity, hereafter its visible light response ability can be further improved by ion doping or composite modification. The catalysts show high photocatalytic activity in the removal of NO, Hg⁰ and VOCs from flue gas, and the feasibility of synergistic catalytic oxidation of Hg⁰ and NO has been theoretically demonstrated. Furthermore, the perovskite-type photocatalyst derived from titanium-bearing blast furnace slag has a good application prospect in the purification of gaseous pollutants. However, the application of perovskite-type photocatalyst in simultaneous removal of multiple gaseous pollutants and the enrichment of perovskite-type components from titanium-bearing blast furnace slag need to be further studied, so as to provide a reference for the optimal preparation of perovskite-type photocatalyst and the improvement of its photocatalytic removal efficiency of gaseous pollutants.

Advanced oxidation technology using peroxymonosulfate driven by solid-phase cobalt-based catalysts has received extensive attention from researchers in recent years due to its high catalytic activity and easy separation from water. This article reviewed the research progress of the solid-phase cobalt-based catalysts for peroxymonosulfate activation in recent years, and summarized the types of the cobalt-based catalysts and their modification methods. The applications of advanced oxidation technology with cobalt-based persulfate in the reduction of refractory organic pollutants were introduced, and the effects of various water quality environmental factors on the reduction efficiency were analyzed. Further, the oxidation mechanism of the cobalt-based catalyst activated peroxymonosulfate was explained. Finally, the future development of solid-phase cobalt-based catalysts is expected to move towards large-scale, low leakage, high circulation, low energy consumption, having magnetic effects, or integration with membrane reactors.

Pd_xS_y is regarded as a undesirable product of metal palladium poisoning by sulfur-containing compounds, and hence has not received much attentions for many years. But in recent years, Pd_xS_ymaterial has been found to exhibit unique catalytic performance in catalytic hydrogenation, catalytic oxidation, electrocatalysis and visible light catalytic hydrogen production. In this paper, the traditional preparation method of Pd_xS_y material and the new green synthesis technology are compared. The research work of Pd_xS_y as catalyst in catalytic hydrogenation, catalytic oxidation, electrocatalysis and visible light catalysis for hydrogen production is also reviewed. It is found that traditional preparation method of Pd_xS_y material has the drawbacks of high toxicity, serious pollution, long cycle, etc., which has greatly limited its development prospect, so more in-depth innovative researches on the preparation method are required. At the same time, the excellent performance of Pd_xS_y material in many catalytic applications, especially in visible light photocatalytic hydrogen production, makes it a very promising catalytic material.

USY zeolites with similar framework SiO₂/Al₂O₃ ratio and increased mesopore volume were prepared, with which globular catalysts were prepared by spray drying. Catalytic cracking of Jatropha curcas L. seed oil (JCO) and soybean oil were performed in a constrained fluidized bed reactor. The results of JCO evaluation showed that the gasoline/diesel yields increased as the increased catalyst’s mesopore volume. The higher the yield of olefins and lower yield of aromatics in gasoline gave rise to lower octane number and the anti-explosion index. As for the product distribution of USY catalyst with mesopore volume of 0.142cm³/g, which was prepared by ammonium exchange and hydrothermal modification, the maximum yield of gasoline/diesel was 62.21% (mass fraction), the yield of coke was lowest, and the research octane number (RON) of gasoline was up to 90.5. The catalytic cracking of soybean oil gave the same reaction trend as that of JCO, and the RON of gasoline was up to 92.2 using the catalyst with moderate mesopore volume. The results showed that the catalytic cracking process, with appropriate mesoporous USY zeolite catalyst, can high-efficiently produce light vehicle fuel and high-octane gasoline from vegetable oil.

Fischer-Tropsch synthesis (FTS) is crucial for the conversion of natural gas, coal and biomass to clean fuels and value-added chemicals. Traditionally, the iron catalysts for FTS are mainly supported on alumina and silica. However, the interaction between metal and support hindered the formation of active phase iron carbide, resulting in low activity of the catalyst. In this study, Fe/Al₂O₃ catalyst was prepared by EDTA complex impregnation and the dispersion of iron species on alumina support was improved by coulomb interaction between positively charged hydroxyl (OH₂⁺) and [Fe(EDTA)]^- complex anion. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), specific surface area (BET), in situ infrared (in-situ IR) and other means were used. The results showed that the addition of EDTA could enhance the sintering resistance of Fe. In the calcining process, EDTA can be decomposed into small organic molecules, which can reduce the iron species in the catalyst to Fe²⁺ and thus is conducive to the reduction of the catalyst. Besides, more active centers enhanced the CO adsorption capacity of the catalyst. In-situ IR experiments showed that the catalyst prepared with EDTA enriched the active species easier, which improved the conversion of CO. The product distribution in hydrocarbons was improved by adjusting the content of alkali metal sodium in the system. The Fe-Na/Al₂O₃ catalyst prepared by EDTA complexation showed high CO conversion (88.5%) and high selectivity of C₂~C{}_{\mathrm{4}}^{=} and C₅~C₁₁ (total of 71.2%) at a low hydrogen carbon ratio (H₂/CO=1/1).

Soot particles released from diesel exhaust are one of the main sources of urban smog, which seriously pollute the environment and endanger human health. Therefore, it is of great significance to reduce and eliminate soot particles. In this paper, a series of manganese oxide catalysts were successfully prepared by self-propagating combustion technique using potassium permanganate acid and citric acid monohydrate as raw materials. The catalysts were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), N₂ adsorption-desorption measurements, H₂ temperature-programmed reduction (H₂-TPR), O₂ temperature-programmed oxidation (O₂-TPD) and X-ray photoelectron spectroscopy (XPS). The catalytic performance of the as-prepared catalysts for soot combustion was also investigated. The results showed that all the as-prepared manganese oxide catalysts had good catalytic activity for soot combustion. When the mole ratio of potassium permanganate and citric acid was 12∶1 and the calcination temperature was 450℃, the obtained catalyst had the lowest reduction peak temperature, the largest specific surface area and pore diameter and chemisorbed oxygen and Mn⁴⁺ content. Thus, it exhibited the best catalytic performance for soot combustion and its T₁₀, T₅₀ and T₉₀ temperatures were 284℃, 327℃ and 360℃ respectively for soot combustion.

The overuse of plastic products has caused serious environmental problems. It is of great importance to recycle waste plastics and convert them into high value-added materials, which can reduce pollution and save energy effectively. In this review, firstly, the application of supercapacitors and the current state of plastic recycling were stated, and waste plastic treatment methods, the energy storage characteristics of supercapacitors and the potential value of using waste plastics to prepare carbon materials for supercapacitors were introduced. Then, the preparation methods of porous carbon electrode materials were presented, and the specific requirements of the methods and their advantages and disadvantages were briefly analyzed. Next, some kinds of common plastics were introduced according to the type of plastics, and the research status of these common plastics used as carbon materials for supercapacitor was summarized. Recycling and converting waste plastics into activated carbon materials for supercapacitors was a new type of waste plastic recycling and reuse mothed, which can solve the problem of white pollution effectively.

Carbide-derived carbon (CDC) is the product by removing the non-carbon elements from the carbide. It can be synthesized by various methods, such as halogen etching, supercritical hydrothermal process, acid immersion, calcium carbide reaction, high temperature pyrolysis, high temperature molten salt electrochemical etching and so forth, among which the chlorine etching method is the most effective. Due to the advantages of lightweight, high porosity, adjustable pore size, high specific surface area, diverse carbon forms and good biocompatibility, CDC can be used in electrochemical energy storage (such as supercapacitors, lithium-ion batteries and fuel cells), adsorption, biomedical and tribology fields. Many synthesis parameters will affect the pore structure of CDC, such as the type of precursor, reaction temperature, reaction atmosphere, reaction time, etching method and activation method. By choosing different synthesis parameters, CDC can be accurately prepared to meet the needs of different application scenarios. In this article, advances in synthesis methods and applications of CDC were reviewed. The advantages and disadvantages of CDC in practical use were analyzed. The possibility of the commercialization of CDC in the future and five requirements that should be addressed were prospected.

Layered double hydroxides (LDHs), as functional materials with unique structures and excellent performance, have shown great application potential to be adsorbents, catalysts and separation materials due to the advantages including the easy exchange of interlayer anions in the surrounding environment, the high controllability between the layers and the abundant active sites in the overall structure. In this paper, the structural characteristics of LDHs were systematically presented, the synthesis methods of LDHs and its composites were described, and the effects of different synthesis conditions on LDHs performance were summarized from the presence of anions, metal molar ratio, reaction temperature and reaction time. The research advance of using LDHS and its composite materials in treating antibiotics in water was reviewed. The relationship between the performance of LDHS materials and the mechanism of removing antibiotics was comprehensively analyzed. The mechanisms of removing antibiotics with adsorption, catalysis and membrane separation were emphatically introduced. Finally, the existing problems in previous research were pointed out, and the future research prospect of developing new LDHs to remove antibiotics from water bodies was discussed including exploring the true structure and rules of the construction process of LDHs and constructing a new type of LDHs capable of removing multiple antibiotic pollutants which would be the main direction of future research in this field.

Polyimide aerogel has the advantages of high specific surface area, low density, low thermal conductivity, etc., but it has problems such as easy moisture absorption, large shrinkage, the use of a large number of organic solvents in the preparation process and the use of expensive chemical crosslinking agents. This article mainly introduced the current preparation methods, properties and applications of polyimide aerogels, focusing on the dianhydride and diamine condensation reaction method, isocyanate method and ring-opening metathesis polymerization method. The preparation principles of several methods were briefly described, and the research progress of polyimide aerogel in the fields of heat insulation, radiation resistance, oil-water separation, filtration and other fields was also summarized. Finally, the preparation method and practical application of polyimide aerogel were summarized and evaluated. It was proposed that in the future research work, it should be focused on solving hygroscopic and shrinkage, and exploring other types of crosslinking agents. In addition, based on the current development trend of polyimide aerogels and their composite materials, the new existing forms and new application fields of polyimide aerogels were prospected in the future.

Hydrated salt phase change materials have become popular materials in the field of heat storage due to their high energy storage rate and ideal phase change temperature. They have broad prospects in the fields of building energy saving, solar energy application, cold chain transportation, clothing textile and aerospace. Disodium hydrogen phosphate dodecahydrate (DHPD) is a typical inorganic hydrated salt phase change material, which has the advantages of moderate phase change temperature (about 35℃), high latent heat value (about 256.6J/g) and low price. However, similar to most hydrated salts, the problems of supercooling and phase separation limit their practical application. In this regard, the research on disodium hydrogen phosphate dodecahydrate mainly focuses on the improvement of the problem by nucleating agent and thickening agent. In recent years, some scholars have begun to study the composite system of the hydrated salt and other materials. This paper reviewed the improvement of the thermal properties of the hydrated salt by various nucleating agents and thickeners, and the research progress and application of composite systems with other hydrated salts, organic fatty acids and minerals.The analysis showed that the properties of these composite materials were more comprehensive and superior than those of single hydrated salt. Further research would focus on finding new materials to promote the richness of the composite system to improve its performance and application.

Silica aerogel has shown great application prospects in the fields of adsorption separation and thermal insulation due to their low density, high specific surface area and stable physical and chemical properties. However, the extended application is limited by the time-consuming and high-cost preparation process, especially the drying process of wet gel to aerogel transforms. This paper introduced the main difficulties and solutions of silica aerogels prepared at ambient pressure drying. Although The method of ambient pressure drying had become a research hotspot in recent years because of its simple process, safe process, low equipment requirements and continuous preparation, there were also some disadvantages for ambient pressure drying method such as long preparation time, large volume shrinkage and large consumption of organic solvents and modifiers. From the following two aspects: enhancement and optimization of gel matrix, reduction of capillary force and reduction of irreversible shrinkage, the improvement methods and development status of ambient pressure drying of silica aerogels were introduced. The advantages and disadvantages of different improvement methods were analyzed and the technical challenges of ambient pressure drying of silica aerogel at present were summarized. In addition, based on the current development trend of matrix enhancement and surface modification technology of silica aerogels, the future development route of ambient pressure drying of silica aerogels, such as controllable structure, low cost and multifunctional products, was proposed.

In order to solve the problems of filtration difficulty of the magnesium hydroxide slurry in the preparation of magnesium hydroxide flame retardant,diatomite supported hydrophobic magnesium hydroxide was prepared by positive precipitation method with MgCl₂·6H₂O and NaOH as raw material and adding diatomite and oleic acid as a surface modifier in the preparation process. The influence of diatomite amount on the filtration property of magnesium hydroxide slurry was discussed by means of filtration property test. Simultaneously, the products were characterized by Automatic specific surface and aperture analyzer (BET), Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetry-differential scanningcalorimetry (STA). The results of filtration property test and BET showed that the filtration rate of magnesium hydroxide slurry was increased evidently after adding diatomite. When the mass ratio of diatomite to magnesium hydroxide was 0.10∶1, the pore volume of diatomite supported hydrophobic magnesium hydroxide was the biggest, and the filtration rate of magnesium hydroxide slurry was increased 61.9%. The result of FESEM indicated that the surface of diatomite was loaded with flake magnesium hydroxide with good dispersion. The result of FTIR showed that OA bonded to the surface of magnesium hydroxide and diatomite with excellent hydrophobic properties. The result of TG found that diatomite had a synergistic flame retardant effect on magnesium hydroxide. Adding a small amount of diatomite can improve the thermal stability of magnesium hydroxide, increase the residual weight ratio, reduce the heat release rate and increase the thermal decomposition time.

Heavy metal ions and organic solvents are common pollutants in water. It is important to develop multifunctional composites to simultaneously remove heavy metal ions and separate organic solvents from water. In this study, a hydrophobic composite (PDMS/PCN-222@NWF) was successfully prepared via surface modification of PDMS and in situ growth of the mercapto functionalized Zr-MOFs (PCN-222) on the surface of the polyester non-woven fabric (NWF). The as-prepared composite had a water contact angle (WCA) of 141.7°, which was probably attributed to both the rough surface derived from in situ growth of PCN-222 crystals and the low surface energy due to coating of hydrophobic PDMS. The PDMS/PCN-222@NWF composite can effectively separate oil-water mixture with a maximum separation efficiency about 98.6%, and the separation efficiency can still reach above 94% after 5 cycles of reuse. In addition, the PDMS/PCN-222@NWF composite can also selectively remove Hg²⁺ ions from water with a maximum adsorption capacity of 294.4mg/g due to the coating of mercapto functionalized PCN-222 crystals on the surface of non-woven fabric.

Blue TiO₂ is considered one of the most promising anodes for degradation of organic pollutants due to the excellent electro-catalytic activity. The electro-catalytic activity is subject to morphological structure and interfacial properties of blue TiO₂. The hierarchically nanostructured blue TiO₂ was prepared by anodization in ice-water bath and cathodic reduction, and the corresponding electrochemical oxidation performance was studied. The top of blue TiO₂ was covered with nanoparticles, followed by a porous layer, and nanotube arrays in sequence. The blue TiO₂ prepared with an ice-water bath possessed more Ti³⁺, electrochemical activity surface and better electron transmission ability compared to that without ice-water bath assisting. The methylene blue was 97.68% removed within 120min under the current intensity of 20mA/cm² and the COD of practical wastewater was completely removed within 180min. The free radical quenching results revealed that adding Na₂SO₄ can promote production of hydroxyl radicals and sulfate radicals on blue TiO₂, while the electrochemical degradation performance of blue TiO₂ mainly relied on hydroxyl radicals. Sulfate radicals could contribute a great deal only under the high concentration of Na₂SO₄, low current density and high initial pH. The blue TiO₂ showed a high service life of 990min, 2.4 times as high as that prepared without an ice-water bath, indicating that this special nanostructure was beneficial to improve the stability of blue TiO₂.

For the aging problem of silicon gel hardening and brittleness in the process used, the silicon gel elastomer was prepared by using vinyl silicone oil as the base adhesive, hydrogen silicone oil as the crosslinking agent and alumina as the filler. By thermo-gravimetric analysis and isothermal weight loss in muffle furnace, the thermal oxygen aging mode of silicon gel and the antithermal oxygen aging property of cerium oxide were determined. The surface modification of cerium oxide with three different types of coupling agents was carried out, and the influence of coupling agent modified cerium oxide on the thermal oxygen aging property of silicon gel was investigated. The results showed that adding cerium oxide modified coupling agent can significantly improve the heat performance of silica gel. After aging at 250℃ for 8 days, the tensile strength of silicon gel with 1%(mass fraction) nano cerium oxide increased by 7.8 times compared with that before aging. Meanwhile, the tensile strength of silicon gel adding 1%(mass fraction) of cerium oxide modified with KH560, 6121 and 7707 of coupling agent enhanced by 2.5 times, 4 times and 4.7 times, respectively. In the early aging stage, the mechanical properties of silicon gel adding cerium oxide modified with KH560 coupling agent had the least change with the best thermal oxygen aging resistance.

Magnetic adsorbents were synthesized to remove the ferrous ion form oilfield. The hydrophilic Fe₃O₄ nanoparticles were prepared by solvothermal method and Fe₃O₄@PDA was obtained by coating with dopamine hydrochloride. Glycidyl methacrylate was also grafted onto Fe₃O₄@PDA to obtain Fe₃O₄@PGMA. Fe₃O₄@PGMA-Arg was obtained by modifying Fe₃O₄@PGMA with arginine. Infrared spectrometer, X-ray photoelectron spectrometer, X-ray diffractometer and vibrating sample magnetometer were used to characterize these adsorbents. Fe₃O₄@PGMA-Arg had primary amine, imine double bond, hydroxyl and carboxyl functional groups. The N on the primary amine group and imine double bond could form coordination bonds with Fe(Ⅱ), and the O on the hydroxyl and carboxyl groups could also form coordination bond with Fe(Ⅱ), which made Fe₃O₄@PGMA-Arg could adsorb Fe(Ⅱ). These synthesized adsorbents maintained the inverse spinel structure of Fe₃O₄ and the magnetic response properties were good. The static adsorption experiment was carried out to explore the influencing factors of adsorption conditions on Fe(Ⅱ) adsorption by Fe₃O₄@PGMA-Arg. The results indicated that the adsorption capacity of Fe(Ⅱ) increased with the increase of temperature and initial concentration, and the suitable pH was 4. Kinetic and thermodynamic studies showed that the process of Fe(Ⅱ) adsorption conformed to the quasi-second-order reaction kinetic model. The adsorption isotherms conformed to the Langmuir model. The activation energy was 45.60kJ/mol, which was chemical adsorption. Fe₃O₄@PGMA-Arg maintained a high removal rate of ferrous ions after 5 times regeneration.

Expanded graphite/paraffin composite phase change materials were prepared by blending method using expanded graphite and paraffin. The effects of EG content and voltage on the volume resistivity of EG/paraffin composites were investigated. The electrothermal properties of EG/paraffin composites unit were also studied under direct heating and positive temperature coefficient (PTC) resistance heating. The results showed that volume resistivity of composite decreased with the increase of EG content and voltage. The effect of voltage on the volume resistivity of composite was related to EG content and the higher EG content was, the more obvious the effect was. The volume resistivity of 4%, 5% and 8% EG/paraffin composites at 4.0V voltage was 0.481 times, 0.185 times and 0.068 times of that at 0.5V voltage, respectively. Both direct load voltage and PTC resistance heating can realize electrothermal conversion and heat storage. The heating power of the composite unit can be controlled flexibly by combining PTC resistance heating, which can realize rapid heat charging.

Lead pollution in water causes great harm to environment and human health. In this paper, TEMPO-oxidized cellulose nanofibers (TOCNF) were cross-linked with magnetic carboxymethyl chitosan nanoparticles (MCCN) to prepare an economically efficient and environmentally friendly material to adsorb Pb²⁺. The structure of TOCNF/MCCN and TOCNF were characterized. The effects of pH, initial concentration of Pb²⁺, contact time and temperature on the adsorption efficiency of Pb²⁺ were studied by single factor experiments. The adsorption effects of TOCNF/MCCN and TOCNF on Pb²⁺ were compared under the optimum reaction conditions. The results showed that Fe₃O₄ was successfully coated by carboxymethyl chitosan nanoparticles and cross-linked with TOCNF. The optimum reaction condition for Pb²⁺ adsorption was obtained at room temperature when the pH was 5, initial concentration of Pb²⁺ was 100mg/L, and contact time was 240min. The absorption saturation capacity of TOCNF/MCCN was 193.5mg/g, which was nearly double that of TOCNF. Moreover, the adsorption process followed the pseudo-second-order model, which indicated that the adsorption rate was mainly determined by chemical adsorption. The correlation coefficient showed that the adsorption equilibrium data fitted well with Langmuir isotherm model, indicating that the adsorption of Pb²⁺ by TOCNF/MCCN was mainly the monolayer adsorption of surface groups. The theoretical saturated adsorption amount calculated by the slope of the linear equation was 201.1mg/g, which was 3.8% different from the actual value. After 5 times of desorption and re-adsorption, the adsorption efficiency of the adsorbent only decreased by 13%, which indicated that the adsorbent had good reproducibility and had a good application prospect.

The feasibility of breaking the trade-off between the heat exchange ratio and waste gas barrier property of polyvinyl alcohol (PVA) based total heat exchange membranes were investigated using montmorillonite (MMT) and CaCl₂ as co-additives. The morphology, water contact angle, thermal stability, mechanical properties, gas transmission permeability and total heat exchange efficiency of the ternary hybrid matrix membranes developed from solution-cast method were investigated at varied content of CaCl₂ and MMT. It was observed that addition of suitable amount of CaCl₂ hybrid can be introduced into the water conduction channel to improve the water vapor permeability and enthalpy exchange efficiency of the membrane. The addition of suitable amount of MMT could improve not only CO₂ gas barrier property, but also surface roughness, thermal stability and mechanical properties of the THEM. However, excess MMT or CaCl₂ content had both shown negative effects. Considering the requirements of low CO₂ gas transmission permeability, good water vapor and heat exchange efficiency and mechanical properties, the hybrid matrix membranes with the mass ratio of PVA∶CaCl₂∶MMT of 8∶1.6∶0.8 was most likely to be used as total heat exchange membranes with improved performance in energy-saving ventilation systems.

The sodium sulphate decahydrate has limited use in solar greenhouses due to problems such as supercooling, phase separation, high temperature of the phase transition and liquid phase leakage. In this paper, Na₂HPO₄·12H₂O was added to improve supercooling, potassium chloride to reduce the phase transition temperature, and resin as a matrix to resolve phase separation and liquid phase leakage. The mass fraction of Na₂SO₄·10H₂O+80%Na₂HPO₄·12H₂O+6%KCl+6% resin was tested for temperature rise and fall, DSC and cycle stability. Because of adding 80% Na₂HPO₄·12H₂O, the degree of supercooling and the latent heat of phase change were 1.35℃ and 268.7J/g, respectively. With adding 6% KCl, the temperature of phase change can reach 23.89℃ and latent heat was 183.25J/g. Finally, adding 6% resin can suppress phase separation and liquid phase leakage of phase change materials. Its crystallization temperature, the temperature of phase change, subcooling degree and phase transition latent heat were 11.56℃, 22.61℃, 1.41℃ and 143.6J/g, respectively. The composite molding phase change material was no liquid phase leakage with heating to 50℃. The latent heat of the cycle after 100 was 127.8J/g, which was 11.2% lower than one cycle. The obtained composite molded phase change material had advantages such as a large latent heat value, the appropriate temperature of phase transition and good thermal stability, and can be applied to the field of solar greenhouses.

The abuse of opioids is becoming more and more serious. The abuse deterrent formulations are limited to the existing technologies, but there are few reports on the development of new materials at present. Therefore, a novel PVA-g-mPEG graft polymer with anti-abuse performance was prepared by grafting modification through molecular design. Polyvinyl alcohol/mono-methoxypolyethylene glycol graft polymer (PVA-g-mPEG) was prepared with polyvinyl alcohol (PVA), mono-methoxypolyethylene glycol (mPEG) and epichlorohydrin (ECH) by a two-step reaction method. The effect of reaction temperature on the grafting rate was studied. The graft polymer was characterized by FTIR, ¹H NMR, DSC and XRD. In addition, using metformin hydrochloride as model drug, the graft polymer matrix tablets were prepared, and the anti-abuse performance of the materials was investigated. The results showed that with the increase of grafting ratio (43.44%, 81.23%, 120.48%), 28.3%, 20.8% and 12.9% of drugs were extracted from water in 20min, respectively, which indicates that the graft polymer had a certain anti-abuse effect and good guiding effect on the development of new anti-abuse pharmaceutic adjuvant materials.

Succinic acid is a four-carbon dicarboxylic acid, which is widely used in food, medicine, plastics and chemical industries. Microbial production of succinic acid has problems such as low yield, low productivity and by-products accumulation. In this study, through compound mutagenesis (ARTP and ⁶⁰Co-γ), a high osmotic pressure-tolerant mutant strain FMME-N-2 was screened, with a succinic acid yield of 0.70g/g_glucose and an accumulation of 18.8g/L lactic acid, 7.6g/L formic acid and 17.3g/L acetic acid. To decrease the accumulation of by-products and further increase succinic acid yields, the strain FMME-N-13 with a yield of 0.92g/g_glucose was constructed by deleting the genesof ldhA, pflB-focA, pta, tdcD, and tdcE, accumulating 0.6g/L lactic acid, 3.6g/L formic acid and 12.3g/L acetic acid. At the same time, the control of RBS intensity combined with optimizing the level of AsPCK (Actinobacillus succinogenes phosphoenolpyruvate carboxykinase) and CbFDH (Candida boidinii formate dehydrogenase) was used to regulate the concentration of intracellular ATP and NADH, and the succinic acid yield of engineering strain FMME-N-26 (FMME-N-13-L-AsPCK-L-CbFDH) increased to 1.04g/g glucose only with an accumulation of 5.5g/L acetic acid. Finally, the glucose concentration of the anaerobic stage was optimized. When the glucose concentration was controlled at 0—5g/L, succinic acid titer of the strain FMME-N-26 was increased to 111.9g/L, with a yield of 1.11g/g glucose (99% of the theoretical yield) and a productivity of 1.76g/L/h, showing great potential for industrial production.

Water pollution and energy crisis are becoming increasingly severe, derived from rapid global industrialization. As a new type of bioelectrochemical process, microbial fuel cell (MFC) can generate electricity through degrading organic matter, which is endowed with attractive superiorities in terms of cleanliness, energy saving and economy. Therefore, many researchers have attached extensive attention on this hotspot. This article firstly introduces the working principle and electron transfer mechanism of MFC, as well as analyzes the key factors affecting its performance (i.e. anode material, cathode material, microbial inoculation, reactor configuration and system operating parameters). Secondly, the investigations of MFC in wastewater treatment in recent years are critically reviewed, especially domestic wastewater, agricultural wastewater and industrial wastewater. Then, the various coupling applications of MFC with other technologies are expatiated, including electro-Fenton, photocatalysis, constructed wetland system and microbial electrolytic cell. Finally, we point out the problems confronted by MFC at present, and propose feasible survey directions for its prospects with comprehensive consideration, especially, thorough investigation of mechanisms, optimization of inoculated microbial populations, improvement of materials and configurations, promotion of inflow modes and operating parameters, as well as development of new hybrid systems coupling with other technologies.

After the implementation of ultra-low emission transformation in coal-fired power plants in China, the trend of escaped ammonia exceeding the standard has become increasingly prominent. Excessive escaped ammonia has a negative impact on the normal operation of flue gas treatment facilities and the atmospheric environment. The control and emission of escaped ammonia have become one of the priorities of coal-fired power plants’ air pollution prevention and control work in the future. In this paper, the source of escaped ammonia in coal-fired power plants is analyzed, and the emission characteristics of escaped ammonia is summarized, including the emission concentration and main forms of fugitive ammonia in various environmental protection facilities. The migration and transformation of the escaped ammonia in the denitrification and downstream flue gas treatment facilities, and the factors that affect the efficiency of the flue gas treatment facilities for the capture of escaped ammonia are analyzed. Finally, based on the current research status of pollutant emission factors, the future research directions of escaped ammonia control in coal-fired power plants are prospected as follows: promoting the establishment and implementation of escaped ammonia inspection and emission standards for coal-fired power plants, optimizing process conditions to promote the synergistic removal of escaping ammonia by the existing flue gas treatment system, and tracking the ammonia re-release of ammonia-containing by-products such as fly ash, desulfurization wastewater and gypsum in the subsequent treatment process.

High salinity limits the efficient biochemical treatment of wastewater, and desalination treatment is imperative. The microbial desalination cell has attracted the attention of many scholars because of its high desalination efficiency and good economy. This article first reviews the mechanism of the microbial desalination tank, analyzes the influence of the ion exchange membrane, pH, electron donor, catholyte and electrode materials on the desalination efficiency of the desalination tank, and explains the further coupling process of the microbial desalination cell. It is considered that the future development trend of microbial desalination cell should focus on the modularization of electrodes, the optimization of ion exchange membranes, the development of coupling systems, and the practical application of processes.

To investigate the mechanism of nitrate removal from water by the combined action of nano zero-valent iron (nZVI)/BC and (Cu-Pd)/BC, nZVI/BC and (Cu-Pd)/BC composites were produced by loading nano-metals on wheat straw biochar, and the materials were characterized by SEM, TEM, EDS, and XRD. The results showed that the nano-zero valent iron was well dispersed on the biochar (BC) and the nano-Cu-Pd was effectively loaded on the BC with uniform distribution. The nitrate removal rate of nZVI/BC: (Cu-Pd)/BC systems could reach 100% and the nitrogen conversion rate reached 42%. The best nitrate removal was achieved at pH 4.05; nitrate removal decreased with increasing initial concentration; the presence of dissolved oxygen reduced the nitrate removal; the presence of PO{}_{\mathrm{4}}^{\mathrm{3}-} had the greatest effect on the removal efficiency and reduced the removal rate to 15.8%, while the presence of CO{}_{\mathrm{3}}^{\mathrm{2}-} and SO{}_{\mathrm{4}}^{\mathrm{2}-} had little effect on nitrogen removal and the removal rate was close to 100%. Kinetic studies showed that the removal of NO{}_{\mathrm{3}}^{-}-N and NO{}_{\mathrm{2}}^{-}-N by the combined action of nZVI/BC and (Cu-Pd)/BC under optimal conditions was in accordance with the quasi-secondary adsorption kinetic model, and the reaction process was dominated by the reduction reaction.

A sulfur autotrophic denitrification (SADN) coupled anaerobic ammonium oxidation (ANAMMOX) autotrophic denitrification system was successfully developed by adding ANAMMOX sludge to an SADN reactor with sodium thiosulfate as electron donor. The nitrogen removal performance of the coupled system during start-up and stable operation was investigated. The coupled system achieved high efficiency and stable operation at (36±1)℃ and a total nitrogen loading rate of 0.8kg/(m³·d), with a maximum total nitrogen removal efficiency of 94.6%, which was higher than the maximum ANAMMOX theoretical total nitrogen removal efficiency of 89%. The influence of S/N (ratio of influent S₂O{}_{\mathrm{3}}^{\mathrm{2}-}-S to NO{}_{\mathrm{3}}^{-}-N) on the nitrogen removal was investigated, and the optimal operating parameters were determined. Among them, the coupled system could maintain the best nitrogen removal efficiency when the influent S/N was in the range of 1.6—2.2. The contribution of ANAMMOX and SADN pathways to nitrogen removal was stable at about 96.2% and 3.8%, respectively, and ANAMMOX dominated the coupled system. The sludge activity after long-term operation was tested by batch experiments, and the results showed that both SADN and ANAMMOX bacteria were able to maintain high activity, and the two were synergistic cooperation with complementary substrates in the coupled system.

The adsorption isotherms of municipal sludge at 30℃, 40℃, and 50℃ were determined by static gravimetric method. Eleven common mathematical models were selected to fit the experimental data, and the best model was analyzed. The thermodynamic properties of sludge were evaluated by net isosteric adsorption heat, differential entropy, diffusion pressure, net integral enthalpy and net integral entropy. The results showed that the isothermal curve belongs to type Ⅱ at constant temperature, the GAB model fitted well the isotherms data of sludge and was considered as the best model for predicting equilibrium moisture changes with water activity.Additionally, sorption isotherms data were used to determine the thermodynamic properties such as isosteric sorption heat, sorption entropy, spreading pressure, net integral enthalpy and entropy. Net isosteric heat of sorption and differential entropy were evaluated through direct use of moisture isotherms by applying the Clausius-Clapeyron equation and used to investigate the enthalpy-entropy compensation theory. The net isosteric adsorption heat and differential entropy decrease obviously with the increase of equilibrium water content. The harmonic mean temperature T_hm was not equal to the constant velocity temperature T_l, so the enthalpy-entropy compensation theory was established. The spreading pressure increased with the increase of water activity at a given temperature, and decreased with the increase of temperature at a given water activity. The net integral enthalpy decreased as the equilibrium moisture content increase. However, the net integral entropy decreased with the increase of equilibrium water content at low equilibrium water content, and reached the minimum values of -75.698J/(K?mol), -78.987 J/(K?mol) and -82.687 J/(K?mol) at 30℃, 40℃ and 50℃, respectively, and then increased.

The release of carbon source from ozonation sludge under the catalysis of activated carbon, activated coke and Mn²⁺ at different concentrations was studied, and it was found that Mn²⁺ was an appropriate one. The effects of different dosage of Mn²⁺ on organic matter release and the differences in sludge characteristics before and after reaction were compared, and the mechanism of catalytic ozonation of Mn²⁺ to promote cellular dissolution was further explored. Results showed that the carbon source solubilization and biodegradability was significantly improved by adding a certain amount of Mn²⁺, and 1.5mmol/L of Mn²⁺ addition was the optimal dosage with the concentration of ΔSCOD of 76mg/L which was about 4 times higher than traditional one (O₃ group). The contents of soluble protein and humus of extracellular polymer in sludge floc were significantly increased compared with that of blank group and O₃ group, which were 2 times and 2.3 times, respectively. It was confirmed that Mn²⁺ catalyzed oxidation promoted the dissolution of intracellular organic matter in activated sludge. Based on further mechanism exploration, it was concluded that Mn²⁺ catalytic oxidation promoted the generation of active free radical especially for ·OH during the reaction, and the yield of ·OH was 1.15—1.74 times that of the O₃ group. Mn²⁺ catalytic ozonation activated sludge can enhance cell lysis with little effect physicochemical properties of it and basically maintains the same level as O₃ group. It has great feasibility and practical significance to apply it to the continuous process of in-situ sludge ozone-reduction system.

In order to explore the feasibility of hydrolysate liquid from the excess sludge by alkyl polyglucose (APG) combined with free nitrous acid (FNA) pretreatment for synthesizing polyhydroxyalkanoate (PHA), two sequencing batch reactors (SBR) with different inoculums were used to enrich PHA-producing mixed cultures. The synthesis of PHA by mixed microorganisms with simulated hydrolysate liquid from the excess sludge by APG combined with FNA pretreatment as substrate was studied. The influence of pH, C/N and C/P on the synthesis of PHA was investigated with batch synthesis experiments. The results showed that: compared with SBR^#1 inoculated with the sludge of the second settling tank, SBR^#2 with the inoculated sludge from a long-running PHA enrichment using glucose as substrate could gain higher PHA yield at 30 days; at 117 days, SBR^#1 with the inoculated sludge from the secondary settling tank had better performance. The optimal parameters for PHA synthesis were pH of 8, C/P of 100∶0.03, and C/N of 125∶1. Under this condition, the maximal PHA content was achieved, which was 57.34%. The cumulative PHA yield was 24.43% with actual hydrolysate liquid from the excess sludge by APG combined with FNA pretreatment as substrate. This research provides technical support for the recycling of sludge.

The CO₂ absorption and desorption performances of nine alcohol amines were compared. Among them, there were two kinds of solutions that showed the better stability of absorption-desorption performance, which contained N-ethylethanolamine (EMEA)+diethylaminoethanol (DEEA)+piperazine (PZ) and 2-amino-2-methyl-1,3-propanediol (AMPD)+piperazine (PZ)+H₂O. The average desorption rate of the solvents were above 94.0% after two cyclic tests. The solutions were subjected to thermal degradation for 144h and oxidative degradation for 96h. It was found that the absorption-desorption performance of EMEA+DEEA+PZ solution after thermal degradation was stable. The average absorption amount and desorption amount of the solution increased slightly by 1.58L CO₂/kg solution and 0.35L CO₂/kg solution, respectively, and the average desorption rate decreased by 2.0%. While oxidative degradation caused the average absorption amount and desorption amount of the solution to decrease by 0.45L CO₂/kg solution and 1.75L CO₂/kg solution, respectively, and the average desorption rate decreased by 2.3%. The thermal degradation had a distinct impact on the absorption-desorption performance of AMPD+PZ+H₂O solution, which caused a decrease in the average absorption amount and desorption amount of the solution by 5.63L CO₂/kg solution and 4.03L CO₂/kg solution, respectively, and the average desorption rate increased by 2.3%. After oxidative degradation, the average absorption amount and desorption amount of the solution decreased by 1.05L CO₂/kg solution and 0.70L CO₂/kg solution, respectively, and the average desorption rate increased by 0.6%.The liquid mass spectrometry analysis showed that the concentrations of EMEA and AMPD decreased by 19.7% and 71.8% due to thermal degradation, 18.2% and 74.5% due to oxidative degradation, respectively. The thermal and oxidative degradation experiments demonstrated that EMEA+DEEA+PZ had the better anti-degradation performance than AMPD+PZ+H₂O. The mechanisms of thermal and oxidative degradation of the two kinds of alcohol amines were speculated based on the results of electrospray mass spectrometry, in which oxazolidinones were generated in thermal degradation and acids were generated in oxidative degradation. In both cases, oxidative degradation had negative effects on both solutions, while thermal degradation did not.

The formation of scale in the industrial circulating cooling water system has caused a series of problems such as decreased heat transfer efficiency and pipeline corrosion. In this study, an electrochemical-microfiltration coupling process was developed for water softening. In this reaction system, Ti/SnO₂-Sb-RuO₂-IrO₂ titanium filter membrane was used as the cathode for OH^- production by H₂O electrolysis and therefore created a basic environment at its surface, where CaCO₃ would become highly supersaturated. Meanwhile, this titanium filter membrane served as a microfiltration unit to effectively separate CaCO₃ particles. Polarity reversal strategy was applied in the membrane backwash phase. At this time the titanium filter membrane was used as the anode for in-situ generation of H⁺ by H₂O electrolysis, which could dissolve the scale attached to the membrane surface and in the membrane pores. The experimental results indicated that the smaller the membrane pore size was, the more calcium hardness was removed. Specifically, the calcium hardness removal efficiency could reach 79% when membrane pore diameter was 2μm. The calcium hardness removal efficiency increased from 28% to 86% with increasing current density from 1mA/cm² to 5mA/cm², and then it dropped to 78% with further increasing current density to 10mA/cm². In addition, increasing the alkalinity facilitated the removal of calcium hardness. The calcium hardness removal efficiency rose from 53% to 83% when elevating the [HCO₃^-]/[Ca²⁺] molar ratio from 0.7∶1 to 1.4∶1. In contrast, the calcium hardness removal efficiency reduced from 84% to 46% as the flow rate increased from 5mL/min to 20mL/min with the energy consumption decreasing from 3.06kWh/kgCaCO₃ to 1.38kWh/kgCaCO₃, which was much less than that in the conventional electrochemical waster softening system. It was found that the fouling was mostly due to the filter cake formation and internal pore blocking. And 78% membrane flux could be recovered after backwash with polarity reversal. The XRD and SEM analysis results showed that the crystal structure of CaCO₃ on titanium filter membrane surface was mainly calcite form. The electrochemical-microfiltration and backwash processes were driven by electron and thus avoided the consumption of detergents, which provided new strategy for water softening in the circulating cooling water.

Sodium percarbonate is the adduct of hydrogen peroxide and sodium carbonate, which is safe and stable during its storage, transportation and use. The method of co-precipitation followed by high-temperature calcination was used to prepare Mn₂O₃@α-Fe₃O₄ nanosheet, with which sodium percarbonate (SPC) was activated to generate free radicals to oxidize and degrade azo dye reactive black 5 (RBK5). The Mn₂O₃@α-Fe₃O₄ nanosheet was characterized by transmission electron microscope (TEM), X-ray powder diffractometer (XRD), scanning electron microscope (SEM), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS) and Brunauer Emmett Teller (BET). The effects of catalyst dosage, SPC concentration, initial pH and RBK5 solution concentration on the degradation efficiency were explored. Under the conditions of SPC dosage 1.0mmol/L, Mn₂O₃@α-Fe₃O₄ dosage 0.3g/L, initial pH=7, the degradation rate of RBK5 in aqueous solution reached 88％ in 90min. The reaction kinetics could be well described by the pseudo first order kinetics model (R²>0.9). ·OH, CO{}_{\mathrm{3}}^{-}·, O{}_{\mathrm{2}}^{-}· and ¹O₂ were the active species in the Mn₂O₃@α-Fe₃O₄/SPC system, and ·OH was the dominant species among them. XPS results reflected the valence states of iron and manganese elements and their synergistic effect. Quenching experiment and XPS were used to analyze the degradation mechanism.

Decomposition of NO with microwave plasma has a very high efficiency, but it is difficult to remove NO_x in the presence of oxygen. In order to solve this problem, a new denitration technology using microwave-induced plasma emission jet with the activated carbon and under aerobic condition was put forward. In a microwave tube furnace, the best denitration conditions were obtained by adjusting the diameter and amounts of activated carbon, and microwave power. Then the process mechanism was analyzed in-depth. The effects of initial concentrations of NO and O₂ on denitration by plasma jet were also studied. When nitrogen was used as carrier gas with a flow of 1L/min, the diameter of activated carbon was 2mm, the mass of activated carbon was 15g and the microwave power was 2kW, the plasma jet could be generated quickly and held for a long time. In the experiments with plasma jet, the denitration efficiency of jet plasma was higher than that of lightning plasma. NO was removed in the activated carbon bed zone and plasma jet zone successively. When the concentration of O₂ was less than 4%, the increase of O₂ concentration promoted the removal of NO. When the concentration of O₂ was greater than 4%, the free radicals (·O) and a large amount of CO₂ from excessive oxygen inhibited the removal of NO.

Electrolytic manganese residue (EMR) is the acid leaching slag of manganese ore produced in the production process of electrolytic manganese, which is rich in active components such as manganese and iron. In theory, the use of electrolytic manganese slag slurry for flue gas desulfurization realizes the resource utilization of electrolytic manganese slag while removing SO₂, which promotes the sustainable development of the electrolytic manganese industry. However, there is no research report on the desulphurization of EMR slurry. The influence of process conditions on the efficiency of desulfurization was studied. The experimental results showed that the bestprocess conditions for EMR slurry desulfurization were: EMR particle size was 200 meshes (<75μm), manganese slag slurry concentration was 5000mg/L, the mixed gas flow rate was 400mL/min, imported SO₂ concentration was 0.20%, and the temperature was 50℃. Under these conditions, the highest desulfurization rate at 180min was 93.87%. By analyzing the changes of ore pulp ion concentration and the XRD, SEM, XPS patterns of the products, the performance and mechanism of flue gas desulfurization of EMR slurry were investigated. MnO₂, MnO, Fe₂O₃ underwent redox reactions with SO₂ and formed metal sulfates. SO₂ was catalyzed and oxidized by transition metal ions such as Mn²⁺ and Fe³⁺ in the ore pulp to generated H₂SO₄.

Since 2007, with the thinking, exploration and accumulation, it is believed that the decarburization transformation of China’s iron and steel industry is still following the current law of steel development in the world from the BF-BOF process to EAF and direct reduction iron (DRI) process. For the low-carbon transition in China, the “stuck neck” problem is that there is no hydrogen resource for DRI production because the world’s DRI production normally uses natural gas as the hydrogen source, while it is not available in China with the current situation (abundant of coal, lack of oil and gas) . According to the practice of the past 15 years, the hydrogen energy which could be regarded as the source to support the low-carbon transformation in hydrogen metallurgy of China’s steel industry were as followed. In the short term, various types of gas could be used as a viable hydrogen source for the production of DRI in China. In the medium term, electricity would replace dry gas in refineries and electrical olefin. In the long term, the source would be achieved by water-electrolytic hydrogen from photovoltaic and wind power. Based on the above-mentioned China’s hydrogen source roadmap, the development of low-carbon with green hydrogen metallurgical technology was a top priority. The integration of the government, leading enterprises and universities in the triple-helix cooperation demonstration would facilitate the role of China’s institutional strengths of focusing on major events, thereby overcoming the bottleneck of low-carbon production in China’s iron and steel industry.

According to that CO₂ has the dual nature of “not only a greenhouse gas that needs to be reduced, but also an indispensable renewable resource for human survival”, the green emission reduction system is constructed for the first time which “prohibit the emission of polluting greenhouse factors,control net CO₂ emissions to zero,regulate CH₄ production and emission” under the constraint of carbon neutrality. At the national level, through the formulation of relevant emission reduction policy system and implementation of national super engineering and actions, the cornerstone and supporting system for the implementation of green carbon emission reduction will be formed to achieve “30·60 double carbon target” for our country. At micro technology level, through the CO₂ green emission reduction technology that controls carbon emissions throughout the whole process, high carbon emissions can be avoided at the source, carbon emissions can be controlled in the process, carbon cycle and capture utilization (3CU) can be enhanced at the end. Rely on green low carbon energy transformation, aiming at saving energy, reducing consumption and biological carbon sequestration, dredging and interception should be combination to meet the demand of natural balance of the carbon cycle. High-quality and low-carbon economic and social development, ecological civilization construction and climate change response to the triple win are achieved of low cost and high efficiency, which promote China to reach its peak by 2030 and achieve carbon neutrality by 2060.