As an important energy carrier, hydrogen energy boasts a green and pollution-free combustion process, which can help achieve carbon peak and carbon neutrality goals. This paper analyses the advantages and disadvantages of each hydrogen production method by comparing hydrogen production methods such as fossil energy hydrogen production, industrial by-product gas hydrogen production, and water electrolysis hydrogen production, and explains the significance of combining PEM water electrolysis hydrogen production with renewable energy. It then describes the internal structure of PEM electrolyzers and hydrogen production from renewable energy sources, and introduces research progress, main problems and future development trends of PEM electrolyzer bipolar plates, catalysts, diffusion layers, and proton exchange membranes in detail. By analyzing the distribution characteristics of solar energy and wind energy in China, and summarizing the existing problems in the utilization of renewable energy, the development of solar hydrogen production, wind power hydrogen production, and renewable energy multi-energy complementary hydrogen production is introduced from the perspective of research status and industrial development. Finally, the future development direction of renewable energy PEM water electrolysis hydrogen production is prospected, and it is expected to provide reference for the development of renewable energy PEM water electrolysis hydrogen production.

In this paper, through the droplet visualization experiment, the dynamic surface wetting characteristics of the freezing droplets on the surface of the aluminum plate at different substrate temperatures were summarized. Based on mechanical analysis, the article summarizes the changing laws of wetting parameters such as droplet wetting area, volume, contact angle and phase transition time. Experimental results showed that the wettability of droplets is mainly affected by gravity, surface tension and thermal capillary force. Gravity promoted the lateral spread of droplets. The surface tension and thermal capillary force were affected by the temperature of the bottom plate, and have the effect of inhibiting the diffusion process of the droplets. Under the two different conditions, the change of the height of the frozen droplets was the same. As the melting progresses, the height of the droplets dropped sharply and then slowly decreases. Under different freezing conditions, the infiltration of frozen droplets in the initial stage of melting was very obvious. At this stage, gravity promotes the wettability of the droplets, and the contact angle of the droplets was between 65° and 85°. In the later stage, the decrease of contact angle led to the weakening of gravity and the increase of surface tension, which hindered the spread of droplets and slows down the trend of volume reduction. Under different heating conditions, the droplets hardly undergo diffusion movement. Thermal capillary force and surface tension dominated the wetting process. As the substrate temperature increases, the temperature difference between the inside of the droplet and the three-phase line gradually increased, and the number of Ma increased from 1802 to 22876. The capillary force always restrained the movement of the droplet.

During the operation of the vacuum exhaust system of a wind tunnel, a large amount of mixed gas with water vapor are produced. In order to improve the exhaust efficiency and reduce energy consumption, the condensing tower process was introduced to cool and condense the mixed gas with water vapor by direct contact heat exchange and condensation. Based on the high mass transfer model of micro element tower, the direct contact heat transfer process between heat flow gas entering the condensation tower and cooling water was analyzed, and the mathematical equation expression of mass transfer coefficient was deduced. Combined with the experimental data, the effects of gas pressure and condensation cooling on the water vapor content of the discharged gas were investigated, and the mathematical expressions of gas pressure and water vapor content at a certain temperature were fitted. The effects of cooling water mass flux and gas-liquid ratio on mass transfer coefficient, volumetric heat transfer coefficient and outlet temperature were also investigated. On this basis, the mathematical relationship between gas-liquid ratio and volumetric heat transfer coefficient for direct contact heat transfer of wind tunnel airflow was fitted, and the optimal gas-liquid ratio was calculated. The rules obtained from the experiment can be a guiding role in the optimal design and application of direct contact heat transfer of wind tunnel airflow.

As an efficient heat dissipation device, microchannel heat sinks have been widely used to solve the problem of high heat flux dissipation in micro-electronic devices, photoelectricity, automotive, aerospace industries and energy field and so on. To solve the problems of small heat transfer area, low heat transfer performance and boiling hysteresis of traditional smooth microchannels, a porous wall microchannel structure was proposed in this paper, and laser direct writing method was used to prepare efficient and stable porous wall microchannels. The porous wall microchannel significantly increases the heat transfer area, promotes the disturbance of the fluid, and provides many stable boiling cores, thereby enhancing single-phase and two-phase heat transfer. By building a microchannel heat transfer performance test system, the single-phase and two-phase heat transfer performance of porous wall microchannels and smooth microchannels were tested and compared. Experimental results indicated that the Nu number of porous wall microchannel was increased by 21%—31% compared with the untreated rectangular microchannel. In two-phase boiling heat transfer, porous structure promoted the nucleation of boiling bubbles and reduced the onset temperature of nucleate boiling (ONB), which was 35% lower than that of the untreated rectangular microchannel. At the same time, porous structure could ensure continuous liquid supply during the boiling process, thereby greatly improving the boiling heat transfer performance and avoiding the occurrence of drying out in advance. The two-phase boiling heat transfer coefficient h_tp was up to 83% higher than that of the untreated rectangular microchannel. The two-phase heat transfer coefficient h_tp of porous wall microchannel structure at the mass flux of G=500kg/(m²·s) was increased by 30% compared with that at the mass flux of G=200kg/(m²·s).

In order to improve the heat storage rate of the latent thermal storage system in practical applications, an experimental platform for visualizing the thermal performance of the shell-and-tube latent thermal storage unit is established, an enhanced heat transfer method of the outside heating method is proposed, and the heat transfer mechanism of the outside heating method in the melting process is discussed. The differences between the outside heating method and the inside heating method in terms of liquid fraction and homogeneity are also analyzed by simulation comparison. The results show that the outside heating method has more uniform heat transfer in the melting process compared with the inside heating method. The outside heating method reduces the melting time by 69.1% due to the larger heat transfer area; after eliminating the effect of heat transfer surface, the outside heating method relies on extensive and strong natural convection to reduce the melting time by 23.2%.

In order to explore the motion characteristics of vapor-liquid interface in a T-shaped micro channel when steam direct contact condensation the visual images under the conditions of subcooled water temperature 33℃ and mass flow 6.325g/min and steam temperature 100℃ and mass flow 0.25g/min were obtained through high-speed camera (5000fps). On this basis, the instantaneous evolution characteristics of vapor-liquid phase interface were qualitatively analyzed. Afterwards, the motion law of the front end of phase interface was quantified by using image batch processing technology, including the instantaneous fluctuation characteristics of phase interface position and velocity. Results showed that the vapor-liquid interface in different condensation cycles exhibited great differences in the morphology when steam bubble was generated to the maximum and the collapse characteristics of steam bubble, which was mainly reflected in "local shrinkage" and "implosion". In addition, for a typical phase interface movement cycle, the time proportion of steam bubble disappearance stage was the smallest, about 12%. By analyzing the instantaneous position fluctuation curve at the front end of the phase boundary, it was found that the condensation frequency under this working condition was 23Hz, and the peak distribution of the curve had strong periodic oscillation characteristics. By analyzing the instantaneous velocity fluctuation curve at the front of phase boundary, it was found that the instantaneous transformation of velocity and violent multiple oscillations occur, and the maximum velocity peak reached 11m/s. Combined with the visual image, the interface evolution during phase interface velocity oscillation was further described in detail, and the mechanism of velocity oscillation caused by "local contraction" and "implosion" was revealed.

To study the effect of inert gases on the explosion limits and chemical kinetics of ethylene, a standard test device was employed to analyze effects of N₂ and CO₂ on the explosion limit, critical oxygen concentration, and explosion triangle of ethylene. The sensitivity was analyzed after the simulation on the gas explosion include the temperature, pressure, concentration of ·H, ·O, ·OH by CHEMKIN software.The results showed that both N₂ and CO₂ narrowed the ethylene explosion limit and reduced the explosion hazard, reaching the explosion critical point with 60.1% N₂ addition and 43.3% CO₂ addition, when the critical oxygen concentration for CO₂ inerting was 11.1% and for N₂ inerting was 7.7%. By analyzing the explosion triangle, the explosion zone and asphyxiation ratio of ethylene under CO₂ inerting were significantly reduced compared with those under N₂ inerting. In addition, both N₂ and CO₂ increased the ignition delay time of ethylene and decreased the temperature and pressure and radical concentration after the explosion, the sensitivity analysis of key radical changes during ethylene explosion under two inert conditions revealed that R38, R46, R112, R119, R285, and R294 promoted the generation of ·H, ·O, ·OH, and R25 and R173 inhibited the generation of ·H, ·O, ·OH. In terms of sensitivity reduction coefficient, the inhibition effect of CO₂ was larger than that of N₂, which also indicated that the inerting effect of CO₂ was better than that of N₂ to a certain extent. This can provide some theoretical basis for the safe use of ethylene in petrochemical industry and the prevention and control of explosion accidents.

In order to analyze the motion laws of particle swarm in vertical converging-diverging tube, the effects of converging-diverging ratio γ, rib height e and particle inlet concentration α on the concentration distribution and convergence characteristics of particle swarm in vertical converging-diverging tube were simulated by the coupled CFD-DEM method. The results showed that the axial concentration of the particle group was relatively uniform, and more particles were retained in the downer part of the tube within the research parameters. The relative concentration of particles in the radial direction followed the rule of low concentration in the center of the tube and high concentration near the wall. When the inlet concentration of particles α≤2%, the particle concentration near the pipe wall was high in the scaler with rib height e=1.0mm. In the relatively stable stage of particle movement in the middle and upper part of the pipe section, when rib height e=2.0mm, scaling ratio γ≤1.0 and particle inlet concentration α≥3%, particle swarm were more likely to convergence.

The physicochemical properties of air nanobubbles (Air-NBs) are the basis of their wide application. In this study, the physicochemical properties of Air-NBs produced by the principle of hydrodynamic cavitation, including the particle size distribution and zeta potential, were studied on the nanoparticle size-zeta potential analyzer. The effects of operating pressure, electrolyte concentration, pH and temperature on the physicochemical properties of Air-NBs were investigated, as well as the stability of Air-NBs respectively in deionized water and CaCl₂ solution. The results showed that the higher the pressure of the nano bubble generator, the larger the proportion of small particle size of Air-NBs, and the addition of electrolyte helped to reduce the particle size of bubbles. The average particle size distribution of Air-NBs decreased with the increase of electrolyte concentration, pH and temperature. However, the coalescence between bubbles was ascribed to the gradual increase of the particle size with time going. The Air-NBs particle size in the two solutions was monitored online. It was found that the Air-NBs could exist in the solutions for 5 days. The stability of Air-NBs in solution can be explained reasonably through DLVO theory and zeta potential effect.

For the purpose of reducing drag and power consumption during the stirring of fluid within the vessel, a hydrophobic Rushton impeller was proposed. Firstly, flow field in the vessel stirred with a non-hydrophobic Rushton impeller was numerically studied. Through comparison with the experimental results from literature, the reliability of the numerical model and the simulation method was verified. Subsequently, the hydrodynamic performance of the hydrophobic Rushton impeller under turbulent flow regime was simulated. The flow field, shear stress and pressure distribution, drag reduction effect and power consumption under different hydrophobic conditions were analyzed, and comparisons were made with their counterparts of the non-hydrophobic Rushton impeller. Results showed that although the flow field was not significantly changed, the axial pumping capacity and the high velocity area within the impeller discharge flow region were slightly increased, especially for the super-hydrophobic Rushton impeller. For the hydrophobic Rushton impeller, the wall shear stress and pressure difference between the front and rear surfaces of the blades were reduced. Besides, the drag reduction effect was observed and the drag reduction ratio of the super-hydrophobic Rushton impeller was as high as 39.56%. Besides, power consumption of hydrophobic Rushton impeller can be reduced. Compared with the non-hydrophobic Rushton impeller, power number of the super-hydrophobic Rushton impeller was decreased by 8.53%, which had a significant energy-saving effect.

Aiming at the characteristics of sample data convergence, high dimension, nonlinear, strong coupling and large local difference in methanol to aromatics (MTA) process, we proposed a local modeling method of K-means-PSO-SVR to solve the problems of low prediction accuracy and weak robustness of single global model. Firstly, K-means algorithm was used to cluster the data in the sample space and divide in to k regions. Then, the support vector regression algorithm (SVR) optimized by particle swarm optimization (PSO) was used to establish mutually independent local models in the divided sample space. Finally, the k mutually independent local models were combined to form an integrated model covering the whole sample space. Under different noise levels, the performance of K-means-PSO-SVR method was compared with that of single global SVR, BP neural network and linear regression algorithm. The results showed that the K-means-PSO-SVR local modeling method was significantly better than the other three modeling methods at all levels of noise with strong robustness to noise. On the basis of the established data model, the key process parameters of the two-stage fixed-bed MTA were optimized which were verified by five independent repeated experiments. When the first and second stage reactor temperatures were 446.2℃ and 467.3℃ respectively, the volume space velocity of methanol was 0.4h^-1 and the pressure was 0.64MPa, and the highest yield total yield of benzene, toluene and xylene (BTX) was 44.30%.

During the blending process of tank batches of finished gasoline,an integrated modeling method for finished gasoline blending general formula was proposed by considering the influence of the remaining oil at the bottom of the tank on product quality indicators, which based on an improved multi-kernel fuzzy C-means (MKFCM) and an extreme gradient boosting tree (XGBoost). Firstly, considering the differences of the blending components, an adaptive kernel parameter calculation method was presented to improve MKFCM, and then it was used for tank bottom oil cluster analysis in order to classify tank bottom oils with similar properties to the greatest extent batch-type. Secondly, XGBoost algorithm was selected on this basis. The sub-formulation model of each batch was established by taking the component proportion of residual oil at the bottom of each batch of tank and the expected quality index of the product as the input. When generating the formula, the membership vector of the current tank bottom residual oil was obtained based on the improved MKFCM and the above membership vectors were used to weight and fuse the sub formula model. Finally, the blended general formula of finished gasoline was obtained by multi-model integration. The experimental analysis by using the actual industrial data of an enterprise showed that compared with a single model or an integrated model without the improved MKFCM, the multi-model integrated formula based on the improved MKFCM-XGBoost possessed better prediction accuracy and generalization ability, and it was more suitable for tank type process of blending batches of finished gasoline.

The gas-liquid linkage valve of the trunk line of the gas pipeline determines whether the pipeline leaks and automatically shuts off the block valve according to the pressure drop rate and its duration of the pipeline. This method is difficult to identify the accident condition that the pressure drop rate of small aperture leakage is lower than the shutdown threshold and the normal operation condition such as compressor pumping suction. Taking the gathering and injection trunk line of Xiangguosi Gas Storage as the object, the pressure drop rate signals related to the three working conditions of pipeline leakage, compressor pumping suction and emergency shut off of block valve were obtained by simulation and a pipeline leakage signals recognition model was established based on support vector machine. The teaching-learning-based -optimization algorithm of chaotic mapping and adaptive inertia weight was proposed, and the optimal values of penalty factor C and kernel function parameter g in the model were obtained. The verification results of 600 sets of data on Tongxiang pipeline of Xiangguosi Gas Storage were obtained. Firstly, the identification accuracy of the optimized model for the three working conditions was 98.5%, which was 4.2% higher than that of previous optimization. Secondly, the optimized model had 100% recognition accuracy for small aperture leakage with equivalent diameter of 50—125mm, which improved the accuracy of small aperture leakage signals recognition. Thirdly, the accuracy of the optimized model for the identification of the compressor pumping suction and the block valve emergency shut off conditions were 96.7% and 100%, respectively. Lastly, when the leakage aperture was less than 50mm and the pressure drop rate was less than 0.01MPa/min, the pressure drop rate signal characteristics detected in the valve chamber were similar. It is suggested to use the gas-liquid linkage valve and the SCADA system monitoring data to comprehensively judge.

Red mud contains catalytic elements and certain pores, which can be used as catalysts. Its strong alkalinity leads to sintering of the catalyst surface and inadequate acidity. In this study, dealkalized red mud catalysts were prepared by exchange of sodium citrate and calcination. The dealkalization rate reached 96%. Characterization found that the dealkalized red mud was more stable. Polymerization degree of aluminosilicate decreased and the content of Al, Fe, Ti and other catalytic elements increased in dealkalized red mud. The specific surface area and the medium strong acid sites were increased. When the dealkalized red mud was used to catalyze the straw pyrolysis, the aldehydes, phenols and furans in the bio-oil products changed significantly. The content of 2,3-dihydrofuran increased by 15.9 times. The dealkalized red mud had little effect on the production rate of bio-oil, with significant changes in non-condensable gas and biochar production rate. It was inferred that the dealkalized red mud promoted the de-hydroxylation and de-carbonylation reactions,and the dehydration rearrangement of glucose, and strengthened the demethylation and de-methoxy reactions. The research would provide an important reference for the efficient preparation of liquid fuels and fine chemicals by the catalytic pyrolysis of biomass.

Propene is an important organic chemical, and its demand has been increasing all over the world recently, resulting in a short supply. Propane dehydrogenation (PDH) is an on-purpose propene production process using propane as the raw material. PDH has attracted much attention due to the advantages of abundant raw materials, high propene selectivity, easy separation of products, etc. The review mainly describes the research progress of structure regulation of high stable Pt based catalysts and processes for PDH in the last ten years. It is concluded that the Pt based catalysts showed the highest activity and propene selectivity. However, Pt based catalysts are easier to deactivate by coking and tend to sinter at high temperature, leading to catalyst stability decease. In order to improve the stability of Pt based catalysts, researches are mainly focused on the design of catalyst structure and the optimization of process conditions. In the regulation of Pt active site, methods of ① modifying the structure properties of Pt sites, such as dispersion, particle size; ② introducing metal promoter, such as Sn, Cu, Ga, Zn; ③ regulating the properties of support, such as its acidity, surface area, porous structure, and metal-support interaction, could be adopted to improve the anti-sintering and anti-coking properties of Pt based catalyst. In process optimization, co-feeding CO₂, H₂, steam or other alkanes with propane, could greatly improve the anti-coking stability of Pt based catalyst and propene yield. Lastly, it is pointed out that effective coupling of the structure of Pt based catalyst and process condition is the key for improving the catalyst stability and propene yield in the future.

The direct conversion of syngas to light olefins such as ethene and propene has become a significant and attractive process in syngas conversion and olefin synthesis due to the abundant resources and its relatively short process. In this review, the direct synthesis of light olefins from syngas via Fischer-Tropsch (FTO) route is introduced at first with the emphasis on the research progress of iron-based and cobalt-based catalysts and the catalytic reaction mechanism. Then the direct conversion based on the recently proposed and developed bifunctional catalytic system consisting of oxides and zeolites (STO) is addressed in detail. The effects of oxide composition and ratio, zeolite acidity and pore structure on the STO catalytic performance are elaborated. The catalytic mechanism for reactions with ketene or methanol/dimethyl ether as key intermediate is also discussed. The directions and challenges on the development of the bifunctional catalysis system are finally proposed.

SAPO-11 catalyst with reduced particle size, hierarchical pores or both can significantly improve the activity and selectivity in the hydroisomerization of hydrocarbons, which has become a hot research topic in recent years. In this paper, the synthesis methods, structural characteristics and hydroisomerization performance of SAPO-11 molecular sieves of small particle size, hierarchical structure and with both small particle size and multi-stage pore structure are systematically introduced. It is pointed out that the research and development of new green and efficient synthesis methods, reducing the synthesis cost and environmental pollution should be the future research directions for the industrial application of small particle size or/and hierarchical SAPO-11 molecular sieve.

Due to their unique acidity and redox performance, polyoxometalate materials have attracted wide attention in oxidative desulfurization. In this work, the research progress on oxidative desulfurization in fuel by polyoxometalate materials is reviewed, including the characteristics of polyoxometalate based ionic liquids and polyoxometalate catalysts supported on metal-organic frameworks, oxide and carbon materials, and their desulfurization performance for various sulfur compounds. The combination of polyoxometalate with ionic liquid or other materials can not only enhance the catalytic activity, but also improve the thermal stability and reusability of the catalyst. Furthermore, the characteristics and development prospects of various carriers were compared in detail. Finally, the development directions of polyoxometalate materials in oxidative desulfurization is prospected, such as the development of polyoxometalate materials with high catalytic activity, excellent recycling performance and good economic and applicability.

The selective hydrogenation of nitrile butadiene rubber (NBR) is an important process for the preparation of high value-added, high-performance hydrogenated NBR (HNBR). The C\stackrel{}{̿}C double bonds in the chain segment are hydrogenated while the nitrile group is unaffected, which can not only maintain its original oil resistance and wear resistance, but also greatly improve its weather resistance and ozone resistance. This article introduces several processes of NBR hydrogenation and emphatically reviewed the research progress and development direction of NBR heterogeneous catalytic hydrogenation. The effects of pore structure, surface properties and the active components of the supported catalyst on the hydrogenation performance of NBR is discussed. Additionally, the solvent effect, and the recovery and regeneration of catalyst in the heterogeneous hydrogenation process are summarized. It is proposed that solvent has an important influence on the catalytic hydrogenation rate and hydrogenation degree, and the hydrogen bond acceptance ability (β value) of solvent is the key factor affecting the hydrogenation performance. The main cause of catalyst deactivation is the coverage of the surface active sites by polymer, and washing with the effective solvent or modification of catalyst surface can expose the active sites again, thereby restoring the hydrogenation activity. Finally, the future research directions of heterogeneous catalytic hydrogenation for high value-added HNBR, including catalyst design, solvent effect and catalyst regeneration, are prospected.

Volatile organic compounds (VOCs) are important precursors of inhalable harmful substances and have caused serious air pollution. Catalytic degradation of VOCs is currently one of the most effective end-treatment technologies to control air pollution. The manuscript discusses the research progress of thermal catalytic oxidation, photocatalytic oxidation, and photothermal synergistic catalytic oxidation of the VOCs, focusing on the mechanism of catalytic oxidation of common VOCs and the design of related catalysts. Among them, thermal catalytic combustion researches mainly focuses on noble metal-based catalysts (Pt, Pd, Au, Ag, etc.), transition metal catalysts (oxidation state of Mn, Co, Cr, etc.), and composite catalysts. Photocatalytic oxidation catalysts are discussed by using TiO₂ and C₃N₄ as the typical catalysts, while the research of photothermal synergistic catalysis mainly included carbon-based catalysts, noble metal-supported catalysts and transition metal-supported catalysts. In addition, further prospects for the development and research of thermal catalysis, photocatalysis, and photothermal catalysis for the elimination of VOCs are given.

Due to the unique layered structure and appropriate band gap, bismuth-based semiconductor materials have favorable visible light response-ability and stable photochemical characteristics. As a new group of environment-friendly photocatalysts, bismuth-based semiconductor materials have attracted extensive attentions in the fields of environmental remediation and energy crisis resolution and hence have become a research hotspot in recent years. However, there are still some urgent yet unsolved problems in the practical large-scale application of bismuth-based semiconductor photocatalysts, such as high recombination rate of photogenerated carriers, limited response range to the visible spectrum, poor photocatalytic activity, weak reduction ability. Firstly, this paper outlines the typical properties, preparation methods, and reaction mechanism of bismuth-based semiconductor materials with the focuses on their research progress in photocatalysis, including morphology regulation, heterojunction of construction, ion doping, carbonaceous material doping, noble metal deposition, dye-sensitized, and other modification methods. It also introduces the applications of bismuth-based semiconductor photocatalysts in the degradation of water pollutants, sterilization, disinfection, air purification, hydrogen evolution, CO₂ reduction, and organic synthesis. Finally, the prospects for the development of bismuth-based semiconductor photocatalysts are also discussed, and it is pointed out that the future research directions should be focused on multi-means coupling modification, expanding the application fields and profoundly exploring the reaction mechanism.

In order to expand the high value utilization of lignin, the lignin biochar-supported iron catalysts were prepared with lignin and iron salt as raw materials by co-pyrolysis method. The influence of iron precursors, iron loading amount, heating rate and pyrolysis temperature on the decomplexation of Ni-EDTA and iron-leaching were investigated, and the effect of pyrolysis temperature on the catalysis performance was systematically discussed through the analysis of the pore structure, surface elements and crystal structure of the catalysts prepared at different pyrolysis temperatures. The results showed that the elemental composition, polarity and iron distribution on the surface of the catalysts were determined by iron precursors, and Fe(NO₃)₃·9H₂O was the best one. The number of active sites on the catalyst surface was increased with iron loading amount, while heating rate changed the porous structure of biochar, and pyrolysis temperature determined the formation of carbonaceous structure and the fixation capacity of iron on its surface. The iron transferred from catalyst surface to its interior when pyrolysis temperature increased, and iron-leaching was lower than 1.0mg/L above 600℃, making the decomplexation of Ni-EDTA transformed from homogeneous Fenton reaction to heterogeneous Fenton one. Meanwhile, high pyrolysis temperature caused the reduction of O, N and S active sites on catalyst surface, resulting in the deactivation of catalyst and decreased decomplexation of Ni-EDTA. The above results provide the basic data for the design and preparation of lignin biochar as catalyst carrier.

For non-degradability of traditional petroleum-based polymer films, biomass-based films such as cellulose, starch and chitosan have attracted much attention due to their advantages of degradability with good development prospects. However, the problems of biomass-based films such as low strength and poor water resistance limit the further development and functional application. This paper summarizes related researches about the lignocellulose as an additive for enhancing the mechanical strength, water resistance, UV shielding and other properties of biomass-based films. It focuses on discussing the effects of lignin with various properties and lignocellulose with different diameter on the physical properties of biomass-based films. Furthermore, the research progress on the application fields of lignocellulose-based composite films in packaging materials, electrode materials and catalytic materials is reviewed. The advantages, disadvantages and development progress of the lignocellulose-based composite films in preparation technology and functional application are also analyzed. It is expected to provide some new insights/inspirations for subsequent study based on lignocellulose- enhanced composite films.

Lignin is increasingly focused on the application of hybrid supercapacitors. It is a polyphenolic polymer with abundant aromatic functional groups and oxygen-containing functional groups, and is easily transformed into graphitized carbon layer via carbonization to form local highly conductive region, which is a high-quality candidate for the preparation of supercapacitors. Hence, it is becoming a cutting-edge spot using lignin based materials in hybrid supercapacitors. This paper reviewed the recent advances of lignin-based carbon materials in the electrode materials for hybrid supercapacitors with the emphasis on the roles/functions of lignin within electrode materials. Three categories including lignin/porous carbon type (e.g., graphene, carbon nanotube), lignin/metal compound type (e.g., metal oxides, sulfides, hydroxides) and lignin/conductive polymer type (e.g., polyaniline, polypyrrole, polythiophene) were introduced, respectively. Furthermore, the application of lignin-based hybrid supercapacitors in flexible supercapacitors was also presented. Finally, the prospects and challenges of lignin-based materials for hybrid supercapacitor applications were summarized.

Covalent organic frameworks (COFs) are a type of porous organic polymers with periodic two-dimensional (2D) or three-dimensional (3D) network structures that are designed and assembled by covalently connected structural units, which have the characteristics of high specific surface area, low density, highly ordered periodic structure and easy functionalization. Compared with single-pore COFs, hierarchically porous COFs have hierarchical pore structure, different pore environments, easily accessible active sites, excellent mass transfer and diffusion performance, and show broad application prospects in the fields of gas separation and storage, environmental improvement, photoelectric, biomedicine, catalysis and so on. However, the structural diversity of COFs with hierarchical porosities is still limited due to their harsh synthesis conditions. In this paper, the research progress of COFs with hierarchical porosities is systematically reviewed from the aspects of reaction types, design strategies, synthesis methods, functional modification and application fields. Moreover, the development trend of developing more monomers, bonding types and topologies, expanding more modification methods and giving full play to the advantages of hierarchical pore structure is put forward. In the future, on the basis of continuous exploration and research, more hierarchically porous COFs with new topologies, continuously improve performance and more new applications can be developed, and the rapid, efficient and low-cost processing and molding of COFs with hierarchical porosities can be achieved. As a result, they would play an irreplaceable role in the fields of energy, biology, environment, catalysis and so on.

Polyamide composite membrane has become one of the most widely-used materials in the field of water treatment and chemical engineering separation due to its excellent stability and separation selectivity. Generally, polyamide composite membrane is fabricated by interfacial polymerization. Due to the high reactivity and numerous reaction parameters of interfacial polymerization, the structure of interfacial layer is difficult to control, and the permeability or selectivity of membrane is not satisfactory. Thus, it is a great challenge to regulate the structure of the membrane and achieve a membrane with high permeability or separation performance. Recent research indicates that addition of additives into the organic phase or aqueous phase solution is to change the interfacial tension. In this case, the monomer diffusion rate and the distribution can therefore be modified. The mechanism of the polymerization might be changed as well and the reaction rate can be regulated. Consequently, the structure of the interfacial layer and the performance of the membrane can be regulated. This review summarizes the recent progress from the perspective of the type, function and effect of additives. On the basis of recent research progress, it is suggested to explore the physicochemical properties of interfacial process at microscale and develop high time-resolution in-situ characterization methods.

As drilling fluids' additives, nanomaterials with small sizes and strong thermal stability can effectively improve high temperature resistance of drilling fluids. Generally, the preparation method of nanomaterials for high temperature resistant drilling fluids can be obtained by material nanoprocess or compositing nanomaterials and polymer, and nanomaterials can be roughly divided into three categories: inorganic nanomaterials, polymer nanospheres and nanocomposites. Moreover, the thermal stability and dispersibility of nanomaterials can be improved by structural optimization, which can be used to plug nano-pores in rock formations, reduce fluid loss of drilling fluids, optimize rheological properties of drilling fluids and enhance temperature resistance of drilling fluids. This article briefly expounded upon the effect of high temperature on drilling fluid performance, analyzed the properties of nanomaterials and their role in drilling fluids, and focused on the application of different types of nanoparticles in high temperature resistant (≥150℃) drilling fluids, especially the rheological properties and filtration performance of drilling fluids. Finally, the article pointed out that the future development direction of nanomaterials as drilling fluid additives would focus on environmental protection, simplification of synthetic processes and the combination of indoor and field research.

Thermal interface materials (TIMs) is a kind of material used to establish thermal conductive path between chip and heat sink for reducing heat transfer resistance and thus improving heat dissipation efficiency. Introducing phase change materials (PCMs) especially solid-liquid PCMs into TIMs is expected to develop a novel kind of TIM, that is, phase change TIM (PCTIM), which has the functions of both thermal storage and heat conductance. However, in view of the low thermal conductivity of solid-liquid PCMs as well as the problem of their liquid flow and leakage, the enhancement on heat conduction along with the improvement in form-stability has become the key to developing high-performance PCTIMs. In this paper, the strategies and research progress on improving thermal conductivity and formability of PCTIMs are reviewed. Specifically, the means of strengthening the thermal conductivity of PCTIMs mainly include adding the fillers with high thermal conductivity, forming the orderly structures of the fillers and employing low melting point metal, etc. As for improving the form-stability, the solid-liquid PCMs could be combined with flexible supporting materials for overcoming the problem of liquid leakage as well as maintaining the flexibility to some extent. The solid-solid PCMs are used to replace solid-liquid PCMs to avoid liquid leakage completely. The solid-liquid PCMs could be encapsulated into micron or nanoscale capsules followed by introducing TIMs, which would develop the PCTIMs with high latent heat and thus exhibiting good performance to resist thermal shock for chips. At present, the thermal conductivities of the PCTIMs are still low, and the synergistic influence mechanism of the two characteristics of heat storage and thermal conductivity on their heat dissipation performance is not well understood. In the future, new strategies should be explored for developing the form-stable PCTIMs with high thermal conductivity, low interface thermal resistance and large latent heat value with the purpose of meeting the heat dissipation requirements of high heat flux chips for the fields such as 5G communication.

Traditional phase change materials are limited by their low thermal conductivity, and its phase change heat storage efficiency is difficult to improve. Adding a metal porous structure with high thermal conductivity to the phase change material is one of the important means to enhance heat transfer. In this paper, a three-dimensional, transient phase-change heat storage model including natural convection of a triply periodic minimal surface (TPMS) porous aluminum-paraffin composite phase change material was established. The solid-liquid interface evolution law, real-time temperature change, heat transfer characteristics and heat storage performance of the aluminum-paraffin composite phase change material in the heat storage process were studied by numerical simulation combined with experiment. The results showed that after adding two TPMS porous aluminum structures, primitive sheet (PS) and primitive network (PN) to pure paraffin, an obvious phase transition temperature platform appeared within the paraffin phase transition temperature range. Compared with pure paraffin wax, the initiation time of PS-paraffin and PN-paraffin composite phase change material decreased by 74.1% and 91.4%, respectively. The maximum temperature gradient in vertical direction decreased from 1605.7℃/m of pure paraffin to 840℃/m and 943.8℃/m of PS-paraffin and PN-paraffin composite phase change material, respectively. The heat storage rate was 3.10 times and 4.69 times higher than that of pure paraffin. Finally, the PS and PN porous aluminum structures were formed by selective laser melting (SLM) technology, and the TPMS porous aluminum-paraffin composite phase change material samples were prepared by casting method. The simulation results were verified by visual experimental platform, and the simulation results were found to be in good agreement with the experiment.

In order to investigate the difference of heat absorption and melting properties between pure paraffin wax and copper foam/paraffin wax phase change composites, and to investigate the effect of copper foam on melting heat transfer process of paraffin wax, the melting phase change processes of pure paraffin wax and copper foam/paraffin wax composites with 0.98 porosity were studied experimentally by visualization, and the melting processes of pure paraffin wax and copper foam/paraffin wax composites were analyzed by numerical simulation. The results showed that there was an intersection point of the liquid phase rate variations between the composite and the pure paraffin wax called the critical liquid phase rate value, indicating that the composite had the same liquid phase percentage as the pure paraffin wax. The filling of copper foam can significantly improve the problem of low heat transfer coefficient of pure paraffin wax and accelerate the overall melting rate of phase change material. When the heat flux was 1200W/m², the filling of copper foam with a porosity of 0.98 shortened the complete melting time of pure paraffin wax by about 12.5%. It also made the overall temperature distribution more uniform and improved the thermal stratification phenomenon. The maximum temperature difference of the composite material was about 27.5K lower than the maximum temperature difference of pure paraffin.

Lactic acid-based DES has shown great capability in removal of lignin from biomass and conversion of lignocellulose to fuels, chemicals and materials. In this work, lignin was extracted by four DESs, in which lactic acid was used as hydrogen bond donor (HBD) and choline chloride, guanidine hydrochloride, arginine or betaine hydrochloride was used as the hydrogen bond acceptor (HBA), and its effect on the hydrolysis efficiency of Avicel was studied. The results showed that the adsorption capacity of lignin towards cellulase shows a good linear positive correlation with the hydrophobicity of lignin, and both of them are linearly negatively correlated with the enzymatic hydrolysis efficiency of Avicel. The non-specific adsorption of lignin towards protein was the major cause of the inhibition, and the hydrophobic effect is mainly responsible for the adsorption of enzymes on lignin. Furthermore, the structural analysis of lignin revealed that the hydrogen bond interaction of aliphatic hydroxyl groups, phenolic hydroxyl groups, and the amino acids residues of proteins was the reason for promoting enzyme protein adsorption and reduced enzyme hydrolysis efficiency. Besides, the electrostatic repulsion generated by carboxyl group of lignin had weak effect on the hydrolysis efficiency of cellulase. DES with strong deconstruction severity may cause high hydroxyl group content, which always lead to strong inhibition of cellulase. Lactic acid/ choline chloride (LC) had the strongest inhibitory effect on enzyme due to its excellent lignin extraction and biomass deconstruction ability, followed by lactic acid guanidine hydrochloride and lactic acid betaine hydrochloride, and finally lactic acid arginine. This work is expected to improve the fundamental understanding of the knowledge of DES application in the field of biorefinery,and lay a foundation for the development of novel solvents-driven lignocellulosic biomass refining.

In this paper, nitrogen-doped activated carbon was prepared with Chinese fir sawdust as raw materials, and zinc chloride and urea as eutectic solvents after carbon activation. The influences of impregnation ratio, activation temperature and activation time on the electrochemical performance of activated carbon were investigated by orthogonal experiment design. Specific surface area (BET), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry, galvanostatical charge/discharge (GCD) and other characterization methods were used to study the pore structure, surface chemical elements and electrochemical performance of sample. The study results showed that the impregnation ratio of 4, the activation temperature of 750℃ and the holding time of 3h were the best process conditions. By analyzing the pore structure of activated carbon, it can be found that the activated carbon activated by eutectic solvent was beneficial to the formation of micropores and the specific surface area can reach 797.82m²/g with nitrogen content of 11.55%, where the main combined states of nitrogen were pyridine type N, pyrrole type N and graphite type N. In the 6mol/L KOH electrolyte, the specific capacitance can reach 233.85F/g when the current density was 1A/g. When the current density increased to 20A/g, the specific capacitance can still be maintained at 159.6F/g.

Mixed matrix membranes (MMMs) have promising applications in the field of gas separation, and metal-organic frameworks (MOFs) are often used as fillers to prepare MMMs due to their high porosity and organic linking groups. However, the improvement of gas separation performance of MMMs is limited due to the interfacial compatibility between MOFs and polymers. Herein, a functionalized Zr-MOF (UiO-66-AC) was synthesized to prepare mixed matrix membranes with poly(ether-b-amide) (Pebax). The introduction of groups such as carbonyl and carboxyl groups in the filler provided strong interfacial interactions between MOFs and the polymer matrix. Compared with pristine Pebax membranes, the gas permeability of UiO-66-AC/Pebax MMMs was significantly improved. When the filler content was 6%, the CO₂ permeability coefficient of the membrane was 102.4 Barrer, the CO₂/N₂ and CO₂/CH₄ selectivities were 90.6 and 26.0, respectively, and the CO₂/N₂ separation performance exceeded the Robeson upper bond (2008), indicating that the UiO-66-AC/Pebax MMMs had potential for CO₂ separation applications.

Carbon materials can be used as excellent adsorption desulfurization materials. Their sulfur dioxide (SO₂) capture performance is affected by physicochemical characteristics and desulfurization conditions. In this study, seven types of carbon materials were selected: activated carbon-1 (specific surface area was 1779m²/g, AC-1700), activated carbon-2 (specific surface area was 970m²/g, AC-900), porous nano-carbon-1 (average pore size was 14nm, NCP-10), porous nano-carbon-2 (average pore size was 85nm, NCP-100), porous nano-carbon-3 (average pore size was 4.7nm, nitrating, CMK-3N), porous nano-carbon-4 (average pore size was 4.1nm without nitrating, CMK-3) and carbon nanofibers (NCF). Based on the comparison of the physicochemical characteristic of these seven different carbon materials and their desulfurization performance, the effects of physicochemica properties, desulfurization temperature, reaction space velocity and so on on the SO₂ capture performance of carbon materials were studied. It provided guidance for the research and development of carbon materials and their composites with suitable physical and chemical properties and high desulfurization performance. The results showed that the SO₂ capture performance of carbon materials was comprehensive affected by the specific surface area, pore structure, surface functional groups, desulfurization temperature and reaction space velocity. The pore structure and surface functional groups of different carbon materials had great influence on the desulfurization performance of the carbon materials. The activated carbon AC-1700 and AC-900 with microporous structure had a higher SO₂ removal rate. The porous nano-carbon NCP-10, NCP-100, CMK-3N and CMK-3 with mesoporous structure had a higher desulfurization capacity. Oxygen functional groups and nitrogen functional groups can improve the adsorption performance of carbon materials for SO₂ capture. The process of SO₂ removal by carbon materials was mainly physical adsorption. The SO₂ capture performance of carbon materials decreased with increasing desulfurization temperature. Above 100℃, the SO₂ capture performance of carbon materials would be ineffective. The reaction space velocity had a great influence on the SO₂ capture performance of carbon materials. With the decrease of reaction space velocity, the SO₂ capture performance of carbon materials increased. When the reaction space velocity was low enough, carbon materials can effectively remove SO₂ pollution. In this study, porous nano-carbon NCP-10 had the best SO₂ capture performance, which can maintain 100% SO₂ removal rate at room temperature for 1 hour, and the 1 hour cumulative desulfurization capacity was up to \mathrm{108}\mathrm{m}{\mathrm{g}}_{\mathrm{S}{\mathrm{O}}_{\mathrm{2}}}/g_material at room temperature while maintaining a SO₂ removal rate of higher than 90%.

To investigate the effect of graphene-based molybdenum disulfide composite lubricant additives on the friction and wear performance of 10^# White Oil (10^# WO), oleic acid-modified reduced graphene oxide/molybdenum disulfide (OA-RGO-MoS₂, ORM) and reduced graphene oxide/molybdenum disulfide (RGO-MoS₂, RM) composites were prepared using the hydrothermal reaction method with oleic acid as a modifier and sodium sulfide as a sulfur source. The effects of ORM and RM on the lubricity of 10^# WO were examined by using a four-ball long-time friction and wear tester. Two composites and wear marks were characterized separately with the help of modern characterization tools. The results showed that ORM had a larger layer spacing, higher graphitization, better thermal stability and better dispersion stability than RM. Both composites exhibited the most excellent lubricating properties at 0.2% mass fraction. ORM was more prominent lubrication performance than RM due to the spatial site resistance effect resulted from its modification by oleic acid. For the ORM, the average friction coefficient decreased by 42.2% under the optimal condition. Friction mechanism analysis indicated that RM and ORM can form a lubrication protective film containing iron, oxygen, molybdenum, carbon and sulfur in the friction process through adsorption or friction chemical reaction in the friction surface, which improved the lubrication state of 10^# WO. Thus, they can play the role of friction reduction and anti-wear.

In this study, nitric acid-modified activated carbon was used as the raw material to prepare the electrodes for electrosorption, and its adsorption and removal characteristics of eight common metal salt ions were investigated. The properties of the materials before and after modification were characterized and analyzed by scanning electron microscopy, specific surface area and porosity analyzer, infrared spectrometer, electrochemical workstation and so on. The results showed that the modified activated carbon had a better pore structure and more oxygen-containing functional groups than before, resulting in better performance of the prepared electrode. According to the results of the desalination experiment, the higher the ion valence state was, the more quickly the electrode removed the ion, but the removal rate of ions was declining with increasing ion valence state. On the other hand, when the ion valence state was the same, the smaller the radius of hydrated ions was, the faster the electrode removed the ion, and the removal rate of ions was rising up with the declining of the radius of hydrated ions. The process of ions moving from the solution to the electrode surface and then to the inside of the pore of the active material was mainly a physical adsorption process, but there was also weak chemisorption. This study provided a reference for the practical application of electrode desalination.

Hydroxyapatite is widely used as a bone repair material and drug carrier in biomedical engineering. However, there are no reports about the hydroxyapatite loaded with the bioactive factor baicalin (BA). Based on this situation, three different loading methods are proposed and compared. In this article, short-rod nano-hydroxyapatite(nHA) and micro-spherical hydroxyapatite(mHA) were synthesized by chemical precipitation method and microwave hydrothermal method, respectively. These two kinds of hydroxyapatite with different morphology were used to load baicalin by physical adsorption, microwave hydrothermal one-step synthesis, and spray drying. Then the morphology, crystal structure and chemical composition of drug-loaded hydroxyapatite prepared by different drug-loading methods were analyzed by TEM, SEM, FTIR, and XRD. Moreover, the advantages and disadvantages of the three drug-loading methods were analyzed. The results show that the spray-drying preparation method of hydroxyapatite-loaded baicalin can ensure the stability of the drug to the greatest extent while achieving a higher drug encapsulation efficiency. This method is simple and rapid with results being reproducible and has advantages of easy industrialization and mass production.

Due to the low temperature in northern winter, the thickener of clean fracturing fluid is easy to crystallize and lose fluidity. Also, the speed of viscosity increase is slower in the process of preparing fracturing fluid. At present, the methods to solve the above problems mainly include physical heating, thermal preservation and development of the new clean fracturing fluids with low freezing point. The characteristics of the above methods were analyzed in this paper, respectively. The physical heating methods included electric heating rods, electric heating belts and so on. Thermal insulation measures mainly included heat insulated ceiling, heat preservation cover and thermal insulation coating. However, above technologies were expensive and difficult to use widely. The freezing point of clean fracturing fluid was effectively decreased when antifreeze additives and low Krafft point surfactant were added. Antifreeze additives were generally alcohols and inorganic salts, among which alcohols can also improve the solubility of active ingredients. The fracturing fluid can still flow at -15℃ by adding antifreeze additives such as alcohols and inorganic salt. And the solubility of constituent of clean fracturing fluid was improved with alcohols. Moreover, wormlike micelle was unfavorable to form in the presence of high concentration alcohols. Generally, there were three methods for the preparation of surfactants with low Krafft point, that was, introducing double bonds into hydrophobic chains, modifying hydrophilic groups and introducing nonionic groups with higher hydrophilicity. It was pointed out that the method of introducing double bonds into the hydrophobic chain had the greatest impact on reducing the Kraft point, which can reduce the Kraft point by about 8—49℃, so as to achieve the purpose of using in low temperature environment. Designing the synthetic route of surfactant with low Krafft point, exploring the formula of low-freezing point clean fracturing fluid and studying the theoretical calculation of Krafft point of surfactant should be the research priority in the future.

1,‍5-Diaminonaphthalene is an important chemical raw material. This paper first briefly introduced the synthesis of 1,‍5-diaminonaphthalene by halogenated amination, naphthol ammonolysis, cyclization, and other processes. The emphasis was put on the traditional industrial nitration reduction method. Then, the research progress of nitration reaction stage was described from "strong acid mixed acid" system to "non-acid" system, and that of the reduction reaction stage from precious metal catalysts to non-precious metal catalysts, from the perspectives of green chemistry and intrinsic safety. Moreover, it was pointed out that the reduction reaction stage of the nitrification reduction method is relatively green and environmental-friendly, while the nitrification reaction stage is still not. The overall processes is complicated. Based on the above-mentioned problems including environmental pollution, and low efficiency, the latest research progress on one-step synthesis of 1,5-diaminonaphthalene from naphthalene and with ammonia or hydroxylamine salt as aminating agents, was further discussed. In summary, the clean and efficient one-step synthesis of naphthylamine under mild conditions would become a research direction in the future.

The nitration of aromatic compounds is a rapid and strong exothermic reaction, and continuous process can reduce the potential risk caused by batch operations. The continuous nitration of chlorobenzene was carried out in a 10mL microtubular reactor on basis of the flow condition study by the visualization method and computational fluid dynamics (CFD) simulation. Some effects on the reaction conversion, yield, o-/p-nitrochlorobenzene ratio and selectivity were investigated, such as the residence time, temperature, mixed acid ratio (the molar ratio of nitric acid to sulfuric acid) and phase ratio (the molar ratio of nitric acid to chlorobenzene). The results showed that the chlorobenzene and mixed acid phases in a microchannel with an inner diameter of 1mm exhibited the Taylor flow pattern, which can enhance the efficiency of mass and heat transfer, leading to increase the macro reaction rate. When the residence time was 8min, the temperature was 80℃, the mixed acid ratio was 1∶1.5 and the molar ratio of nitric acid to chlorobenzene was 1∶1, the ratio of o-/p-nitrochlorobenzene was between 0.7—0.8, the single-pass conversion of chlorobenzene was 81.24% and the selectivity of mononitrochlorobenzene was 93.77%. The continuous nitrification can greatly shorten the residence time and significantly improve the o-/p-nitrochlorobenzene ratio. Compared with conventional kettle process, the continuous nitration of chlorobenzene in microtubular reactor was safer and more efficient.

Owning to the advantages of mild conditions, green process and high valuable, biotransformation will become an important approach for waste recycling in the near future. Plastics are synthetic organic polymer materials, which have been widely used in human daily life. However, the massive accumulation of waste plastics has caused a serious environmental pollution and huge resources waste. Due to the complex degraded fractions, high degradation energy barrier, multifarious stress factors and poor recycling economy regard to waste plastics recycling, a single utilization of biotechnology is not yet able to deal with them in real time. Therefore, based on interdisciplinary and process integration, coupling the use of a variety of technologies for waste plastic recycling, so that to establish a diversified, personalized and crossed new route for waste plastic recycling, has become the key to improve the recycling and utilization level of waste plastics resources and develop a circular economy in China. This paper summarized the current research progress of multi-disciplinary combined technology launched around biotechnology during waste plastics recycling, including biological-physical, biological-chemical and biological-informationalized cross-used technologies, with emphasis on the bottlenecks lying in interdisciplinary research, aiming to provide new ideas and theoretical guidance for construction of a more efficient route to waste plastics recycling.

The anaerobic digestion of sludge to produce methane is of great significance to the realization of "carbon reduction" in wastewater treatment plants, however, its efficiency of methane production and the stability of process are easily affected by many factors. Microplastics, as an emerging pollutant, are treated by wastewater treatment, and about 99% are enriched in the sludge, which has an impact on the anaerobic digestion process of sludge. Therefore, in this article, the sources and properties of microplastics in wastewater and their destination in wastewater treatment processes were overviewed. Simultaneously, the effects of common microplastics such as polystyrene (PS), polyamide 6 (PA6), and polyvinyl chloride (PVC) on the solubilization, hydrolysis, acidification and methanogenesis stages of sludge were elaborated. Furthermore, the mechanism of microplastics affecting anaerobic digestion was summarized from the perspectives of cell structure, microorganisms and enzyme activities. Finally, on the basis of the current research, it was proposed that the systematic engineering researches (pretreatment technologies, operating conditions, reactor type, etc.), the suppression mechanism of microplastics and their extracts (interactions of microplastics with extracellular polymer substance and cell membrane, iconic coenzymes and cofactors, and characteristic microorganisms), and the synergy/inhibition mechanism between microplastics and other components in the sludge should be carried out in-depth, providing theoretical basis and technical support for the utilization of sludge resources.

The serious emulsion of petroleum refinery desalter effluent is hard to break and presents difficult operating challenges for wastewater treatment, which is a major problem for pollution prevention and control in refineries. In this study, the fluctuation of desalter effluent quality was investigated in a typical refinery according to its discharge and treatment requirements. Based on the characteristics of desalter effluent, the stability was studied and tube electrocoagulation was used for the first time to treat the actual desalter effluent. When the desalter unit was backwashed, oil in the desalter effluent was higher than 400mg/L with the highest concentration of 1700mg/L, which was significantly beyond the design value. The average COD was about 4484mg/L and closely related to the properties of crude oil. Average dissolved COD was about 765mg/L, which mainly arose from desalter feed water. Resin and asphaltene in backwashed wastewater accounted for 28% of total oil, which was higher than that of normal desalter effluent. Spontaneous demulsification could occur in desalter effluent but it took a long time. Pretreatment by aeration for 30min reduced the COD of desalter effluent to be 26.2% of raw water, and electrocoagulation further decreased its COD and dissolved COD significantly. Under the operating conditions of initial current of 1.0A and reaction time of 15min, the average removal efficiencies of COD and dissolved COD were 80% and 50%, respectively. The pseudo first order kinetic model was more suitable to describe the removal of COD and dissolved COD from desalter effluent. Under the optimum conditions, 0.92CNY/m³ of total operation cost was obtained.

The "electro-Fenton + bioelectrochemistry" was used to treat pharmaceutical wastewater, and degradation effect of dissolved organic matter (DOM) and refractory organic matters was analyzed to explore the effective degradation of refractory organics in pharmaceutical wastewater by three-dimensional fluorescence spectroscopy(EEMs) and gas chromatography-mass spectrometry(GC-MS). When Electro-Fenton was used to pretreat pharmaceutical wastewater,the average removal rate of COD_Cr in wastewater was 28.75%±1.29%, and the average removal rate of tetrahydrofuran was 41.18%±2.95%, which initially reduced the biological toxicity of wastewater and achieved good pre-treatment of pharmaceutical wastewater. The electrochemical bioreactor had a significant degradation effect on the chemical oxygen demand (COD_Cr) of pharmaceutical wastewater and was significantly better than the single biofilm reactor. After the electrochemical bioreactor operated for 39 days, COD_Cr was decreased from (3438.30—4775.70)mg/L to (20.18—331.09)mg/L, and the average removal rate was 95.89%±1.63%; after the single biofilm reactor operated for 10 days, COD_Cr was decreased from (3943.90—4631.20)mg/L to (345.08—1264.3)mg/L, and the average removal rate was 79.86%±6.21%. The soluble organic components in the pharmaceutical wastewater were mainly tyrosine-like proteins, tryptophan-like proteins and soluble microbial by-products (SMPs). The electrochemistry bioreactor had a significant degradation effect on the fluorescent components in the 3 areas with the removal rates of 58.88%, 37.16% and 36.26% respectively. Tetrahydrofuran, the main refractory organic matter in pharmaceutical wastewater, could be effectively degraded by the electrochemistry bioreactor, and the removal rate of tetrahydrofuran was as high as 97.65%. This study investigated the treatment effect of bioelectrochemical system on pharmaceutical wastewater from the three aspects of COD_Cr removal rate, EEMs degradation effect and refractory organics degradation effect, and provided a scientific basis for the application of electrochemistry bioreactor in the field of pharmaceutical wastewater treatment.

Chlorophenol compounds are a kind of persistent organic pollutants, which are toxic to microorganisms during anaerobic wastewater treatment. In this experiment, the magnetite- modified biochar was added to improve the removal of chlorophenol in the upflow anaerobic sludge bed (UASB) reactors by enhancing the sludge conductivity and accelerating the iron reduction process. Results show that the removal rate of COD and 2,4-dichlorophenol in the reactor with magnetite-loaded biochar increases by 20% and 54.1%, respectively. Magnetite-loaded biochar has multiple functional groups and strong ability to accept/donate electrons, and thus the charge and discharge performances of sludge in the reactor with biochar are increased by 23.8%. Microbial community structure analysis shows that the addition of magnetite-loaded biochar increases the abundances of hydrolytic bacteria such as Mesotoga and bacteria capable of electron transfer function such as Petrimona, which accelerates the degradation of phenolic compounds.

In this study, by optimizing the preparation conditions, the bamboo-based cellulose nanofibrils was cross-linked with polyamide-epichlorohydrin resin (PAE), and then loaded with Fe(OH)₃ to obtain a new composite material, CNFs-PAE-Fe, to remove low concentrations of phosphorus from wastewater. Compared to other crosslinkers, bamboo-based cellulose nanofibrils crosslinked with PAE and loaded iron showed better mechanical strength and adsorption properties. BET specific surface area measurement, thermogravimetric analysis, FTIR and scanning electron microscopy were used to characterize the materials, and the pore size, surface morphology, thermal stability and elemental composition of the materials before and after crosslinking and loading Fe(OH)₃ were investigated. The adsorption of phosphorus by CNFs-PAE-Fe conformed to the quasi-second-order kinetic model and the Langmuir isotherm adsorption model, which indicated that the adsorption process of phosphorus by the modified material was a monolayer adsorption based on chemical adsorption. CNFs-PAE-Fe maintained good adsorption performance for low concentrations of phosphorus in a wide pH range. The highest adsorption capacity of the prepared adsorbent could reach 9.11mg/g at pH 4.0. The regeneration of the modified material with saturated adsorption was studied, and the regeneration effect was best when the ratio of eluent V (NaCl):V (NaOH) was 3∶2. The desorbed material was freeze-dried and reused 5 times, and still maintained good strength and complete morphology.

In order to certificate the feasibility of joint remediation of chemical oxidation method with microorganism method for petroleum-contaminated soil. Using urea peroxide as the oxidant and Fe²⁺ as the activator, joint repair experiments and the orthogonal experiment design were used to investigate the conditions for urea peroxide (UHP) to remove petroleum pollutants in soil and the effect of UHP combined with microorganism on the remediation of petroleum contaminated soil. The optimal conditions for the chemical oxidation experiment were as followings: 4% mass fraction of UHP, UHP∶Fe²⁺ (molar ratio) = 30∶1 and water∶soil = 3∶2. Compared to the single microbial remediation method and single urea peroxide oxidation remediation method, the degradation rate of petroleum hydrocarbons with the urea peroxide combined with microbial methods for remediation of petroleum contaminated soils was increased by 35.45%—47.26% and 3.35%—15.16%, respectively. The sequence of urea peroxide and microorganism remediation was optimized. Compared to microbial remediation followed by urea peroxide remediation, the urea peroxide remediation followed by microbial remediation increased the degradation rate of petroleum hydrocarbons by 11.81% . This study shows that urea peroxide combined with microbial remediation is a good way to degrade petroleum in the soil.

Supercritical water oxidation (SCWO) process is suitable for the treatment of high concentration waste liquids. Aiming at the problems of high energy consumption and single energy reuse mode of SCWO treatment system, the energy recovery mode of traditional process flow is introduced, the energy utilization efficiency of the system is analyzed, and the turbine and organic Rankine cycle (ORC) are innovatively used to recover pressure energy and thermal energy, respectively. Aspen Plus was used to establish the energy recovery model of SCWO system to study the influence of different process flows on the system energy efficiency, efficiency and output power. On this basis, the effects of turbine inlet temperature and outlet pressure and orc evaporation temperature on system performance are discussed. The results show that the best energy recovery method is to recover the pressure energy and heat energy of the reaction products in turn. Increasing inlet temperature and outlet pressure of supercritical turbines can improve system performance and the stability of the turbine output power at the same time. Reducing the evaporation temperature of ORC will increase the steam output of the system, but also reduce the generation of directly available electric energy.

Towards the high standard of urban sewage discharge, attapulgite supported catalysts were prepared to improve the performance of ozonation of low concentration of organic matters. The catalysts were characterized by particle size analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared absorption spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of calcination temperature and calcination time on the performance of the catalysts were investigated, and the efficiency of the optimized catalyst was analyzed. The results showed that the optimal calcination temperature and calcination time were 500℃ and 3h respectively, and when the influent flow, catalyst dosage and reaction time were 0.3L/min, 0.4g/L and 15min respectively, the COD concentration was decreased from 72.5mg/L to 47.5mg/L. The loading of iron-based oxides on attapulgite showed significant synergetic effect.

The chemical oxygen demand value is high for the fracturing flow-back solution of shale containing a few organic additives. This paper studied the coagulation effect of a novel inorganic compound coagulant polysilicate aluminum ferric (PCM) and the flocculation properties of a comb-like polymer flocculant poly[(p-vinyl benzyl po1yoxyethylene octylphenol ether)-acrylamide-(sodium 2-acrylamido-2-methylpropane sulphonate)] (PAVA) combined with PCM. The objective was to enhance the pre-treating efficiency for fracturing flow-back fluid of shale. Then some results were obtained. When the dosage of PCM alone was at 0.3g/L, the removal efficiencies of turbidity and COD were 96.1% and 71.4%, respectively. These data were obviously higher than those using the typical polyaluminum chloride (PAC). When PCM was used together with PAVA at 5mg/L, the PCM dosage decreased markedly but the treating efficiency was higher. For example, when the dosage of PCM was at 0.2g/L, the removal efficiencies of turbidity and COD were up to 90.0% and 86.1%, respectively. The bridging flocculation effect was stronger for PAVA than for typical anionic and cationic polymer flocculants. The higher the ξ-potential value was in the flow-back fluid, the higher the coagulation efficiency was.

Electrolytic manganese residue (EMR) has become a bottleneck hindering the development of electrolytic manganese industry, and the large amount of gypsum in EMR is the key to limit its resource utilization. Aiming at the problem of gypsum leaching from EMR, the effects of NH₄HCO₃ and NH₄Cl dosage, initial pH of leaching, leaching time and leaching temperature on the transformation law of gypsum in manganese residue were studied. The results showed that the leaching efficiency of gypsum in EMR was 90.0% when the mass ratio of manganese residue to NH₄HCO₃ and NH₄Cl was 20∶8∶1.5, the solid-liquid ratio was 1∶5, the initial pH of leaching was 7.5, the leaching temperature was 70℃ and the leaching time was 120min. The main phases of the leaching EMR included CaCO₃, SiO₂, Ca₂Mn₂(OH)₄Si₄O₁₁·2H₂O, Mg_5.0Al₆Fe₄Si_2.5Al_1.5O₁₀(OH)₈ and KAl₃Si₃O₁₀(OH)₂, and the content of MnO in EMR increased from 7.45% to 14.71% after leaching. The transformation law of gypsum in EMR indicated that NH₄HCO₃ reacted with gypsum in EMR to convert into (NH₄)₂SO₄ and CaCO₃, and NH₄Cl as a salt reagent can further promote the dissolution of gypsum, and thus improving the leaching efficiency of gypsum.

Waste selective catalytic reduction (SCR) denitrification catalyst contains amounts of valuable metals, which directly landfill will cause resources waste and environmental pollution. The effects of leaching conditions on selective acid leaching of Ce and Mn elements from waste CeO _x -MnO _x SCR denitrification catalyst were investigated by thermodynamic analysis and hydrometallurgy experimental study. The results confirmed that the direct-acid leaching rates of Ce and Mn from waste CeO _x -MnO _x SCR catalyst were very low, the reduction-acid leaching of Ce and Mn was feasible under thermodynamic conditions, and the ascorbic acid had obvious reduction effect on Ce and Mn high-valence oxides. When the experimental conditions were as follows: ascorbic acid mass ratio of 30%, sulfuric acid concentration of 2mol/L, liquid-solid ratio of 6∶1, stirring speed of 350r/min and constant temperature of 80℃ with reaction time of 5h, the leaching rates of Ce and Mn reached 92.09% and 95.51%, respectively, and the mass ratios of Ce⁴⁺/Ce and Mn⁴⁺/Mn decreased from 75.82% to 71.62% and 29.39% to 27.17%, respectively. It was indicated that the addition of the ascorbic acid reduced part of Ce⁴⁺ (Mn⁴⁺) to Ce³⁺ (Mn²⁺) and weakened the positive effect of high valence Ce on the transition of Mn from the low-valence, thus improving the leaching rates of Ce and Mn, which had laid the groundwork for resource utilization of Ce and Mn in waste CeO _x -MnO _x -based SCR denitrification catalysts.

Membrane filtration is an efficient water treatment technology, which has been widely used in industrial wastewater treatment, domestic wastewater reuse and seawater desalination in recent years. However, the long-term operation of ultrafiltration can cause membrane fouling. This study used different forms of aluminum coagulants [Al₂(SO₄)₃, AlCl₃ or poly aluminum chloride (PAC)] to treat simulated raw water containing different dissolved organic matter (DOM) components (humic acid, bovine serum albumin and kaolin solution). Online coagulation combined with ultrafiltration was used to investigate the effects of different aluminum forms and components and their interactions on the ultrafiltration membrane fouling process were also studied. This study established a flow attenuation model to simulate the membrane fouling process. An infrared attenuated total reflection (IR-ATR) combined with multivariate curve resolution-alternating least squares (MCR-ALS) was used to qualitatively and quantitatively analyze various pollutants on the membrane. The results showed that both aluminum sulfate and aluminum chloride coagulants can significantly improve the membrane-specific flux and mitigate membrane fouling. The coagulant dosage was lower than the conventional treatment and significantly reduced membrane fouling. The coagulation effect of aluminum chloride was better when the dosage of AlCl₃ was 0.4mg/L. The coagulation effect of aluminum sulfate was better when the dosage was 2.4mg/L. Low dosage of PAC (0.2mg/L and 0.4mg/L) was not obvious to alleviate the degree of membrane fouling, but rather aggravate the membrane fouling. The fouling of ultrafiltration membrane by bovine serum albumin was more serious than humic acid because the presence of BSA greatly reduced the effect of coagulation and hindered the formation of the loose filter cake layer. When aluminum sulfate was added to the raw water, membrane fouling mainly occurred in the pre-filtration stage due to narrowing and clogging of the membrane pores. At the end of filtration, a loose cake layer was formed on the membrane surface, which had little effect on the membrane flux and membrane fouling was slowed down.