In this paper, biotreatments applied to ground processing and underground mining in oilfield were summarized and discussed mainly on as the present development situation and existing problems. In ground processing system, biological technology is involved in many research areas, such as bioremediation, biological demulsification, and biofloculation. It has been extensively researched, but moderately applied. However, further promotion and application are severely hindered due to the constraints of the technology maturity, the actual working conditions and treatment costs. In underground mining system, the application scope of biological technology is comparatively narrow, and microbial enhanced oil recovery (MEOR) has become the most profound forefront research area in oilfield during decades of development. Some achievements have been applied on small scale, yet this technology would be greatly influenced by different characteristics of reservoirs. Hence, it is of great difficulty to apply MEOR in the controlled environment, which would be the restraint from its popularization. Besides, microbial prospecting of oil and gas (MPOG), a recently-developed microbiological exploration technology to identify the location of the reservoir based on the surface composition of microbial community, has already achieved some results. With the future improvement of the related technologies and the solutions to the actual working condition problems, biological technology is bound to be developed more broadly in oilfield production.

As energy-efficient, high-performance and environment-friendly method the fluidized-bed silane pyrolysis makes its potential to become the dominating way for production of granular polysilicon, while the domestic research on this process is still in its infancy. The review starts with a brief induction of the basic principle of fluidized-bed silane pyrolysis, including the operating principle and the reaction model, and discusses the effects of temperature, silane concentration, particle size and gas flow rate on stable fluidization and fines formation. Developing the technology of fluidized-bed silane pyrolysis faces many technical challenges, such as fines formation, unwanted depositions on internals, heating and temperature control, seed particles generation, gas distribution and quality. The advantages and disadvantages of solutions of these technical challenges are summarized by analyzing different fluidized-bed reactor designs and the industrial application prospects of these solutions are pointed out. The difference between the CFD simulation of the fluidized-bed silane pyrolysis and the general fluidization is discussed and related researches are reviewed. Finally, the review proposes that the domestic research on fluidized-bed silane pyrolysis should put emphasis on optimizing the reaction conditions, improving fluidized-bed designs and completing the multi-scale model of fluidized-bed silane pyrolysis.

The dilute particle of fluid-solid two phase flow widely exists in practical application of chemical engineering, storage and transportation, separation etc. The description of the complex turbulent motion is one of the research hotspot and difficulty of two phase flow. The growing process of the dilute discrete phase model was reviewed in this paper, which from the theoretical basis, the modeling process, the numerical simulation method and the application of several aspects of the discrete phase model, the discrete phase model, the stochastic trajectory model, the improved stochastic trajectory model has carried on the detailed elaboration. The interaction coupling relationship between discrete and fluid phase was theoretically analyzed, and the corresponding model was evaluated. Then, the paper pointed out that the present problems and the future development direction of the discrete phase orbit model. This paper puts forward an advanced stochastic trajectory model which based on random Fourier series describing the discrete phase resultant force to describe the motion law of discrete phase to deal with fluid phase fluctuation velocity randomly in the future, so as to better describe the motion law of discrete phase, at the same time considering of the coupling two phase, to establish full coupling vibration dynamic model of two phase flow, and describe the movement characteristics of discrete phase of fluid-solid in the two phase flow comprehensively andsystematically, providing theoretical basis for the in-depth development of the dilute discrete model in fluid-solid two phase flow.

R290(propane)and its refrigerant mixtures have been treated as ideal alternative refrigerants due to their favourable environmental and thermo-physical properties. However, they are flammable. The heat exchangers of the refrigeration system can be optimized, and the charge amount of R290 and its refrigerant mixtures can be reduced by studying the phase change heat transfer of R290 and its refrigerant mixtures in horizontal tube. In this paper, studies on phase change heat transfer of R290 and its refrigerant mixtures in horizontal tube were review. The results showed that the heat transfer performance of R290 and its refrigerant mixtures can be comparable to or above synthetic refrigerants. The phase change heat transfer correlations of R290 and its refrigerant mixtures obtained in related research were listed and compared, and the influence of mass flow, heat flux, vapor quality and other factors on phase change heat transfer from relevant researches were summarized. Finally, it is pointed out that all above researches have been conducted mainly on the traditional heat transfer pipes, the phase change heat transfer correlations and factors of R290 and its refrigerant mixtures in small tube (with the diameters of 7mm、6mm、5mm or even 4mm) should be studied in order to reduce the charge amount and flammability.

The horizontal liquid-solid circulating fluidized bed heat exchanger with Kenics static mixer was studied by this experiment. The effects of Kenics static mixer twist rate, the installation method of Kenics static mixer, flow rate and particle volume fraction on heat transfer performance and flow resistance performance were investigated, which were analyzed by the comprehensive heat transfer performance evaluation criteria index. It was found that the heat transfer and resistance coefficient decrease with the increase of twist rate. Results showed that the performance evaluation criteria of Kenics static mixer with twist rate Y=1.5, 2, 2.5, 3.5 were over 1 without exception in the range of Reynolds number 10000—45000, which indicates that the horizontal fluidized bed heat exchanger with Kenics static mixer can enhance heat transfer. The performance evaluation criteria of horizontal fluidized bed heat exchanger reached 1.18 at most, when the Reynolds number reached about 25000, the twist rate of Kenics static mixer is Y=2.5 and the particle volume fraction is 4%. The performance evaluation criteria of horizontal fluidized bed heat exchanger is the highest on the condition that the distance between two Kenics static mixers with twist rate Y=2.5 is 200mm.

A maximum organic loading rate of 361.5kgCOD/(m³·d) is achieved in spiral symmetry stream anaerobic bioreactor (SSSAB) under mesophilic condition (35℃). However, the performance and sludge features, which require further research, are still unclear under room temperature (10—30℃). In comparison to three compartmentalized anaerobic bioreactor (TCAB) and upflow anaerobic sludge blanket reactor (UASB), the performance and sludge features were studied with same operational conditions under room temperature. The results showed that:the average COD removal efficiency of SSSAB (88%) was higher than that of TCAB and UASB (80% and 78%). The first-order kinetic constant of SSSAB was 5.4d^-1, higher than that of TCAB (3.6d^-1) and UASB (2.2d^-1). In macro scale, compared with that from TCAB and UASB, the anaerobic granular sludge from SSSAB was clearer, more black and denser. Moreover, the surface of anaerobic granular sludge from SSSAB was rough and full of channels. The total amount of extracellular polymeric substance (EPS) of anaerobic granular sludge from SSSAB was higher than that of TCAB and UASB, which provided conditions for mass transfer between sludge and substrates. The protein (PN) / polysaccharide (PS) ratio of the sludge from SSSAB was lowest, which might indicate that it had more favorable strength and settling ability. The distribution of flocculability of the sludge from SSSAB was more reasonable, and its fluctuation was smaller compared with that from UASB.

Based on image processing technology and chaos theory, a novel method for quantitative characterization of gas jet images was proposed, which reflects the mixing performance. The Otsu method was used to find the best threshold value and hence the best segmented images. The mixing performance (M) is defined as the ratio of proportion of gas jet pixels (W) to standard deviation of the grayscale values in gas jet region (N) for characterizing spatial distribution of gas jet. Unsteady motions of the gas jet were characterized by the nonlinear time series of the mixing performances. As have shown, the stability of gas jet (1/V) decrease with the increasing modified Froude number under jetting regime, which confirms the validity of our approach. On top of that, the linear relation between stability and largest Lyapunov exponent (LLE) was obvious with a correlation coefficient of 0.954. For further research a linear model of stability and LLE were constructed. The results showed that the LLE can not only judge the mixing process is nonchaotic or chaotic, also the numerical size of LLE reflected the stability of gas jet.

In order to analyze the low wettability about the bituminous coal dust with medium metamorphic grade from the microscopic aspect, taking Zhaolou gas-fat coal in Juye coalfield as the example, the methods of nuclear magnetic resonance and X-ray photoelectron spectroscopy were utilized to achieve the microscopic molecular structures, and the molecular parameters' influence on the wettability was investigated. According to the experimental results, the aromatic degree of the coal dust in Zhaolou mine was 0.77, and the content of aromatic structure was large, which mainly contained protonated aromatic ring. Moreover, chain alkanes and cycloalkanes side chains held the most part of aliphatic chain structures, also some methyl side chains were included. Ether group (C—O—C) was the first superficial oxygen-containing functional group of coal dust in Zhaolou mine. The second was carbonyl (C=O). The third was hydroxy (C—OH). The last was carboxyl (COOH). Moreover, the content ratio of the above four groups was about 4:2:2:1.5. Not only the aromatic degree of the coal dust was high, the size of aromatic cluster was large and the condensation degree was high, but also the alkyl side chains were few and short, which made the coal's molecular structure unit shows a strong hydrophobicity. However, the carboxyl (COOH) and hydroxy (C—OH), which contributed much to the surface hydrophilicity, only held 13.53% and 21.45% of the whole content of superficial oxygen-containing functional groups, respectively. Therefore, influenced by microscopic molecular structures, the coal dust of Zhaolou mine showed an overall characteristic of hydrophobicity and poor wettability.

In order to study the characteristics of composite microbial fouling and the method of restraining fouling in the future, we chose iron bacteria (IB) and slime-forming bacteria (SFB) as the research objects which are the most common in microbial fouling. An experimental study was carried out on the plate heat exchanger for the relationship of the two bacteria in the composite microbial fouling formation and the fouling characteristics under different conditions. The results show that the microbial fouling has obvious induction period. The asymptotic value of fouling resistance of the iron bacteria is 2×10^-4m²·K/W, and the asymptotic value of fouling resistance of the slime-forming bacteria is 1.2×10^-4 m²·K/W. The iron bacteria have strong ability of fouling formation than the slime-forming bacteria. The fouling resistance of mixed bacteria with the proportion 1:1 is between the two above. No matter what kind of bacteria occupy the main volume, synergistic effects between the two kinds of bacteria prompt the ability of the fouling formation. The asymptotic values of fouling resistance of the mixed bacteria in 30℃ is lower than it in 35℃, and the time get to stabilization is twice that of 35℃. The velocity has obvious effect on the composite microbial fouling characteristics. The asymptotic values of fouling resistance of the mixed bacteria in 0.1m/s is twice that of 0.15m/s, and the time get to stabilization is 2.7 times that of 0.15m/s.

In order to find an effective way to test the micro oil leakage and judge the end point of sublimation drying during the biochemical medicine vacuum freeze-drying process, the leakage of silicone oil in the lyophilizer and primary sublimation drying process online were monitored by mass spectrometer. The results showed that the original silicone oil quantity was 1×10^-12 in the freeze-drying chamber tested by mass spectrometer. The mass spectrometer could test the leakage of silicone oil when the concentration was 1×10^-6 in 15 minutes. With the lyophilizer no-load running, N₂、O₂、H₂O、and Ar gas accounted for 82.31%、15.68%、1.37%、0.64% respectively. In the late period of medicine primary sublimation drying process, the four gases accounted for 82.47%、14.9%、1.75%、0.88% respectively. Each gas can be used to judge the end of the medicine sublimation drying progress in a no-load freeze-drying chamber. The present study provides a new method for the judgement of silicone oil leakage and biochemical medicine primary freeze-drying progress.

Thermodynamic and kinetic parameters of angiotensin converting enzyme (ACE) catalyzed hydrolysis of simulating substrate Hippuryl-Histidyl-Leucine (HHL) in vitro were determined by isothermal titration calorimetry (ITC). The effect of temperature on kinetic parameters was investigated; the results showed that the ACE-catalyzed reaction was endothermic with a small constant pressure specific heat capacity [c_p=0.2126kJ/(mol·K)]. The value of molar hydrolysis enthalpy ΔH_hydr was positive and increased as temperature rose. The reaction mechanism was in accordance with the Michaelis-Menten model in the temperature range (298.15—313.15K) ;the effect of temperature on the Michaelis constant (K_m) was negative, while catalytic constant (k_cat) first increased then decreased with the increase of temperature, reaching the maximum value of 2.534s^-1 at 308.15K. Initial rate method was also used in order to compare with ITC method. The K_m measured by the initial rate method was relatively large because of the limitation in itself. The inhibitory type of the drug enalapril, known as ACE inhibitor, was determined by ITC and enzymatic kinetics analysis. The results show that the inhibitor was a competitive inhibitor with inhibition constant K_I=12.1nmol/L. The ITC method is applicable for determining the inhibitor type in comparison with literature. It is a new approach for the development of ACE inhibitors. We determined that the active peptides Arg-Tyr-Leu-Gly-Tyr (RY-5) were noncompetitive inhibitors with K_I of 1.0μmol/L by using this method.

1,2,3-trimethylbenzene-indane system in the C₉ arene mixture has difficulty in separation due to their close boiling point. Purification of 1,2,3-trimethylbenzene was carried out by extractive distillation with sulfolane. Aspen Plus software was employed to simulate the extractive distillation process. The simulated values matched well with the experimental data, and their deviations were all less than 5%. The effects of theoretical tray, solvent ratio, reflux ratio and feeding location of the C₉ arene and solvent on the separation were investigated during the extractive distillation experiments and the Aspen process simulation. The results showed that under the optimized process parameters of the theoretical tray of 60—65, solvent ratio of 5—7, reflux ratio of 3—4, C₉ feeding location of No. 34—36 tray and solvent feeding location of No.8—10 tray, the high-purity 1,2,3-trimethylbenzene product can be obtained at overhead, and the mass fraction and yield can reach above 99% and 93%, respectively.

The methyl formate/methanol/water is one of the most common ternary systems in chemical processes. There are few studies on the separation of the methyl formate/methanol/water using batch distillation process and the dynamic control strategies are rarely reported. In this paper, the batch distillation process of this ternary system with a middle vessel was studied and the dynamic control strategies for this process were optimized. Dynamic control strategies were studied by adding the level control structure and the composition control structure based on the steady-state results using Aspen Plus and Aspen Dynamics. The results showed that the level control structure performed poorly with low methanol and water purities after the steady state was reached. Though the composition control structure improved the product purities, the abnormal oscillations occurred. A modified composition control structure was developed after analyzing the results from the composition control structure. The results indicated that the new control structure yielded a robust control of the middle vessel batch distillation process and improved all the product purities.

Heavy oil, oil shale and oil sands need heating to exploit or upgrade the crude oil, whereas microwave heating is a new heating technology with high-efficiency, quickness and purity which has great significance in cutting costs and improving efficiency in the unconventional oil resources development. The applications of microwave heating technology in the above mentioned three kinds of oil resources are described and discussed in details. The analysis shows that the microwave heating, which is in high energy utilization and environmentally friendly, can not only heating the whole reservoir rapidly and uniformly, but also assist to perform desulfurization and cracking reactions in order to upgrade the crude oil under the effect of catalyst. Conclusions have been drawn that the researches on high power microwave generator and laboratory evaluation device with more realistic formation conditions and the development of nanometer microwave additives as well as the combining microwave heating with other exploitation methods are the directions of development in the future. In the end, it is suggested that the relevant departments should give support to do field test in the small block.

Oil sand is a kind of unconventional oil resources and the pyrolysis technique of oil sand is suitable for industrial application. In this paper the fundamental research of oil sand pyrolysis was summarized, including the three stages of oil sand pyrolysis, properties of gaseous, liquid and solid products and various pyrolysis kinetic models of oil sand. Atmospheric retorting, pyrolysis under inert gas, hydropyrolysis, vacuum pyrolysis and combined pyrolysis technology were analyzed. The effects on the products yields and characteristics of different pyrolysis technologies were reviewed. The pyrolysis equipment were summarized, including fixed bed reactor, rotary retort, fluidized-bed retort and Alberta Taciuk Process (ATP) reactor. And special emphasis was placed on the rotary and fluidized-bed retorts using different ways of heat carrier and energy recovery. From the perspective of energy efficiency, the advantages and disadvantages of different technologies and equipments were analyzed by comparison. It was indicated that reducing energy consumption and improving energy efficiency were the key problems of pyrolysis technologies. Furthermore, the rotary and fluidized-bed retorts were more suitable for industrial application.

Adding appropriate proportion of catalysts can improve the coal gasification rate and reduce the initial gasification temperature．In order to study the effect of different anions (CO₃^2-、SO₄^2-、Cl^-) salts on the thermal weight loss process of FG coal, the CO₂ gasification experiments of coal were conducted in a thermogravimetric analyzer by loading eight kinds of catalysts (K₂CO₃, K₂SO₄, KCl;Na₂CO₃, Na₂SO₄, NaCl;FeSO₄, FeCl₂).And the loading amount of K⁺、Na⁺、Fe²⁺ was 0.001 mol/g, respectively．In addition, the non-isothermal dynamic model was used to fit data．The experiment results showed that the catalysts exhibit weaker effect on coal-CO₂ low-temperature pyrolysis, while the catalysis was obvious in high-temperature gasification．For potassium and sodium salts, when kations were the same, the activity order was CO₃^2-＞SO₄^2-＞Cl^-．For the iron catalysts, the FeSO₄ was observed to be superior to FeCl₂ in catalyzing gasification．The dynamics results indicated that the apparent activation energy of coal with catalysts within the range of 169～232.6kJ/mol was consisted with the above rules．It was reduced in different degree compared to that of raw coal (267.9kJ/mol).

To develop a step conversion process of coal pyrolysis/circulating fluidized bed (CFB) combustion, this paper focuses on realizing an optimal ash/coal mixing effect of moving bed within a limited height space of mixing section. A solid-solid cold mixing apparatus with adjustable cone shaped baffles inside was built and the mixing characteristics of particles were studied. Silica and quartz sand were used to simulate coal and circulating ash heat carrier from CFB, respectively. The influences of the material mixing ratio, the angle of baffles, the number and placement method (opposite and revolving) of baffles on mixing effect by using gravity mixing method were investigated, and the results were compared with those achieved by mechanical mixing. Mixing and dispersing coexist in the process of particles mixing. It was found that the more layers of 30°baffle by revolving placed, the more uniform of the silica and quartz mixture. The uniform mixture was obtained at the higher proportion of quartz sand to silica. Optimizing baffle structure and setting mode enhances convection mixing and shear mixing, which improves the solid-solid mixing effect obviously. Although the mixing effect of the cone shaped baffle is slightly worse compared with that of mechanical mixing, baffle mixing can still meet the requirements of the ash/coal mixing operation of coal pyrolysis with a solid heat carrier.

Facing the ever growing attention of environmental protection issues, many countries have formulated stringent standards of clean fuel, and the use of low sulfur diesel oil is the development trend, while the research of hydrodesulfurization (HDS) catalysts with high efficiency and stability is one of main directions. In this paper, we introduce the main research results about HDS, such as the reaction mechanism, main active components, the assistants and supports. The results indicate that the main reaction pathways of HDS are direct desulfurization and hydrogenation, and the main HDS route of 4,6-DMDBT of high steric hindrance should be hydrogenation and/or alkyl transfer. The catalytic mechanism of HDS is analyzed based on the composition and structure of catalysts, and the results indicate that the HDS activity is closely related to the catalyst's surface microstructure. At present, the supports of the catalysts are mainly alumina and modified alumina.

Thermodynamics of sulfur poisoning and coking on nickel-based catalyst for coal-based synthesis gas methanation were systematically analyzed. It was found that the reactions of the active metal Ni, Mo with H₂S, COS were spontaneous under the methanation reaction condition. The Ni-based catalysts could be poisoned by H₂S, COS at a partial pressure magnitude of 10^-10 and 10^-14, respectively, and the sulfur content for Mo added catalysts could be no more than 10^-6. Different types of coking reactions occurred at different temperature ranges, and the carbon deposition was mainly from the CO disproportionation reaction and the CO reduction reaction when temperature was 633.15—898.15K, while that was mainly from CH₄ cracking reaction when temperature was 898.15—983.15K. In addition, Ni-based catalysts could avoid carbon deposition at 0.1MPa by adding water vapor with the amount above 11.11% (mole fraction).

Catalysts of Co-Cu composite oxides doped with metals cocatalysts were prepared using the impregnation method and their activity in the catalytic decomposition of N₂O were tested. The results showed that the catalytic activity of Co-Cu composite oxide was largely enhanced by the addition of rare earth Ce and transition metal Fe. XRD, BET, SEM, and H₂-TPR were used to characterize the Cu-Co composite oxide catalysts, and the results showed that the addition of the cocatalyst did not change the catalysts' crystal structures, but did enhance the reduction ability of the Co and Cu ions. The reduction peaks even shifted to the low temperature region after adding Ce and Fe, and therefore the catalytic activity for the decomposition of N₂O was improved.

1,3-propanediol was synthesized without generating aldehyde by-products by catalytic hydrogenation of diethyl malonate over Cu/HMS catalyst in a continuous high pressure fixed-bed reactor．Effects of raw material concentration, ratio of H₂/DEM, liquid hourly space velocity, reaction temperature and reaction pressure on the hydrogenation reaction were investigated. And the main causes of the catalyst deactivation were analyzed by XRD and TEM characterizations．Under the condition of raw material concentration as 7.5wt%, ratio of H₂/DEM as 400, liquid hourly space velocity as 1.8h^-1, reaction temperature as 200℃ and reaction pressure as 1.8MPa, the catalyst showed good catalytic hydrogenation performance, and diethyl malonate conversion and 1,3-propanediol yield reached 93.4% and 52.8%, respectively．The catalyst was deactivated completely after 120h．From both XRD and TEM results, the main causes for the catalyst deactivation were considered as the agglomeration of particles, loss of active components or the partial oxidation to Cu⁺．

Nano-CeO₂ (20nm) was prepared by hydrothermal method, and then alkaline-earth metal oxides (MgO、CaO and BaO) of different concentrations were introduced into the nano-CeO₂. The catalytic results showed that the doping of these three alkaline-earth metal oxides all had negative effects on the catalytic performance of nano-CeO₂. In addition, the prepared nano-CeO₂ were characterized with TEM, XRD, BET, XPS and TPD. The results show that a small amount of doped alkaline-earth metal oxideswere in the form of disorder and they couldn't lead to the lattice deformation and showed little effects on the morphology, particle size and textural properties, but they had great effect on the ratio of Ce(Ⅳ)/Ce(Ⅲ) as well as the amount of the acid and base sites. In addition, high ratio of Ce(Ⅳ)/Ce(Ⅲ) and a large amount of acid and base sites are essential for the catalytic performance of nano-CeO₂.

A series of ZSM-5 nanozeolites with hierarchical porosity were prepared by a seeding method of adding cetyltrimethyl ammonium bromide (CTAB). The hierarchical ZSM-5 molecular sieves were characterized by XRD, SEM, NH₃-TPD, XRF and N₂ sorption. The impacts of CTAB amount on the zeolite structure, acid property and the catalytic performance in methanol aromatization were investigated. The results indicated that the CTAB amount significantly affected the crystal morphology, pore structure, acidity and thus influenced the catalytic stability and aromatic selectivity considerably. The hierarchical ZSM-5 catalysts exhibited an increased mesopores by introducing CTAB and high stability for the MTA reaction due to the enhanced mass transfer and reduced diffusion limitation. Also, the formation of framework Al was suppressed by the addition of CTAB. The Si/Al ratio was increased by increasing the amounts of CTAB, which decreased the acidity of hierarchical ZSM-5 molecular sieves and the aromatics selectivity.

Using cationic surfactant CTAB as organic template agent, mesoporous La_0.6A_0.4NiO₃ (A=Ce、Sr、Y、Nd、Pr) perovskite-type oxides were synthesized by co-precipitation method, and the crystalline structures, surface topography, superficial area, pore size distribution and surface properties were characterized by XRD, SEM, FTIR, BET and temperature-programmed technology, respectively. At the same time, the catalytic performances, liquefaction product distributions and liquefied oil production of mesoporous La_0.6A_0.4NiO₃ perovskite with A-site ions replaced and were studied. The results showed that the A-site ions could dope with different degrees of crystal, and Pr³⁺could better replace La³⁺ by isomorphous substitution, and La_0.6Pr_0.4NiO₃ perovskite had larger specific surface area and pore size distribution and stronger surface conductivity and oxygen species alkaline center, therefore it possessed high yield of liquefied oil and low rate of residue on bagasse high-pressure liquefaction reaction, and the main components of bio-oil products were acetyl citric acid three butyl ester、tributyl citrate、ethyl phenol、6-ethyl-3-peptide ester, with improved product quality.

Due to their unique physical and chemical properties, nanostructured metal sulfide materials have shown excellent electrochemical performance. Herein, we present a review on the research progresses of the nanostructured cobalt sulfides materials for supercapacitors following the clues of the various morphologies of cobalt sulfides, their compositing with graphene and the nanoarrays grown directly on the conductive substrates. The preparation methods of the nanostructured cobalt sulfides and the principles of improving their electrochemical performance are summarized. Both the compositing with graphene and the growth on the conductive substrates strengthen the structure stability and facilitate the electron-transport, and the rate capability and cycling stability are improved accordingly. It indicates that the design and modification of hollow nanostructure, the compositing ways with graphene and the pretreatment of conductive substrates are the research emphases in the future. Additionally, it is crucial to develop a simple and cheap route for the large-scale production of cobalt sulfides in order to meet the need of the commercial applications.

The graphene and molybdenum carbide were prepared by the modified Hummers method and carbon thermal reduction method, respectively. The morphology of the materials were revealed using scanning electron microscope (SEM), and the structures were characterized with XRD. The electro catalytic activity of oxygen reduction of the materials were measured by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The results revealed that α-MoC/graphene composite exhibited better electro catalytic activity than pure graphene or α-MoC, with a higher oxygen reduction peak current and more positive onset potential. The microbial fuel cell assembled with 12mg/cm² α-MoC/graphene composite as cathode catalyst delivered a higher power density of 417.6mW/m², which was 68.2% of that obtained using Pt/C-catalyst cathode. Therefore, using the inexpensive α-MoC /graphene composites as MFCs cathode oxygen reduction catalyst holds great potential for application.

The iron nanoparticles have been synthesized through sodium borohydride chemical solution reduction of ferric iron-impregnated montmorillonite (Mt) in the presence of polyvinylpyrrolidone (PVP) as a stabilizer. A combination of scanning electron microscope, transmission electron microscope, X-ray diffraction, and X-ray photoemission spectroscopy was used to characterize the materials. As a result, these obtained iron particles were well dispersed on the external surface of Mt and were of roughly spherical morphology and uniform particle size with a mean diameter about 34nm. The metallic iron cores remained in these iron nanoparticles were protected from further oxidation by their native iron oxide shell with a thickness of about 3nm. Compared with the iron nanoparticles synthesized in the absence of Mt and PVP, these obtained iron nanoparticles exhibited reduced size and improved dispersity, which should be attributed to the dispersing action of the polymer stabilizer and the delaminated structure of Mt as a results of the interfacial interactions between Mt particles and PVP.

Interconnected ordered macroporous SnO₂ were prepared via template method by utilizing polystyrene (PS) microspheres as template and SnO₂ nanocrystals as framework. The pore size of the macropores can be controlled by changing the diameter of PS microspheres. Macroporous SnO₂ with average pore sizes of 200nm and 260nm were prepared via PS microspheres with the diameters of 284nm and 356nm, respectively. The as-prepared samples were characterized by thermogravimetric analysis, scanning electron microscope (SEM), X-ray diffraction (XRD), and Nitrogen adsorption-desorption analysis. The as-prepared samples are consist of ordered macropores, interconnected nanopores, and SnO₂ nanocrystals. The as-prepared sample possess macro-/meso-/micro-structure with large surface area, which is beneficial for gas-sensing. The responses of macroporous SnO₂ with average pore size of 200nm and 260nm towards 300mL/L ethanol vapor at 280℃ are 145 and 245 respectively, which are 2.2 and 3.7 times higher than that of SnO₂ nanocrystals.

Using graphene oxide and carboxylated carbon nanotube as base material and gluconic acid β lactone as crosslinking promoter, we prepared a three-dimensional (3D) porous aerogel material functionalized by polyethylenepolyamine (PEPA) with a freeze-drying method. The PEPA loading was adjusted by changing the PEPA dosage. The as-synthesized 3D porous aerogel material were characterized by FTIR, XRD, TG, SEM, XPS, Raman and N₂ adsorption-desorption. The results indicated that PEPA was grafted by an amide bond between PEPA and graphene oxide. The 3D porous material had a honeycomb like-appearance. The specific surface area, pore volume and average pore size were decreased with increasing PEPA loading. The adsorption of CO₂ on the 3D honeycomb-like material was based on a mechanism of chemisorption. At 200kPa and 328K, the CO₂ adsorption capacity on the 3D porous material with a PEPA content of 55.8% reached up to 3.9mmol/g, which was 9.8 times to that on the aerogel without PEPA loading. The results showed that crosslinking polyethylenepolyamine with graphene oxide sheet and carboxylated carbon nanotube to prepare 3D porous aerogel material effectively improved the CO₂ adsorption capacity.

Aliphatic polyether-polyurethanes elastomer (PUs) were prepared by transesterification polycondensation from polytetramethylene glycol (PTMEG), dimethyl-hexane-1,6-dicarbamate (HDU) and 1,4-butanediol in the presence of dibutyltin oxide as catalyst. The degradation mechanism of PU and effects of raw material ratio on its thermal stability were examined by TGA and FTIR. The results showed that PU samples presented a two-stage degradation associated with the degradation of urethane hard segment and PTMEG soft segment, and the degradation products of urethane hard segment included carbondiimide, CO₂, tetrahydrofuran (THF) and water, while that of PTMEG soft segment were tetrahydrofuran (THF) and water. Moreover, thermal stability of PU increased with the decrease of hard segment content, and the initial degradation temperature was raised from 282℃ to 327℃.

Self-assembled pseudopolyrotaxane hydrogel formed by polyethylene glycol (PEG) and cyclodextrin (CD) can be used as a slow-release carrier for proteins. In this ternary system, there may be certain interactions between PEG, CD and proteins. With bovine serum albumin (BSA) as the model protein, the structure changes of BSA in the PEG/a-CD pseudopolyrotaxane hydrogel was studied by ultraviolet-visible absorption spectrum, fluorescence spectrum, powder X-ray diffraction (XRD) techniques, and NOESY spectra. The results showed that BSA had a significant effect on the formation rate of the hydrogel. The fluorescence and synchronous fluorescence spectrum analysis showed that the ternary structure of BSA had minor changes in the hydrogel, which led to red-shift of the maximum fluorescence emission wavelength, and the microenvironment of Trp and Tyr residues also changed slightly in the hydrogel. These changes became more significant with the increasing of BSA concentration. Moreover, when BSA was added, the diffraction angles in XRD spectra at 2q = 6.56°, 11.54°, 12.06°, 20.56°, 22.04°and 26.04°showed remarkable changes compared with those of the pure pseudopolyrotaxane, demonstrating that the crystalline pattern of PEG/a-CD pseudopolyrotaxane was changed in the presence of BSA. The results reflected that BSA was not simply physically mixed with the PEG/a-CD pseudopolyrotaxane hydrogel, but that it might prefer to form complexes with the hydrogel. 2D NOESY spectra also showed that the presence of mutual coupling of hydrogen atoms between BSA and PEG/a-CD, demonstrated the interaction between them.

Ligninsulfonates are byproducts of the sulfite-pulping procedure. In this paper, we prepared CSL/GQDs composites by uni-form modification the GQDs with lignosulfonate calcium (CSL) via in-situ reaction in a green and facile preparative route. This article uses fluorescence spectroscopy、UV-vis spectra and TEM to investigate the optical properties, the molecular structure and the ion detection of composites. The composites exhibit strong fluorescence emission and nice selectivity which is dramatically enhanced as high as four times that of the free GQDs. The prepared sensor allows high sensitivity and specificity toward Fe³⁺ analysis and presents a good linearity in range of 10—500μmol/L. Furthermore, this fluorescent probe preparation is simple, low cost, and highly sensitive and specific toward Fe³⁺ analysis.

Consolidated bioprocessing (CBP), refers to bioprocessing by exploitation and utilization of ideal chassis microorganisms to directly convert lignocellulose into bioproducts in one processing. The research background, development concepts and technology roadmaps of the CBP were briefly introduced in this paper. Subsequently, we comprehensively reviewed the different strategies and the recent research progress in CBP lignocellulose to second generation bioethanol production. Then, the advantages and bottleneck factors of the native, recombinant and co-culture strains used in CBP bioethanol fermentation were analyzed. The genetic engineering, metabolic engineering and other techniques' application value and potential for overcoming the barrier factors of CBP bioethanol production and increasing bioethanol yield were assessed. Ultimately, this review provided a brief commentary on the contribution of emerging biotech, such as ‘omics’ and synthetic biology and on CBP bioethanol production and the recent conditions of the lignocellulosic bioethanol production toward commercialization scale, as well as opportunities and challenges in the future.

Gibberellins (GAs) are one of the five plant hormones which play an important role in plant growth and development. They affect stem elongation, seed germination, elimination of dormancy, flowering and so on. Gibberellins have been widely used in the agriculture, forestry and brewing industries, and have brought great economic benefits. The industrial production of gibberellins is based on submerged fermentation by Fusarium fujikuroi. Although gibberellins have a diversity of applications and huge economic benefits, high production costs severely restrict their widespread application. This review summarizes the metabolic pathway and the regulatory mechanism for gibberellins biosynthesis. Also, the strains, nutritional factors, fermentation conditions, fermentation techniques and separation and purification process are discussed in detail. Meanwhile, it is pointed out that the focus of future research should be placed on screening high-yield strains as well as improving fermentation technology, in order to reduce the production cost and achieve large-scale application of gibberellins.

With the development of metabolic engineering, the metabolic engineering research method of single pathway regulation has evolved into global metabolic network regulation. In order to realize the chemical industrial vision of ‘biorefineries’ in the field of industrial biotechnology, metabolic engineering requires a systematic study with well-defined principles and tools. One of the key problems is balancing metabolic flux. Based on the traditional, rational metabolic engineering and the rise of the problems existing in the combinatorial engineering in recent years, the researchers proposed a modular metabolic network optimization strategy using multiple module projects. The modular strategies in progress of application in metabolic engineering during recent years are summarized. In addition, the main problem and future direction of this strategy to optimize metabolic pathways are presented in light of the current knowledge of multiple module application.

3-Phenyllactic acid (PLA) is a high-value organic acid and also an important metabolite of some lactic acid bacteria with effective activities against a wide range species of gram-positive and gram-negative bacteria and some fungi. This interesting compound has potential applications in chemical and pharmaceutical industry, biotechnology, and material and food areas as either a potential alternative to the chemical preservatives or a promise key monomer for the preparation of new polymer materials of poly(phenyllactic acid)s by polymerization, which have enhanced properties compared with those of wide-used poly(lactic acid)s. The present review summarizes the advances in the antibacterial activities, the available microbial strains, the biotransformation and biosynthesis, the metabolic pathways within these microorganisms, and the downstream separation and purification methods of PLA. The bacteria strains are crucial to the bioconversion or biosynthesis production of PLA. Although the recombinant engineering strains always have high conversion efficiencies, the construction of these strains is complex. The screening of new, safe strains with satisfactory bioconversion properties from natural resources is of great importance and an interesting approach for the enhancement of the bioconversion efficiency and the final concentration of PLA in the biotransformation broth. Moreover, the separation of PLA from the fermentation or biotransformation feedstocks is mostly focused on the laboratory scale, which cannot match industrial requests. Further investigations on the novel isolation and purification techniques are still needed.

The crude PVA-degrading enzymes were extracted from a mixed culture obtained by selective culturing with PVA as the sole carbon source. The degradation capability, enzymatic properties and degradation products of the enzymes were investigated in this study. The results indicated that the degradation of PVA1799 by the PVA-degrading enzymes was much better than those of PVA1788 and PVA124. The optimal temperature for the crude enzymes was 40℃ and the optimal pH was 7.0. Fe²⁺ addition promoted the PVA-degrading enzymes' activity. It could increase the enzyme activity by about 26%. The relative molecular mass of PVA1799 decreased by 14.8% after 6 hours under the optimum conditions. At the same time, the melting point of the PVA sample was reduced from 221.3℃ to 216.7℃ after 6h. The results of High Performance Liquid Chromatography (HPLC) analysis indicated degradation products containing acetic acid. The iodoform reaction indicated the presence of methyl ketone in degradation products. A possible degradation pathway of PVA was oxidation to carbonyl group and breaking of the two adjacent hydroxyl groups on the long carbon chain. Acetic acid is the final product.

Unconventional reservoirs were very important oil-gas areas. Traditional water fracturing fluid had the trouble of rheological property and friction which made the fluid unable to satisfy the technology for reducing pressure and increasing injection. To solve the problem, the polyacrylamide fracturing fluid drag reducing agent (PAM-FR) was synthesized by polyacrylamide (PAM) and 2-acrylamido-2- methyl propane sulfonic acid (AMPS) and stearyl acrylate (SA) with inverse emulsion polymerization. Using an infrared spectrometer, projection electron microscope and laser particle size analyzer, the structure and size of PAM-FR were characterized. In PAM-FR containing sulfonic acid groups, the emulsion particle size of PAM-FR is 80nm. When testing the ability of drag reduction and rheological property, compared to water, the drag reduction rate of 1g/L PAM-FR solution exceed 78% at 25℃ and 10m/s. The PAM-FR has obvious characteristics of good resistance to shearing and solution and more compatibility with clay stabilizer and clean up additive. The PAM-FR adapts to the volume of fracturing of unconventional reservoirs.

The synthesis process of polycarboxylic water reducer was mainly composed of heating. The synthesis process at ambient temperature has been less reported. To solve this problem, the paper researched the influences of reaction temperature, holding time, feeding time of A and B, acid ether ratio, and ammonium persulfate (APS) weight on the performance of polycarboxylic water reducer that was synthesized by using methyl allyl polyethenoxy ether (TPEG) and acrylic acid (AA) as the main polymeric monomers. Orthogonal experiments showed that when the temperature is 30℃, holding time is 1.5 hours, feeding time of A is 2.25 hours, feeding time of B is 3.5 hours, n(AA):n(TPEG)=3.5:1, and APS ratio is 0.5%, the polycarboxylic water reducer achieves optimum performance. When water-binder ratio is 0.29 and a dosage of 0.25% of such obtained water reducer is used, the initial cement paste fluidity reaches 240mm and the slump loss is 5mm after 1 hour. It has better dispersity and dispersion stability than other polycarboxylic water reducers at the same dosage.

NO_x and SO_x, which account for high proportions in the exhaust gas of ocean ships burning low quality heavy oil, result in threats to the marine ecological environment and the health of residents in the coastal area. In this paper, various types of post-treatment technologies for purification of marine exhaust were introduced, and their main advantages and disadvantages were analyzed. The techniques of desulfurization, denitration, and desulfurization-denitration integrated technology for the control of ship exhaust gas pollutants emission, were reviewed. It is concluded that, in practice, the current post-treatment technologies which can only treat a single pollutant was not suitable for effective marine exhaust emission reduction, while the desulfurization-denitration integrated technology would be the main direction which can achieve the comprehensive treatment of ship exhaust gas currently. The future direction of marine exhaust post-treatment technology development is still being explored. There are two main bottlenecks of the desulfurization-denitration integrated technology. First, although low temperature plasma and photocatalysis which were developed in recent years show great potentials, the high cost and security concerns still hinder their applications in ships. On the other hand, sea water modification method which shows high treatment efficiency, small foot print and lower cost, may become one of the most promising methods in the effective treatment of ship exhaust gas in the future.

Different seawater pretreatment processes were studied in terms of comparative analysis of turbidity, chemical oxygen demand (COD_Mn), pollution density index (SDI₁₅), etc and the effects on ultrafiltration membrane flux of different pretreatment processes. Coagulation-sedimentation or air flotation process can reduce seawater turbidity effectively. With sand filtration or fibre filtration, turbidity can be reduced to around 0.3NTU. When seawater was treated by the ultrafiltration, regardless of the method, the turbidity of the water and SDI₁₅ can meet the requirement of reverse osmosis. When ultrafiltration is adopted directly, the removal effect of COD_Mn was very bad. When ultrafiltration combines with coagulation-sedimentation or air flotation, the removal rate of COD_Mn was enhanced. Pretreament methods have a great influence on ultrafiltration membrane flux. Ultrafiltration membrane flux declined rapidly by ultrafiltration directly. Membrane flux attenuation slows by coagulation-sedimentation or air flotation. Membrane flux attenuation was well controlled after sand filtration or fibre filtration. Membrane flux attenuation is lowest by using coagulation-sedimentation/ fibre filtration.

Azo dyes, with high chromaticity, are difficult to degrade by traditional methods to meet the industrial emission standard, which become great threat to the environment. In this paper, Acid Red B, as a selected azo dye, was degraded with advanced oxidation process by Fe₃O₄ activating peroxymonosulfate (PMS) with ultrasound irradiation. This study focus on the effect of parameters on the degradation rate such as the addition of Fe₃O₄, the concentration of PMS, the ultrasound power and frequency, the initial concentration of Acid Red B and the initial pH of the solution. The optimized operating parameters are Fe₃O₄ 1.0g/L, PMS 60 mmol/L, ultrasound frequency 50kHz, ultrasound power 80W. This method can be applied in a wide range of pH from 3.5 to 8.5 and is capable of degrading high concentration of Acid Red B up to 1g/L. The study also investigated the reusability of the catalyst. The catalyst was recycled for 3 times and the decoloration rate still remained above 95%. These results can be applied to the industrial process of wastewater treatment of azo dyes.

In order to study the feasibility of the treatment of heavy metal ions and COD in electroplating wastewater by water-quenched blast furnace slag (WBFS), the effect of factors, such as adsorbent dosage, pH, contact time and temperature on the adsorption of Cu²⁺、Zn²⁺ and COD were investigated. On the basis of single factor experiments, a three-factor, three-level Box-Behnken central composite design (CCD) was utilized. Two multinomial mathematical models were established by response surface methodology, and the effectiveness of the model was verified. Response surface analysis was used to discuss the interaction of the three factors and determine the optimum level of the main effects. The results showed that the optimal adsorption conditions were adsorbent dosage 1.4g, pH 8, contact time 120 min, and under these conditions, the removal of Cu²⁺、Zn²⁺ and COD was 99.35%、98.46% and 53.63%, respectively. The experimental data and model predictions agreed well. The concentrations of Cu²⁺ and Zn²⁺ in the effluent were lower than the standard limitation of newly-built enterprises in electroplating wastewater (GB 21900—2008), and COD could not satisfied with the emission requirement. So the application of blast furnace slag adsorption technology was not enough to remove all harmful substances in electroplating wastewater. Therefore, it could be used as an assistant process, combined with other technologies to remove heavy metal ions and organic compounds in electroplating wastewater, so that the water quality of the effluent achieved national level of discharging standard.

In order to discuss effect of seasonal variation on the enhanced nitrification of suspended carriers in typical engineering project, static breaker test method as well as the high-throughput sequencing method was employed to study variation of nitrification rate and composition of nitrobacteria of the activated sludge system and the combined process of suspended carriers and activated sludge system (shortened form combined process) in autumn and winter, based on a sewage treatment plant which adopted a modified A²/O-MBBR process in Qingdao. The results showed that the specific ammonia oxidation rate (K_A) of the activated sludge system was generally greater than that of the specific nitrification rate (K_N). However, the K_A of combined process was roughly equivalent to that of K_N. The K_A and K_N both dropped as the temperature decreased in autumn and winter either for activated sludge system or combined process. K_A dropped slightly larger than K_N. Compared with activated sludge system, the K_A and K_N were improved by combined process in autumn and winter, especially the K_N in winter. Suspended carrier has significant enrichment ability for AOB and NOB, and better for NOB.

The degradation of Ametryn (AMT) was evaluated by UV activated persulfate (PS).The degradation process was based on generation of sulfate radical (·SO₄^-), hydroxyl radical (·OH).The effectiveness and the reaction kinetics model of the UV/PS process in the degradation of AMT was investigated. Effects of different concentrations of inorganic anions (Cl^-, HCO₃^-, NO₃^-), natural organic matter (humic acid) in aqueous solution for the effectiveness and the kinetics of AMT degradation was studied, while emphasis was given on the degradation of AMT in ultrapure water, tap water, effluent water of different process in XiDong Water Plant as the solution backgrounds, and the possible degradation products and pathways of AMT were proposed.The results showed that the degradation of AMT in UV/PS would follow the first-order reaction kinetics model (R²≥0.94). When Cl^- concentration was 5mmol/L, the decomposition of AMT would be inhibited, while the influence of other Cl^-concentration were ignored. k_obs decreased with the increase of HCO_3-, NO_3-would speed up the removal of AMT, when NO_3- concentration was 200mmol/L, the increasing extent was weakened. k_obs decreased with the increase of humic acid.The degradation rate of AMT in ultrapure water was highest among different water matrices.The major degradation products in this study are 2-methylthio-4,6-diamino-1,3,5 -triazine, 2-hydroxy -4-ethylamino-6-isopropylamino-1,3,5-triazine.

Based on the optimized parameters in achieving the in situ salt reduction, the evaluation of coking wastewater treatment process in Shaogang Steel Plant was conducted with special emphasis on the evolution of conductivity. The analysis of water quality, operation parameters, types and quantity of reagents were carried out to examine the variation of conductivity in each unit, and then to elucidate the influencing factors for salinity changes. The influence of biodegradation of coking wastewater, the applied reagent dosage and the coagulation process on the concentration evolution of main anions were investigated and the fate of salt residual in water as well as sludge during biochemical and physiochemical process were studied. The results showed that the optimized biodegradation and physiochemical degradation of coking wastewater can lead to partial reduction in salinity. The increase of salt concentration is mainly attributed to the addition of phosphorus and alkalinity in the biochemical process, the employment of coagulation in physiochemical process, as well as the mineralization of organics. The reduction of salt was resulted from the transformation of N, S constituent and strong electrolyte C₆H₅O^- into N₂, H₂S, CH₄, CO₂, H₂O. Also, the complexing precipitation, insoluble salts of coagulation sedimentation coming from the combination of Fe²⁺ with CN^-, S^2-, SCN^-, OH^-, CO₃^2-in the physicochemical process contributed to the decrease of salt. The separation of refractory organics in biochemical procedure, the dosage and the order of chemical reagent, the optimization of pH were found to be beneficial for in situ reduction of salt. It was suggested that the choice of process principle, reaction control and optimization of conditions are the significant factors that influence the changes of salt during coking wastewater treatment.

A series of Ce-Cu-Al-O mixed metal oxide adsorbents for deep removal of H₂S at low temperature was prepared by a co-precipitation method. Characterization methods such as XRD, N₂ physical adsorption, SEM, XPS were used to analyze the samples before and after desulfurization. The influence of Ce content, calcination temperature, space velocity, adsorption temperature and impurity gas on the removal of H₂S was investigated. It was found that Ce-Cu-Al-O adsorbents were able to remove H₂S from CO₂ at 40℃and the adsorbent with 10% Ce (10Ce-Cu-Al-O) exhibited the highest breakthrough capacity of 94.1mg/g. The characterization results show that the addition of CeO₂ could effectively improve the dispersion of CuO, the BET surface areas and pore volumes of the adsorbents. A relatively high calcination temperature, high space velocity and balance gas CO₂ will all inhibit the H₂S adsorption. The H₂S breakthrough capacity of 10Ce-Cu-Al-O increased with temperature and there was no COS impurities generated when the desulfurization temperature was not higher than 100℃. The characterization results of the used adsorbents showed that the aggregate components resulted in the decrease of the BET surface areas and pore volumes. In addition, the regeneration experiment indicated that a relatively low temperature of 100℃ can be applied to regenerate the used 10Ce-Cu-Al-O adsorbents in air.

Adsorption of toluene on four aluminium based metal-organic framework (Al-MOF) was investigated by grand canonical Monte Carlo simulation (GCMC) method and laboratory adsorption tests. It was found that the adsorption of toluene on Al-MOF could be well described by the Dreiding force field. Due to the Al-MOF's high surface areas and abundant pore volumes, the adsorbed capacity of toluene molecules at 298K, 1.5kPa reached 1375mg/g, 866mg/g, 807mg/g and 504mg/g for MIL-101, CYCU-3, MOF-519 and CAU-3-BDC respectively, which were all higher than that of most traditional adsorbents (＜400mg/g). The preferential adsorption sites of Al-MOF for toluene molecules were analyzed using snapshot and density distribution profile. Results demonstrated that toluene molecules were preferentially adsorbed into small pores when the loading amount was small. Subsequently, more molecules were adsorbed into large pores when the loading amount increased. In addition, the interaction between toluene molecules and organic ligand was stronger than that between toluene and metal cluster, which indicated that organic ligands are preferential sites. The adsorbed amount of toluene on MOF at 298K and 1.5kPa were found to change linearly with the BET surface area, pore volume and density of frameworks, respectively.

Phosphogypsum (PG) desulfurization slag is the residue from chemical decomposition of PG, of which the main component is CaO. Leaching PG desulfurization slag with an ammonium chloride solution and carbonating with CO₂ to prepare calcium carbonate is an effective way to utilize the calcium in the slag. In this paper, the composition, calcium leaching rate and pH of leaching liquid in different concentrations of ammonium chloride were analyzed. To find out the influence of ions such as ammonia, iron, aluminum and magnesium in the leaching liquid on the crystal form of calcium carbonate, NH₄Cl-NH₃·H₂O solution containing impure ions were prepared and the XRD crystal forms of products were compared with the products obtained by PG desulfurization slag under the same conditions. It turned out that with the increasing of ammonium chloride concentration, pH value and content of aluminum decreased, while the content of iron and magnesium increased. Within the scope of the concentration of ammonium chloride, NH₄⁺ has a promoting effect on the formation of vaterite; iron and magnesium facilitate the formation of calcite. Because aluminum's form is different with the increasing of ammonium chloride concentration, aluminum facilitates the formation of vaterite when the concentration of ammonium chloride was 1mol/L, but facilitates the formation of calcite when the concentration of ammonium chloride was up to 1mol/L. The interaction of impurities made the crystal form of vaterite when the concentration of ammonium chloride was below 4mol/L. However, when the concentration of ammonium chloride was 4mol/L, the interaction of impurities made the product a mixture crystal form of vaterite and calcite.

With the increasing depletion of fossil fuels, recovering industrial low temperature waste heat is becoming an effective way to save energy. Aimed at the problem of energy recovery and reuse, based on the organic Rankine cycle and using low-temperature coal-fired waste gas (about 70℃) and cold energy of liquefied natural gas (LNG, about -162℃), this paper presents a three-stage system by which CO₂ liquefaction and power generation are achieved. The effects of expander inlet pressure and temperature on thermal performance of the LNG three-stage cold energy utilization system were analyzed in detail, and the optimal cycle parameters were obtained. HYSYS software simulation for the system was done with comparative analysis on a three-stage system and a two-stage system. The results show that for a three-stage cold energy utilization system, the thermal efficiency and energy efficiency of the generating unit increased 57.74% and 36.67% compared to those of a two-stage system;the net work output was 61.16% greater than that of a two-stage system. According to the efficiency of 90% power generation and 0.5 Yuan/(kW·h) calculation, the three-stage cold energy utilization system can result in saving of 0.52 million RMB every year. At the same time, the CO₂ liquefaction capacity is 1580kg/h which can reduce emission of CO₂ about 1.365×10⁴t/a. The system can bring considerable economic benefit and achieve better emission reduction.