Accurate prediction of the onset of turbulent fluidization still remains elusive owing to the dependence of the transition velocity on several factors including measurement methods and interpretation of results. In this work, numerical simulations using the two fluid model (TFM) are performed in an attempt to predict the regime change reported by Gopalan et al. (2016) in a small scale pseudo-2D gas-solid fluidized bed containing Geldart D particles. Various time and frequency domain analyses were applied on predicted absolute and differential pressure time series data to reveal the bed dynamics. Numerical predictions of the transition velocity, U_c are in reasonably good agreement with experimental results from the small scale challenge problem. The literature correlations completely fail to predict the transition velocity for the system considered in this work. This work thus provides a different approach for validating the CFD model against experimental measurements.

For a fully baffled tank stirred by a Rushton turbine (RT), the flow pattern will change from double-to single-loop as the off bottom clearance (C) of the RT decreases from one third of the tank diameter. Such a flow pattern transition as well as its influence on the macro mixing efficiency was investigated via CFD simulation. The transient sliding mesh approach coupled with the standard k-ε turbulence model could correctly and efficiently reproduce the reported critical C range where the flow pattern changes. Simulation results indicated that such a critical C range varied hardly with the impeller rotation speed but decreased significantly with increasing impeller diameter. Small RTs are preferable to generating the single-loop flow pattern. A mechanism of the flow pattern transition was further proposed to explain these phenomena. The discharge stream from the RT deviates downwards from the horizontal direction for small C values; if it meets the tank wall first, the double-loop will form; if it hits the tank bottom first, the single-loop will form. With the flow pattern transition, the mixing time decreased by about 35% at the same power input (P), indicating that the single-loop flow pattern was more efficient than the double-loop to enhance the macro mixing in the tank. A comparison was further made between the single-loop RT and pitched blade turbine (PBT, 45°) from macro mixing perspective. The single-loop RT was found to be less efficient than the PBT and usually required 60% more time to achieve the same level of macro mixing at the same P.

This work focuses on drop breakage for liquid-liquid system with an adoption of numerical simulation by using computational fluid dynamics and population balance model (PBM) coupled with two-fluid model (TFM). Two different breakage kernels based on identical breakage mechanism but different descriptions of breaking time are taken into account in this work. Eight cases corresponding to distinct configurations of agitator are carried out to validate numerical predictions, namely agitators with different porosity and hole diameters, respectively implemented in Cases 1 to 5 and Cases 6 to 8. The results are compared with experimental data for testing the applicability of both kernels. Simulations are implemented, in this work, with an approach of class method for the solution of population balance model by the special-purpose computational fluid dynamics solver Fluent 16.1 based on finite volume method, and the grids used for meshing the solution domain are accomplished in a commercial software Gambit 2.4.6. The effects of configurations of agitator corresponding to different parameters mentioned above on final Sauter mean diameter are equally concentrated in this work. Analysis of both kernels and comparisons with experimental results reveal that, the second kernel has more decent agreement with experiments, and the results of investigations on effects of agitator configurations show that the influences of these parameters on Sauter mean diameter are marginal, but appropriate porosity and hole diameter are actually able to decrease Sauter mean diameter. These outcomes allow us to draw general conclusions and help investigate performances of liquid-liquid system.

The heat transfer efficiency during the pyrolysis process is a key factor to be considered in the design of pyrolysis reactors. In this study, the average apparent heat transfer characteristics of molten plastic pyrolysis in a vertical falling film reactor were explored by experiments and numerical simulation and the apparent heat transfer coefficients were determined. In addition, the temperature distribution and the thickness of the liquid film in the reactor were predicted and the influences of pyrolysis temperatures on the average apparent heat transfer coefficients were discussed.

In this study, the performance of stable nanofluid containing SiO₂ nanoparticles dispersed and stabilized in high salinity brine for asphaltene inhibition in dynamic condition is evaluated. In the first stage of this work, the stability of silica nanoparticles in different range of water salinity (0-100000 mg·L^-1) is investigated. Next, stable nanofluid containing highest salinity is selected as asphaltene inhibitor agent to inject into the damaged core sample. The estimated values of oil recovery for base case, after damage process and after inhibition of asphaltene precipitation using nanofluid are 51.6%, 36.1% and 46.7%, respectively. The results showed the reduction in core damage after using nanofluid. In addition, the relative permeability curves are plotted for the base case, after damage process and also after inhibition of asphaltene precipitation using nanofluid. Comparison of relative permeability curves shows, relative permeability of oil phase decreased after damage process as compared with the base case. But after using nanofluid the oil relative permeability curve has shifted to the right and effective permeability of oil phase has been improved.

Underground salt cavern reservoirs are ideal spaces for energy storage. China is rich in salt rock resources with layered lacustrine sedimentary structures. However, the dissolution mechanism of layered salt rocks remains poorly understood, resulting in significant differences between the actual measurements and the designed indices for the layered salt rock water-soluble cavity-making cycle and the cavity shape. In this work, the dissolution rates of 600 groups of layered salt rocks in China under different conditions were determined experimentally. Thus, the established artificial neural network prediction model was used to assess the effects of the contents of NaCl, Na₂SO₄, and CaSO₄ in the salt rocks, concentrations, dissolution angles, and flow rates on their dissolution rates by performing ANOVA and F-test. The results provide a theoretical basis for evaluating the dissolution rate of layered salt rocks under different conditions and for the numerical simulation of the layered salt rock water-soluble cavity-making process.

The removal of chloride from the zinc electrolyte produced during hydrometallurgical zinc production is challenging. The ion-exchange method is a promising way to remove chloride if the resin washing wastewater can be recycled. This paper focuses on chloride removal from resin washing wastewater to enable its reuse. Various processing factors including the oxygen gas velocity, temperature, and reaction time were investigated systematically. The results show that the optimal conditions for dechlorination are an oxygen gas velocity of 0.5 L·min^-1, a reaction temperature of 80℃, and a reaction time of 30 min. A dechlorination efficiency of 80% with a residual chloride ion concentration less than 200 mg·L^-1 was achieved, which meets the requirements for the recycling of wastewater. The presence of manganese accelerates the dechlorination by forming a Mn²⁺-MnO_2-MnO₄^--Mn²⁺ redox cycle. In this process, about 15 kg of the MnO₂ and all of the zinc can be recovered from 100 m³ wastewater, and the wastewater can be reused, which makes the ion-exchange method a promising technique for chloride removal.

Samples of methane molecules grade diameter channel CHA-type molecular sieves (Chabazite-K, SAPO-34 and SSZ-13) were investigated using the adsorption separation of CH₄/N₂ mixtures. The isotherms recorded for CH₄ and N₂ follow a typical type-Ι behavior, which were fitted well with the Sips model (R²>0.999) and the selectivity was calculated using IAST theory. The results reveal that Chabazite-K has the highest selectivity (S_CH4/N2=5.5). SSZ-13 has the largest capacity, which can adsorb up to a maximum of 30.957 cm³·g^-1 (STP) of CH₄, due to it having the largest pore volume and surface area, but the lowest selectivity (S_CH4/N2=2.5). From the breakthrough test, we can conclude that SSZ-13 may be a suitable candidate for the recovery of CH₄ from low concentration methane (CH₄<20%) based on its larger pore volume and higher CH₄ capacity. Chabazite-K is more suited to the separation of high concentration methane (CH₄>50%) due to its higher selectivity.

Iron element is one of the main impurities in wet-process phosphoric acid and it has a significant impact on the subsequent phosphorus chemical products. This paper studied the feasibility of using Sinco-430 cation exchange resin for iron removal from phosphoric acid. The specific surface area and the total exchange capacity of resin were 8.91 m²·g^-1 and 5.18 mmol·g^-1, respectively. The sorption mechanism was determined by FTIR and XPS and the results indicated that iron was combined with—SO₃H in resin. The removal process was studied as a function of temperature, H₃PO₄ content and mass ratio between resin and solution. The unit mass of resin to remove iron was 0.058 g·g^-1 resin when the operating parameters were T=50℃, H₃PO₄ content=27.61 wt% and S/L=0.1, respectively. Kinetics study demonstrated that pseudo-second-order reaction model fits this study best and the calculated activation energy of overall reaction is 29.10 kJ·mol^-1. The overall reaction process was mainly controlled by pore diffusion.

Membranes were fabricated with high-density polyethylene (HDPE) and ethylene vinyl acetate (EVA) blend through thermally induced phase separation and were then used for vacuum membrane distillation (VMD). The membranes were supported by nonwoven polyester fabric with a special cellular structure. Different membrane samples were obtained by adjusting the polymer concentration, HDPE/EVA weight ratio, and coagulation bath temperature. The membranes were characterized by scanning electron microscopy (SEM) analysis, contact angle test, and evaluation of porosity and pore size distribution. A series of VMD tests were conducted using aqueous NaCl solution (0.5 mol·L^-1) at a feed temperature of 65℃ and permeate side absolute pressure of 3 kPa. The membranes showed excellent performance in water permeation flux, salt rejection, and long-term stability. The HDPE/EVA co-blending membranes exhibited the largest permeation flux of 23.87 kg·m^-2·h^-1 and benign salt rejection of ≥ 99.9%.

Utilization of biomass-derived materials or chemicals plays a significant role in reducing the dependence of unsustainable resources of petroleum and coal. A series of sulfonated glucose-derived solid acids (SGSAs) were developed in this study through a one-step method. These catalysts were characterized by XRD, FT-IR, SEM, and BET to determine their physiochemical properties, and their acid content was measured by acid-base titration. The catalytic performances of SGSA catalysts were evaluated in two esterification reactions:propionic acid or oleic acid with methanol (a typical reaction to upgrade biodiesel). Conversion of oleic acid and selectivity of methyl oleate can reach as high as 93.3% and 94.7% respectively over SGSA-6, which has the highest—SO₃H density. Moreover, regeneration of spent catalysts by sulfuric acid solution can significantly enhance their stability and reusability.

HZSM-5/MCM-41 molecular sieve (H-ZM) catalysts with well-defined micro/mesoporous structures were synthesized and showed high performance for selective synthesis of triacetin via the esterification reaction of glycerol with acetic acid. The conversion of glycerol was demonstrated to be 100% and the triacetin selectivity was over 91%, which can be attributed to the synergistic effect regarding suitable acidic property, excellent diffusion efficiency and good stability derived from the combined advantages of microporous molecular sieve HZSM-5 and mesoporous molecular sieve MCM-41.

Microchannel reactors are widely used in different fields due to their intensive micromixing and, thus, high masstransfer efficiency. In this work, a single countercurrent-flow microchannel reactor (S-CFMCR) at the size of~1 mm was developed by steel micro-capillary and laser drilling technology. Utilizing the Villermaux/Dushman parallel competing reaction, numerical and experimental studies were carried out to investigate the micromixing performance (expressed as the segregation index X_S) of liquids inside S-CFMCR at the low flow velocity regime. The effects of various operating conditions and design parameters of S-CFMCR, e.g., inlet Reynolds number (Re), volumetric flow ratio (R), inlet diameter (d) and outlet length (L), on the quality of micromixing were studied qualitatively. It was found that the micromixing efficiency was enhanced with increasing Re, but weakened with the increase of R. Moreover, d and L also have a significant influence on micromixing. CFD results were in good agreement with experimental data. In addition, the visualization of velocity magnitude, turbulent kinetic energy and concentration distributions of various ions inside S-CFMCR was illustrated as well. Based on the incorporation model, the estimated minimum micromixing time t_m of S-CFMCR is~2×10^-4 s.

Based on a typical gas composition from a methanol-to-propylene (MTP) reactor, and guided by a requirement to recover both propylene and ethylene, three separation strategies are studied and simulated by using PROⅡ package. These strategies are sequential separation, front-end dethanization, and front-end depropanization. The process does not involve an ethylene refrigeration system, using the separated stream as absorbent, and absorbing further the medium-pressure demethanization, and a proprietary technology by combining intercooling oil absorption and throttle expansion. Influences of different process streams as absorbent are studied on energy consumptions, propylene and ethylene recovery percentages, and other key-performance indicators of the separation strategies. Based on a commercial MTP plant with a methanol capacity of 1700 kt·a^-1, the simulated results show that the front-end dethanization using the C₄ mixture as absorbent is the optimal separation strategy, in which the standard fuel oil consumption (a key-performance indicator of energy consumption) is 18.97 kt·h^-1, the total power consumption of two compressors is 22.4 MW, the propylene recovery percentage is 99.70%, and the ethylene recovery percentage is 99.70%. For a further improvement, the pre-dethanization and thermal coupling methods are applied. By using front-end pre-dethanization (partial cutting) with debutanizeroverhead, i.e. the C4 mixture, as absorbent, the power consumption of the compressors decreases to 19.9 MW, an 11% reduction compared with the clear-cutting method. The energy consumption for the dual compressors for crude gaseous product mixture and main product propylene refrigeration is 16.69 MW, 16.55% lower than that of the present MTP industrial plant with the same scale, and a total energy consumption of 20 MW for the triple compressors including product gas mixture compression, and ethylene and propylene refrigeration.

Process safety in chemical industries is considered to be one of the important goals towards sustainable development. This is due to the fact that, major accidents still occur and continue to exert significant reputational and financial impacts on process industries. Alarm systems constitute an indispensable component of automation as they draw the attention of process operators to any abnormal condition in the plant. Therefore, if deployed properly, alarm systems can play a critical role in helping plant operators ensure process safety and profitability. However, in practice, many process plants suffer from poor alarm system configuration which leads to nuisance alarms and alarm floods that compromise safety. A vast amount of research has primarily focused on developing sophisticated alarm management algorithms to address specific issues. In this article, we provide a simple, practical, systematic approach that can be applied by plant engineers (i.e., non-experts) to improve industrial alarm system performance. The proposed approach is demonstrated using an industrial power plant case study.

This work develops a heuristic method for the design of batch water-using networks of multiple contaminants with regeneration unit based on the concepts of concentration potential. A water-using network involving regeneration unit can be formed by adding the regenerated stream(s) into the network involving reuse only. In the design procedure of the network operated in a single batch mode, time is taken as the primary factor and concentration potentials as the secondary one. For the networks operated in a repeated mode, the design procedure is similar to that for continuous processes, besides designing the storage tanks with the rules proposed. Continuous regeneration unit is selected in this work. With the proposed method, the network structure corresponding to the minimum freshwater consumption can be obtained. It is shown that the method proposed in this article is simple, effective and has clear engineering meaning.

It is a challenge to conserve energy for the large-scale petrochemical enterprises due to complex production process and energy diversification. As critical energy consumption equipment of atmospheric distillation oil refining process, the atmospheric distillation column is paid more attention to save energy. In this paper, the optimal problem of energy utilization efficiency of the atmospheric distillation column is solved by defining a new energy efficiency indicator-the distillation yield rate of unit energy consumption from the perspective of material flow and energy flow, and a soft-sensing model for this new energy efficiency indicator with respect to the multiple working conditions and intelligent optimizing control strategy are suggested for both increasing distillation yield and decreasing energy consumption in oil refining process. It is found that the energy utilization efficiency level of the atmospheric distillation column depends closely on the typical working conditions of the oil refining process, which result by changing the outlet temperature, the overhead temperature, and the bottom liquid level of the atmospheric pressure tower. The fuzzy C-means algorithm is used to classify the typical operation conditions of atmospheric distillation in oil refining process. Furthermore, the LSSVM method optimized with the improved particle swarm optimization is used to model the distillation rate of unit energy consumption. Then online optimization of oil refining process is realized by optimizing the outlet temperature, the overhead temperature with IPSO again. Simulation comparative analyses are made by empirical data to verify the effectiveness of the proposed solution.

Phosphogypsum (PG) is a solid waste produced in the phosphate fertilizer industry and is environmentally harmful. The decomposition of PG to recycle calcium and sulfur is a proper way to reutilize PG. Current work aims at enriching the basic theory of coal decomposition process of PG. The emphasis was laid on the exploration of impact of main impurities on the process. On the other hand, according to Reaction Module, Equilib Module, and Phase Diagram Module of FactSage, the simulation computation was done on the systems of pure gypsum mixed with coal, with or without impurities for avoiding other impurities interference. Later, possible reactions in the process were deduced. Additionally, experiments were conducted in a TG-DTA integrated thermal gravimetric analyzer and a tube furnace. The products from the experiments were characterized and analyzed to verify the accuracy of theoretical calculations. The results showed that these impurities can change the decomposition process of PG. For example, aluminum oxide was transformed to calcium sulfoaluminate, while iron oxide was transformed to dicalcium ferrite. Furthermore, the results help to further improve the basic theory of phosphogypsum decomposition.

A four-parameter, Ghoderao-Dalvi-Narayan 2 cubic equation of state (GDN2 CEOS), is presented which incorporates the following:1. The experimental value of the critical compressibility factor has been used as a fixed input parameter for calculations; 2. All the parameters (a, b, c, d) of CEOS are temperature dependent functions in the subcritical region and are temperature independent functions in the supercritical region and; 3. A new α function is introduced with two compound specific parameters which are estimated by matching saturated vapor pressure at two fixed temperature points T_r=0.5, 0.7. Our formalism enables us to cast three of the four parameters of the CEOS as a function of the remaining parameter. The proposed CEOS is used to predict properties of 334 pure compounds, including saturated vapor pressure and liquid density, compressed liquid density, heat capacities at the constant pressure and volume, enthalpy of vaporization, sound velocity. To calculate thermodynamic properties of a pure compound, the present CEOS require the critical temperature, the critical pressure, the Pitzer's acentric factor, the critical compressibility factor, and two parameters of the alpha function. The saturated liquid density predictions for pure fluids are very accurate when compared with GDN1 (Ghoderao-Dalvi-Narayan 1), MPR (Modified Peng-Robinson), and PT (Patel-Teja) equations of state. Unlike MPR EOS, the proposed temperature dependent covolume parameter b in the present work satisfies all the constraints mentioned in the literature to avoid thermodynamic inconsistencies at the extreme temperature and pressure. Using van der Waals one-fluid mixing rule, the present CEOS is further used to predict bubble pressure and the vapor mole fraction of binary mixtures.

In this study, the solubility of m-phenylenediamine in four pure solvents (methanol, ethanol, acetonitrile and water) and three binary solvent (methanol + water), (ethanol + water) and (acetonitrile + water) systems were determined in the temperature ranging from 278.15 K to 313.15 K by using the gravimetric method under atmospheric pressure. In the temperature range of 278.15 K to 313.15 K, the mole fraction solubility values of m-phenylenediamine in water, methanol, ethanol, and acetonitrile are 0.0093-0.1533, 0.1668-0.5589, 0.1072-0.5356, and 0.1717-0.6438, respectively. At constant temperature and solvent composition, the mole fraction solubility of o-phenylenediamine in four pure solvents was increased as the following order:water < ethanol < methanol < acetonitrile; and in the three binary solvent mixtures could be ranked as follows:(ethanol + water) < (methanol + water) < (acetonitrile + water). The relationship between the experimental temperature and the solubility of m-phenylenediamine was revealed as follows:the solubility of mphenylenediamine in pure and binary solvents could be increased with the increase of temperature. The experimental values were correlated with the Jouyban-Acree model, van't Hoff-Jouyban-Acree model, modified Apelblat-Jouyban-Acree model, Sun model and Ma model. The standard dissolution enthalpy, standard dissolution entropy and the Gibbs energy were calculated based on the experimental solubility data. In the binary solvent mixtures, the dissolution of m-phenylenediamine could be an endothermic process. The solubility data, correlation equations and thermodynamic property obtained from this study would be invoked as basic data and models regarding the purification and crystallization process of m-phenylenediamine.

The decomposition and combustion characteristics of ammonium dinitramide (ADN) based non-toxic aerospace propellant are analytically studied to determine the effects of catalytic bed structure (slenderness ratio) and operation parameters (mass fraction ratio of ADN/CH₃OH) on the general performance within the ADN-based thruster. In the present research, the non-equilibrium temperature model is utilized to describe the heat transfer characteristics between the fluid phase and solid phase in the fixed bed. We determined the fluid resistance characteristics in the catalytic bed by experiments involving the method of pressure-mass. We have done the simulation study based on the available results in the literature and found the complex physical and chemical processes within the ADN thruster. Furthermore, an optimized catalytic bed slenderness ratio was observed with a value of 1.75 and the mass fraction ratio of 5.73 significantly influenced the propellant performance. These results could serve as a reference to explore the combustion characteristics within the thruster and the preparation of future propellants.

A xylanase-producing bacterium, isolated from deep sea sediments, was identified as the cold-adapted marine species Acinetobacter Johnsonii. A cold-adapted marine species Acinetobacter Johnsonii could grow at 4℃. The optimum temperature and pH of xylanase from a cold-adapted marine species Acinetobacter Johnsonii were 55℃ and pH 6.0. Xylanase from a cold-adapted marine species Acinetobacter Johnsonii remained at 80% activity after incubation for 1 h at 65℃. The xylanase activity was 1.2-fold higher in 4% ethanol solution than in ethanol free solution. Gibbs free energy of denaturation, ΔG, was higher in 4% ethanol solution than in ethanol free solution. Thermostable ethanol tolerant xylanase was valuable for bioethanol production by simultaneous saccharification and fermentation process with xylan as a carbon source.

A deeper understanding of the biological events occurring when bioprocess parameters changed will be of great value in improving the monoclonal antibodies (mAbs) production. Design of experiment (DoE) was applied to investigate the effect of process parameters (pH, temperature shift and dissolve oxygen (DO)) on protein titer. The key metabolites connecting the critical process parameters (CPPs) with monoclonal antibody production were identified by different chemometrics tools. Finally, the biological events of marker metabolites relating with titer improvement were concluded. pH and temperature shift were identified as CPPs that affect the target protein titer. A series of metabolites influenced by the altered CPPs and correlated with protein titer were screened by principal component analysis (PCA) and Pearson' correlation test. The marker metabolites and their pathways linking CPPs to target protein titer in different culture phases were summarized. Metabolomics and chemometrics are promising data-driven tools to shine light into the biological black box between the bioprocess parameters and process performance.

Nitrogen oxides are one of the most significant pollution sources during coal combustion. This experimental study was conducted in a 15 kW_th lab-scale pressurized fluidized bed (inner diameter=81-100 mm, H=2100 mm) firing with bituminous coals. The effects of operating parameters, including bed temperature (800℃-900℃), operating pressure (0.1-0.4 MPa), excess air level (16%-30%) and flow pattern on NO_x and N₂O emissions were systematically studied during the tests. During each test the interaction effects of all the operating parameters were properly controlled. The results show that most operating parameters have an opposite effect on NO_x and N₂O emissions, and the N₂O emissions mainly depend on the bed temperature. Increasing the operating pressure can significantly suppress the fuel-N conversion to NO_x but enhance its conversion to N₂O. With the rise of the excess air level and fluidization number, NO_x emissions grow distinctly while N₂O emissions remain almost unchanged. Total nitrogen oxide emissions increase with the bed temperature while decrease with the operating pressure.

While roasting has been widely applied to reduce the negative effect of carbonaceous matters on gold extraction from fine-grained carbonaceous gold ores, the phase and structure changes of minerals during roasting and their influences on the leaching rate of gold have not been fully understood. This limits the extraction of carbonaceous gold deposits. The current work examines the oxidation process of a fine-grained carbonaceous gold ore during roasting using a range of techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy Dispersive Spectrometer (EDS) analysis and pore structure analysis together with gold leaching tests. The results show that during the process of oxidative roasting, the carbonaceous matters (organic carbon and graphitic carbon) and pyrite were completely decomposed at 600℃ with the carbonaceous components burned and pyrite oxidized into hematite. At 650℃, while dolomite was decomposed into calcia, magnesia, calcium sulfate etc., the calcine structure became loose and porous, leading to a high gold leaching rate from the roasted product. Above 750℃, the porous calcite structure started to collapse along with the agglomeration, leading to the secondary encapsulation of gold particles, which contributed to the sharp drop in the gold leaching rate of the roasted product. This study suggests optimum phase and structure changes of minerals during roasting to achieve maximum gold extraction from fine-grained carbonaceous gold deposits.

The present paper reports a new fluoride-free and energy-saving lead electrolytic refining process in order to solve the serious problems of the existing Betts lead electrorefining process, such as low production efficiency, high energy consumption and fluorine pollution. In the process, a mixed solution of perchloric acid and lead perchlorate (HClO₄-Pb(ClO₄)₂) with the additives of gelatin and sodium lignin sulfonate is employed as the new electrolyte. The cathodic polarization curves show that HClO₄ is very stable, and there is no any reduction reaction of HClO₄ during the electrolytic process. The redox reactions of lead ions in HClO₄ solution are very reversible with an ultrahigh capacity efficiency, so the HClO₄ acts as a stable support electrolyte with higher ionic conductivity than the traditional H₂SiF₆ electrolyte. The results of the scale-up experiments show that under the optimal conditions of 2.8 mol·L^-1 HClO₄, 0.4 mol·L^-1 Pb(ClO₄)₂ and electrolysis temperature of 45℃, the energy consumption is as low as 24.5 kW·h·(t Pb)^-1, only about 20% of that by Betts method at the same current density of 20 mA·cm^-2, and the purity of the refined lead is up to 99.9992%, much higher than that specified by Chinese national standard (99.994%, GB/T 469-2013) and European standard (99.99%, EN 12659-1999).

The melting temperature of Z coal ash was reduced by adding calcium-magnesium compound flux (W_CaO/W_MgO=1). In the process of simulated coal gasification, the coal ash and slag were prepared. The transformation of minerals in coal ash and slag upon the change of temperature was studied by using X-ray diffraction (XRD). With the increase of temperatures, forsterite in the ash disappears, while the diffraction peak strength of magnesium spinel increases, and the content of the calcium feldspar increases, then the content of the amorphous phase in the ash increases obviously. The species and evolution process of oxygen, silicon, aluminum, calcium, magnesium at different temperatures were analyzed by X-ray photoelectron spectroscopy (XPS). The decrease of the ash melting point mainly affects the structural changes of silicon, aluminum and oxygen. The coordination of aluminum and oxygen in the aluminum element structure, e.g., tetracoordinated aluminum oxide, was changed. Tetrahedral[AlO₄] and hexacoordinated aluminoxy octahedral[AlO₆] change with the temperature changing. The addition of Ca²⁺ and Mg²⁺ destroys silica chain, making bridge oxide silicon change into non-bridge oxysilicon; and bridge oxygen bond was broken and non-bridge oxygen bond was produced in the oxygen element structure. The addition of calcium and magnesium compound flux reacts with aluminum oxide tetrahedron, aluminum oxide octahedron and silicon tetrahedron to promote the breakage of the bridge oxygen bond. Ca²⁺ and Mg²⁺ are easily combined with silicon oxide and aluminum oxide tetrahedron and aluminum. Oxygen octahedrons combine with non-oxygen bonds to generate low-melting temperature feldspars and magnesite minerals, thereby reducing the coal ash melting temperatures. The structure of kaolinite and mullite was simulated by quantum chemistry calculation, and kaolinite molecule has a stable structure.

Here we report the WO₃ thin films on F-doped SnO₂ conducting glass (FTO) substrates which were prepared by using dip film-drawing method. Dip film-drawing was a simple, convenient, economical method and in largescale to prepare photoanodes for future applications. The FTO substrates were dipped in tungstic acid solution then film-drawn included 3, 6, 9, 12 and 15 times for prepared different thicknesses of WO₃ thin film photoanodes. Then the photoanodes were employed as the electrodes in photoelectrochemical property measurements, which include scan linear sweep, repeated on/off illumination cycles, electrochemical impedance spectroscopy and incident photon to current conversion efficiency, respectively. The results showed that the WO₃ thin films dipped 9 times with 175 nm thicknesses had the best photoelectrochemical performance of 0.067 mA·cm^-2 at 1.23 V versus RHE.

The methane hydrate formation and the methane hydrate dissociation behaviors in montmorillonite are experimentally studied. Through the analyses of the microstructure characteristic, the study obtains the porous characteristic of montmorillonite. It is indicated that methane hydrate in montmorillonite forms the structure I (sI) crystal. Meanwhile, molecular dynamics simulation is carried out to study the processes of the methane hydrate formation and the methane hydrate dissociation in montmorillonite. The microstructure and microscopic properties are analyzed. The methane hydrate formation and methane hydrate dissociation mechanisms in the montmorillonite nanopore and on the montmorillonite surface are expounded. Combining the experimental and simulating analyses, the results indicate the methane hydrate formation and methane hydrate dissociation processes have little influence upon the crystal structure of porous media from either micro-or macro-analysis. It is beneficial to the fundamental researches on the exploitation and security control technologies of natural gas hydrate in deep-sea sediments.

Access to natural resources is increasingly more difficult and more costly, partly due to their economic significance and to continuous increase of their global consumption in the recent years. In the case of phosphorus (P), which is a critical raw material, geological distribution of its primary nonrenewable source (phosphate rock) is concentrated in particular regions leading to high supply risk of this raw material. In Europe (EU-28), where phosphate rock reserves are scarce, import of phosphorus has been the main source of supply. It means that Europe relies highly on the foreign exporters. From decision makers' perspective, recycling of phosphorus was taken into account as one of the possible solutions to decrease the dependence on imports and extraction of reserves. The question, however, is to what extent does the recycling of phosphorus help in reducing the reliance on typical supply resources? Hence, the main objective of this paper is to quantify the dynamic flow of phosphorus and show potential benefits of its recycling in Europe. This article presents a system dynamics model for representation of the element P flow and helps to quantify to what extent the recycled phosphorus could mitigate its criticality. Analysis of the results supports previous studies indicating the high reliance of EU on P imports, estimating around 96% as the reliance percentage on imports. The results imply that improving P recycling has the potential to decrease the level of P imports to a certain extent, which may reach 79%.

Herein, three kinds of Li₂CO₃ and two kinds of MgCO₃·3H₂O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li₂CO₃ ranging from micro-flaky, flower to nanobranch, MgCO₃·3H₂O ranging from nanosphere to nanorod. Compared with coupled reaction and solvent extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology. Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.