Numerical calculations were conducted to simulate the flow and mass transfer in narrow membrane channels with and without flow disturbers. The channel consists of an impermeable solid wall and a membrane surface with a spacing of 2.0mm. The flow disturbers studied include rectangular winglets, which are often used as longitudinal vortex generators to enhance heat transfer in heat exchanger applications, as well as square prism, triangular prism, and circular cylinder, which are used here to mimic the traditional spacer filaments for comparison of their abilities in enhancing the convective mass transfer near the membrane surface to alleviate the concentration polarization. The disturber performance was evaluated in terms of concentration polarization factor versus consumed pumping power, with a larger factor meaning a more serious concentration polarization. Calculations were carried out for NaCl solution flow with Reynolds numbers ranging from 400 to 1000. The results show that the traditional flow disturbers can considerably reduce the concentration polarization but cause a substantial pressure drop, while the rectangular winglets can effectively reduce the concentration polarization with a much less pressure drop penalty. The rectangular winglets were optimized in geometry under equal pumping power condition.

In our previous work, a low-shear stirred bioreactor was explored. With a pitched blade turbine impeller downflow (PBTD) used, the shear stress generated is high compared with that in some low shear axial flow impellers. KHX impeller is an efficient axial flow impeller, which provides large onflow diffusivity and low shear force. In thiswork, the KHX impellerwas applied in a lower-shear bioreactor and the performance of this reactor was evaluated and comparedwith that of the PBTD impeller. The experimental results showthat the KHX impeller can disperse gas at lower power consumption and gives greater gas-liquid volumetric mass transfer coefficients than PBTD at the same power consumption. An empirical correlation for evaluating the mass transfer coefficient of the KHX impeller in the bioreactor is presented to provide reference for its industrial application.

The velocity distribution in Rayleigh convection caused by acetone volatilization in acetone-ethyl acetate binary system was observed in a vertical cross section of an initially quiescent liquid layer by utilizing particle image velocimetry. Obvious turbulent vortexes that were induced by Rayleigh convection appeared in the bulk liquid, and its statistic features indicated that Rayleigh convection became more intensewith the increase of Ra number and ReG number. Mass transfer coefficient was measured and the computed enhancement factor indicated that Rayleigh convection could promote the surface renewal of the liquid phase and intensify the interfacial mass transfer significantly. A method was proposed for the prediction of mass transfer coefficient based on the measured velocity vector, and the predicted mass transfer coefficients are in reasonable agreement with the experimental results.

In this paper heat exchange coefficient and separation efficiency of an annular structured internal heat-integrated distillation column (HIDiC) were experimentally measured. About 50% heat of the inner column could be transferred to the outer column. The overall heat exchange coefficient decreased with an increase in pressure ratio of the inner column and the outer column, but was little affected by the F-factor. The increase of the pressure ratio decreased obviously the separation efficiency of the outer column but had little effect on that of the inner column.

Detailed atomistic structures are constructed for polydopamine membranes containing different amounts of catechol and quinone groups to investigate the effect of pH value in themembrane casting solution on sorption and diffusion of small gas molecules (water and propylene) in the membranes. Interactions between dopamine oligomers are calculated, and it is found that the interactions decrease from -2356.52 kJ·mol^-1 in DOP-1 to -1586.69 kJ·mol^-1 in DOP-3 when all of the catechol groups are converted to quinone groups. The mobility of polymer segments and free volume properties of polydopamine membranes are analyzed. The sorption quantities of water and propylene in the membrane are calculated using Grand Canonical Monte Carlo method. The sorption results show that water adsorbed in DOP-1, DOP-2 and DOP-3 are 17.3, 18.6 and 20.0 mg water per gram polymer, respectively, and no propylene molecule can be adsorbed. The diffusion behavior of water molecules in the membrane is investigated by molecular dynamics simulation. The diffusion coefficients of water molecules in DOP-1, DOP-2 and DOP-3 membranes are (1.80 ± 0.52) × 10^-11, (3.40 ± 0.64) × 10^-11 and (4.50 ± 0.92) × 10^-11 m²·s^-1, respectively. The predicted sorption quantities and diffusion coefficients of water and propylene in the membrane present the same trends as those from experimental results.

Novel MgO-SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein (MAL) with methanol to methyl methacrylate (MMA). The MgO-SBA-15 supports were synthesized with different magnesia loadings fromdifferentmagnesiumprecursors and hydrochloric acidmolar concentrations. The MgO-SBA-15 supports and Pd-Pb/MgO-SBA-15 catalysts were characterized by several analysismethods. The results revealed that the addition ofMgO improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd₃Pb particles onmagnesia-modified Pd-Pb/MgO-SBA-15 catalystswas smaller than that on the pure silica-based Pd-Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd-Pb/MgO-SBA-15 catalysts had higher activity than pure silica-based Pd-Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd-Pb/SBA-15 catalysts and Pd-Pb/MgO-SBA-15 catalystswas due to the discrepant structural properties and surface alkalinity provided by MgO, which led to the different Pd₃Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.

The formation mechanism of K₂Ti₂O₅ was investigated with TiO₂ microparticles and nanoparticles as precursors by the thermogravimetric (TG) technique. Amethod of directmultivariate non-linear regression was applied for simultaneous calculation of solid-state reaction kinetic parameters fromTG curves. TG results showmore regular decrease from initial reaction temperature with TiO₂ nanoparticles as raw material compared with TiO₂ microparticles, while mass losses finish at similar temperatures under the experimental conditions. From the mechanism and kinetic parameters, the reactions with the two materials are complex consecutive processes, and reaction rate constants increase with temperature and decrease with conversion. The reaction proceedings could be significantly hindered when the diffusion process of reactant species becomes rate-limiting in the later stage of reaction process. The reaction active sites on initial TiO₂ particles and formation of product layers may be responsible to the changes of reaction rate constant. The calculated results are in good agreement with experimental ones.

In this study, diphenyl sulfide (Ph₂S) was employed to prepare a series of Ph₂S-modified Pd/C catalysts (Pd-Ph₂S/C). Catalyst characterization carried out by Brunner-Emmet-Teller (BET), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and CO chemisorption uptakemeasurements suggested a chemical interaction between Ph₂S and Pd. The ligand was preferably absorbed on the active site of Pd metal but after increasing the amount of Ph₂S, the adsorption of Ph₂S on Pd metal tended to be saturated and the excess of Ph₂S partially adsorbed on the activated carbon. A part of Pd atoms without adsorbing any Ph₂S still existed, even for the saturated Pd-Ph₂S/C catalyst. The Pd-Ph₂S/C catalysts exhibited a good selectivity of p-chloroaniline (p-CAN) in the hydrogenation of p-chloronitrobenzene (p-CNB). However, the chemisorption between Ph₂S and Pdwas not so strong that part of Ph₂Swas leached fromPd-Ph₂S/C catalyst during the hydrogenation,which caused the decline of the selectivity of p-CAN over the used Pd-Ph₂S/C catalyst. Resulfidation of the used Pd-Ph₂S/C catalystwas effective to resume its stability, and the regenerated Pd-Ph₂S/C catalyst could be reused for at least ten runs with a stable catalytic performance.

In order to develop the catalysts with low corrosiveness for the oxidative carbonylation of methanol to dimethyl carbonate (DMC), CuBr₂ was selected as the metal source to prepare Cu coordination compounds, Cu(phen)Br₂, [Cu(phen)₂Br]Br and [Cu(phen)₃]Br₂ (phen = 1,10-phenanthroline). These complexes were characterized by thermogravimetric analysis and temperature-programmed reduction. Their catalytic performances were investigated. It was found that the metal coordination environments and thermal stability of the complexes played an important role in their catalytic activities. Cu(phen)Br₂ exhibited the highest activity due to the lowest steric hindrance, themost positions occupied by the bromide ions and the highest thermal stability. The turnover number was up to 47.6 DMC mol·(Cumol)^-1 with selectivity of 92.8% under conditions of 120 ℃, ratio of partial pressure of CO to O₂ of 19:1 (below the explosion limit of CO) and catalyst concentration of 0.011 mol·L^-1. Furthermore, a plausible reaction mechanism was suggested on the basis of the experimental data.

This paper introduces a practical solving scheme of gradetransition trajectory optimization (GTTO) problems under typical certificate-checking-updating framework. Due to complicated kinetics of polymerization, differential/algebraic equations (DAEs) always cause great computational burden and system non-linearity usually makes GTTO non-convex bearing multiple optima. Therefore, coupled with the three-stage decomposition model, a three-section algorithm of dynamic programming (TSDP) is proposed based on the general iteration mechanism of iterative programming (IDP) and incorporated with adaptivegrid allocation scheme and heuristic modifications. The algorithm iteratively performs dynamic programming with heuristic modifications under constant calculation loads and adaptively allocates the valued computational resources to the regions that can further improve the optimality under the guidance of local error estimates. TSDP is finally compared with IDP and interior point method (IP) to verify its efficiency of computation.

The approaches to discrete approximation of Pareto front using multi-objective evolutionary algorithms have the problems of heavy computation burden, long running time and missing Pareto optimal points. In order to overcome these problems, an approach to continuous approximation of Pareto front using geometric support vector regression is presented. The regression model of the small size approximate discrete Pareto front is constructed by geometric support vector regression modeling and is described as the approximate continuous Pareto front. In the process of geometric support vector regression modeling, considering the distribution characteristic of Pareto optimal points, the separable augmented training sample sets are constructed by shifting original training sample points along multiple coordinated axes. Besides, an interactive decision-making (DM) procedure, inwhich the continuous approximation of Pareto front and decision-making is performed interactively, is designed for improving the accuracy of the preferred Pareto optimal point. The correctness of the continuous approximation of Pareto front is demonstrated with a typical multi-objective optimization problem. In addition, combined with the interactive decision-making procedure, the continuous approximation of Pareto front is applied in the multi-objective optimization for an industrial fed-batch yeast fermentation process. The experimental results show that the generated approximate continuous Pareto front has good accuracy and completeness. Compared with the multi-objective evolutionary algorithm with large size population, a more accurate preferred Pareto optimal point can be obtained from the approximate continuous Pareto front with less computation and shorter running time. The operation strategy corresponding to the final preferred Pareto optimal point generated by the interactive DM procedure can improve the production indexes of the fermentation process effectively.

The solubility of nonivamide in dimethyl sulfoxide,methanol, acetone, ethyl acetate,methyl tert-butyl ether, acetonitrile, n-hexane and water over the temperature range of 293.2 K to 323.2 K wasmeasured. The results reveal that the solubility of nonivamide is greatly influenced by the hydrogen-bond basicity of solvent and increases with temperature. The experimental data were correlated with the modified Apelblat equation. The dissolution enthalpy and entropy of nonivamide in different solvents were obtained from the correlation of lnx with 1/T using the van't Hoff equation. The calculated nonivamide solubility is in good agreement with experimental data for most of the solvents.

The vapor pressures of n-butyl carbamate were measured in the temperature range from 372.37 K to 479.27 K and fitted with Antoine equation. The compressibility factor of the vapor was calculated with the Virial equation and the second virial coefficient was determined by the Vetere model. Then the standard enthalpy of vaporization for n-butyl carbamate was estimated. The heat capacity was measured for the solid state (299.39-324.2 K) and liquid state (336.65-453.21 K) by means of adiabatic calorimeter. The standard enthalpy of formation Δ_fH^ϴ[crystal (cr),298.15 K] and standard entropy S^ϴ(crystal,298.15 K) of the substance were calculated on the basis of the gas-phase standard enthalpy of formation Δ_fH^ϴ(g,298.15 K) and gas-phase standard entropy S^ϴ(g,298.15 K), which were estimated by the Bensonmethod. The results are acceptable, validated by a thermochemical cycle.

TiO₂ microspheres containing carbon have been synthesized viaa one-pot hydrothermal process using CTAB as the mesoporous template and nanoparticle stabilizer and Ti(SO₄)₂ and sucrose as titanium and carbon precursors, respectively. Through well designed calcinations, TiO₂ microspheres with various amounts of carbon-residue, such as core/shell C@TiO₂, hollow neat H-TiO₂, and hollow C/TiO₂ composites, are obtained.When these microspheres are used as anode materials for lithium ion batteries, the lithium storage performance is significantly influenced by the structure and carbon-residue. With a thin shell of TiO₂ nanoparticles and carbon-residue, the capacity of hollow C/TiO₂ composites maintains at 143.3 mA·h·g^-1 at 0.5 C (83.5 mA·g^-1) after 100 cycles. Moreover, after high rate charge/discharge cycles from 0.2 C to 20 C and back to 0.2 C again, the reversible capacity recovers atas high as 195.1 mA·h·g^-1 with respect to its initial value of 205.0 mA·h·g^-1. The results of cycle voltammograms and electrochemical impedance spectroscopy further reveal that Li⁺ insertion/extraction processes are reversible, and the diffusion coefficient of Li⁺ in the hollow C/TiO₂ composites is much higher than those of others, because the hollow structure can act as the ion-buffering reservoir and facilitate Li⁺ transfer from both sides of the shell, and the carbon-residue in the shell improves the conductivity as well.

Due to the large-scale production and wide applications,many nanoparticles (NPs) enter wastewater treatment plants and accumulate in activated sludge. It is reported that titaniumdioxide (TiO₂) NPs showsevere damage to many model microbes. However, it is still unknown whether the long-term (e.g., 100 d) presence of TiO₂ NPs would affect the performance of sludge fermentation. In this study, long-term exposure experiments (105 d) were conducted to investigate the potential risk of TiO₂ NPs to sludge fermentation system. It is found that the presence of environmentally relevant [6 mg·(g TSS)^-1] and higher [150 mg·(g TSS)^-1] concentrations of TiO₂ NPs does not affect methane production fromsludge fermentation. The analysis of fluorescence in situ hybridization indicates that these concentrations of TiO₂ NPs present marginal influences on abundances of bacteria and methanogenic archaea in sludge fermentation system. The viability of sludge microorganisms and activities of key enzymes related tomethane production such as protease, acetate kinase, and coenzyme F₄₂₀ are unchanged by the long-term presence of 6 and 150 mg·(g TSS)^-1 of TiO₂ NPs. Further investigations reveal that the insolubility of NPs and the protection role of sludge extracellular polymeric substances are the main reasons for the marginal influence of TiO₂ NPs on sludge fermentation.

The adsorption of mesoporous Fe₃O₄-SiO₂-TiO₂ (MFST), which can be separated easily from solution by a magnet, for the removal ofmethyl orange (MO)was investigated. The nitrogen adsorption-desorption measurement shows successful synthesis of MFST with an average pore size of 3.8 nm and a large specific surface area of 55 m²·g^-1. About 95% adsorption percentage of MO is achieved with an initial concentration of 10 mg·L^-1 in the dark and the MFST exhibits superior adsorption ability under acid conditions. The adsorption data fit well with the pseudo-second order model for adsorption. After 4 cycles, the adsorption rate for MO remains 74% in the dark and the MFST can be recovered in a magnetic field with a recovery of about 80% (by mass). It demonstrates that the samples have significant value on applications of wastewater treatment.

The extraction kinetics of La(Ⅲ) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12] (tricaprylmethylammonium sec-octylphenoxy acetic acid) was investigated using a constant interfacial cell with laminar flow. The effects of stirring speed, temperature and specific interfacial area on the extraction rate were examined. The results indicate that mass transfer kinetics of La(Ⅲ) is a mixed-controlled process influenced by interfacial reaction. On the basis ofmass transfer kinetic results in the extraction of La(Ⅲ) by [A336][CA-12], the extraction rate equation of La(Ⅲ) is proposed in terms of pseudo-firstorder constants, which is supported by the measured thermodynamic equations. The mass-transfer kinetic model deduced from the rate controlling step is adequate to interpret the experimental data qualitatively.