A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved. In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption.

Based on viscous drag-induced breakup mechanism, a simple model was proposed to predict the dripping droplet size as a function of controllable parameters in flow focusing micro devices. The size of thread before breakup was also investigated through laminar flow theory. Experiments and numerical simulations by VOF are carried out simultaneously to validate the theoretical analysis, showing that droplet size decreases rapidly with the increase of the flow rate ratio and capillary number.

This work presents a numerical investigation on steady internal, external and surface flows of a liquid sphere immersed in a simple shear flow at low and intermediate Reynolds numbers. The control volume formulation is adopted to solve the governing equations of two-phase flow in a 3-D spherical coordinate system. Numerical results show that the streamlines for Re = 0 are closed Jeffery orbits on the surface of the liquid sphere, and also closed curves outside and inside the liquid sphere. However, the streamlines have intricate and non-closed structures for Re≠0. The flow structure is dependent on the values of Reynolds number and interior-to-exterior viscosity ratio.

Double diffusion convection in a cavity with a hot square obstacle inside is simulated using the lattice Boltzmann method. The results are presented for the Rayleigh numbers 10⁴,10⁵ and 10⁶, the Lewis numbers 0.1, 2 and 10 and aspect ratio A (obstacle height/cavity height) of 0.2, 0.4 and 0.6 for a range of buoyancy number N=0 to -4 with the effect of opposing flow. The results indicate that for |N|< 1, the Nusselt and Sherwood numbers decrease as buoyancy ratio increases,while for |N|>1, they increase with |N|. As the Lewis number increases, higher buoyancy ratio is required to overcome the thermal effects and the minimum value of the Nusselt and Sherwood numbers occur at higher buoyancy ratios. The increase in the Rayleigh or Lewis number results in the formation of the multi-cell flow in the enclosure and the vortices will vanish as |N| increases.

This paper reports the effect of sol size on nanofiltration performances of sol-gel derived microporous zirconia membranes. Microstructure, pure water flux, molecular weight cut-off (MWCO) and salt retention of zirconia membranes derived fromzirconia solswith different sizeswere characterized. Thermal evolution, phase composition, microstructure and chemical stability of unsupported zirconia membranes (powder) were determined by thermogravimetric and differential thermal analysis, X-ray diffraction, nitrogen adsorption-desorption and static solubility measurements. Results show that nanofiltration performance of zirconia membranes is highly dependent on sol size. The solwith an average size of 3.8 nm, which is smaller than the pore size of the γ-Al₂O₃ support (pore size: 5-6 nm), forms a discontinuous zirconia separation layer because of excessive penetration of sol into the support. This zirconiamembrane displays a MWCO value towards polyethylene glycol higher than 4000 Da. A smooth and defect-free zirconiamembrane with a MWCO value of 1195 Da (pore size: 1.75nm) and relative high retention rates towards MgCl₂ (76%) and CaCl₂ (64%) was successfully fabricated by dip-coating the sol with an appropriate size of 8.6 nm. Zirconia sol with an average size of 12 nm exhibits colloidal nature and forms a zirconia membrane with a MWCO value of 2332 Da (pore size: 2.47 nm). This promising microporous zirconia membrane presents sufficiently high chemical stability in a wide pH range of 1-12.

This paper studies the mass transfer performance of structured packings in the absorption of CO₂ from air with aqueous NaOH solution. The Eight structured packings tested are sheet metal ones with corrugations of different geometry parameters. Effective mass transfer area and overall gas phase mass transfer coefficient have been measured in an absorption column of 200 mm diameter under the conditions of gas F-factor in 0.38-1.52 Pa^0.5 and aqueous NaOH solution concentration of 0.10-0.15 kmol·m^-3. The effects of gas/liquid phase flow rates and packing geometry parameters are also investigated. The results show that the effective mass transfer area changes not only with packing geometry parameters and liquid load, but also with gas F-factor. A new effective mass transfer area correlation on the gas F-factor and the liquid load was proposed, which is found to fit experiment data very well.

Activated carbons were prepared by two chemical methods and the adsorption of Cu (II) on activated carbons from aqueous solution containing amino groups was studied. The first method involved the chlorination of activated carbon following by substitution of chloride groups with amino groups, and the second involved the nitrilation of activated carbon with reduction of nitro groups to amino groups. Resultant activated carbons were characterized in terms of porous structure, elemental analysis, FTIR spectroscopy, XPS, Boehm titration, and pH_zpc. Kinetic and equilibrium tests were performed for copper adsorption in the batch mode. Also, adsorption mechanism and effect of pH on the adsorption of Cu (II) ions were discussed. Adsorption study shows enhanced adsorption for copper on the modified activated carbons, mainly by the presence of amino groups, and the Freundlich model is applicable for the activated carbons. It is suggested that binding of nitrogen atoms with Cu (II) ions is stronger than that with H⁺ ions due to relatively higher divalent charge or stronger electrostatic force.

Enantioselective liquid-liquid extraction has attracted considerable attention for its potential use in largescale production. Kinetic data are needed for the reliable scale-up of the process. This paper reports the kinetic study of reactive extraction of phenylalanine (Phe) enantiomers with BINAP-copper complex (BINAP-Cu) as a chiral selector. The theory of extraction accompanied by a chemical reaction was applied. The effects of agitation speed, interfacial area, pH value of aqueous phase, initial concentration of Phe enantiomers and initial concentration of BINAP-Cu on the specific rate of extraction were investigated. The forward rate constants of the reactions in the reactive extraction process are 7.93 × 10^-5m^5/2·mol^-1/2·s^-1 for D-Phe and 1.29 × 10^-4 m^5/2·mol^-1/2·s^-1 for L-Phe.

The adsorption process was studied for separating para-xylene fromxylenemixture on modified nano-zeolite X in a breakthrough system. Nano-zeolitic adsorbent with different ratios of SiO₂/Al₂O₃ was synthesized through hydrothermal process and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The product was characterized by X-ray diffraction, scanning electron microscopy (SEM), nitrogen adsorption, transform electron microscopy (TEM) and in situ Fourier transform infrared (FTIR) spectroscopy. The influence of nano-zeolite water content and desorbent type on the selectivity of para-xylene toward other C₈ aromatic isomers was studied. The optimization of adsorption process was also investigated under variable operation conditions. The isotherm for each isomer of C₈ aromatics and the desorbents possess the adsorption characteristics of Langmuir type. The selectivity factor of para-xylene relative to each of meta-xylene, ortho-xylene and ethylbenzene under the optimum conditions obtained to be 5.36, 2.43 and 3.22, in the order given.

To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C-Cl bond. The promoting effect of the chloromethane withmore chlorine atomswas better than thosewith less chlorine atoms. Intermediates detected fromthe reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.

Ni/Mg-Al catalysts derived fromhydrotalcite-type precursorswere prepared by a co-precipitation technique and applied to steamreforming of methane. By comparison with Ni/γ-Al₂O₃ and Ni/α-Al₂O₃ catalysts prepared by incipientwetness impregnation, the Ni/Mg-Al catalyst presented much higher activity as a result of higher specific surface area and better Ni dispersion. The Ni/Mg-Al catalyst with a Ni/Mg/Almolar ratio of 0.5:2.5:1 exhibited the highest activity for steam methane reforming andwas selected for kinetic investigation. With external and internal diffusion limitations eliminated, kinetic experiments were carried out at atmospheric pressure and over a temperature range of 823-973 K. The results demonstrated that the overall conversion of CH₄ and the conversion of CH₄ to CO₂ were strongly influenced by reaction temperature, residence time of reactants aswell asmolar ratio of steam to methane. A classical Langmuir-Hinshelwood kinetic model proposed by Xu and Froment (1989) fitted the experimental data with excellent agreement. The estimated adsorption parameters were consistent thermodynamically.

The performance characteristics of isothermal fluidized bed syngas methanation for substitute natural gas are investigated over a self-made Ni-Mg/Al₂O₃ catalyst. Via atmospheric methanation in a laboratory fluidized bed reactor it was clarified that the CO conversion varied in 5% when changing the space velocity in 40-120 L·g^-1·h^-1 but the conversion increased obviously by raising the superficial gas velocity from 4 to 12.4 cm·s^-1. The temperature at 823 K is suitable for syngas methanation while obvious deposition of uneasyoxidizing C_γ occurs on the catalyst at temperatures around 873 K. From a kinetic aspect, the lowest reaction temperature is suggested to be 750 K when the space velocity is 60 L·g^-1·h^-1. Raising the H₂/CO ratio of the syngas increased proportionally the CO conversion and CH₄ selectivity, showing that at enough highH₂/CO ratios the active sites on the catalyst are sufficient for CO adsorption and in turn the reaction with H₂ for forming CH₄. Introducing CO₂ into the syngas feed suppresses the water gas shift and Boudouard reactions and thus increased H₂ consumption. The ratio of CO₂/CO in syngas should be better below 0.52 because varying the ratio from 0.52 to 0.92 resulted in negligible increases in the H₂ conversion and CH₄ selectivity but decreased the CH₄ yield. Introducing steam into the feed gas affected little the CO conversion but decreased the selectivity to CH₄. The tested Ni-Mg/Al₂O₃ catalyst manifested good stability in structure and activity even in syngas containing water vapor.

A novel thermal-assisted ultra-violet (UV) photocatalysis digestion method for the determination of total phosphorus (TP) in water sampleswas introduced in thiswork. The photocatalytic experiments for TP digestionwere conducted using a 365 nm wavelength UV light and TiO₂ particles as the photocatalyst. Sodium tripolyphosphate and sodium glycerophosphate were used as the typical components of TP and the digested samples were then determined by spectrophotometry after phosphomolybdenum blue reaction. The effects of operational parameters such as reaction time and temperature were studied for the digestion of TP and the kinetic analysis of two typical components was performed in this paper. The pseudo-first-order rate constants k of two phosphorus compounds at different temperatures were obtained and the Arrhenius equation was employed to explain the effect of temperature on rate constant k. Compared with the conventional thermal digestion method for TP detection, it was found that the temperature was decreased from 120 ℃ to 60 ℃ with same conversion rate and time in this thermal-assisted UV digestion method, which enabled the digestion process work at normal pressure. Compared with the individual ultra-violet (UV) photocatalysis process, the digestion time was also decreased from several hours to half an hour using the thermal-assisted UV digestion method. This method will not lead to secondary pollution since no oxidant was needed in the thermal-assisted UV photocatalysis digestion process, which made it more compatible with electrochemical detection of TP.

In this work, esterification of acetic acid and methanol to synthesize methyl acetate in a batch stirred reactor is studied in the temperature range of 305.15-333.15 K. Sulfuric acid is used as the homogeneous catalyst with concentrations ranging from 0.0633mol·L^-1 to 0.3268 mol·L^-1. The feed molar ratio of acetic acid to methanol is varied from 1:1 to 1:4. The influences of temperature, catalyst concentration and reactant concentration on the reaction rate are investigated. A second order kinetic rate equation is used to correlate the experimental data. The forward and backward reaction rate constants and activation energies are determined from the Arrhenius plot. The developed kineticmodel is compared with themodels in literature. The developed kinetic equation is useful for the simulation of reactive distillation column for the synthesis of methyl acetate.

The acid-functionalized ionic liquid ([HSO₃Pmim]HSO₄) was synthesized by a two-step method. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FT-IR) showthat the synthesis method is feasible and high purity of ionic liquid can be obtained. Using [HSO₃Pmim]HSO₄ as the catalyst, we studied the reaction kinetics of synthesizing sec-butyl alcohol from sec-butyl acetate and methanol by transesterification in a high-pressure batch reactor. The effects of temperature, initial molar ratio of methanol to ester, and catalyst concentration on the conversion of sec-butyl acetate were studied. Based on its possible reaction mechanism, a homogeneous kineticmodelwas established. The results showthat the reaction heat ΔHis 10.94 × 10³ J·mol^-1, so the reaction is an endothermic reaction. The activation energies E_a+ and E_a- are 60.38 × 10³ and 49.44 × 10³ J·mol^-1, respectively.

One measurement-based dynamic optimization scheme can achieve optimality under uncertainties by tracking the necessary condition of optimality (NCO-tracking), with a basic assumption that the solution model remains invariant in the presence of all kinds of uncertainties. This assumption is not satisfied in some cases and the standard NCO-tracking scheme is infeasible. In this paper, a novel two-level NCO-tracking scheme is proposed to deal with this problem. A heuristic criterion is given for triggering outer level compensation procedure to update the solution model once any change is detected via online measurement and estimation. The standard NCO-tracking process is carried out at the inner level based on the updated solutionmodel. The proposed approach is illustrated via a bioreactor in penicillin fermentation process.

The paper defines the Safety Capacity of Chemical Industrial Park (SCCIP) from the perspective of acceptable regional risk. For the purpose of exploring the evaluation model for the SCCIP, a method based on quantitative risk assessment was adopted for evaluating transport risk and to confirm reasonable safety transport capacity of chemical industrial park, and then by combining with the safety storage capacity, a SCCIP evaluation model was put forward. The SCCIP was decided by the smaller one between the largest safety storage capacity and the maximum safety transport capacity, or else, the regional risk of the park will exceed the acceptable level. The developed method was applied to a chemical industrial park in Guangdong province to obtain the maximum safety transport capacity and the SCCIP. The results can be realized in the regional risk control of the park effectively.

Solid oxide fuel cell-proton exchange membrane (SOFC-PEM) hybrid system is being foreseen as a valuable alternative for power generation. As this hybrid system is a conceptual design, many uncertainties involving input values should be considered at the early stage of process optimization. We present in this paper a generalized framework of multi-objective optimization under uncertainty for the synthesis/design optimization of the SOFC-PEM hybrid system. The framework is based on geometric, economic and electrochemical models and focuses on evaluating the effect of uncertainty in operating parameters on three conflicting objectives: electricity efficiency, SOFC current density and capital cost of system. Themulti-objective optimization provides solutions in the form of a Pareto surface, with a range of possible synthesis/design solutions and a logical procedure for searching the global optimum solution for decision maker. Comparing the stochastic and deterministic Pareto surfaces of different objectives, we conclude that the objectives are considerably influenced by uncertainties because the two trade-off surfaces are different.

To explore the problems of monitoring chemical processes with large numbers of input parameters, a method based on Auto-associative Hierarchical Neural Network (AHNN) is proposed. AHNN focuses on dealing with datasets in high-dimension. AHNNs consist of two parts: groups of subnets based on well trained Autoassociative Neural Networks (AANNs) and a main net. The subnets play an important role on the performance of AHNN. A simple but effective method of designing the subnets is developed in this paper. In this method, the subnets are designed according to the classification of the data attributes. For getting the classification, an effective method called Extension Data Attributes Classification (EDAC) is adopted. Soft sensor using AHNN based on EDAC (EDAC-AHNN) is introduced. As a case study, the production data of Purified Terephthalic Acid (PTA) solvent system are selected to examine the proposed model. The results of the EDAC-AHNN model are compared with the experimental data extracted from the literature, which shows the efficiency of the proposed model.

Tubular flow reactors are mainly used in chemical industry and waste water discharged units. Control of output variables is very difficult because of the existence of high dead-time in these types of reactors. In the present work, sodium hydroxide and acetic acid solutions were sent to the tubular flow reactor. The aim was to control pH at 7 in the nonlinear region. The pH control of a tubular flow reactor with high time delay and a highly nonlinear behavior in pH neutralization reaction was investigated experimentally in the face of the various load and set point changes. Firstly, efficiency of conventional Proportional-Integral-Derivative (PID) algorithm in the experiments was tested. Then self-tuning PID (STPID) control system was applied by using the ARMAX model. The model parameters were calculated from input-output data by using PRBS signal as disturbance and Bierman algorithm. Lastly, the experimental fuzzy control of pH based on fuzzy model was achieved to compare the success of fuzzy approach with the performance of other control cases studied.

Nonlinear characteristic fault detection and diagnosis method based on higher-order statistical (HOS) is an effective data-driven method, but the calculation costs much for a large-scale process control system. An HOS-ISM fault diagnosis framework combining interpretative structural model (ISM) and HOS is proposed: (1) the adjacency matrix is determined by partial correlation coefficient; (2) the modified adjacency matrix is defined by directed graph with prior knowledge of process piping and instrument diagram; (3) interpretative structural for large-scale process control system is built by this ISM method; and (4) non-Gaussianity index, nonlinearity index, and total nonlinearity index are calculated dynamically based on interpretative structural to effectively eliminate uncertainty of the nonlinear characteristic diagnostic method with reasonable sampling period and data window. The proposed HOS-ISM fault diagnosis framework is verified by the Tennessee Eastman process and presents improvement for highly non-linear characteristic for selected fault cases.

Conventional process monitoring method based on fast independent component analysis (FastICA) cannot take the ubiquitous measurement noises into account and may exhibit degraded monitoring performance under the adverse effects of themeasurement noises. In this paper, a newprocessmonitoring approach based on noisy time structure ICA (NoisyTSICA) is proposed to solve such problem. A NoisyTSICA algorithm which can consider the measurement noises explicitly is firstly developed to estimate the mixing matrix and extract the independent components (ICs). Subsequently, a monitoring statistic is built to detect process faults on the basis of the recursive kurtosis estimations of the dominant ICs. Lastly, a contribution plot for the monitoring statistic is constructed to identify the fault variables based on the sensitivity analysis. Simulation studies on the continuous stirred tank reactor system demonstrate that the proposed NoisyTSICA-based monitoring method outperforms the conventional FastICA-based monitoring method.

In reality, traditional process control system built upon centralized and hierarchical structures presents a weak response to change and is easy to shut down by single failure. Aiming at these problems, a new agent-based service-oriented integration architecture was proposed for chemical process automation system. Web services were dynamically orchestrated on the internet and agent behaviors were built in them. Data analysis, model, optimization, control, fault diagnosis and so on were capsuled into different web services. Agentswere used for service compositions by negotiation. A prototype system of poly(ethylene terephthalate) process automation was used as the case study to demonstrate the validation of the integration.

The scheduling process of cracking furnace feedstock is important in an ethylene plant. In this paper it is described as a constraint optimization problem. The constraints consist of the cycle of operation, maximum tube metal temperature, process time of each feedstock, and flow rate. A modified group search optimizer is proposed to dealwith the optimization problem. Double fitness values are defined for every group. First, the factor of penalty function should be changed adaptively by the ratio of feasible and general solutions. Second, the "excellent" infeasible solution should be retained to guide the search. Some benchmark functions are used to evaluate the newalgorithm. Finally, the proposed algorithmis used to optimize the scheduling process of cracking furnace feedstock. And the optimizing result is obtained.

Considering that the on-line measurement and automatic control of element component content (ECC) are difficult to perform in rare earth cascade extraction process, the ECC distribution profile is dynamically regulated at all stages to assess the effect of product purity control. Focusing on the theory of countercurrent extraction, the technology parameters and pre-setting flow-rates during the extract process are designed. Under varying process parameters, a novel step by step model is also proposed for each stage to analyze the impact on the distribution profile change. Combining the mass balance model and ECC changing trend at the monitoring stage, the ECC distribution profile can be automatically regulated by dynamically compensating the related extract or scrubbing liquid flow-rate. To this end, the required product purity at the two outlets is achieved. Based on Wincc and Matlab dynamic simulators, a specific Pr/Nd cascade extraction process is used to illustrate and demonstrate the application of the present approach.

Auto cascade refrigeration (ACR) cyclewith phase separators is widely used in the cryogenic system. The composition of mixed refrigerant has a great effect on the performance of the system. Based on the assumption of infinite volume of phase separator, ACR systemwith one phase separator is simulated in this paper. The variation of refrigerant composition under different valves opening is obtained. A related experimental systemis set up to verify the variation. The result shows that when the valve opening connected to the evaporator increases or the valve opening under the phase separator decreases, the low-boiling component concentration of the working mixture passing through the compressor and condenser increases, while the high-boiling component concentration decreases. Furthermore, the variations of condensation pressure and evaporation pressure under different valves opening are also observed. This paper is helpful to deepen the understanding of ACR system.

Partial oxidation gasification in supercriticalwater could produce fuel gases (such as H₂, COand CH₄) and significantly reduce the energy consumption. In this work, an energetic model was developed to analyze the partial oxidative gasification of biomass (glucose and lignin) in supercritical water and the related key factors on which gasification under autothermal condition depended upon. The results indicated that the oxidant equivalent ratio (ER) should be over 0.3 as the concern about energy balance but less than 0.6 as the concern about fuel gas production. Feedstocks such as glucose and lignin also had different energy recovery efficiency. For materials which can be efficiently gasified, the partial oxidation might be a way for energy based on the combustion of fuel gases. Aromatic materials such as lignin and coal are more potential since partial oxidation could produce similar amount of fuel gases as direct gasification and offer additional energy. Energy recovered pays a key role to achieve an autothermal process. Keeping heat exchanger efficiency above 80% and heat transfer coefficient below 15 kJ·s^-1 is necessary to maintain the autothermal status. The results also indicated that the biomass loading should be above 15% but under 20% for an autothermal gasification, since the increase of biomass loading could improve the energy supplied but decrease the efficiency of gasification and gaseous yields. In general, some specific conditions exist among different materials.

The densities, conductivities, and viscosities were measured for ternary solutions of N-hexyl, methylpyrrolidinium bromide ([PP_1,6]Br)-N-butyl,methylpyrrolidinium bromide ([PP_1,4]Br)-H₂O and its binary subsystems [PP_1,6]Br-H₂O and [PP_1,4]Br-H₂O at (298.15, 303.15, 308.15, and 313.15) K, respectively. The results were used to test the predictability of the simple equations established for the prediction of density, conductivity, and viscosity of the mixed electrolyte solutions. The results show that the examined simple equations can offer good predictions for density, conductivity, and viscosity of the mixed ionic liquid solutions in terms of the corresponding properties of its binary subsystems of equal ionic strength.

Fermentation of bioflocculant with Corynebacterium glutamicum was studied by way of kinetic modeling. Lorentzian modified Logistic model, time-corrected Luedeking-Piret and Luedeking-Piret type modelswere proposed and applied to describe the cell growth, bioflocculant synthesis and consumption of substrates, with the correlation of initial biomass concentration and initial glucose concentration, respectively. The results showed that thesemodels could well characterize the batch culture process of C. glutamicumat various initial glucose concentrations from 10.0 to 17.5 g·L^-1. The initial biomass concentration could shorten the lag time of cell growth, while the maximum biomass concentration was achieved only at the optimal initial glucose concentration of 16.22 g·L^-1. A novel three-stage fed-batch strategy for bioflocculant production was developed based on the model prediction, in which the lag phase, quick biomass growth and bioflocculant production stages were sequentially proceeded with the adjustment of glucose concentration and dissolved oxygen. Biomass of 2.23 g·L^-1 was obtained and bioflocculant concentration was enhanced to 176.32 mg·L^-1, 18.62% and 403.63% higher than those in the batch process, respectively, indicating an efficient fed-batch culture strategy for bioflocculant production.

Bioconversion of lignocellulosic wastes to higher value products through fungal fermentation has economic and ecological benefits. In this study, to develop an effective strategy for production of manganese peroxidase (MnP) fromcassava residue by Phanerochaete chrysosporiumin solid state fermentation, the stimulators of MnP production were screened and their concentrations were optimized by one-at-a-time experiment and Box-Behnken design. The maximum MnP activity of 186.38 nkat·g^-1 dry mass of the sample was achieved after 6 days of fermentation with the supplement of 79.5mmol·L^-1·kg^-1 acetic acid, 3.21 ml·kg^-1 soybean oil, and 28.5 g·kg^-1 alkaline lignin, indicating that cassava residue is a promising substrate for MnP production in solid state fermentation. Meanwhile, in vitro decolorization of indigo carmine by the crude MnP was also carried out, attaining the ratio of 90.18% after 6 h of incubation. An oxidative mechanism of indigo carmine decolorization by MnP was proposed based on the analysis of intermediate metabolites with ultra-high performance liquid chromatography and gas chromatography tandemmass spectrometry. Using the crude MnP produced fromcassava residue for indigo carmine decolorization gives an effective approach to treat dyeing effluents.

Promoters are themost important tools to control and regulate the gene expression in synthetic biology and metabolic engineering. The expression of target genes in Escherichia coli is usually controlled by the high-strength inducible promoter with the result that the abnormally high transcription of these genes creates excessive metabolic load on the host, which decreases product formation. The constitutive expression systems are capable of avoiding these defects. In this study, to enrich the application of constitutive promoters in metabolic engineering, four promoters from the glycolytic pathway of E. coli were cloned and characterized using the enhanced green fluorescent protein as reporter. Among these promoters, P_gapA was determined as the strongest one, the strength of which was about 8.92% of that of the widely used inducible promoter P_T7. This promoter was used to control the expression of heterologous xylose reductase in E. coli for xylitol synthesis so as to verify its function in pathway engineering. Themaximumxylitol titer (40.6 g·L^-1) produced by engineered E. coli under the control of the constitutive promoter P_gapA was obviously higher than that under the control of the inducible promoter P_T7, indicating the feasibility and superiority of promoter P_gapA in the metabolic engineering of E. coli.

A sodium-zinc sorbent based flue gas desulfurization technology (Na-Zn-FGD) was proposed based on the experiments and analyses of the thermal decomposition characteristics of CaSO₃ and ZnSO₃·2.5H₂O, the waste products of calcium-based semi-dry and zinc-based flue gas desulfurization (Ca-SD-FGD and Zn-SD-FGD) technologies, respectively. Itwas found that ZnSO₃·2.5H₂O first lost crystal H₂O at 100 ℃ and then decomposed into SO₂ and solid ZnO at 260 ℃ in the air, while CaSO₃ is oxidized at 450 ℃ before it decomposed in the air. The experimental results confirm that Zn-SD-FGD technology is good for SO₂ removal and recycling, but with problem in clogging and high operational cost. The proposed Na-Zn-FGD is clogging proof, and more cost-effective. In the newprocess, Na₂CO₃ is used to generate Na₂CO₃ for SO₂ absorption, and the intermediate product NaHSO₃ reacts with ZnO powders, producing ZnSO₃·2.5H₂O precipitate and Na₂CO₃ solution. The Na₂CO₃ solution is clogging proof, which is re-used for SO₂ absorption. By thermal decomposition of ZnSO₃·2.5H₂O, ZnO is re-generated and SO₂ with high purity is co-produced as well. The cycle consumes some amount of raw material Na₂CO₃ and a small amount of ZnO only. The newly proposed FGD technology could be a substitute of the traditional semi-dry FGD technologies.

Biogas upgrading for removing CO₂ and other trace components from raw biogas is a necessary step before the biogas to be used as a vehicle fuel or supplied to the natural gas grid. In this work, three technologies for biogas upgrading, i.e., pressuredwater scrubbing (PWS), monoethanolamine aqueous scrubbing (MAS) and ionic liquid scrubbing (ILS), are studied and assessed in terms of their energy consumption and environmental impactswith the process simulation and green degree method. A non-random-two-liquid and Henry's law property method for a CO₂ separation system with ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf₂N]) is established and verified with experimental data. The assessment results indicate that the specific energy consumption of ILS and PWS is almost the same and much less than that of MAS. High purity CO₂ product can be obtained by MAS and ILS methods, whereas no pure CO₂ is recovered with the PWS. For the environmental aspect, ILS has the highest green degree production value, while MAS and PWS produce serious environmental impacts.

Numerical simulations were performed on flow and heat transfer performances of heat exchangers having six helical baffles of different baffle shapes and assembly configurations, i.e., two trisection baffle schemes, two quadrant baffle schemes, and two continuous helical baffle schemes. The temperature contour or the pressure contour and velocity contour plots with superimposed velocity vectors on meridian, transverse and unfolded concentric hexagonal slices are presented to obtain a full angular view. For the six helix baffled heat exchangers, the different patterns of the single vortex secondary flow and the shortcut leakage flow were depicted as well as the heat transfer properties were compared. The results show that the optimum scheme among the six configurations is a circumferential overlap trisection helix baffled heat exchanger with a baffle incline angle of 20° (20°TCO) scheme with an anti-shortcut baffle structure, which exhibits the second highest pressure drop Δp_o, the highest overall heat transfer coefficient K, shell-side heat transfer coefficient h_o and shell-side average comprehensive index h_o/Δp_o.

Amodified mathematical model is used to study the effects of various forces on the stability of cavitation bubbles within a diesel droplet. The principal finding of the work is that viscous forces of fluids stabilize the cavitation bubble, while inertial force destabilizes the cavitation bubble. The droplet viscosity plays a dominant role on the stability of cavitation bubbles comparedwith that of air and bubble. Bubble-droplet radius ratio is a key factor to control the bubble stability, especially in the high radius ratio range. Internal hydrodynamic and surface tension forces are found to stabilize the cavitation bubble, while bubble stability has little relationship with the external hydrodynamic force. Inertia makes bubble breakup easily, however, the breakup time is only slightly changed when bubble growth speed reaches a certain value (50 m·s^-1). In contrast, viscous force makes bubble hard to break. With the increasing initial bubble-droplet radius ratio, the bubble growth rate increases, the bubble breakup radius decreases, and the bubble breakup time becomes shorter.

This paper presents the characteristics of a double helix capacitance sensor formeasurement of the liquid holdup in horizontal oil-water two-phase flow. The finite elementmethod is used to calculate the sensitivity field of the sensor in a pipe with 20 mm inner diameter and the effect of sensor geometry on the distribution of sensitivity field is presented. Then, a horizontal oil-water two-phase flowexperiment is carried out to measure the response of the double helix capacitance sensor, in which a novelmethod is proposed to calibrate the liquid holdup based on three pairs of parallel-wire capacitance probes. The performance of the sensor is analyzed in terms of the flow structures detected by mini-conductance array probes.

Surface dilational rheological behavior and foam stability of starch/surfactant mixed solutions were studied at different starch concentrations and constant surfactant concentration. The results show that dilational viscoelasticity modulus, dilational elasticity modulus and dilational viscosity modulus increase with the concentration of starch particles. Foam stability increaseswith dilational viscoelasticity. Foamstrength also increases with starch concentration. Starch particles play a positive effect on foamstability and dilational viscoelasticity and the effect becomesmore significant as drainage proceeds. Film pictures indicate that the film with 20% (by mass) starch particles is thicker than that without starch. Starch particles gather in Plateau border and resist drainage, making the foammore stable.

In this study, biodiesel was produced from waste vegetable oil using a heterogeneous base catalyst synthesized by impregnating potassium hydroxide (KOH) onto diatomite. Response surface methodology based on a central composite design was used to optimize four transesterification variables: temperature (30-120 ℃), reaction time (2-6 h), methanol to oil mass ratio (10%-50%) and catalyst to oil mass ratio (2.1%-7.9%). A quadratic polynomial equationwas obtained to correlate biodiesel yield to the transesterification variables. The diatomite-KOH catalyst was characterized using X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR) and a scanning electron microscope (SEM) equipped with an energy dispersive X-ray detector (EDS). A maximum biodiesel yield of 90%(by mass) was obtained. The reaction conditions were as follows: methanol to oil mass ratio 30%, catalyst to oil mass ratio 5%, reaction time 4 h, and reaction temperature 75 ℃. The XRD, FTIR and SEM (EDS) results confirm that the addition of KOH modifies the structure of diatomite. During impregnation and calcination of the diatomite catalyst the K₂O phase forms in the diatomite structural matrix and the active basicity of this compound facilitates the transesterification process. It is possible to recycle the diatomite-KOH catalyst up to three times. The crucial biodiesel properties fromwaste vegetable oil arewithin the American Standard Test Method specifications.

In this paper, different particle sizes of coal fly ash FA-R (D₅₀ = 15.75 μm), FA-A (D₅₀ = 3.61 μm) and FA-B (D₅₀= 1.73 μm) were treated with NaOH solution to prepare the forming adsorbents FFA-R, FFA-A and FFA-B. The structure and adsorption properties of the forming adsorbents for methylene blue (MB) from aqueous solution were examined. The results showed that the specific surface areas and adsorption capacities of the forming adsorbent for MB increased with decreasing particle size of raw coal fly ashes. The adsorption kinetic data of MB on FFA-R, FFA-A and FFA-B fitted the second-order kinetic model very well with the rate constants (k₂) of 3.15 × 10^-2, 3.84×10^-2 and 6.27 × 10^-2 g·mg^-1·min^-1, respectively. The adsorption processwas not only controlled by intra-particle diffusion. The isotherms of MB on FFA-R, FFA-A and FFA-B can be described by the Langmuir isotherm and the Freundlich isotherm, and the adsorption processes were spontaneous and exothermic.

Fe₃O₄ magnetic nanoparticles (MNPs) were synthesised, characterised, and used as a peroxidase mimetic to accelerate levofloxacin sono-degradation in an ultrasound (US)/H₂O₂ system. The Fe₃O₄ MNPs were in nanometre scale with an average diameter of approximately 12 to 18 nm. The introduction of Fe₃O₄ MNPs increased levofloxacin sono-degradation in the US/H₂O₂ system. Experimental parameters, such as Fe₃O₄ MNP dose, initial solution pH, and H₂O₂ concentration, were investigated by a one-factor-at-a-time approach. The results showed that Fe₃O₄ MNPs enhanced levofloxacin removal in the pH range from 4.0 to 9.0. Levofloxacin removal ratio increased with Fe₃O₄ MNP dose up to 1.0 g·L^-1 and with H₂O₂ concentration until reaching the maximum.Moreover, three main intermediate compounds were identified by HPLC with electrospray ionisation tandem mass spectrometry, and a possible degradation pathway was proposed. This study suggests that combination of H₂O₂, Fe₃O₄ MNPs and US is a good way to improve the degradation efficiency of antibiotics.

In this study, the performance of a sequencing batch biofilm reactor (SBBR) for removal of nitrogen and phosphorus from swine wastewater was evaluated. The replacement rate of wastewater was set at 12.5% throughout the experiment. The anaerobic and aerobic times were 3 h and 7 h, respectively, and the dissolved oxygen concentration of the aerobic phase was about 3.95 mg·L^-1. The SBBR process demonstrated good performance in treating swine wastewater. The percentage removal of total chemical oxygen demand (COD), ammonia nitrogen (NH₄⁺-N), total nitrogen (TN), and total phosphorus (TP) was 98.2%, 95.7%, 95.6%, and 96.2% at effluent concentrations of COD 85.6mg·L^-1,NH₄⁺-N 35.22mg·L^-1, TN44.64 mg·L^-1, and TP 1.13mg·L^-1, respectively. Simultaneous nitrification and denitrification phenomenon was observed. Further improvement in removal efficiency of NH₄⁺-N and TN occurred at COD/TN ratio of 11:1, with effluent concentrations at NH₄⁺-N 18.5 mg·L^-1 and TN 34 mg·L^-1, while no such improvement in COD and TP removal was found. Microbial electron microscopy analysis showed that the filler surfacewas coveredwith a thick biofilm, forming an anaerobic-aerobicmicroenvironment and facilitating the removal of nitrogen, phosphorus and organicmatters. A long-termexperiment (15 weeks) showed that stable removal efficiency for N and P could be achieved in the SBBR system.

Waterborne acrylic emulsions modified with organic siloxanes and aziridine crosslinker were synthesized and applied as coating of controlled release fertilizer. The free films were characterized and the nutrient release profiles of the coated fertilizers were determined. The results show that methyl silicone oil and methylsilanolate sodiumcould not improve water resistance performance and glass transition temperature T_g of coatings, while the firmness is enhanced. Aziridine crosslinker improves the water resistance performance, firmness and T_g. Incorporation of methyl silicone oil and aziridine crosslinker gives an excellent aqueous acrylic emulsion for coated controlled release fertilizer, with the 30-day cumulative nutrient release reduced to 16% and an estimated nutrient release duration over 190 days. Therefore, this waterborne coating is promising to meet the requirements for controlled release of nutrient and environmental protection.

The LiNi_1/3Co_1/3Mn_1/3O₂ is first obtained by the controlled crystallization method and then coatedwith Ni₃(PO₄)₂ particles. The effects of the coating on rate capability and cycle life at high cut-off voltage are investigated by electrochemical impedance spectroscopy and galvanostatic measurements. The element ratio of Ni:Mn:Co is tested by inductively-coupled plasma spectrometer (ICP) analysis and it testified to be 1:1:1. It is indicated that Ni₃(PO₄)₂-coated LiNi_1/3Co_1/3Mn_1/3O₂ has an outstanding capacity retention, where 99% capacity retention is maintained after 10 cycles at 5C discharge rate between 2.7 V and 4.6 V. The electrochemical impedance spectroscopy (EIS) results show that the current exchange density i0 of the coated sample is higher than that of LiNi_1/3Co_1/3Mn_1/3O₂, which is beneficial to its electrochemical performances. All the conclusions show that the Ni₃(PO₄)₂ coating can prominently enhance the high rate performance of the LiNi_1/3Co_1/3Mn_1/3O₂, especially at high cut-off voltage.

This study was to examine the influence of reactions of char-O₂ and char-steamon the char reactivity evolution. A newly-designed fixed-bed reactor was used to conduct gasification experiments using Victorian brown coal at 800 ℃. The chars prepared from the gasification experiments were then collected and subjected to reactivity characterisation (ex-situ reactivity) using TGA (thermogravimetric analyser) in air. The results indicate that the char reactivity from TGA was generally high when the char experienced intensive gasification reactions in 0.3% O₂ in the fixed-bed reactor. The addition of steaminto the gasification not only enhanced the char conversion significantly but also reduced the char reactivity dramatically. The curve shapes of the char reactivity with involvement of steam were very different from that with O₂ gasification, implying the importance of gasifying agents to char properties.