The flooding characteristics of hydrofoil impeller were systematically investigated in a two-and three-phase 383 mm i.d. stirred tank operated on air, water and spherical glass beads. The volumetric solid concentration C_s was varied from 0 to 25%. And the superficial gas velocity U_g was at the range of 0-0.096 m·s^-1. A fast and objective method for identifying flooding point N_F is developed based on the statistical analysis of the pressure fluctuation signals. It is found, the effect of solid concentration on the flooding point N_F depends on the gas velocity. At the lower gas velocity (U_g=0.010 m·s^-1), the solid concentration has only a minor effect. However, it displays a very significant effect on the flooding point N_F at the medium and high gas velocity. The flooding point N_F linearly increases with the gas velocity U_g, at lower solid concentration (C_s=0, 10%). When C_s=20%, the behavior of N_F versus U_g becomes more complex. The correlations of the flooding characteristics in the slurry stirred tank are proposed by considering the solid concentration effect.

The Intalox metal tower packing was used to simulate an industrial relevant extractive distillation column for purifying azeotropic multicomponent mixture.In order to explain the inconsistencies in the modeling of transfer process in nonideal multicomponent distillation column,a method was developed with equilibrium stage models(EQ)and non-equilibrium model(NEQ)incorporated with Maxwell-Stefan diffusion equations in the framework of AspenONE simulator.Dortmund Modified UNIFAC(UNIFAC-DMD)thermodynamic model was employed to estimate activity coefficients.In addition,to understand the reason for the diffusion against driving force and the different results by EQ and NEQ models,explicit investigations were made on diffusion coefficients, component Murphree efficiency and mass transfer coefficients.The results provide valuable information for basic design and applications associated with extractive distillation.

The adsorption and mechanism of Re(Ⅶ)on resin D318 were studied using chemical methods and IR spectrometry.At pH 5.2,the static and dynamic saturation adsorption capacities were 351.4 and 366.5 mg·g^-1,respectively.The adsorption behavior obeyed the Freundlich empirical equation and the adsorption rate constant k₂₉₈ was 6.37×10^-4s^-1.The desorption percentage was up to 99.7%when 2.0 mol·L^-1 KSCN was used for dynamic desorption.

Ceramic capillary membrane has received much attention due to its relatively high pack density and favorable mechanical strength.However,it is difficult to prepare capillary membrane on its thin support by a dip-coating method.In this study,alumina microfiltration membranes were prepared on the inner surface of alumina capillary support(outer diameter 4 mm,inner diameter 2.5 mm)by a dip-coating method.Scanning electron microscopy(SEM)observation,gas bubble pressure(GBP)method and membrane permeation test were carried out to evaluate membrane performance.Two major effects in preparation of crack-free membrane,capillary filtration and film-coating,upon the thin support were studied.The as-prepared crack-free membrane presents a narrow pore size distribution,a mean pore size of about 0.6μm and a high pure water flux of 86000 L·m^-2·h^-1·MPa.It is proved that the membrane thickness should be sufficiently large to overcome the defects of support surface,but it is only one of the prerequisites for the formation of crack-free membrane.Furthermore,it is demonstrated that the capillary filtration effect is greatly restricted for thin capillary support with the dip-coating method and the film-coating effect plays a crucial role in the formation of crack-free membrane.

A series of Cu-ZnO-Al₂O₃ catalysts with various metal compositions of Cu/Zn/Al were prepared by the co-precipitation method,and screened for glycerol hydrogenolysis to propylene glycol.The catalyst with a Cu/Zn/Al molar ratio of 1:1:0.5 exhibited the best performance for glycerol hydrogenolysis,and thus selected for kinetic investigation.Under elimination of external and internal diffusion limitation,kinetic experiments were performed in an isothermal fixed-bed reactor at a hydrogen pressure range of 3.0-5.0 MPa and a temperature range of 493-513 K. Based on a dehydration-hydrogenation two-step hydrogenolysis mechanism,a two-site Langmuir-Hinshelwood kinetic model taking into account competitive adsorption of glycerol,acetol and propylene glycol was proposed and successfully fitted to the experimental data.The average relative errors between observed and predicted outlet concentrations of glycerol and propylene glycol were 6.3% and 7.6%,respectively.The kinetic and adsorption parameters were estimated by using the fourth-order Runge-Kutta method together with the Rosenbrock algorithm.The activation energies for dehydration and hydrogenation reactions were 86.56 and 57.80 kJ·mol^-1,respectively.

The chemical kinetics of the monoesterification between terephthalic acid(TPA)and 1,4-butanediol (BDO)catalyzed by a metallo-organic compound was studied using the initial rate method.The experiments were carried out in the temperature range of 463-483 K,and butylhydroxyoxo-stannane(BuSnOOH)and tetrabutyl titanate[Ti(OBu)₄] were used as catalyst respectively.The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)₄ were measured at a series of initial concentrations of BDO(or TPA) with the concentration of TPA(or BDO)kept constant.The reaction orders of reagents were determined by the initial rate method.The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)₄ respectively.However,the order for BDO is the same 0.9 for the two catalysts.Furthermore,the effects of temperature and catalyst concentration are investigated,and the activation energies and the reaction rate constants for the two catalysts were determined.

Perovskite-type La_0.8Sr_0.2MnO₃ was prepared by stearic acid gel combustion method.The obtained powders were characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scaning electron micrograph(SEM)and X-ray photoelectron spectroscopy(XPS)techniques.The catalytic activity of La_0.8Sr_0.2MnO₃ was investigated on thermal decomposition of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX)by thermal gravity-differential scanning calorimetry(TG-DSC)techniques.The experimental results show that La_0.8Sr_0.2MnO₃ is an effective catalyst for HMX thermal decomposition.The surface-adsorbed species such as H₂O,OH^- and adsorbed oxygen(Oad)could result in an advance in the onset temperature of HMX thermal decomposition.The mixture system of Mn³⁺ and Mn⁴⁺ ions and lattice oxygen could play key roles for the increase of the decomposition heat of HMX because these exothermic reactions could be catalyzed by La_0.8Sr_0.2MnO₃ between CO and NO_x(from the thermal decomposition of HMX)and the oxidation reaction of CO.According to the previous researches and our results,perovskite-type La_0.8Sr_0.2MnO₃ may be used as a novel catalyst or modifier for nitrate ester plasticized polyether(NEPE)propellant.

A novel methodology is presented for simultaneously optimizing synthesis and cleaning schedule of flexible heat exchanger network(HEN)by genetic/simulated annealing algorithms(GA/SA).Through taking into account the effect of fouling process on optimal network topology,a preliminary network structure possessing two-fold oversynthesis is obtained by means of pseudo-temperature enthalpy(T-H)diagram approach prior to simultaneous optimization.Thus,the computational complexity of this problem classified as NP(Non-deterministic Polynomial)-complete can be significantly reduced.The promising matches resulting from preliminary synthesis stage are further optimized in parallel with their heat exchange areas and cleaning schedule.In addition,a novel continuous time representation is introduced to subdivide the given time horizon into several variable-size intervals according to operating periods of heat exchangers,and then flexible HEN synthesis can be implemented in dynamic manner.A numerical example is provided to demonstrate that the presented strategy is feasible to decrease the total annual cost(TAC)and further improve network flexibility,but even more important,it may be applied to solve large-scale flexible HEN synthesis problems.

State estimation is the precondition and foundation of a bioprocess monitoring and optimal control. However,there are many difficulties in dealing with a non-linear system,such as the instability of process, un-modeled dynamics,parameter sensitivity,etc.This paper discusses the principles and characteristics of three different approaches,extended Kalman filters,strong tracking filters and unscented transformation based Kalman filters.By introducing the unscented transformation method and a sub-optimal fading factor to correct the prediction error covariance,an improved Kalman filter,unscented transformation based robust Kalman filter,is proposed. The performance of the algorithm is compared with the strong tracking filter and unscented transformation based Kalman filter and illustrated in a typical case study for glutathione fermentation process.The results show that the proposed algorithm presents better accuracy and stability on the state estimation in numerical calculations.

In this paper,a third-generation dry gas-to-ethylbenzene process in a factory of PetroChina is considered.For the gradual catalyst deactivation in the alkylation reactor,a model is established with the parameters estimated from the reaction rate equation of alkylation based on the on-site data and those from laboratory analysis. The real-time dynamic simulation of the alkylation process is carried out,in which the module accuracy is ensured by using OPC(Object linking and embedding for Process Control)technique and adaptive correction of model parameters.Both the current and future operation temperature can be predicted.

Density(ρ)and viscosity(η)are measured for glycine,DL-α-alanine DL-α-valine,and DL-α-leucine in 0.05,0.10,0.15 and 0.20 mol·L^-1 aqueous metformin hydrochloride at 308.15,313.15 and 318.15 K.The measured values are used to estimate some important parameters,such as partial molal volume V_φ,standard partial molal volume V_φ⁰,transfer volume ΔV_φ⁰,hydration number n_H,the second derivative of infinite dilution of partial molal volume with respect to temperature,viz.,∂²V_φ⁰/∂T²,viscosity B-coefficient,variation of B with temperature,viz., dB/dT,free energy of activation per mole of solvent Δμ₁⁰ and solute Δμ₂⁰ of the amino acids.These parameters are interpreted in terms of solute-solute and solute-solvent interactions and structure making/breaking ability of solutes in the given solution.In addition,V_φ⁰, ΔV_φ⁰,viscosity B-coefficient,ΔB and Δμ₂⁰ are split into group contributions(NH₃⁺COO^-)and —CH₂ of the amino acids using their linear correlation and their behavior is discussed.

The viscosities of pure water,the acetic acid+water binary system,and the p-xylene+acetic acid+ water ternary system at different concentrations were determined with a rolling-ball viscometer at temperatures from 313.15 to 473.15 K and pressures from 0.10 to 3.20 MPa.The viscosity data were fitted by a correlation equation for the estimation of the mixture viscosities.The average absolute deviations(AAD)of the correlation for binary and ternary systems are 2.48% and 1.77%,respectively.

With the energy parameters obtained from ¹H nuclear magnetic resonance(NMR)chemical shifts data by local composition model and coupled with azeotropic point,the low-pressure vapor-liquid equilibrium is satisfactorily predicted for alcohol+hexane,alcohol+cyclohexane,and alcohol+benzene binary systems at different temperatures.The relationship between the spectroscopic information and thermodynamic property is presented.

The gas phase thermodynamic properties of 135 polychlorinated xanthones(PCXTs)are calculated using a combination of quantum mechanical computations performed with the Gaussian 03 program at the B3LYP/6-311G^** level.It is found that the chlorine substitution pattern strongly influences the thermodynamic properties of the compounds.The thermodynamic properties of congeners with the same number of chlorines also depend on the chlorine substitution pattern,especially for ortho-substituted congeners.PCXT congeners with one phenyl ring fully chlorinated are found to be the least stable among the analogues.The effect of the chlorine substitution pattern is quantitatively studied by considering the number and position of Cl atom substitution(N_PCS).The results show that the N_PCS model may be used to predict the thermodynamic properties for all 135 PCXT congeners. In addition,the values of molar heat capacities at constant pressure(c_p,m)from 200 to 1000 K for PCXT congeners are calculated,and the temperature dependence relation of this parameter is obtained using the least-squares method.

In order to investigate the competition for carbon source between denitrification and phosphorus release processes,simultaneous phosphorus release and denitrification in sludge operated in anoxic,aerobic mode are investigated by varying the ratio of influent COD to nitrogenous compound concentration under anoxic condition using a lab-scale sequencing batch reactor(SBR).The results show that the nitrate reduction rate is nearly independent of the ratio of influent COD to nitrate under anoxic condition.More NO_x^--N in the influent leads to less PO₄^3--P release during the feeding period.However, PO₄^3--P release proceeds at a low rate simultaneously with denitrification even when the influent NO_x^--N concentration is as large as 20 mg·L^-1 and its rate is increased obviously when NO_x^--N is denitrified to a concentration lower than 0.5 mg·L^-1.The variation of pH during anoxic period gives some information about the biochemical reactions of denitrification and PO₄^3--P release.When more nitrate is present in the influent,more acetate uptake in feeding period is used for direct microorganism growth.

Activated sludge process has been widely used to remove phosphorus and nitrogen from wastewater. However,the nitrogen and phosphorus removal is sometimes unsatisfactory due to the low influent COD.Another problem with the activated sludge process is that large amount of waste activated sludge is produced,which needs further treatment.In this study,the waste activated sludge alkaline fermentation liquid was used as the main carbon source for phosphorus and nitrogen removal under anaerobic followed by alternating aerobic-anoxic conditions,and the results were compared with those using acetic acid as the carbon source.The use of alkaline fermentation liquid not only affected the transformations of phosphorus,nitrogen,intracellular polyhydroxyalkanoates and glycogen, but also led to higher removal efficiencies for phosphorus and nitrogen compared with acetic acid.It was observed that ammonium was completely removed with either alkaline fermentation liquid or acetic acid as the carbon source. However,the former resulted in higher removal efficiencies for phosphorus(95%)and nitrogen(82%),while the latter showed lower ones(87% and 74%,respectively).The presence of a large amount of propionic acid in the alkaline fermentation liquid was one possible reason for its higher phosphorus removal efficiency.Exogenous instead of endogenous denitrification was the main pathway for nitrogen removal with the alkaline fermentation liquid as the carbon source,which was responsible for its higher nitrogen removal efficiency.It seems that the alkaline fermentation liquid can replace acetic acid as the carbon source for phosphorus and nitrogen removal in anaerobic followed by alternating aerobic-anoxic sequencing batch reactor.

Biodegradation of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane(DDT)in soil by laccase extract from white rot fungi under different experimental conditions was investigated.DDTs,which stands for the sum of p,p′-DDE,o,p′-DDT,p,p′-DDD and p,p′-DDT in soil was degraded efficiently,and the residue decreased rapidly during the first 15 days and then slowly during the period of 16-25 days.The biodegradation of DDTs in soil fitted the pseudo-first-order kinetics.For 5,10,15 and 25 days of incubation with laccase,the residue of DDTs in soil under different atmospheres was decreased by 20%-33%,34%-52%,41%-61%and 41%-69%respectively,under different flooding conditions that was decreased by 12%-17%,17%-30%,30%-45%and 35%-52%respectively, and for different soils that was decreased by 25%-34%,39%-53%,44%-58%and 47%-62%respectively.The half-life of DDTs in soil ranged from 15.07 to 32.95 days under O₂,air or N₂ atmospheres,23.07 to 40.71 days under different flooding conditions,and 18.78 to 28.88 days for different soils.Laccase is an efficient and safe agent for bioremediation of DDT-contaminated soil.

In this paper,the effects of pore-size of SBA-15 on the adsorption kinetics and equilibrium of large protein molecules Bovine serum albumin(BSA)and lysozyme(LYS)have been investigated.The mesoporous molecular sieve SBA-15 with six different pore sizes were synthesized with P123 triblock copolymer as the template agent,and 1,3,5-trimethylbenzene(TMB)and isopropyl alcohol as the pore-expanding agent.The samples were characterized by N₂ adsorption/desorption,Scanning Electron Microscopy(SEM),Transmission Electron Microscopy(TEM)and X-Ray Diffraction(XRD).It is found that BSA and LYS were adsorbed rapidly on SBA-15 materials with large pores.The BSA adsorption capacity of sieve with the pore diameter of 21.4 nm reached 500 mg·g^-1 within 25 minutes.However,if the pore diameter was smaller than 14 nm,the BSA adsorption capacity of the sieve was only about 220 mg·g^-1.The adsorption equilibrium data fits in the Langmuir model,where the coefficient of effective use of specific area of mesoporous molecular sieve was found to be 0.03,0.18,0.37 and 0.48,corresponding to the pore diameter of 10.1 nm,13.2 nm,15.4 nm and 21.4 nm,respectively.The equilibrium loading amount of LYS on SBA-15 materials with pore size of 15.4 nm could be up to 1000 mg·g^-1.The coefficient of effective use of surface area of mesoporous molecular sieve with diameter of 3.9 nm,7.4 nm,10.1 nm,13.2 nm and 15.4 nm was 0.10,0.47,0.56,0.71 and 0.79,respectively.It is also noted that greater pore size of mesoporous molecular sieve would lead to a higher coefficient of effective use of surface area.

Hydrogen peroxide(H₂O₂)precipitation from sodium aluminate(SA)solution at close-ambient temperature is an efficient method to synthesize boehmite and its derived alumina with high surface area,but the precipitation yield of Al₂O₃ is usually below 50%in highly alkaline SA solutions.Here the synthesis of boehmite is enhanced through a precarbonization-assisted H₂O₂ route in highly alkaline SA solutions.It is found that the crystal structure of the precipitation product is evidently influenced by the precipitation conditions.As the precipitation temperature increases from 273 to 325 K,a small amount of gibbsite by-product is formed.As the aging temperature increases from 301 to 333 K,the crystallinity of boehmite decreases and part of the boehmite dissolves due to an increase in the pH value.Based on the above results,a precarbonization-assisted H₂O₂ route is proposed to obtain pure boehmite with more complete recovery of Al₂O₃ from highly alkaline SA solutions.The route includes a controllable precarbonization step of SA solutions with a molar ratio of Na₂O to Al₂O₃ higher than 2:1,followed by the H₂O₂-precipitated step with a molar ratio of H₂O₂ to Al₂O₃ less than 7:1.Because of its facile operation conditions,no extraneous impurity,time saving and a possible recycle of the filtrate,the route has great potential to be an alternative method for preparation of boehmite and its derived alumina.

Zr-substituted,Tm-doped SrCeO₃(SrCe_0.95-xZr_xTm_0.05O_3-δ,0≤x≤0.40)were synthesized via citrate complexing method,and the membranes of SrCe_0.95-xZr_xTm_0.05O_3-δwere prepared by pressing followed by sintering. X-ray diffraction(XRD)was used to characterize the phase structure of sintered membrane.The microstructure of the sintered membranes was studied by scanning electron microscopy(SEM).Protonic and electronic conductivities were measured under different circumstance.Hydrogen permeation through the SrCe_0.75Zr_0.20Tm_0.05O_3-δmembranes was carried out using gas permeation setup.Hydrogen permeation fluxes(J_H2) of the SrCe_0.75Zr_0.20Tm_0.05O_3-δ membrane reach up to 0.042 ml·min^-1·cm^-2 at H₂ partial pressure of 0.4×10^-1 Pa at 900℃.The hydrogen permeation fluxes(J_H2)obtained in this paper are slightly lower than that of SrCe0.95Tm0.05O_3-δ on the same orders,and Zr doping can increase chemical stability of the SrCe_0.75Zr_0.20Tm_0.05O_3-δ membranes.

Storage modulus and loss modulus is the main performance index of visco-elastic properties.In this paper the storage modulus and loss modulus of a new diverting acid and their influencing factors were systematically investigated.Besides,the constitutive equations of the diverting acid at different temperatures were elicited from shearing experiments,which show that the visco-elastic surfactant(VES)acid system is a non-Newtonian power law fluid at low temperature and a Newtonian fluid at high temperature.The storage modulus and loss modulus at different temperatures,pH,and VES content in the acid are critical for the design of acid stimulation for oil well,especially when the VES acid is used in this field only on trial and the basic data are in urgent needed for the design and construction of the acidification stimulation.

At relatively high cellulose mass concentrations(8%,10%,and 12%),homogeneous acetylation of cellulose was carried out in an ionic liquid,1-allyl-3-methylimidazolium chloride(AmimCl).Without using any catalyst,cellulose acetates(CAs)with the degree of substitution(DS)in a range from 0.4 to 3.0 were synthesized in one-step.The effects of reaction time,temperature and molar ratio of acetic anhydride/anhydroglucose unit(AGU) in cellulose on DS value of CAs were investigated.The synthesized CAs were characterized by means of FT-IR, NMR,and solubility,mechanical and thermal tests.After the acetylation,the used ionic liquid AmimCl was easily recycled and reused.This study shows the potential of the homogeneous acetylation of cellulose at relatively high concentrations in ionic liquids in future industrial applications.

Elemental mercury(Hg⁰)re-emissions from slurries and solutions were evaluated in a lab-scale simulated scrubber.Oxidized mercury(Hg²⁺)standard solution was injected into the simulated scrubber at a desired rate to simulate absorbing and dissolving of Hg²⁺ in the flue gas across wet flue gas desulfurization(WFGD)systems. PS analytical mercury analyzer was used to continuously determine Hg0re-emission concentrations in the carrier gas from the scrubber.Sulfite ion in the slurry of CaSO₃ was validated to reduce Hg²⁺ to Hg⁰,while no Hg⁰ re-emission occurred from slurries of CaSO₄ and CaO.Transitional metal ions with low chemical valence such as Fe²⁺,Pb²⁺,Ni²⁺,AsO₂^-+-1.Reduction reaction of Hg²⁺ to Hg⁰ was observed from these solutions.Reduction capabilities for the different transitional metal ions in the solutions were:Pb²⁺>Cu⁺>Fe²⁺>AsO₂^->Ni²⁺.

Polyethersulfone(PES)film with regular microporous structure was formed using dichloromethane as the solvent via water vapor induced phase separation(VIPS).The effects of solution concentration,atmospheric humidity and temperature,as well as molecular weight of PES on the surface morphology of the polymer film were investigated.The surface morphology characterized by SEM showed that the pore size reduced as the solution concentration increased.There was an optimum range of relative humidity for the formation of regular pore structure, which was from 60%to 90%at concentration of 20 g·L^-1 and 20℃.With the atmospheric temperature varied from 20 to 30℃,the pore became larger and the space between pores increased.The pore size in the PES film with low molecular weight was smaller than that with high molecular weight.