One of the bottlenecks for bioproduction of butyric acid as bulk chemical is the difficulty in separating butyric acid from the fermentation broth,compared with the petroleum-based chemical synthesis method.In the present work,a novel separation methodology was developed based on an aqueous two-phase system with inor-ganic salts.Calcium chloride was screened out for effective separation of butyric acid from butyric acid-water-salt systems.Within appropriate concentration range of butyric acid and salt,butyric acid was enriched in the upper phase and most of calcium ions remained in the lower phase.This"salting out"effect is very efficient to separate butyric acid from the simulated butyrate fermentation broth,which consists of butyric acid and acetic acid with concentration ratio of 4:1,so that the final ratio of butyric acid/acetic acid in the upper phase is improved to 9.87. The aqueous two-phase system was used to separate butyric acid from the actual fermentation broth with satisfactory result.

In this work,the regeneration mechanism of potassium carbonate solution after absorption of CO₂ using ion-exchange membrane electrolysis was presented.The solutions of potassium carbonate (K₂CO₃) and potassium bicarbonate (KHCO₃) were used to simulate the solution after absorbing CO₂.Experiments were carried out at various electrodes,temperatures and current densities.The results indicate that the membrane electrolysis can in-crease concentration ratio of K₂CO₃ and KHCO₃,and achieve 100% conversion.In thisprocess,not only CO₂ is desorbed from carbonate solution,but also hydrogen,as a byproduct,is generated at the cathode,which is the main contributor to reduce energy consumption.Thus,the membrane electrolysis is valuable in the regeneration of the K₂CO₃ absorbent.

Understanding the interaction between a fluid and a solid phase is of fundamental importance to the design of an adsorption process.Because the heat effects associated with adsorption are comparatively large,the as-sumption of isothermal behavior is a valid approximation only when uptake rates are relatively slow.In this article,we propose to determine when it is needed to choose the isothermal or non-isothermal assumption according to two physical parameters α (ratio convection/capacity) and β(quantity of energy/capacity) .The proposed problem is solved by a mathematical method in the Laplace domain.When α→∞ (infinitely high heat transfer coefficient) or β→0 (infinitely large heat capacity),the limiting case is isothermal.When the diffusion is rapid (α<10) the kinetics of sorption is controlled entirely by heat transfer.If the adsorption process is to be used as a heat pump,it shall be represented by an isotherm model withαandβas high as possible.

Cyclic total reflux (CTR) batch distillation is a promising mode of the process but lacking of appropriate modeling for the period of filling the reflux drum.A new dynamic modeling method for the simulation of CTR batch distillation is proposed in this work,in which the changes in column holdup and liquid flow rate during the filling of the drum,and the consequent change in valid number of theoretical plates are considered.The effect of drum holdup on operation time is investigated and the optimal drum holdup is obtained from the simulation.The dynamic modeling is compared to the conventional modeling without consideration of change in liquid flow rate. The experimental result shows that the present modeling is more reliable and more accurate,especially for the column with large liquid holdup.

The mechanical dewatering of activated sludge is troublesome due to its high compressibility of solids. The dewatering can be enhanced dramatically by the use of electroosmosis,in which an electric field is applied to the sludge cake.In this study,the influence of filter cloth on the cathode on the dewatering of activated sludge was investigated.It was found that thicker filter cloth led to lower water removal from the sludge cake,so a stainless steel cathode net with small pore size instead of filter cloth was applied,which improves the dewatering efficiency and reduces the electric power consumption.Moreover,water absorbent materials were helpful to remove the water from the sludge cake.For the electroosmotic dewatering at 7 kPa and 24 V·cm^-1,the water content in the sludge cake decreased to 60% (by mass) with the average 0.075 kW·h·kg^-1 of water removed by using the cathode net.

A novel composite charged mosaic membrane (CCMM) was prepared via interfacial polymerization (IP) of polyamine[poly (epichlorohydrin amine) ]and trimesoyl chloride (TMC) on the polyethersulfone (PES) support. Fourier transform infrared spectroscopy (FT-IR),environmental scanning electron microscopy (ESEM),atomic force microscopy (AFM) and water contact angle analysis were applied to characterize the resulted CCMM.The FT-IR spectrum indicates that TMC reacts sufficiently with polyamine.ESEM and AFM pictures show that the IP process produces a dense selective layer on the support membrane.The water contact angle of the CCMM is smaller than that of the substrate membrane because of the cross-linked hydrophilic polyamine network.Several factors affecting the IP reaction and the performance of the CCMM,such as monomer concentration,reaction time,pH value of aqueous phase solution and post-treatment,were studied.The pure water flux of the optimized CCMM is 14.73 L·m ^-2 ·h ^-1 ·MPa ^-1 at the operating pressure of 0.4 MPa.The values of separation factorαfor NaCl/PEG1000/water and MgC_l2/PEG1000/water are 11.89 and 9.96,respectively.These results demonstrate that CCMM is promising for the separation of low-molecular-weight organics from their salt aqueous solutions.

The phenomenon of direct-contact condensation,used in steam driven jet injectors,nuclear reactor emergency core cooling systems and direct contact heat exchangers,was investigated computationally by introducing a thermal equilibrium model for direct-contact condensation of steam in subcooled water.The condensation model presented was a two resistance model which takes care of the heat transfer process on both sides of the interface and uses a variable steam bubble diameter.The injection of supersonic steam jet in subcooled water tank was simulated using the Euler-Euler multiphase flow model of Fluent 6.3 code with the condensation model incorporated. The findings of the computational fluid dynamics (CFD) simulations were compared with the published experimental data and fairly good agreement was observed between the two,thus validating the condensation model.The results of CFD simulations for dimensionless penetration length of steam plume varies from 2.73-7.33,while the condensation heat transfer coefficient varies from 0.75-0.917 MW·(m²·K) ^-1 for water temperature in the range of 293-343 K.

The turbulence structure in the stirred tank with a deep hollow blade (semi-ellispe) disc turbine (HEDT) was investigated by using time-resolved particle image velocimetry(TRPIV) and traditional PIV.In the stirred tank,the turbulence generated by blade passage includes the periodic components and the random turbulent ones.Traditional PIV with angle-resolved measurement and TRPIV with wavelet analysis were both used to obtain the random turbulent kinetic energy as a comparison.The wavelet analysis method was successfully used in this work to separate the random turbulent kinetic energy.The distributions of the periodic kinetic energy and the random turbulent kinetic energy were obtained.In the impeller region,the averaged random turbulent kinetic energy was about 2.6 times of the averaged periodic one.The kinetic energies at different wavelet scales from a6 to d1 were also calculated and compared.TRPIV was used to record the sequence of instantaneous velocity in the impeller stream.The evolution of the impeller stream was observed clearly and the sequence of the vorticity field was also obtained for the identification of vortices.The slope of the energy spectrum was approximately-5/3 in high frequency representing the existence of inertial subrange and some isotropic properties in stirred tank.From the power spectral density (PSD),one peak existed evidently,which was located at f0 (blade passage frequency) generated by the blade passage.

A non-isothermal injection molding process for a non-Newtonian viscous pseudoplastic fluid is simulated.A conservative interface capturing technique and the flow field solving method are coupled to perform a dynamic simulation.The validity of the numerical method is verified by a benchmark problem.The melt interface evolution versus time is captured and the physical quantities such as temperature,velocity and pressure at each time step are obtained with corresponding analysis.A"frozen skin"layer with the thickness increasing versus time during the injection process is found.The fact that the"frozen skin"layer can be reduced by increasing the injection velocity is numerically verified.The fountain flow phenomenon near the melt interface is also captured.Moreover,comparisons with the non-isothermal Newtonian case show that the curvatures of the interface arcs and the pressure contours near the horizontal mid-line of the cavity for the non-Newtonian pseudoplastic case is larger than that for the Newtonian case.The velocity profiles are different at different positions for the non-Newtonian pseudoplastic case,while in the case of Newtonian flow the velocity profiles are parabolic and almost the same at different positions.

Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes (STT) and plain twisted tapes (PTT) are investigated experimentally using the water as working fluid.The tapes (STT and PTT) have three twist ratios(y=2.0,4.4 and 6.0) and the Reynolds number ranges from 2000 to 12000.The experimental results reveal that heat transfer rate,friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance.Over the range considered,the Nusselt number,friction factor and thermal enhancement factor in a tube with STT are respectively,1.03 to 1.14,1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT.An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.

A heterogeneous model is developed for the regeneration of the Cr₂O₃/Al₂O₃ catalyst for the propane dehydrogenation process by considering the internal mass transfer and external mass/heat transfer during the coke combustion.Simulation shows that under practical operating conditions,multi-steady states exist for the catalyst pellets and the catalyst temperature is sensitive to gas temperature.However,at increased mass flow rate or lowered oxygen concentration,multi-steady states will not appear.Under the strong influences of film diffusion,the coke in the packed bed reactor will first be exhausted at the inlet,while if the film diffusion resistance is decreased,the position of first coke exhaustion moves toward the outlet of the reactor.

Production of biodiesel with supercritical methanol is a green synthesis process. A study was carried out in a vertical tubular reactor with a length of 3700 mm and a diameter of 20 mm at 275-375℃ ,15 MPa,and molar ratio of methanol to soybean oil of 40:1.The phase holdup,intermediate product,yield and axial distribution of methyl ester (ME) were investigated.Methanol and oil were mixed non-uniformly due to the formation of biodiesel and difference in their densities,even when the reaction system was in the supercritical state.From top to bottom,the phase holdup of methanol increased and that of oil decreased.As temperature increased,the concentrations of monoglyceride and diglyceride decreased gradually and the ME yield increased.When the temperature reached 300℃ ,the critical temperature of the system,the ME yield was 50%.Further increase in temperature led to a sharp in-crease of ME yield.However,at 375℃ after 1200 s of reaction time,the decomposition rate of ME was greater than its formation rate,reducing the ME yield.

Determination of probable mechanism function and kinetic parameters is important to hydrometallurgical kinetics.In this work,the most probable mechanism function and kinetic parameters of gibbsite dissolution in NaOH solution are studied.The sample,the mixture of synthetic gibbsite and sodium hydroxide solution,was scanned in high-pressure differential scanning calorimetry (DSC) equipment with the heating rate of 10 K·min^-1. Integral equation and differential equation of non-isothermal kinetics were solved to fit the data related to DSC curve.According to the calculation results,the most probable mechanism function for pure synthetic gibbsite dissolution in sodium hydroxide solution is presented based on the optimum procedure in the database of the mechanism function.The apparent activation energy obtained is (75±1) kJ·mol^-1,the frequency factor is 10^8±;1mol·s^-1,and the reaction is a second order reaction.

Salt-forming regions for a complex salt-water system in non-equilibrium state of evaporation process are usually different from those in solubility diagrams.To understand the solid-forming region of NaCl and improve the utilization of bittern resources,experiments were carried out to evaporate 20 representative mixture solution samples of Na⁺,Mg²⁺//Cl^-,SO₄^2--H₂O system with an average evaporation intensity of (1.4±0.4) g·L^-1 ·min^-1 (water) at boiling temperature 348 K,and determine the NaCl solid-forming regions in non-equilibrium state.Because of the complexity of salt-forming region,a maximal region and a minimal region were proposed to express the non-equilibrium state salt-forming region with different crystal seed,and a conditional salt-forming region was proposed to present the characteristic region of non-equilibrium salt-forming phase diagram.The areas of the maximal and minimal regions are 2.00 and 1.56 times those in solubility diagram,so it is possible to utilize bittern resources in high efficiency.The recovery rates of NaCl were 99.65%,93.14%,88.57%,72.76%,and 83.68%for six typical bittern sources from Tulantai Salt Lake (China),Dongtai Salt Lake (China),Jilantai Salt Lake (China),Qarun Salt Lake (Egypt) and seawater,respectively.It is testified that the non-equilibrium state salt-forming phase diagram can be used in industrial processes.

Lubricating mineral base oils are normally extracted from lube-oil cuts with furfural solvent.Aromatic content in the raffinate phase from extraction process is an essential parameter that affects the quality of the lubricating base-oils.For determination of aromatic content by the usual ASTM D3238 method,density,refractive index and molecular weight of the raffinate are required.In this work,a new generalized correlation is developed for determination the aromatic content by using only the measured viscosity of lubricating oil.With a mole fraction of aromatic compounds,the kinematic viscosity may be obtained at any temperature between 60-100℃ along with their molecular weight and refractive index.

The solubility of disperse dyes and their mixture in supercritical carbon dioxide is an important property in study and development of supercritical fluid dyeing technology.In this study,solubilities of C. I. Disperse Red 73,C.I.Disperse Blue 183 and their mixture in supercritical CO₂ are measured at temperatures from 343.2 to 383.2 K and pressures from 12 to 28 MPa with a static recirculation method.Under the experimental conditions for the binary(C. I.Disperse Red 73+CO₂ or C. I. Disperse Blue 183+CO₂) and ternary (C. I. Disperse Red 73+C. I. Disperse Blue 183+CO₂) systems,the solubilities increase with pressure.The solubility of C. I.Disperse Blue 183 decreases with the increase of temperature when the pressure is lower than 16 MPa,and the trend is opposite when the pressure is higher than 16 MPa.However,there is no crossover pressure for C.I.Disperse Red 73.The solubilities are also affected by molecular polarity of dyes.The co-solvent effect exhibited in the dissolving process of mixed dyes promotes their dissolution in supercritical CO₂ .The experimental data of solubilities of C. I.Disperse Red 73,C. I.Disperse Blue 183,and their mixture are correlated with the Chrastil model and Mendez-Santiago/Teja model. The former is more accurate.

2-Chloro-5-chloromethylpyridine is a crucial intermediate of pesticides.Its solid-liquid equilibrium data will provide essential support for industrial design and further theoretical studies.The solubilities of 2-chloro-5-chloromethylpyridine in water,methanol,ethanol,ethyl acetate,acetone,trichloromethane and toluene at different temperatures were measured using the synthetic method by a laser monitoring observation technique. The solubility data were correlated with the modified Apelblat equation and Wilson equation.The calculated values were in good agreement with the experimental values.

Ultrasonic speeds of 4-aminobutyric acid in 0.0041,0.0125 and 0.0207 mol·kg^-1 aqueous salbutamol sulphate (SBS) solutions are measured at 308.15,313.15 and 318.15 K.Isentropic compressibility kS,change in isentropic compressibility △k S,relative change in isentropic compressibility (△k_s/k_s⁰),apparent molal compressibility k_φ,limiting apparent molal compressibility k_φ⁰ ,transfer limiting apparent molal compressibility k_φ⁰,hydration number nH,pair and triplet interaction parameters kAS,kASS are estimated.The above parameters are used to interpret the solute-solute and solute-solvent interactions of 4-aminobutyric acid in the aqueous salbutamol sulphate solutions.

Supermacroporous composite cryogels embedded with SiO₂ nanoparticles were prepared by radical cryogenic copolymerization of the reactive monomer mixture of acrylamide (AAm) and N,N-methylene-bis-acrylamide (MBAAm) containing SiO₂ nanoparticles (mass ratios of nanoparticles to the monomer AAm from 0.01 to 0.08) under the freezing-temperature variation condition in glass columns.The properties of these composite cryogels were measured.The height equivalent to theoretical plate(HETP) of the cryogel beds at different liquid flow rates was determined by residence time distribution (RTD) using tracer pulse-response method.The composite cryogel matrix embedded with the mass fraction of SiO₂ nanoparticles of 0.02 presented the best properties and was employed in the following graft polymerization.Chromatographic process of lysozyme in the composite cryogel grafted with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) was carried out to evaluate the protein breakthrough and elution characteristics.The chromatography can be carried out at relatively high superficial velocity,i.e.,15 cm·min^-1,indicating the satisfactory mechanical strength due to the embedded nanoparticles.

The biodegradability of wastewater containing priority pollutant pesticideVydine or triadimenol (C14H18CLN3O2) in different bio-reactor configurations was investigated.Two laboratory scale biological reactors were employed:one reactor under aerobic condition and the other under anaerobic condition.The aerobic reactor was operated at an ambient temperature (22±2) ℃ ,while the anaerobic reactor was run in the lower mesophilic range (30±2) ℃ .The effect of pesticide concentration,hydraulic retention time(HRT),and co-substrate on the treatment process was explored,using glucose as a supplemental carbon substrate.More than 96%pesticide was removed after an acclimation period of approximately 172 d (aerobic) and 230 d (anaerobic) .The aerobic reactor achieved complete Vydine utilization at feed concentrations up to 25 mg·L^-1 .On the other hand,the anaerobic reactor was able to degrade 25 mg·L^-1 of Vydine.Moreover,glucose was consumed first throughout the experiment in a sequential utilization pattern.The combination of anaerobic and aerobic biological processes yielded higher biomass concentration and lower retention time than individual units.The biomass in the combined reactors was first acclimated with the corresponding pesticide.Then,the target pesticide,at a concentration of 25 mg·L^-1,was sequentially treated in a semi batch mode in the reactors.HRT studies showed that 24 h HRT of aerobic and 12 h HRT of anaerobic were the optimum combination for the treatment of simulated wastewater containing Vydine,which produced Vydine effluent at concentration below 0.1 mg·L^-1 .The optimum ratio of substrate (Vydine) to co-substrate (glucose) was 1:100.

The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L^-1,while it had negative effects when its concentration was higher than 500 mg·L^-1.The hydrogen production was the highest 1.29 mol·mol^-1(H₂/glucose) when 300 mg·L^-1 L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP),which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range -300 mV to -150 mV when the L-cysteine concentration was higher than 500 mg·L^-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L^-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.

The effects of oxidant dosage,oxidation temperature and time on the degradation of soda lignin by hydrogen peroxide with and without the presence of microwave irradiation were investigated.It is found that the oxidative degradation of lignin includes the cleavage of ether bond in β-O-4 structure,the partial destruction of aromatic ring,and the re-condensation of the degraded lignin.Compared to the conventionally heated oxidation of lignin,the microwave irradiation efficiently facilitates the degradation of the lignin with high molecular weight and the re-condensation of that with low molecular weight at a low oxidant dosage,low oxidation temperature,or a short oxidation time,which leads to the formation of the degraded lignin with narrower molecular weight distribution and lower molecular weight.Additionally,the lignin degraded in the presence of microwave irradiation has the characteristics of higher content of phenolic hydroxyl group,lower content of methoxyl group,and lower degree of condensation,which enhances the reactivity of lignin.Therefore,the oxidative degradation of lignin assisted by microwave irradiation may be a new pretreatment approach for efficiently utilizing the soda lignin.

Composition estimation plays very important role in plant operation and control.Extended Kalman filter(EKF) is one of the most common estimators,which has been used in composition estimation of reactive batch distillation,but its performance is heavily dependent on the thermodynamic modeling of vapor-liquid equilibrium,which is difficult to initialize and tune.In this paper an inferential state estimation scheme based on adaptive neuro-fuzzy inference system(ANFIS),which is a model base estimator,is employed for composition estimation by using temperature measurements in multicomponent reactive batch distillation.The state estimator is supported by data from a complete dynamic model that includes component and energy balance equations accompanied with thermodynamic relations and reaction kinetics.The mathematical model is verified by pilot plant data.The simulation results show that the ANFIS estimator provides reliable and accurate estimation for component concentrations in reactive batch distillation.The estimated states form a basis for improving the performance of reactive batch distillation either through decision making of an operator or through an automatic closed-loop control scheme.