IN SITU SEPARATION OF ETHANOL DURING BATCH FERMENTATION WITH CO_2 STRIPPING AND ACTIVATED CARBON ADSORPTION

In situ separation of ethanol during batch fermentation with CO_2 stripping and activated carbon adsorption was studied. The higher initial glucose concentration and fermentation rate were reached due to the elimination of ethanol inhibition on the cell growth by means of CO_2 stripping. The stripped ethanol vapor was selectively adsorbed by an activated carbon column. The conde(?)sate desorbed from the adsorption column can be higher than 50% by weight. Ar unstructured model was used to simulate the experimental data satisfactorily.     

Adsorption equilibrium of citric acid from supercritical carbon dioxide/ethanol on cyano column

Supercritical adsorption equilibrium has a significant role in defining supercritical adsorption behavior. In this paper, the adsorption equilibrium of citric acid from supercritical CO2/ethanol on a cyano column was systemat-ical y investigated with the elution by characteristic point method. Equilibrium loading was obtained at 313.15 K and 321.15 K with supercritical CO2/ethanol densities varying from 0.7068 g·cm?3 to 0.8019 g·cm?3. The exper-imental results showed that the adsorption capacity of citric acid decreased with increasing temperature and in-creasing density of the supercritical CO2/ethanol mobile phase. The adsorption equilibrium data were fitted wel by the Quadratic Hill isotherm model and the isotherms showed anti-Langmuir behavior. The monolayer satura-tion adsorption capacity of citric acid is in the range of 44.54 mg·cm?3 to 64.66 mg·cm?3 with an average value of 56.86 mg·cm?3.     

Removal of Cd（II） by Nanometer AIO（OH） Loaded on Fiberglass with Activated Carbon Fiber Felt as Carrier

A new nanometer material, nanometer AlO（OH） loaded on the fiberglass with activated carbon fibers felt（ACF） as the carrier, was prepared by hydrolytic reaction for the removal of Cd（II） from aqueous solution using column adsorption experiment. As was confirmed by XRD determination, the hydrolysis production loaded on fiberglass was similar to the orthorhombic phase AlO（OH）. SEM images showed that AlO（OH） particles were in the form of small aggregated clusters. The Thomas model was applied for estimating the kinetic parameters and the saturated adsorption ability of Cd（II） adsorption on the new adsorbent. The results showed that the maximum adsorption capacity of Cd（II） was 128.50 mg·g^-1 and 117.86 mg·g^-1 for the adsorbent mass of 0.3289 g and the adsorbent mass of 0.2867 g, respectively. The elution experiment result indicated that the adsorbed Cd ions was easily desorbed from the material with 0.1 mol·L^-1 HCl solution. Adsorption-desorption cycles showed the feasibility of repealed uses of the composited material. The adsorption capacities were influenced by pH and the initial Cd（II） concentration. The amount adsorbed was greatest at pH 6.5 and the initial Cd（II） concentration of 0.07 mg·L^-1, respectively. Nanometer AlO（OH） played a major role in the adsorption process, whereas the fiberglass and ACF were assistants in the process of removing Cd（II）. In addition, the adsorption capacities for Cd（II） were obviously reduced from 128.50 mg·L^-1 to 64.28 mg·L^-1 when Pb ions were present because Pb ions took up more adsorption sites.     

AB-8树脂吸附反式1,2环己二醇热力学和动力学(英文)

AB-8 resin was used as an adsorbent for the removal of trans-1,2-cyclohexandiol(CHD) from aqueous solutions.Batch experiments were carried out to investigate the effect of contact time and temperature on sorption efficiency.The adsorptive thermodynamic properties and kinetics of CHD from water onto AB-8 resin were studied.The Langmuir and Freundlich isotherm models were employed to discuss the adsorption behavior.Thermodynamic parameters such as G,H and S were calculated.The results indicate that the equilibrium data are perfectly represented by Langmuir isotherm model.Thermodynamic study reveals that it is an exothermic process in nature and mainly physical adsorption enhanced by chemisorption with a decrease of entropy process.The kinetics of CHD adsorption is well described by the pseudo second-order model.The adsorbed CHD can be eluted from AB-8 resin by 5% ethanol aqueous solution with 100% elution percentage.     

Adsorption equilibria of paeoniflorin and albiflorin on cyano-silica column from supercritical carbon dioxide/ethanol

Adsorption equilibria of paeoniflorin and albiflorin on a cyano-silica column(CN column) from the solution of supercritical carbon dioxide(scCO_2) modified with ethanol were studied. The adsorption capacity at 308.15 K,313.15 K, 318.15 K and 323.15 K under pressures corresponding to carbon dioxide/ethanol densities from0.347 g·cm~(-3) to 0.662 g·cm~(-3) were determined using the elution by characteristic point method(ECP). The effects of temperature and pressure on the solute loading were investigated. The results showed that the lower the temperature, the higher the adsorption capacity. With the decrease of density of scCO2, the adsorption capacity strengthens. The maximum adsorption capacity of paeoniflorin(albiflorin) on the CN column was15.24 mg·ml~(-1)(31.14 mg·ml~(-1)) in the range of 0–1.84 mg·ml~(-1)(0–1.67 mg·ml~(-1)) of paeoniflorin(albiflorin)standard solution. The adsorption capacity of albiflorin was twice as much as that of paeoniflorin under the same conditions. Adsorption data of paeoniflorin and albiflorin could be well described by the Langmuir model and Freundlich model. Compared with the two model fitting results, the adsorption of paeoniflorin and albiflorin belonged to the monolayer adsorption under conditions of 308.15–323.15 K and 10–17 MPa.     

凝胶型强酸型阳离子交换树脂分离阿卡波糖:平衡、动力学与热力学研究(英文)

Acarbose, a potentα-glucosidase inhibitor, is widely used as an oral anti-diabetic drug for the treatment of the type 2, non-insulin-dependent diabetes. In this work, a gel type strong acid cation exchange resin 001×4 was applied to isolate acarbose from fermentation broth. It was demonstrated that cation exchanger 001×4 displayed a large adsorption capacity and quick exchange rate for acarbose. The static adsorption equilibrium data were well fitted to the Langmuir equation. Column adsorption experiments demonstrated that high dynamic adsorption capacity was reached at bed height of 104.4 mm, feed flow rate of 1.0 ml·min-1 and acarbose concentration of 4.0 mg·ml-1. Under the optimized conditions, the column chromatography packed with cation exchanger 001×4 recovered 74.3%（by mass） of acarbose from Actinoplanes utahensis ZJB-08196 fermentation broth with purity of 80.1%（by mass）, demonstrating great potential in the practical applications in acarbose separation.     

Adsorptive potential of Acacia nilotica based adsorbent for chromium(Ⅵ) from an aqueous phase

The objective of this research was to enhance adsorption capacity of Acacia nilotica(keekar) sawdust for the abatement of chromium bearing wastewater and to investigate the effect of process parameters on adsorption capacity. The sawdust was activated by acid wash and functionalized subsequently with formaldehyde.Functionalization of activated sawdust raised its chromium removal efficiency of almost 10% as compared to its adsorption removal efficiency of HCl treated sawdust in a batch adsorption study. Adsorption kinetic data provided better fitting with pseudo second order model. Maximum adsorption capacity calculated through the best fitting Langmuir model was 6.34 mg·g~(-1) and 8.2 mg·g~(-1) for HCl treated and formaldehyde functionalized sawdust adsorbents, respectively. The adsorption of Cr(Ⅵ) was endothermic when studied by varying temperature from 20 °C to 50 °C for both activated and functionalized adsorbents.     

非泡沫气泡分离法回收青霉素生产废水中的乙酸丁酯

Two nonfoaming bubble separation techniques, air stripping and solvent sublation, are presented and discussed in order to recover butyl acetate (BA) from discharged wastewater after solvent extraction of penicillin. Results show air stripping is not suitable for the recovery of BA from the wastewater. Axial concentration of BA had a noted maximum point along the column. In contrast, solvent sublation is very effective to recover BA from the wastewater. In solvent sublation experiments, axial concentration of BA along the column first increased and then decreased from the bottom to the top because of two primary mass transport processes. One is the transport by adsorption or attachment to ascending bubbles, and the other is by dispersion at water-solvent interface and by water film in organic solvent layer. In order to elucidate the high removal efficiency in solvent sublation, the microstructure of the wastewater was studied with optic microscope, which was showed to be an emulsion of BA in water at large concentration of BA. Solvent sublation can be successfully used in the removal of BA from its emulsion in the wastewater. The surface tension of simulated solution composed of lysozyme and BA was studied to understand mutual effect of biological materials and BA. Results show that lysozyme affects the adsorption of BA at air-water interface and they may form a complex between BA and lysozyme molecules.     

Reversible adsorption of metalworking fluids (MWFs) on Cu-BTC metal organic framework

Metalworking fluids(MWFs) are classified as hazardous substances. Due to the characteristics of the stable oil–water emulsions, it requires more costly and complicate treatment techniques to remove oil from spent MWFs. Metal organic frameworks(MOFs) are a porous network material used to remove contaminants from environment. One of the most prominent of MOFs is HKUST-1 or Cu-BTC. In this study, the Cu-BTCs were prepared by solvothermal method in various conditions and used as absorbent for removing oil micelles in MWF emulsion. The particle size of all synthesized Cu-BTCs ranged from ≈80 to 400 nm. The ability of all synthesized Cu-BTCs to remove oil micelle was greater than 95% in 60 min, while the capacity of GAC was obtained the result for only 6.8%. The maximum adsorption capacity(q _(max)) of oil micelles on Cu-BTCs was 1666.7 mg·g~(-1). The highest removal capacity of oil micelles in MWF emulsion is greater than 99% in 24 h by using Cu-BTCs washed with either butanol or ethanol.     

不同膨润土对模拟酒溶液中蛋白质的吸附

The adsorption of protein from model wine was investigated under different temperatures, pH values, contact times, and concentrations of ethanol, by certain bentonites. The results showed that ethanol molecules could broaden the protein molecules＇ channel to the interlayer of bentonite, and the maximum protein adsorption amount occurred under an ethanol concentration of 12% （by volume） and a pH value of 3.56. The increased single point Brunauer-Emmitt-Teller （BET） surface area （SBET） and adsorption pore volume （VAds） suggested a larger amount of active adsorption sites of the bentonite surface and a wider protein channel from the surface to the inner adsorption sites of bentonite, respectively. At the same time, higher methylene blue test （MBT） and swelling index （Sw） indicated that it was easy for the entrance of water and the absorbance of protein. Higher temperature was found favorable to eliminate more proteins and it took about 20 to 40min to arrive at the maximum adsorption.     

表面活性素集成生产过程(Ⅲ)吸附柱的模型

The study is focused on modeling of separation process and optimization.An adsorption separation process is simulated.The surfactin production process by Bacillus subtilis ATCC 21332 followed by surfactin adsorption in a fixed-bed column packed with commercial active carbon is studied in laboratory.The adsorption column achieves high surfactin recovery(94%)by up-flow methanol elution at 25°C.The adsorption column is simulated with a complex one-dimensional plug flow dispersion model coupled with nonlinear adsorption equilibrium,based on the assumption that the adsorption of surfactin is monomolecular layer and no micelle is formed.The molecular diffusion coefficient of surfactin in water solution with electric neutrality is estimated to be 0.428×10 -5 cm 2 ·s -1 by molecular dynamics simulation.The model developed can describe the complex interplay of adsorption kinetics,fluid dynamics,and mass-transfer phenomena based on the assumption of no radial temperature and concentration gradients,and is of adequate precision.The work involved in this paper is valuable for the optimization of the production process of surfactin.     

Removal of Phosphate from Aqueous Solution with Modified Bentonite

Bentonite combined with sawdust and other metallic compounds was used to remove phosphate from aqueous solutions in this study. The adsorption characteristics of phosphate on the modified bentonite were investigated, including the effects of temperature, adsorbent dosage, initial concentration of phosphate and pH on removal of phosphate by conducting a series of batch adsorption experiments. The results showed that 98% removal rate of phosphate was obtained since sawdust and bentonite used in this investigation were abundantly and locally available. It is concluded that modified bentonite is a relatively efficient, low cost and easily available adsorbent for the removal of phosphate from aqueous solutions.     

复合生物反应器亚硝酸型同步硝化反硝化脱氮

Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.     

利用天然浓缩丹宁合成新型凝胶吸附剂通过表面沉淀去除水溶液中铅

Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weak base with valid basic groups of 1.2mmol·g-1 tannin gel particles and therefore results in the elevation of pH value of aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pH value for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surface precipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity for adsorption of Pb is up to 92 mg·g-1 (based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbent does offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value, which     

段塞流的流量瞬变特性试验研究

An investigation of the characteristics of flowrate transients within slug flow was conducted in a largescale outdoor testing facility.The test section consisted of a 378m long,7.62cm diameter stainless steel pipe. Air and water were used as the test fluids.The response to a change of flowrate o either phase or two phases was measured using a series of pressure transducers and differential pressure transducers.An increase or decrease in gas flowrate caused a pressure overshoot above the value at new steady state or led to a pressure undershoot to form a temporary stratified flow.Pressure waves existed in the pipeline,spreading from the entrance to the exit.The magnitude of pressure overshoot in “up-gas”transient or of pressure undershoot and period of the temporary stratified flow in “Down-gas” transient are related to the change of gas flowrate and the distance away from the entrance.In contrast,the change in liquid flowrate was accommodated by smooth transitions between the corresponding steady states,and only one obvious change was found in the slug frequency.According to experimental results,the pressure overshoot,pressure undershoot and the pressure wave propagation were analyzed,and the phenomena were explained reasonably.Some correlations for the calculation of the pressure overshoot and undershoot were proposed.     

Removal of Reactive Red 198 from aqueous solution by combined method multi-walled carbon nanotubes and zero-valent iron:Equilibrium,kinetics, and thermodynamic

Dyes often include toxic,carcinogenic compounds and are harmful to humans' health.Therefore,removal of dyes from textile industry wastewater is essential.The present study aimed to evaluate the efficiency of the combination of zero valent iron(ZVI) powder and multi-walled carbon nanotubes(MWCNTs) in the removal of Reactive Red 198(RR198) dye from aqueous solution.This applied research was performed in a batch system in the laboratory scale.This study investigated the effect of various factors influencing dye removal,including contact time,p H,adsorbent dose,iron powder dose,initial dye concentration,and temperature.The equilibrium adsorption data were analyzed using three common adsorption models:Langmuir,Freundlich and Temkin.Besides,kinetic and thermodynamic parameters were used to establish the adsorption mechanism.The results showed,in pH =3,contact time = 100 min,ZVI dose = 5000 mg·L~(-1),and MWCNTs dose = 600 mg·L~(-1)in 100 mg·L~(-1)dye concentration,the adsorption efficiency increased to 99.16%.Also,adsorption kinetics was best described by the pseudo-second-order model.Equilibrium data fitted well with the Freundlich isotherm(R2= 0.99).The negative values of ΔG0and the positive value of ΔH0(91.76) indicate that the RR198 adsorption process is spontaneous and endothermic.According to the results,the combination of MWCNTs and ZVI was highly efficient in the removal of azo dyes.     

加压下规整填料塔内气液两相轴向返混实验研究

An experimental study of the extent of axial backmixing in both gas and liquid phases was conducted in a 150 mm ID column packed with Mellapak 250Y corrugated structured packing. The column was operated at pressures ranging from 0.3 MPa to 2.0MPa with nitrogen and water flowing countercurrently through the packing. The amount of axial backmixing was experimentally evaluated by the pulse response techniques using hydrogen in gas phase and an aqueous solution of NaCl in liquid phase as inert tracers. The response of the tracer was monitored by means of thermal conductivity in the gas phase and electrical conductance in the liquid phase. The experimentally determined residence time distribution (RTD) curves were interpreted in terms of the diffusion-type modei. The results indicated that the axial backmixing in the gas increased notably with gas flowrate and slightly with operating pressure and liquid flowrate. The liquid-phase axial backmixing was an increasing function of both gas and liquid flowrates an     

锰氧化物负载沸石固定床离子交换柱去除铀(VI)的研究

The adsorption of uranium (VI) on the manganese oxide coated zeolite (MOCZ) from aqueous solution was investigated in a fixed-bed column. The experiments were conducted to investigate the effects of bed height, flow rate, particle size, initial concentration of uranium (VI), initial pH, presence of salt and competitive ions. The U-uptake by MOCZ increased with initial uranium (VI) concentration and bed height, but decreased as the flow rate and particle size increased. In the presence of salt and competitive ions, the breakthrough time was shorter. The ad-sorption capacity reached a maximum at pH of 6.3. The Thomas model was applied to the experimental data to de-termine the characteristic parameters of the column for process design using linear regression. The breakthrough curves calculated from the model were in good agreement with the experimental data. The BDST model was used to study the influence of bed height on the adsorption of uranium (VI). Desorption of uranium (VI) in the MOCZ column was investigated. The column could be used for at least four adsorption-desorption cycles using 0.1 mol•L－1 NaHCO3 solution as the elution. After desorption and regeneration with deionized water, MOCZ could be reused to adsorb uranium (VI) at a comparable capacity. Compared to raw zeolite, MOCZ showed better capacity for uranium (VI) removal.     

固定化Candida sp. 99-125脂肪酶催化合成蜡酯(英文)

Wax esters were synthesized in a solvent free system catalyzed by immobilized lipase from Candida sp. 99-125, with oleic acid and cetyl alcohol. The effects of substrate molar ratio, lipase dosage and water removal were investigated in a 50 ml flask incubated in a thermostatic cultivation cabinet. The optimized conditions were: temperature 40 ℃, shaking at 170 r·min-1, acid/alcohol molar ratio 1:0.9, lipase dosage in 10% (by mass) of oleic acid, and open reaction for water removal. As a result, the conversion rate reached 98% for reaction of 8 h. The volume of reactor was scaled up to 1 L three-neck flask. The optimized parameters were: 200 r·min-1 agitation speed, 2.5% (by mass) lipase dosage, others were the same as the parameters described above. The conversion rate reached 95% for reaction of 24 h. The lipase retained 46% conversion rate after reuse for 6, 7 batches. The products were purified by removing remained cetyl alcohol and fatty acids with ethanol and saturated sodium carbonate so-lution, respectively. The purity of the wax ester, cetyl oleate, was 96%. The physical and chemical properties of cetyl oleate were tested and compared with those of jojoba oil. The results show that the product cetyl oleate has great potential to use as the substitute of natural jojoba oil.