Pervaporation properties of polyvinyl alcohol/ceramic composite membrane for separation of ethyl acetate/ethanol/water ternary mixtures

Shanshan Xia,Wanqin Jin,Wang Wei,Gongping Liu,Xueliang Dong 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.2

In further purification of ethyl acetate (EAC) process, azeotropic distillation or extractive distillation is usually applied. High energy consumption limits the economic profit of the process. In this study, pervaporation separation of EAC/ethanol (EA)/water ternary mixtures using the ceramic-supported polyvinyl alcohol (PVA) composite membrane was investigated to substitute the azeotropic distillation or extractive distillation. Swelling experiments were performed to evaluate the sorption characteristic of the membrane. Flory-Huggins theory was applied to study the interaction between the membrane and the penetrant. The UNIFAC model was adopted to investigate the variation of the penetrant activity in the membrane. The effects of operation temperature, feed water content and feed flow rate on the PV performance of the membrane were systematically investigated. The composite membrane exhibited high PV performance with the total flux of 2.1 kg·m−2·h−1 and 94.9 wt% permeate concentration of water (operation condition:feed composition 82.6 wt% EAC, 8.4 wt% EA, 9 wt% water, feed temperature 60 oC, feed flow rate 252 mL·min−1). The PV performance of the membrane varied slightly over a continuous PV experiment period of 110 h. Our results demonstrated that the PVA/ceramic membrane was a potential candidate for the purification of EAC/EA/water ternary mixtures.

Catalytic mechanism and reaction pathway of acetone ammoximation to acetone oxime over TS-1

Weihong Xing,Zhaohui Li,Rizhi Chen,Wanqin Jin 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.5

A series of two-step reactions and several special experiments were designed and carried out to discover the reaction pathway of acetone ammoximation to acetone oxime over titanium silicalites-1 (TS-1) employing 25 wt%ammonia and 30 wt% hydrogen peroxide as the ammoximation agents. The experimental results show that the acetone oxime can form even if there is no direct contact between acetone and TS-1 catalysts, indicating the hydroxylamine route may be the most important catalytic mechanism for the reaction. HPLC, GC/MS and ion chromatography characterization results show that hydrogen peroxide can oxidize acetone oxime to acetone, nitrite and nitrate in the presence of TS-1. In addition, nitrite and nitrate can form in the reaction of H2O2 and NH3 over TS-1. Based on these results,a possible overall reaction pathway of acetone ammoximation over TS-1 has been proposed.

Effect of initial solution apparent pH on the performance of submerged hybrid system for the p-nitrophenol hydrogenation

Rizhi Chen,Yan Du,Weihong Xing,Wanqin Jin 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.6

Coupling nanocatalysis with ceramic membrane separation can solve the problem of nanocatalyst separation in situ from a reaction mixture. A submerged hybrid system combining nanocatalysis and ceramic membrane separation was designed for the liquid phase hydrogenation of p-nitrophenol to p-aminophenol, and the effect of initial solution apparent pH (pHa) on the performance of submerged hybrid system was investigated in detail. It is demonstrated that as the initial solution pHa is adjusted from 4.5 to 7.5, the catalytic stability of nano-sized nickel is remarkably improved, possibly because the formation of impurity on the nickel surface can be restrained at weak alkaline condition, while the catalytic activity and selectively almost do not change. The membrane permeability is not affected significantly by the initial solution pHa .

Metal–organic framework membranes fabricated <i>via</i> reactive seeding

Hu, Yaoxin,Dong, Xueliang,Nan, Jiangpu,Jin, Wanqin,Ren, Xiaoming,Xu, Nanping,Lee, Young Moo Royal Society of Chemistry 2011 Chemical communications Vol.47 No.2

<P>A facile reactive seeding (RS) method was developed for the preparation of continuous MOF membranes on alumina porous supports, in which the porous support acted as the inorganic source reacting with the organic precursor to grow a seeding layer.</P>

A simple seed-embedded method to prepare ZIF-8 membranes supported on flexible PESf hollow fibers

Hangliao Zhang,Xiaobin Wang,Luyang Wei,Bo Meng,Xiaoyao Tan,Wanqin Jin,Shaomin Liu 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

With intrinsic porous structure, unique chemical versatility and abundant application opportunities,MOF membranes have attracted substantial research enthusiasm. Most of these supported MOFmembranes are prepared on the rigid ceramic substrates. If the MOF membrane possessesflexibility, theapplication opportunities will be expanded. This paper presents the synthesis of ZIF-8 membranes on theflexible polyethersulfone (PESf) hollowfibers by using a facile seed-embedded method. The resultantmembranes were characterized by scanning electron microscopy, energy dispersive X-ray, X-raydiffraction and fourier transform infrared spectroscopy. The prepared membranes were in a continuousand compact structure and showed good molecular sieve performance of H2 over CO2, N2 and CH4 with H2permeance up to 1.110 5 mol m 2 s 1 Pa 1. Due to the preferential adsorption, ZIF-8/PESf compositemembrane exhibited high permeance of H2, N2, and CH4 compared to CO2, showing potential applicationsin efficient CO2 capture from industrial mixtures. The association between the gas permeation, theamount of embedded ZIF-8 crystals and the membrane thickness was also clarified. The reproducibilitywas significantly improved compared to the conventional secondary seeding method. Attributed to thestrong adhesion between the ZIF-8 and the PESf, the membranes displayed excellent stability andflexibility which could sustain bending up to 90 without breaking the ZIF-8 membrane. This seedembeddedmethod is not only simple, but also has good reproducibility and scalability.

Continuous phenol hydroxylation over ultrafine TS-1 in a side-stream ceramic membrane reactor

Rizhi Chen,Xiulong Jiang,Fei She,Hong Jiang,Weihong Xing,Wanqin Jin 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.4

A side-stream ceramic membrane reactor system was developed that can facilitate the in situ separation of ultrafine catalysts from the reaction mixture and make the production process continuous. Continuous hydroxylation of phenol to dihydroxybenzene over ultrafine titanium silicalites-1 (TS-1) was taken as a model reaction to evaluate the feasibility and performance of the membrane reactor system. The effects of membrane pore size and operation conditions (residence time, temperature, catalyst concentration, phenol/H2O2 molar ratio) on the performance of the reactor system were examined via single factor experiments. We demonstrated that the membrane pore size and operation conditions greatly affect the conversion, selectivity and filtration resistance. The phenol conversion and dihydroxybenzene selectivity remain stable at about 11% and 95% in a 20-h continuous run, respectively.

3‐Hydroxymorphinan, a metabolite of dextromethorphan, protects nigrostriatal pathway against MPTP‐elicited damage both <i>in vivo</i> and <i>in vitro</i>

Zhang, Wei,Shin, Eun‐,Joo,Wang, Tongguang,Lee, Phil Ho,Pang, Hao,Wie, Myung‐,Bok,Kim, Won‐,Ki,Kim, Seong‐,Jin,Huang, Wen‐,Hsin,Wang, Yongjun,Zhang, Wanqin,Hong, Jauȁ Federation of American Society for Experimental Bi 2006 The FASEB Journal Vol.20 No.14

<P>We investigated the neuroprotective property of analogs of dextromethorphan (DM) in lipopolysaccharide (LPS) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models to identify neuroprotective drugs for Parkinson's disease (PD). In vivo studies showed that daily injections with DM analogs protected dopamine (DA) neurons in substantia nigra pars compacta and restored DA levels in striatum using two different models for PD. Of the five analogs studied, 3-hydroxymorphinan (3-HM), a metabolite of DM, was the most potent, and restored DA neuronal loss and DA depletion up to 90% of the controls. Behavioral studies showed an excellent correlation between potency for preventing toxin-induced decrease in motor activities and neuroprotective effects among the DM analogs studied, of which 3-HM was the most potent in attenuating behavioral damage. In vitro studies revealed two glia-dependent mechanisms for the neuroprotection by 3-HM. First, astroglia mediated the 3-HM-induced neurotrophic effect by increasing the gene expression of neurotrophic factors, which was associated with the increased acetylation of histone H3. Second, microglia participated in 3-HM-mediated neuroprotection by reducing MPTP-elicited reactive microgliosis as evidenced by the decreased production of reactive oxygen species. In summary, we show the potent neuroprotection by 3-HM in LPS and MPTP PD models investigated. With its high efficacy and low toxicity, 3-HM may be a novel therapy for PD.</P>