Papers by Keyword: Pervaporation

Abstract: Dense membranes made of polybenzodioxane (PIM-1) were developed for pervaporation of toluene/TEG mixtures. The effect of experiment time on membrane characteristics such as flux and separation factor was investigated. The neat PIM-1 membranes showed high toluene flux of 2.45 kg/m²∙h, but low separation factor of 4. The cross-linking of PIM-1 using AlCl₃ leads to an increase in the separation factor up to 20, with some compromise of toluene flux down to 0.76 kg/m²∙h.

Abstract: Clean water is essential source for household purpose. However, many surface water contain high salt concentration was found. In this work, membrane was made using tetraethyl orthosilicate (TEOS) as silica precursors and citric acid as single organo catalyst. Membranes were calcined at 200 and 250 °C using Rapid thermal processing (RTP). All membranes were tested via pervaporation. Pervaporation processes allow membrane to separate salt from water as vapour phase with vacuum condition required. Permeate was collected in the cold trap after condenses. This study focus to the performance of organo silica membrane in variance of refluxed 0 and 50 °C and feed concentrations (0.3, 3.5 and 5wt% NaCl) at room temperature (~25 °C). Optimum condition was obtained at reflux 50 °C with high siloxane and Si-C bonds. Carbon content from citric acid promote silica network more strength. The good performances in variance feed concentration were also showed at reflux 50°C with 0.3324 kg.m-2.h-1 (0.3 wt%), 0,2290 kg.m^-2.h^-1 (3.5 wt%) and 0.2168 kg.m^-2.h^-1 (5 wt%). These membranes are categorized as mesoporous and achieve excellent salt rejection >95%.

Abstract: This work shows the performance of cobalt-silica membranes through water desalination via pervaporation process. The aim of this work is to find out the performance of the cobalt oxide as a templating agent in the silica cobalt membranes for water desalination via pervaporation process. It also aims to investigate the water flux and salt rejection of silica cobalt membranes using artificial saline water. The concentration of cobalt oxide as a template for fabricating cobalt-silica membranes were 5 – 35 wt%. The feed solution applied during pervaporation process were 0.3 – 5 wt% NaCl with operating temperatures of 25, 40 and 60 °C. The silica xerogels were characterized using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET). From the FTIR result, it is known that the higher the concentration of cobalt in the membrane, the more silanol and siloxane groups. Based on BET analysis, Si-Co 35 wt% membrane has largest pore volume (0.129387 cm³g^-1). In addition, the highest value of water flux (7.2660 kg.m^-2.h^-1) and salt rejection (100%) is achieved by Si-Co 5% membrane in 0.3% NaCl feed at 60 °C. The value of water flux decreases and the value of salt rejection increases with increasing feed concentration.

Abstract: Sodium acrylate (NaAA) and acrylamide (AM) were grafted onto poly (vinyl alcohol) (PVA) using potassium persulfate as an initiator, Graft copolymerization namely poly (vinyl alcohol)-g-poly (acrylamide/sodium acrylate) (PVA-g-PAM/SAC). The poly (vinyl alcohol)-g-poly (vinylamine/sodium acrylate) (PVAMC) was prepraed by Hofmann rearrangement.The PVAMC homogeneous membrane was characterized by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM).The water resistance of the PVAMC membranes is the best when pH of the PVAMC solutions was 4, at that time the numbers of-NH₃⁺ and-COO^- groups trended to be equal, so the isoelectric point was pH=4. At 90 °C the pervaporation of PVAMC composite membrane was tested and showed that the separation factor and the permeate flux were about 1001 and 1341 g/(m²·h) for 90wt% ethanol aqueous solution, and they were about 1297 and 1040 g/(m²·h) for 90wt% isopropanol aqueous solution.

Abstract: This study focuses on the utilization of natural polysaccharides as membrane material for the separation of liquid-liquid systems and the potential of membrane pervaporation process to recover drilling mud. Hydrophilic membranes derived from chitosan and sago starch were developed and modified for the pervaporation of ethanol-water, ethyl acetate-water and cesium/potassium formate-water. Membranes were modified through polymer blending, chemical cross-linking as well as heat treatment. Response surface methodology (RSM) was also used to study the optimum preparation conditions of sago starch membranes for the recovery of drilling mud. Increasing feed concentration increases flux and decrease separation factor for both chitosan and sago based membranes. Using RSM, the optimum preparation conditions of sago based membranes was found to be at 65 wt.% of sago, 1.5 wt.% of glutaraldehyde and heat treated at 110°C. Pervaporation was also demonstrated to be feasible for the recovery of cesium/potassium formate drilling mud.

Abstract: Polyimide membrane pervaporation was introduced to separate the costly diene mixtures of cyclopentadiene/methylcyclopentadiene (CPD/MCPD) from cracking C5 fractions. Four kinds of membrane solutions were prepared and two kinds of polyimide homogenous membranes were fabricated by thermal imidizations using the dianhydrides (BPADAand PMDA) and the diamines (ODA and DDS). The effect of the casting solutions viscosity on the membrane formation was revealed, and the formation of functional groups and the synthesis mechanisms of the thermal imidizations were indicated by FT-IR. The adsorption behaviors and the pervaporation performances were studies for BPADA-ODA and PMDA-ODA membranes. The results show that the permeation fluxes are 164g∙m^-2∙h^-1 and 4.2g∙m^-2∙h^-1 for BPADA-ODA and PMDA-ODA membranes respectively, while the separation factor are 1.93 and 8.9 for these two membranes respectively. 88.5 wt% concentration of MCPD was achieved in the circulated feed side ultimately.

Abstract: Polydimethylsiloxane (PDMS) pervaporation (PV) membranes are promising for the recovery of aromatic compounds in water. The novel oleyl alcohol-modified PDMS membranes were prepared using n-heptane as solvent, tetraethyl orthosilicate (TEOS) as crosslinker, di-n-butyltin dilaurate (DBTL) as catalyst and oleyl alcohol as organic modifier. The PV performances were investigated for separating phenol/water mixtures at different temperatures. The results showed that the oleyl alcohol-modified PDMS membranes had better selectivity than those without oleyl alcohol. For 0.50 wt% phenol in feed mixture at 80 °C, these membranes had a flux of 0.115 kg m^-2 h^-1 and separation factor of 8.77.

Abstract: Sago composite membrane possesses a microporous polysulfone substrate were prepared and tested for dehydration of ethyl acetate/water mixture. Sago composite membrane has been cross-linked successfully by glutaraldehyde. The membranes were characterized by Degree of swelling (DS) and scanning electron micrographs (SEM). Pervaporation of ethyl acetate –water mixture was conducted over a range of water concentration (1-4wt %) in feed solution at varied temperature from 30°C to 60°C. Keywords Sago starch: Pervaporation; Ethyl acetate; Polyvinyl alcohol; Composite Membrane;

Abstract: Silicalite-1 membranes with high-thermal stability were prepared on silica tubes by two-step hydrothermal synthesis after filling the tubes with water and glycerol mixtures. It was found that the filling method can improve the membrane separation performance effectively. After filling the silica tubes with mixed solution, the average flux of silicalite-1 membranes was improved by 23% while keeping the separation selectivity nearly unchanged. The results showed that the silicalite-1 membrane still showed high separation performance towards ethanol/water mixture after the repeated calcination at 400°C for 5 h, even with a calcination rate of 4 °C/min, which suggested that silica tubes may be very suitable to synthesize high-performance silicalite-1 membranes in large area.

Abstract: We utilized pressure-, vacuum-, and evaporation-assisted self-assembly techniques through which graphene oxide (GO) was deposited on modified polyacrylonitrile (mPAN). The fabricated composite GO/mPAN membranes were applied to dehydrate 1-butanol mixtures by pervaporation. Varying driving forces in the self-assembly techniques induced different GO assembly layer microstructures. XRD results indicated that the GO layer d-spacing varied from 8.3 Å to 11.5 Å. The self-assembly technique with evaporation resulted in a heterogeneous GO layer with loop structures; this layer was shown to be hydrophobic, in contrast to the hydrophilic layer formed from the other two techniques. From the pressure-assisted technique, the composite membrane exhibited exceptional pervaporation performance at 30 °C: concentration of water at the permeate side = 99.6 wt% and permeation flux = 2.54 kg m-2 h-1. This excellent separation performance stemmed from the dense, highly ordered laminate structure of GO.