Volatile organic compounds pervaporation

Pervaporation Liquid Vapor 1.5-60 (permeate is under vacuum) Nonporous Volatile organic compounds... 

The cross-flow pervaporation system is an ex situ technology for the removal of volatile organic compounds (VOCs) from contaminated aqueous waste streams. Permeable hollow-fiber membranes preferentially adsorb VOCs. A vacuum on the other side of the membrane puUs the compounds through the membrane and partitions the VOCs from the aqueous stream. The organics may be recovered for reuse. 

Papaefstathion and Luque de Castro [ 130] used pervaporation as an alternative to headspace analysis for the analysis of down to 1 ng/g of volatile organic compounds in soils. 

In the case of pervaporation of dissolved volatile organic compounds (VOCs) from water, the magnitude of the concentration polarization effect is a function of the enrichment factor. The selectivity of pervaporation membranes to different VOCs varies widely, so the intrinsic enrichment and the magnitude of concentration polarization effects depend strongly on the solute. Table 4.2 shows experimentally measured enrichment values for a series of dilute VOC solutions treated with silicone rubber membranes in spiral-wound modules [15], When these values are superimposed on the Wijmans plot as shown in Figure 4.12, the concentration polarization modulus varies from 1.0, that is, no concentration polarization, for isopropanol, to 0.1 for trichloroethane, which has an enrichment of 5700. 

FIGURE 26 Removal of trace volatile organic compounds from wastewater streams by pervaporation. (Membrane Technology and Research, Inc.)... 

Ji W, Hilaly A, Sikdar SK, and Hwang ST. Optimization of multicomponent pervaporation for removal of volatile organic compounds from water. J. Memb. Sci. 1994 97 109-125. 

Vane LM, Hitchens L, Alvarez FR, and Giroux EL. Field demonstration of pervaporation for the separation of volatile organic compounds from a surfactant-based soil remediation fluid. J. Hazard. Mater. 2001 81(1-2) 141-166. 

Dutta BK and Sikdar SK. Separation of volatile organic compounds from aqueous solutions by pervaporation using S-B-S block copolymer membranes. Env. Sci. Tech. 1999 33(10) 1709-1716. 

Sirkar KK, Yang D, Majumdar S, Kovenklioglu S, and Sengupta A. Hollow fiber-containing liquid membrane pervaporation for removal of volatile organic compounds from aqueous solution. Patent No. US 5637224 Kind A Date 19970610. 

Baker, R. W. et al.. Development of Pervaporation to Recover and Reuse Volatile Organic Compounds from Industrial Waste Streams, US Dept, of Energy Final Report DOE/AL/98769-1 (DE97006846) March 1997. 

Trifunovi O, Tragardh G. 2002. Transport of dilute volatile organic compounds through pervaporation membranes. Desalination 149 1-2. 

The dense polyvinyl alcohol layer is supported by a porous PAN substrate membrane. Polyelectrolyte material [24] and chitosan [25], a natural product, are also potentially useful for dehydration by pervaporation. Sihcone rubber membranes developed for the removal of organic vapors from air can also be used for the removal of volatile organic compounds (VOCs) from water by pervaporation [23]. Because of the high hydrophobic nature of silicone rubber, VOCs are preferentially sorbed and transported through the membrane. 

Jou, J.D., Yoshida, W. and Cohen, Y. 1999. A novel ceramic-supported polymer membrane for pervaporation of dilute volatile organic compounds. EMen Sa. 162 269-284. 

Uragami, T., Yamada, H. and Miyata, T. 2001. Removal of dilute volatile organic compounds in water through graft copolymer membranes consisting of poly(alkyhnethacrylate) and poly(dimethylsiloxane) by pervaporation and their memhrane morphology,... 

Despite the low number of existing works on PVPRs, the investigations tend to cover the two main common applications of organophihc pervaporation i.e. the recovery of aroma compounds from process streams (Karlsson and Tragfirdh, 1993 Pereira et al, 2006 Trifunovic et a/., 2006) and the removal of volatile organic compounds (VOC) from aqueous effluents (Konieczny et al, 2008 Lipnizki and Field, 2002 Peng et al, 2003 Urkiaga et al, 2002). 

Removal of volatile organic compounds (VOCs) from aqueous solutions by pervaporation... 

Hydrophobic membranes can be used to extract organic solvents or volatile organic compounds (VOCs) from water. The membranes are made of hydrophobic cross-Unked polymers. The membrane chemistry is designed to attract VOC molecules to the surface of the membrane. Pervaporation takes place in the membrane. VOCs diffuse through the membrane and evaporate on the permeate side with the help of a vacuum. These VOCs later condense in a condenser. Examples of these membrane applications include extraction of numerous types of VOCs from water, extraction of aromatics from water, ketones from water, esters from water, and many more. 

S. Sikdar, and L. Vane, Recovery of volatile organic compounds from emulsion of volatile organic compounds in water by pervaporation, US. Patent 6,039,878, assigned to the U.S.A. as represented by the US. Environmental Protection Agency, March 21,2000. 

When ionic liquids are used as replacements for organic solvents in processes with nonvolatile products, downstream processing may become complicated. This may apply to many biotransformations in which the better selectivity of the biocatalyst is used to transform more complex molecules. In such cases, product isolation can be achieved by, for example, extraction with supercritical CO2 [50]. Recently, membrane processes such as pervaporation and nanofiltration have been used. The use of pervaporation for less volatile compounds such as phenylethanol has been reported by Crespo and co-workers [51]. We have developed a separation process based on nanofiltration [52, 53] which is especially well suited for isolation of nonvolatile compounds such as carbohydrates or charged compounds. It may also be used for easy recovery and/or purification of ionic liquids. 

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