Removal of trace VOCs from water through PDMS membranes and analysis of their permeation behaviors

Abstract

ABSTRACT:The removal of trace chlorinated hydrocarbons from water has been performed through poly(dimethylsiloxane), which had been fabricated by addition crosslinking reaction. The membrane had a more hydrophobic characteristic than that fabricated by a condensation reaction because it has no polar groups in the polymeric chain, such as hydroxyl and chlorine groups. This study concentrated on the comparison of the permeation behaviors of homologous series of chloromethanes aqueous solutions with that of a chloroethane solution. It was suggested that when the hydrophobic characteristics of a membrane system is greater, water molecules in the membrane tend to exist in the form of clusters; thereby, the permeating size of water component increases, resulting in suppressing water permeation and increasing the enrichment factor for the organic component. The permeation behaviors at various temperatures and membrane thicknesses were indirectly interpreted in terms of the effect of concentration polarization and the effect of interactions of organic-membrane, and water-organic-absorbing membrane.

Pervaporation dehydration of isopropanol using blend membranes of chitosan and hydroxypropyl cellulose

“…5 shows the exact composition of water in permeate as a function of wt.% of water in feed for different HPC content in the CS matrix. From this, one can conclude as noted before that the polymer plasticization effect would be the responsible factor for decreased selectivity [29,30]. An increase in HPC content of the blend matrix leads to a more flexible polymer network, thereby inducing higher free volume in the membrane, resulting in the increase of permeation rates.…”

Poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) membranes for ethyl acetate removal from water

“…The dependence of diffusivity (D) on the concentration and temperature can be expressed with the following equations [22]:…”

Pervaporative recovery of volatile aroma compounds from fruit juices

“…More traditionally, K L i has been either experimentally determined [90,[101][102][103][104][105] or estimated with the aid of semi-empirical correlations in terms of Sherwood, Reynolds and Schmidt numbers [106][107][108], which were reviewed by Gekas and Hallström [109]. As evidenced by a great number of researchers [56,[93][94][95][96][97][98]101,[110][111][112][113], the feed-side resistance commonly represents a significant fraction of the overall mass-transfer resistance during the pervaporative recovery of diluted volatile organic compounds (VOC's) from aqueous solutions. This additional mass-transfer resistance implies a flux reduction for a given concentration difference between feed and permeate streams.…”