Removal of chlorinated volatile organic contaminants from water by pervaporation using a novel polyurethane urea–poly (methyl methacrylate) interpenetrating network membrane

Abstract

Polymer membranes are potentially selective for separation of organic compounds from a mixture by pervaporation. A novel crosslinked hydroxyterminated polybutadiene based (HTPB) polyurethane urea (PUU)–poly (methyl methacrylate) (PMMA) interpenetrating network (IPN) membrane has been developed for the selective removal of chlorinated volatile organic compounds (VOCs) such as 1 , 1 , 2 , 2 -tetrachloroethane, chloroform, carbon tetrachloride, trichloroethylene present in water in very low concentration by pervaporation. IPNs of different PMMA content and also different crosslink density were used. Since the selective permeation and diffusion of the VOCs through the membrane are dependent on their interaction with the membrane material, their sorption and diffusion behaviors through the membrane were also investigated by swelling the membrane in pure VOCs. The sorption and diffusion behaviors were explained with the help of their solubility parameter data and calculated interaction parameter data of the membrane polymers with the VOCs. From the swelling kinetics data, diffusion coefficients of the VOCs through the membrane were calculated. Diffusion coefficients increased with the increase in crosslink density and PMMA content in the membrane. In pervaporation experiment, concentrations of chlorinated organic compounds in feed were varied from 100 ppm (0.01%) to 1000 ppm (0.1%). All the three IPN membranes showed excellent separation performances of the chlorinated VOCs from water. One IPN containing 26% PMMA (PUU–PMMA-3) produced 88.7% trichloroethylene in permeate, 0.2 kg / m 2 h trichloroethylene flux and a separation factor of 7842 from a 0.1% aqueous feed after a pervaporation run of 3 h at 30 ∘ C . All the three IPN membranes of different compositions have shown the separation performances, viz., flux and separation factor for all the VOCs in the order 1 , 1 , 2 , 2 - tetrachloroethane < carbon tetrachloride < chloroform < trichloroethylene .