PERVAPORATIVE REMOVAL OF VOLATILE ORGANIC COMPOUNDS FROM MULTICOMPONENT AQUEOUS MIXTURES

Abstract

The present study concerns with the separation of binary and ternary water–organics mixtures by pervaporation using different organophilic membranes (i.e., PERVAP-1060—polydimethylsiloxane, PERVAP-1070—zeolite filled polydimethylsiloxane, PEBAX-4033—polyether block amide). The following binary and ternary liquid mixtures were investigated: water–methyl acetate; water–ethyl acetate; water–butyl acetate, water–methyl t-butyl ether (MTBE), and water–methanol–MTBE. The organic components of these mixtures can be found in the wastewaters from textile, pharmaceutical, and petrochemical industries. The experiments were focused on the efficiency of investigated membranes used for the removal of organics from water. During the experiments, the following parameters characterizing system were determined: the separation factor (α), the permeate flux (J), and the degree of the removal of organics from water (D r) in the batch mode pervaporation. The influence of the feed temperature, the initial content of organics in the feed, and the feed volume to the membrane area (V/S) ratio were investigated. It was proved that all membranes were selective in the removal of volatile organic compounds from water. The selectivity and transport properties as well as the efficiency parameters were dependent strongly not only on the kind of the membrane and the kind of the separated feed mixture but also on the process parameters. The PERVAP-1060 membrane showed the best efficiency in the removal of organics from water, whereas the PERVAP-1070 membrane was the most selective one. Much lower efficiencies found for PEBAX-4033 membrane were caused by the fact that the selective layer of PEBAX-4033 membrane contained both the hydrophobic and hydrophilic blocks. Comparing the properties of a given membrane in contact with binary and ternary mixtures, it was stated that the selectivities and permeate fluxes were lower in contact with the latter ones.