Porous polyurethane urea membranes for pervaporation separation of phenol and chlorophenols from water

Porous hydrophobic polyurethane urea (PUU) membrane was prepared for pervaporation separation of phenol and two chlorophenols namely p-chlorophenol (PCP) and 2,4-dichlorophenol (DCP). Polyurethane urea was synthesized by reacting hydroxy terminated polybutadiene (HTPB) with 2,4-toluene diisocyanate (TDI) using oxydianiline (ODA) as chain extender. Porosity was generated in the dense PUU by incorporating lithium chloride (LiCl) during PUU formation and then leaching out LiCl after PUU membrane formation. Both the pore size and number of pores per unit area was found to increase with increase in amount of LiCl addition during synthesis of membrane. The porous PUU showed better pervaporation separation efficiency than the dense PUU. The porous polyurethane membranes performed separation of phenol and chlorophenols with separation factors ranging from about 570 to 1760 at total permeate fluxes of 7.7-14.1 kg/m(2) h over feed concentrations of 1000-4000 ppm (0.1-0.4%, w/v) at 30 degrees C. Phenol and chlorophenol fluxes have been increased remarkably by incorporation of porosity in the membrane. But the separation factor has not been increased to the extent of increase in flux. (C) 2007 Elsevier B.V. All rights reserved.