Removal and recovery of metal anions via functional polymer based PEUF

Abstract

Most of the metal contamination comes from industrial sources and many metal anions in the effluents of these industries like chromate and borate are toxic even at very low concentrations and give rise to increasingly strict regulations. According to world health organization, boron and chromium content of the water should be less than 0.3 ppm and 0.1 ppm, respectively. Therefore, it is required to remove those metals down to very low concentrations. One promising method that may meet this requirement is polymer enhanced ultrafiltration (PEUF). PEUF is the combination of two phenomena; binding of the target metal ion to a water soluble polymer to form macromolecular complexes, and ultrafiltration. This macromolecule which has a larger molecular weight than the molecular weight cut off of the membrane will be retained, while the non-complexed ions pass through the membrane [1]. Metal anions are especially complex targets as they are coordinatively saturated and they cannot form covalent bonds to polymers easily. Therefore, it may be necessary to insert a suitable specific functional group into the polymeric matrix that makes them capable of interacting with metal anions [2]. In this study borate and chromate are selected as target metal anions to be removed. A commercial polymer, PVA (as a model agent), and two specially synthesized polymers, hydroxyethylamino glycerol modified polyglycidyl methacrylate and poly(N,N-diallyl morpholinium bromide) are employed as chelating agents and the effect of loading (metal/polymer), pH and ionic strength on chromate and borate removal are investigated using PEUF.