Investigations and characterization of radiation grafted copolymers for possible practical use in waste water treatment

Selective removal and recovery of metals from industrial effluent is an environmental problem and economic concern. There are a number of heavy metals that are candidates for removal prior to having waste solutions coming in contact with the environment. Therefore, a study has been made on the preparation of hydrophilic membranes having both anionic and cationic exchangers. To achieve such properties in the required membranes, a trial has been made on the radiation graft copolymerization of binary monomers possessing anionic and cationic exchangers such as acrylic acid/2- and 4-vinyl pyridine (AAc/2-VP) (AAc/4-VP) onto available commercial polymeric substrate such as low-density polyethylene (LDPE). The preparation conditions at which the grafting process proceeds homogeneously are determined. Characterization and some selected properties of the prepared grafted membranes were studied and accordingly the possibility of its practicable use in waste water treatment from heavy and toxic metals such as Pb, Zn, Cd, Fe,... etc, was investigated. The metal uptake by such prepared membranes was determined by using atomic absorption technique. The membrane efficiency and durability was investigated. The maximum uptake for a given metal was higher for the LDPE-g-P (AAc/2VP) membranes than that for the LDPE-g-P (AAc/4VP). The chelated metal ions were easily desorbed by treating the membrane with 0.1 N HCl for 2 h at room temperature. A mixture of two or three metals in the same feed solution was used to determine the selectivity of the membrane towards different metals. The results obtained for the prepared membranes showed a great promise for their applicability in the removal of heavy metals from wastewater. (C) 1999 Elsevier Science Ltd. All rights reserved.