Removal of heavy metals by surface tailored copper ion enhanced ceramic-supported-polymeric composite nanofiltration membrane

Abstract

Ceramic-supported-polymeric (CSP) composite membranes combine the benefits of robust ceramic support with tunable surface properties of polymeric active layer. The present work reports the fabrication of novel CSP composite nanofiltration membranes wherein surface ionization of the membrane active layers has been carried out by a facile process of chelating copper ions with the crosslinked polyethyleneimine polymer matrix of membrane top layer. Different concentrations of copper chloride solutions were used and their effect on membrane surface properties was investigated using EDX, XPS and AFM analyses. Performance of the membranes in removal of both cationic and anionic heavy metals, namely, Ni(II), Cd(II), Pb(II), Zn(II), As(V) and Cr(VI) from aqueous solution was studied. Excellent removal (> 95%) of all the heavy metals and optimum flux was achieved in case of GPCu0.5 membrane (surface modified with 0.5 wt% copper chloride solution). No significant decrease in flux and rejection rate of the membrane during 10 h high pressure (8 bar) operation suggested longevity of the membrane. The slow release of copper ions indicated the much-expected anti-biofouling nature of the membrane. Appreciable rejection behavior of the copper ion enhanced CSP composite membrane towards multiple heavy metals demonstrates its potential for practical water treatment application.