Fig. 9: Adsorption and long-term performance studies of fabricated membranes.

a Adsorbed amount of Pb2+, Ni2+, Cu2+, and Zn2+ by the developed composite membranes CQACNT, MWCNT-OH-6 and CASCNT-6; b Normalized PWP and normalized removal of CQACNT-0 and CQACNT-6 membranes. Error bars represent the standard deviation between three reported values.