Separation of Lead (Pb2+) and Cadmium (Cd2+) from Single and Binary Salt Aqueous Solutions Using Nanofiltration Membranes

Abstract

The present work reports on the performance of three types of nanofiltration membranes in the removal of highly polluting and toxic lead (Pb²⁺) and cadmium (Cd²⁺) from single and binary salt aqueous solutions simulating real wastewaters. The effect of the operating variables (pH (5.5-6.5), types of NF membrane and initial ions concentration (10-250 ppm)) on the separation process and water flux was investigated. It was observed that the rejection efficiency increased with increasing pH of solution and decreasing the initial metal ions concentrations. While the flux decreased with increasing pH of solution and increasing initial metal ions concentrations. The maximum rejection of lead and cadmium ions in single salt solution was 99%, 97.5 % and 98 % at pH 6, 6.5 and 6.2 and 78%, 49.2% and 44% at pH 6.5, 6.2 and 6.5 for NF1, NF2 and NF3 respectively. On the other hand, maximum permeate flux for single NF2 (32.2)> NF3 (16.1)>NF1 (14.2) (l/m².h) for 100 ppm, higher than binary salt solution was NF2 (23.7) ˃ NF3 (13) ˃ NF1 (8) (l/m².h) for (10 Pb²⁺/50 Cd²⁺) ppm. The NF membranes proved able to achieve high separation efficiency of both lead and cadmium ions in very suitable conditions, leaving wastewaters in a condition suitable prior discharged into the environment.