Recovery of Zinc, Copper, Nickel, and Cobalt from Electroplating Wastewater by Electro-Nanofiltration

The work is devoted to recovery of zinc, copper, nickel and cobalt from electroplating wastewater by electro-nanofiltration. The objects of study were the domestically produced nanofiltration membranes OPMN-K, OPMN-P (JSC Vladipor) and multicomponent technological solutions and wastewater from electroplating lines containing ions Cu2+, Zn2+, Co2+, Ni2+. The dependences of the retention coefficients of metal cations and the specific output flow on the applied pressure are obtained. The optimal current density for carrying out the electro-nanofiltration separation of electroplating wastewater has been determined. It was found that with an increase in the transmembrane pressure as the main driving force of the process, the retention coefficient rises, and at values exceeding the nominal working pressure by 25%, the retention coefficient begins to decrease for both types of membranes. The transfer numbers for the studied membranes were calculated for the retained cations. It is noted that the retention capacity of the OPMN-P membrane is higher than that of the OPMN-K membrane. The specific output flow increases with an increase in transmembrane pressure due to a rise in the driving force of the process on account of an increase in flow rate.