Separation of cerium from feed solution by nanofiltration

The aim of this work was to evaluate the separation of cerium ions from dilute cerium feed solution by nanofiltration and to study the performance of commercial NF-300 membrane to accomplish an effective cerium removal at various operating conditions. The feed and permeates were analyzed for solute concentration by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Experimental results indicated that the rejection of cerium ions increases with increase in applied pressure (2–10 bar) and decreases with increase in feed concentrations (10–80 mg/L of CeCl3) at constant cross flow rate. Cerium rejection by nanofiltration assisted by complexation with ethylene diamine tetra aceticacid (EDTA) as chelating agent, was markedly influenced by pH (2–10), where higher degree of cerium removal was achieved for basic medium than that in acidic medium. The maximum observed rejection of Ce(III) was found to be 94.37% and 90.03% for an initial feed concentration of 10 and 80 mg/L, respectively. It was also observed that Ce rejection by NF assisted with EDTA complexation changed from 11% (2 pH) to 99% (8–12 pH). © 2011 Elsevier B.V. All rights reserved.

different ionic form at different pH condition. This phenomenon can be explained well by the comparative studies on the speciation of Ce(III)-EDTA system and the experimental rejections of Ce(III) performed by NF assisted by complexation as a function of pH. The free Ce(III) ions concentration and the ionic species of EDTA in solution as a function of increasing pH in acidic medium kept on decreasing and the complex [Ce-EDTA] 1− formation becomes significant and at around 6–7 pH only cerium complex was present in the feed thereby increasing rejection. The effect of pH on the permeate flux was very small. The Jv remained constant in the acidic pH and a stepwise lowering was seen in the basic pH. This may be due to increased concentration build up of Ce(III) on the membrane due to its increased rejection [25].