Metal ions removal from wastewater or washing water from contaminated soil by ultrafiltration-complexation

In the present paper a process for removal of ions from wastewater or from washing water of contaminated soil byusing the weakly basic water-soluble polymer polyethylenimine (PEI) as chelating agent and the Cu2+ ion as model incombination with an ultrafiltration process was investigated. The complexing agent was preliminarily tested to establishthe best operative conditions of the process. Next, ultrafiltration tests by using five different membranes were realised tocheck membrane performance like flux and rejection. Finally, the possibility for recovering and recycling the polymerwas tested in order to obtain an economically sustainable process. Obtained results showed that complexationconditions depends on pH: indeed, at a pH>6 PEI–Cu2+ complexes are formed, while at pHo3 the decomplexationreaction takes place. Saturation condition is 0.333 mg Cu2+/mg PEI, meaning a ratio PEI/Cu2+=3(w/w). UF testsshowed good results using the PAN 40 kDa membrane reaching an average copper concentration in the permeate of2 mg/l and a flux of 135.4 and 156.5 l/h.m2 at 2 and 4 bar, respectively. Metal rejection, permeate flow rate, andpossibility to regenerating and recycling the polymer makes the polymer-assisted ultrafiltration process (PAUF) veryinteresting for metal ion removal from waters.r 2003 Elsevier Ltd. All rights reserved.Keywords: Ultrafiltration–complexation; Polymer-assisted ultrafiltration; Cu (II) ion removal from water; Wastewater treatment; Soilremediation