Electroextraction of Pb2+ ions from diluted solutions by a process combining ion-exchange textiles and membranes

The extraction of Pb2+ ions from diluted solutions was achieved using a hyb rid process combining cation exchange textiles, ion-exchange membranes and electric current. Two methods were investigated: an electroextraction proce ss in two steps where the fixation of Pb2+ ions was followed by electrorege neration of the cation-exchange textiles; the second one a continuous elect roextraction process where the ion exchange and regeneration take place sim ultaneously. For these electroextraction processes, the cation-exchange tex tile is introduced into an electrodialysis cell and compressed between two cation-exchange membranes. Under an applied current, the Pb2+ ions are subs tituted by regenerating ions coming from the anodic compartment and are tra nsferred into a receiver compartment at the cathodic side where they are co ncentrated. Cation-exchange textiles having strong or weak acid functional groups, sulfonic (SCET) and carboxylic (CCET), respectively, were used. Dif ferent regenerating ions, H+, Na+, K+ and NH4+ were investigated under vari ous current densities. Electroregeneration ratios between 85% and 100% were obtained with sulfonic and carboxylic textiles previously loaded with Pb2 ions. In the continuous electroextraction, removal efficiencies higher tha n 95% were obtained with a 10 ppm Pb2+ feed solution giving an outlet conce ntration of less than 1 ppm. The efficiency of the two textiles was compare d in terms of mass transfer and energy consumption.