| Popis: |
The extraction of Pb2+ ions from diluted solutions was achieved using a hybrid process combining cation exchange textiles, ion-exchange membranes and electric current. Two methods were investigated: an electroextraction process in two steps where the fixation of Pb2+ ions was followed by electroregeneration of the cation-exchange textiles; the second one a continuous electroextraction process where the ion exchange and regeneration take place simultaneously. For these electroextraction processes, the cation-exchange textile is introduced into an electrodialysis cell and compressed between two cation-exchange membranes. Under an applied current, the Pb2+ ions are substituted by regenerating ions coming from the anodic compartment and are transferred into a receiver compartment at the cathodic side where they are concentrated. Cation-exchange textiles having strong or weak acid functional groups, sulfonic (SCET) and carboxylic (CCET), respectively, were used. Different regenerating ions, H+, Na+, K+ and NH4+ were investigated under various 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 than 95% were obtained with a 10 ppm Pb2+ feed solution giving an outlet concentration of less than 1 ppm. The efficiency of the two textiles was compared in terms of mass transfer and energy consumption. |
Full Text from ScienceDirect