Adsorption/photo-electrodialysis combination system for Pb2+ removal using bentonite/membrane/semiconductor

A combination system combining adsorption/photo electrochemistry/dialysis is investigated for the first time for the Pb2+ removal. The Pb2+ adsorption on the Algerian bentonite is studied in batch mode. The initial Pb2+ concentration, adsorption dosage, pH and temperature are optimized. The maximum removal is observed at pH 6 for a concentration of 100 mg L−1 at 25 °C. The adsorption is fast with ∼90% occurring within 40 min of contact time. The process is spontaneous and endothermic. The Langmuir model is successfully applied to fit the experimental data. The remaining concentration is lowered by photo-electrodialysis below the threshold required by the water standards. The ion exchange membrane, configured as a horizontal electrode, is an essential part of the process. The membrane is polymerized from cellulose triacetate modified by poly-ethyleneimine and plasticized by 2-nitrophenyl pentyl ether. It is characterized by FTIR and thermal analysis (TGA). The photo-electrodialysis indicates that the combined system p-CuCrO2/membrane/n-Sr2Fe2O5 enhances considerably the electrons transfer and the diffusion flux of Pb2+. 35 percent of Pb2+ are photo-electrochemically reduced under artificial light. The rate conversion increases up to 86% under solar light.