Selective removal of Hg2+/As3+/5+ from water system using Suaeda maritima plant based bio-adsorbent hybrid electro-deionization process

Heavy metal pollution is a critical environmental issue to provide safe potable water. Here, we prepared bioadsorbent (PC@PN) by blending of phytochelatins (PCs) (derived from Suaeda maritima (L.) Dumort plant) in poly(acrylonitrile) (PN). We report bio-adsorbent hybrid electro-deionization (EDI) for the selective removal of Hg2+/As3+/5+ in aqueous medium, and in-situ regeneration of adsorbent by using water-splitting process. EDI process effectively reduced the Hg2+/As3+/5+ concentration from 100 ppb to < 1.0 ppb, while Na+ (present in natural water system) was partial removed (500 ppm to 200-300 ppm). Interestingly, removal efficiency of Hg2+/As3+/5+ was close to 100%, while < 50% removal of Cd2+, and Pb2+ were observed under similar conditions. Quite low energy requirement (1.02-1.53 kWh/kg) corresponding to about 90% current efficiency, revealed the sustainability of the process. In addition, adsorbent exhibited high regeneration up to 60 cycles of experiments, without any significant performance deterioration. The EDI process with bio-adsorbent is promising for selective trace removal of ionic toxicants from the water system.