The use of bidentate ligands for heavy metal removal from contaminated water

Abstract

Water pollution is responsible for over 1.8 million global death annually. Among the water pollutants are heavy metals including chromium, nickel, copper, arsenic, mercury, and lead. Interestingly, some of the heavy metals copper, cobalt, chromium, iron, zinc, and manganese are components of important biological enzymes involved in redox reactions in the body. However, the transitions between the various oxidation states of these essential heavy metals are sources of free radicals leading to oxidative stress. Adsorption has been a well-researched means of removing heavy metal pollutants, nevertheless, there are problems associated with adsorption processes like the generation of sludge ballasting, high quantity of adsorbent due to surface area, and toxicity of spent adsorbent. In this work, the utilization of bidentate ligands for the removal of heavy metals in contaminated water via complexation was examined. Reports have shown that bidentate ligands and popular adsorbents (biochar, activated carbon, charcoal, and cellulose) functionalized with bidentate ligands provided drastically improved heavy metal complexation and adsorptive capacities. Specifically, bidentate ligands such as dithiocarbamate, 5-sulfosalicylic acid, and 1,10-phenanthroline removed 99-100 % of Pb2+ and Hg2+ ions.

Keywords

• Bidentate ligand
• Heavy metals
• Immunotoxicity
• Metal complexes
• Polyaromatic hydrocarbons
• Pollution