The Quick-silver problem : conquering mercury pollution using a green chemical solution.

Abstract

Pollution of surface and ground water with heavy metals threatens living organisms and their environment. Mitigation techniques are required to reduce the amount of heavy metals to safer levels, complying with the EPA concentrations. One of the established techniques towards the removal of heavy metals is chemical treatment, namely metal chelation, of contaminated water. Building on the knowledge gained from various chemical treatment approaches of water purification, we are reporting a ‘green’ chemical treatment approach, where minimal chemical waste is generated in the process of water treatment. We are reporting a study that employs commercially available organic compounds (aniline and aldehyde) used to prepare dynamic pyridylimine ligands (receptor) capable of detecting and removing mercury(II) ions from water. The suggested receptor was prepared and its capability in removing mercury ions from water was investigated. It was found out that two receptors bind to one Hg(II) ion tightly (binding affinity KG =7.8 x 10⁷ M⁻¹) in water. It was observed that the used organic ligand can effectively remove 250 mg-L Hg(II) ions from mercury contaminated water, with a complete removal (100percent removal efficiency) in 30 mins. The receptor: Hg (II) complex was removed from water and isolated for further characterizations. Formation of the metal-organic complex (2 receptors: 1 Hg (II)) can be reversed under controlled conditions, regenerating the pyridylimine ligand up to four other cycles of water treatment.