The mechanisms of removal of heavy metals from water by ionizing radiation

• Published in: Radiation physics and chemistry (Oxford, England : 1993) England : 1993), 1998-08, Vol.53 (2), p.145-150
• Main Authors: Chaychian, Mahnaz, Al-Sheikhly, Mohamad, Silverman, Joseph, McLaughlin, William L.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemistry; Exact sciences and technology; General and physical chemistry; Industrial wastewaters; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Pollution; Radiation chemistry; Wastewaters; Water treatment and pollution
• ISSN: 0969-806X; 1879-0895
• DOI: 10.1016/S0969-806X(98)00001-2

The removal of heavy metal ions from water using electron beam and gamma irradiation has been investigated for the cases of Pb 2+ and Hg 2+ ions. These metal ions are reduced by hydrated electrons and hydrogen atoms to lower or zero valence state and eventually precipitate out of solution. Ethanol is applied as a relatively non-toxic additive to scavenge · OH radicals, to enhance reduction and inhibit oxidation. Mercury can be completely (>99.9%) removed from aqueous solution of 1×10 −3 mol L −1 mercury (II) chloride by using a 3 kGy dose. However, a 40 kGy dose is required to remove 96% of lead ions from a 1×10 −3 mol L −1 of PbCl 2 solution. The effect of dissolved oxygen and carbonate were also investigated. E-beam irradiation of 1×10 −3 mol L −1 lead ions complexed with ethylenediamine tetraacetic acid (EDTA) in deoxygenated as well as air-saturated solutions in the absence of ethanol resulted in removal of about 97% of the lead.