Removal of heavy metals (Cu2+ and Cd2+) from effluent using gamma irradiation, titanium dioxide nanoparticles and methanol

Heavy metal pollution has become one of the most serious environmental problems. The aim of this study was to achieve an efficient treatment process of effluents containing 1mM copper (Cu2+) and cadmium (Cd2+) ions using a combination of gamma irradiation, methanol and TiO2 nanoparticles under different pH values. The results showed that in acidic conditions, removal of Cu2+ and Cd2+ ions by physical adsorption was less than 15% and adsorption of Cd2+ was more than that of Cu2+. In the same condition, the Cu2+ removal percentage by irradiation was greater than that of Cd2+. In basic solutions, due to precipitation of Cd and Cu hydroxides, it was not possible to carry out adsorption experiments on Cd2+ and Cu2+ ions removal by TiO2 and gamma irradiation. Cu2+ and Cd2+ ions removal processes under different conditions could be depicted by the first order kinetics model. The combined application of TiO2 and methanol enhanced Cu2+ and Cd2+ ions removal at all pH levels examined. However, using the combination of TiO2 and methanol at acidic solutions facilitated completely removal of Cu2+ and Cd2+ ions. So that, only using 50kGy irradiation dose with combination of TiO2 nanoparticles and methanol led to the removal of 99% of coexisting Cu2+ and Cd2+ ions from the acidic wastewater.