Journal of Chemical Technology and Biotechnology, Vol.85, No.4, 478-484, 2010
The recovery and recycling of mercury from fluorescent lamps using photocatalytic techniques
BACKGROUND: Release of mercury from fluorescent lamps must be minimized to avoid its hazardous effects on human beings and other living organisms. Because of this, increasing attention is given to the improvement of existing techniques for its recovery as well as the development of new ones. This paper describes the application of heterogeneous photocatalysis for the selective reduction of mercury from fluorescent lamps. The whole process involves mercury chemical extraction using aqueous solutions of sodium hypochlorite. After pH adjustment of the resulting aqueous solution, the photocatalytic reduction of mercury is performed in the presence of titanium dioxide and citric acid as an auxiliary organic agent. RESULTS: Mercury removal from the aqueous solution is higher than 99% and the final residual concentration is 4 ppb. A mixture of different mercury compounds is obtained in solid form deposited on the titanium oxide photocatalyst which can easily be redissolved into a small volume of sodium hypochlorite. Metallic mercury could be obtained from the residual Hg(II) solution by conventional cementation techniques with iron as reducing agent. CONCLUSION: Results show high efficiencies of the photocatalytic technique for recovery and recycling of mercury from fluorescent lamps. (C) 2009 Society of Chemical Industry