Arsenic removal by photo-catalysis hybrid system

Abstract

Arsenic is a toxic semi-metallic element that can be fatal to human health. Arsenic pollution in water is found in many parts of the world, especially in developing countries such as Bangladesh, India, Nepal, and Vietnam. Photo-oxidation experiments with titanium dioxide (TiO2) as photo-catalyst showed that photo-oxidation of As(III) to As(V) is possible within minutes. Further, TiO2 can also adsorb both As(III) and As(V) on its surface. Photo-catalysis reaction with TiO2 reduced about 98% of arsenite from water containing 500 mu g/L of arsenite. By adding nano-scale zero valent iron (nZVI) of 0.05 g/L in the photo-reactor, arsenic removal can be significantly enhanced. Further the TiO2 requirement is five times less in this photo-catalysis nZVI hybrid system. The photo-catalytic degradation processes was modeled using the first-order, second-order and Langmuir-Hinshelwood kinetics equations and removal rates were simulated. (C) 2007 Elsevier B.V. All rights reserved.