The simultaneous photocatalytic degradation of phenol and reduction of Cr(VI) by TiO2/CNTs

The main objective of this paper is to verify the potential of TiO2/CNTs in the simultaneous photocatalytic degradation of phenol and reduction of Cr(VI). From the present results it can be concluded that there is a synergistic effect between the photocatalytic degradation of phenol and reduction of Cr(VI). Under all tested conditions, the degradation of phenol and reduction of Cr(VI) were examined to follow pseudo-first-order kinetic. The rate constant of 40 mg/L of Cr(VI) was evaluated as 4.34 x 10(-3) min(-1) in the absence of phenol, and was increased up to 9.27 x 10(-3) min(-1) by adding 10 mg/L of phenol, and to 10.73 x 10(-3) min(-1) by adding 15 mg/L of phenol. The presence of Cr(VI) also accelerated the degradation process of phenol, with a factor of 1.84-3 times. Such a great synergistic effect was likely to be attributed to two kinds of effects from CNTs: adsorption effect and electron trap effect. The synergistic effect induced by CNTs was also confirmed by the detection of degradation intermediates of phenol. (C) 2011 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.