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 × 10−3 min−1 in the absence of phenol, and was increased up to 9.27 × 10−3 min−1 by adding 10 mg/L of phenol, and to 10.73 × 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.