Photo enhanced detoxification of chromium (VI) by formic acid using 3D palladium nanocatalyst

Abstract

The detoxification of Cr(VI) to Cr(III) at room temperature by formic acid is investigated in the presence of 3D urchin shaped monometallic palladium (Pdurc) nanocatalyst. The rate of detoxification reaction is found to enhance with the intensity of light. Kinetic analysis reveals that the detoxification of Cr(VI) in presence of Pdurc nanocatalyst is most efficient in sunlight with a pseudo-first-order rate constant of 0.274 ± 0.067 min−1 as compared to commercially available Pd/C nanoparticles and radiolytically synthesized spherical Pd nanoparticles. The synergistic effect of high surface area of porous Pdurc nanocatalyst and higher rate of photodecomposition of formic acid in presence of Pdurc is proposed for the photo enhanced catalytic conversion of Cr(VI) to Cr(III). The reaction mechanism is confirmed by increase in the evolution of carbon dioxide (CO2) in the presence of light, monitored using gas chromatography. The sunlight enhanced conversion of Cr(VI) to Cr(III) in aqueous media, under ambient reaction condition, room temperature, low catalyst loading and recyclability of the Pdurc nanocatalyst will be helpful in developing new strategies for the detoxification of waste water.