Catalytic reduction-adsorption for removal of p-nitrophenol and its conversion p-aminophenol from water by gold nanoparticles supported on oxidized mesoporous carbon.

A highly efficient method for removal of p-nitrophenol and its conversion p-aminophenol from water was proposed using a novel catalyst-adsorbent composite of gold nanoparticles supported on functionalized mesoporous carbon (Au@CMK-3-O). The immobilized gold nanoparticles presented excellent catalytic ability to converse p-nitrophenol into p-aminophenol with the help of sodium borohydride, and the oxidized mesoporous carbon (CMK-3-O) serving as both carrier and adsorbent also exhibited high efficiency to remove p-aminophenol. The morphology and structure of the composite were characterized via SEM, TEM, FTIR and XPS analysis. Moreover, the mechanism of reaction process and the parameters of kinetics and thermodynamics were investigated. The activation energy was figured as 86.8 kJ mol(-1) for the adsorption and reduction of p-nitrophenol to p-aminophenol. The thermodynamic analysis based on the rate constants evaluated by pseudo-first-order model reveals that the adsorption-reduction process is an endothermic procedure with the rise of randomness. The anti-oxidation and regeneration study indicates that Au@CMK-3-O can be reused for 6 times with more than 90% conversion efficiency and keep high activity after exposing in air for 1 month, which possesses great prospects in application of nitroaromatic pollutant removal.