Ultrasound-assisted synthesis of gold nanoparticles supported on β-cyclodextrin for catalytic reduction of nitrophenols

Abstract

Nitrophenols with high toxicity are well known as one of the main pollutants in water environment while aminophenols, products of the reduction, are important intermediates in the fabrication of several drugs. Thus, the reduction of nitrophenols is considerably attractive in wastewater treatment and pharmaceutical fields. In this work, gold nanoparticles (AuNPs) catalyst was straightforwardly fabricated using β-cyclodextrin as a reducing and stabilizing agent under ultrasound irradiation. The synthetic conditions were explored via the changes in concentration of β-cyclodextrin, environmental pH, temperature and time. The synthesized AuNPs under the optimal condition showed a size distribution in range of 3–21 nm with a mean size of 12 nm. The dynamic lighting scatter and zeta potential data showed the stable colloidal solutions and X-ray diffraction and selected area electron diffraction patterns confirmed crystalline structure of AuNPs. The influence of reagents and the nanoparticles on kinetic data of the reduction was investigated. The kinetic data showed that the performance of 2-nitrophenol reduction is better than that of 4-nitrophenol while rate constants of the reduction is linear to both initial concentrations of nitrophenol substrates and catalyst amount.