Innovation of novel nanocomposites for photocatalytic removal of some organic pollutants

Abstract

In this research work, novel nanoparticles were prepared by loading various proportions of metallic silver nanoparticles in the matrix of ZnO and TiO2 nanoparticles by sol-gel route in attempt to ultimately produce a reactive photocatalyst. Chitosan is used as a steric stabilizer for the prepared nanoparticles and a reducing agentforthe silver ions.The crystalline, morphology and the nanostructure of the prepared nanoparticle were monitored by XRDand HRTEM, whereas the textural changes are obtained by low temperature N2 adsorption. The optical properties of the prepared nanoparticles were analyzed by DRS and PL. The photocatalytic degradation of methylene blue and indigo carmine dyes as cationic and anionic primary pollutants model were performed over the prepared nanoparticles to select the most reactive photocatalyst. The results have pointed out the excellent dispersion of metallic silver nanoparticles within titania and zinc oxide matrix. A red shift in the absorption of the samples toward visible region was associated with silver doping. Photocatalytic degradation results reflect the complete degradation of both dyes on the surface of silver doped titania and zinc oxide with 5 and 3 wt.%, respectively. Chemical oxygen demand confirms the mineralization of methylene blue without formation of secondary pollutant. The high reactivity of the doped samples was related to the ability of silver nanoparticles to shift the photocatalytic response to the visible region and to prevent the electron-hole recombination.