Novel insights into the properties of AgBiO3 photocatalyst and its application in immobilized state for 4-nitrophenol degradation and bacteria inactivation

This study focuses on the synthesis of novel AgBiO3 nanoparticles by the hydrothermal route and investigating its properties responsible for waste water treatment. The temperature and time of hydrothermal reaction was optimized to 150 degrees C and 24 h to obtain highly active crystalline nanoparticles, as determined by XRD. The oxidation state of each element in the material was determined from XPS analysis. The morphology and size of the nanoparticles was obtained from SEM and TEM analysis. The optical and electrochemical properties of the material were studied by UPS and Mott Schottky plot. AgBiO3 was found to have a low band gap that facilitates the absorption of higher wavelength range as confirmed by Tauc plots and UV-vis DRS analysis. The excellent photocatalytic activity of the immobilized material towards the degradation of 4-nitrophenol and inactivation of E. coil was confirmed from kinetic studies and stability tests. A maximum degradation of 90% was achieved for 4-NP and a 5-log reduction was observed for viable E. coli cells in 5 h and 1 h respectively. Scavenger studies were performed to identify that superoxide radicals were responsible for the photocatalytic activity of the material. To eliminate the cost of separation and ease the reusability of the material, the nanoparticles were immobilized on cellulose acetate. Leaching of Ag and Bi ions from immobilized as well as free AgBiO3 nanoparticles into water was obtained via ICP-MS analysis. The results indicated that the leaching of Ag and Bi was controlled to a considerable extent due to immobilization on cellulose acetate matrix.