Assessment of TiO2 and Ag/TiO2 photocatalysts for domestic wastewater treatment: synthesis, characterization, and degradation kinetics analysis

In this study, the synthesis and characterization of the TiO2 and Ag/TiO2 nanoparticles were carried out and their influence on the oxidation of organic matter of domestic wastewater was evaluated using a heterogeneous photocatalytic system. The TiO2 and Ag/TiO2 nanoparticles were synthesized by the sol-gel method and the chemical reduction method. The nanoparticles were characterized by four different techniques (X-ray diffractometry, UV-Vis spectrophotometry, Fourier transform infrared spectroscopy, and scanning electron microscopy). The importance of the synthesized nanoparticles in the treatment of residual water was evaluated using a photocatalysis process with UV light (lambda = 254 nm). Raw domestic wastewater generated at the local university was used. Due to the complexity of the wastewater composition, the Chemical Oxygen Demand (COD) was used to evaluate the oxidation of organic matter in the photocatalytic system. Three different concentrations of TiO2 and Ag/TiO2 were evaluated: 0.25, 0.5 and 1 g L-1. The photocatalysis process achieved a maximum degradation of 68% and 77% when using TiO2 and Ag/TiO2 after 2 h operation. A maximum kinetic rate value of 0.013 min(-1) was obtained when Ag/TiO2 was used as a catalyst, like the observed in other advanced oxidation processes.