Degradation of paraquat from contaminated water using green TiO nanoparticles synthesized from Coffea arabica L. in photocatalytic process.

The TiO nanoparticles synthesized from the extract of Coffea arabica L. (or TiO/C) were used to remove paraquat from contaminated water in heterogeneous photocatalysis process. In this work, the sol-gel process using Coffea arabica L. as the solvent chemical were performed to obtain the TiO nano-catalyst. The value of pH of TiO/C was 2.9 which caused a highly acidic surface of catalyst. The paraquat is effectively removed in alkaline medium due to the adsorption ability of paraquat on the surface of TiO/C. The paraquat degradation followed the pseudo-first-order model with the apparent rate constants of 5.84 × 10, 4.08 × 10, and 2.28 × 10 min for TiO/C, TiO, and without TiO, respectively, under the presence of ultraviolet (UV) and HO. The combined TiO/C with UV and HO was the most efficient process, exhibiting a maximum 66.3% degradation of 50 mg/L over 90 min at pH 10.