Degradation of paraquat from contaminated water using green TiO2 nanoparticles synthesized from <i>Coffea arabica</i> L. in photocatalytic process

摘要： The TiO2 nanoparticles synthesized from the extract of Coffea arabica L. (or TiO2/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 TiO2 nano-catalyst. The value of pHpzc of TiO2/C was 2.9 which cause 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 TiO2/C. The paraquat degradation followed the pseudo-?rst-order model with the apparent rate constants as of 5.84 × 10?2, 4.08 × 10?2, and 2.28 × 10?2 min?1 for TiO2/C, TiO2, and without TiO2, respectively, under the presence of UV and H2O2. The combined TiO2/C with UV and H2O2 was the most ef?cient process, exhibiting a maximum 66.3% degradation of 50 mg/L over 90 min at pH 10.