Kinetic comparison of photocatalysis with H2O2-free photo-Fenton process on BiVO4 and the effective antibiotic degradation

• A H 2 O 2 -free photo-Fenton process was established for organic pollutant degradation. • The process was further expanded to degrade the refractory antibiotics completely. • Kinetics character and detailed mechanism of the process were explored. In order to eliminate the serious environment pollution and the super bacteria generation caused by antibiotics discharge, it is an urgently challenging task for effective degradation of antibiotics. Many advanced oxidation technologies including Fenton and photocatalytic reactions have been adopted to face with the challenge of this issue. Herein, we developed a H 2 O 2 -free photo-Fenton process using BiVO 4 as a light absorbing semiconductor with the addition of Fe 3+ to degrade antibiotic under a 300 W Xenon lamp and further comparably investigated the kinetics of H 2 O 2 -free photo-Fenton and photocatalytic reactions to degrade rhodamine B (Rh B) and rhodamine 6G (Rh 6G). The corresponding reaction mechanism was proposed based on detailed experiments and data analysis. Subsequently using norfloxacin (NOR) as a model, the H 2 O 2 -free photo-Fenton reactions were adopted to evaluate the effectiveness of antibiotic degradation with the optimized conditions of pH = 3.0 and the Fe 3+ concentration of 100 mg/L. The results displayed that the H 2 O 2 -free photo-Fenton reaction on BiVO 4 conformed to pseudo-first-order kinetics and exhibited excellent antibiotic removing performance, the degradation ratio of NOR reached 96% within 1 h. While its photocatalytic cousin abided by pseudo-zero-order kinetics and its degradation ratio was only 25% with the absence of Fe 3+ under the same conditions. It is anticipated that this study can deepen the understanding of mechanism and kinetics between photo-Fenton with photocatalytic reactions on the same catalyst and the expansion of H 2 O 2 -free photo-Fenton reactions on other semiconductors has great potential in the treatment of wastewater containing various antibiotics.