Photocatalytic oxidation of tetracycline by magnetic carbon-supported TiO2 nanoparticles catalyzed peroxydisulfate: Performance, synergy and reaction mechanism studies

Abstract

Abstract TiO2 decorated on ferroferric oxides coupled with activated carbon (TFOC), as a magnetic heterogeneous catalyst, was synthesized and its photocatalytic ability was assessed in coupling with UV light towards peroxydisulfate (PS) activation to degrade tetracycline (TC). Main properties of the catalyst were analyzed by using UV–visible DRS, FESEM, VSM, PL, EDS, TEM, XRD and BET techniques. A proposed reaction mechanism was suggested for activating PS and TC degradation. Both TiO2 and Fe3O4 (FO) were synthesized and dispersed successfully on the carbon surfaces in nano-sized scale. It was found that the photocatalytic activity of TiO2 was accelerated significantly after loading on the magnetic carbon. TFOC showed an excellent magnetic response in the presence of a magnet. According to PL analysis, FO nanoparticles and carbon played a critical role in the suppression of recombination of excited electrons and holes. TFOC in coupling with UV showed a best performance, compared to the other single and binary processes for TC decontamination. After 15\xa0min reaction, the highest level of elimination, 96% TC (60\xa0mg/L) and 72.1% TOC were obtained at optimum operational conditions: pH:5.0, TFOC: 0.3\xa0g/L and PS:1.0\xa0mM. A noticeable synergistic effect was found for TFOC in combination with UV and PS. Both negligible Fe leaching and high efficiency of degradation were achieved with reused times, illustrating that TFOC has an excellent durability and reusability. Based on trapping tests, the importance of involved oxidizing species during TC decontamination over TFOC/PS/UV system was in order of 1O2\xa0>\xa0SO4•– > h+ > O2•– > HO•. Among studied anions, the highest quenching impact was observed for chloride ions. Particularly, TFOC composite showed the high catalytic activity as well excellent potential in recovery and its coupling with UV light and PS can be introduced as a promising strategy for efficient destroying TC antibiotic.