Advanced photo-Fenton assisted degradation of tetracycline antibiotics using -Fe₂O₃/CdS/SiO₂ based S-scheme photocatalyst

In the present work, we have explored the construction of ternary alpha-Fe2O3/CdS/SiO2 S-scheme nanocomposite for the removal of tetracycline (TC) antibiotic. The ternary alpha-Fe2O3/CdS/SiO2 nanocomposite was fabricated using the co-precipitation method and was characterized via various analytical and spectroscopic techniques to explore their structural properties. The alpha-Fe2O3/CdS binary magnetic nanocomposite was attached to the surface of SiO2 nanoparticles, which served as an effective support material with improved chemical stability and good visible-light absorption capabilities. Among the synthesized bare (alpha-Fe2O3, CdS, SiO2) and ternary photocatalysts, the alpha-Fe2O3/CdS/SiO2 nanocomposite exhibited the highest TC photodegradation efficiency (99 %) at pH 3 within 120 min of light illumination using 60 mg/L catalyst dose and 7 x 10(-4) M of H2O2 concentration (30 % V/V). In comparison to bare photocatalysts, the photo-Fenton assisted photocatalytic reactions of ternary heterojunction boosted charge carrier separation and mobility (confirmed from PL and EIS analysis). Additionally, it could prolong the reactive oxygen species generation which significantly improved the degradation rate of TC by ternary nanocomposite. Furthermore, the generation of superoxide (O-center dot(2)-) and hydroxyl ((OH)-O-center dot) radicals, i.e. reactive oxygen species, played an imperative role in the TC degradation process which were validated through scavenging experiments and ESR analysis. This study displayed the effectiveness of the S-scheme alpha-Fe2O3/CdS/SiO2 ternary heterostructure-based Photo-Fenton system exhibiting enhanced charge separation and migration for boosted photocatalytic efficiency. After four rounds, the photocatalytic activity demonstrated only a minor decline in catalytic efficiency.