Enhanced molecular oxygen activation via Z-scheme Bi₂MoO₆/Bi₄Ti₃O₁₂ heterojunction for photocatalytic degradation of tetracycline and ciprofloxacin: Performance and intermediate toxicity appraisement

Abstract

The environmental persistence of tetracycline (TC) and ciprofloxacin (CPX) in water systems necessitates the development of efficient and environmentally safe treatment methods. In this study, a Bi₂MoO₆/Bi₄Ti₃O₁₂ (BMTO) composite with hierarchical nanoplates-on-microsphere morphology was synthesized via a one-pot low-temperature solvothermal method using non-toxic precursors. The optimized catalyst achieved degradation efficiencies of 97.4 % for TC (20 mg/L, 0.5 g/L catalyst, pH 7) within 90 min and 90 % for CPX (10 mg/L, 0.5 g/L catalyst, pH 9) within 120 min under visible light, with corresponding TOC removal rates of 70.5 % and 58 %, respectively. Compared to previously reported Bi-based systems, the BMTO composite showed improved activity due to its direct Z-scheme configuration, which preserves strong redox potentials and promotes efficient charge separation, as supported by Mott–Schottky analysis, band alignment, and radical scavenging studies. LC-MS analysis revealed pollutant-specific degradation pathways, primarily driven by h⁺ and •O₂⁻ species. Eco-toxicological assays using E. coli indicated reduced toxicity in treated water, suggesting potential for reuse, pending further validation. This study provides a scalable and environmentally benign approach for designing Bi-based photocatalysts with effective pollutant degradation and mechanistic clarity

Topics & Concepts