Carbon nitride coupled with Fe-based MOFs as an efficient photoelectrocatalyst for boosted degradation of ciprofloxacin: Mechanism, pathway and fate

This paper reports a heterostructure composites, g-C3N4/MIL-101(Fe), that was synthetized through effortless solvothermal method by g-C3N4 coupled with MIL-101(Fe) containing terephthalic acid (H2BDC) as organic linker. Eminent photoelectrocatalytic degradation effect was demonstrated by the heterojunctions coordinated with visible light and low current (PEC) for the treatment of ciprofloxacin (CIP) in model matrix and realistic water samples. Moreover, morphological, physicochemical and photocatalytic properties of the catalyst were appraised. Compared with g-C3N4, MIL-101(Fe) and the heterojunction in various systems, the CIP degradation was up to 87.55% by 0.5 g/L of g-C3N4/MIL-101(Fe) addition along with 12 W LED lamp and 50 mA current in 240 min. The realization of PEC synergism for an intensified treatment effect to this organic molecule has mainly been implemented through electro-Fenton and visible light catalysis, which was based on circulation of the FeII/FeIII along with a correct band structure between g-C3N4 and MIL-101(Fe). Active species capture and electron spin resonance (ESR) test uncovered that •OH, •O2– and h+ contributed to the elimination of CIP. The degradation pathway and toxicity assessment of intermediates was conducted using LC-MS, DFT calculation and QSAR theory. Seventeen kinds of intermediates were detected, which showed a reduced toxicity. Findings of the paper provide incisive insights on the mechanism of the degradation of organic pollutants through PEC synergy over g-C3N4/MIL-101(Fe) heterojunction catalyst. Moreover, the results constitute a meritorious instance for preparing catalyst in this application field.