UV-light-induced photocatalytic performance of reusable MnFe-LDO–biochar for tetracycline removal in water

Abstract A high-efficiency layered double oxide-biochar hybrid (MnFe-LDO–biochar) catalyst was successfully synthesized by the co-precipitation-calcination process and used to effectively remove tetracycline (TC) pollution. The characterization results verified that MnFe-LDO–biochar possesses a specific surface area of 524.8 m2 g−1, appropriate bandgap (2.85 eV), a high photocurrent response (3.8 µA cm–2), a saturation magnetization of 28.5 emu g−1 and a mixture of interconnected pores. 40% of TC was removed after 30 min when 50 mL TC solution (20 mg L−1) was treated with 50 mg MnFe-LDO–biochar in the dark and reached ∼98% degradation rate within 240 min upon exposure to a UV light. Notably, in the presence of H2O2 or K2S2O8, the degradation rate of MnFe-LDO–biochar was shortened to 60 min with an average pseudo-first-order rate constant of 0.0445 min−1. The antibiotic removal rate of the cost-competitive MnFe-LDO–biochar surpassed several reported materials and maintained ∼80% reuse efficiency after 3rd successive cycles. The TC photodegradation mechanism is multiprocess induced majorly by •OH and •SO4− while h+ and •O2− contributed partly to the mineralization. This work highlights the powerful synergistic combination of layered double oxide (LDO) and biochar.