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Reactive dyes like methylene blue (MB) from textile industries significantly affect the environment due to their high carcinogenic and mutagenic potential. The pre-sent study aims at visible light induced photocatalytic degradation of MB using magnetically recyclable biochar (MBC) supported bismuth oxybromide (BiOBr) nanocomposite in aqueous medium. Magnetization of biochar was done by impregnation of iron precursors. The photocatalysts were prepared by supporting BiOBr with various weight percentage of MBC (25, 50 and 75 %) using solvothermal method and symbolised as BiOBr/MBC-1, BiOBr/MBC-2 and Bi-OBr/MBC-3 respectively. BiOBr/MBC-2 showed the highest degradation efficiency of 85 % at 1 g/L of catalytic dosage and 10 mg/L of initial MB concentration. Morphological study revealed the porous structure of BiOBr/MBC-2. EDS analysis demonstrated successful impregnation of Fe, Bi, and Br on the biochar. The presence of Bi-O-Bi and Fe-O bonds were indicated by FTIR absorbance peaks at around 845 cm-1 and 630– 660 cm-1 respectively. The pHzpc was found to be 4, thus beyond this pH, BiOBr/MBC-2 has anionic surface charge which is feasible for adsorption of the cationic MB. Optimization of operating parameters revealed 88 % of MB degradation with 1.5 g/L of BiOBr/MBC-2 at 10 mg/L of initial MB concentration for 320 min at neutral pH. Under similar condition and on exposure to direct sunlight for 280 min, the MB degradation efficiency increased to around 95 %, which makes it highly suitable for practical applications. Moreover, BiOBr/MBC-2 exhibited promising reusable performance with around 90 % degradation efficiency of MB after the fourth cycle of photocatalytic degradation under direct sunlight. The TOC removal efficiency reached 70 % after 280 min of sunlight exposure. Scavenger study suggested the major reactive species in degradation of MB were superoxide radical (O2·-) and hydroxyl radical (•OH).
