Photocatalytic degradation of methylene blue dye from aqueous systems by HKUST-1 and CuO@HKUST-1

Abstract

High concentrations of methylene blue (MB) in aqueous environments have detrimental effects to both plants and animals and hence its removal is very important. Metal Organic Framework, HKUST-1 and composite, CuO@HKUST-1, were synthesized and characterised for their functional groups before and after degradation of methylene blue. Studies were done to optimize the degradation of methylene blue and to characterize the degradation system with respect to photocatalytic degradation kinetics. The optimum methylene blue degradation conditions were pH 4, catalyst dosage of 50 mg and contact time of 180 minutes for CuO@HKUST-1 and pH 6, catalyst dosage of 100 mg and contact time of 180 minutes for HKUST-1. The pseudo first order kinetics best described the data (R2 0.991 and 0.992 for HKUST-1 and CuO@HKUST-1 respectively). Methylene blue showed negligible self catalysis properties suggesting that it is very stable to light. CuO@HKUST-1 was found to have better photocatalytic degradation efficiency (95 %) as compared to HKUST-1 (75%). CuO@HKUST-1 proved to be an effective and stable catalyst which can be re used for 4 times producing a degradation efficiency of more than 80 %.