Azo dye removal by acid pretreated biomass and its regeneration by visible light photocatalysis with incorporated CuO

Abstract

ABSTRACT In this work, we synthesized self-regenerative biosorbent BM-H3PO4-(CuO) by combining the photocatalyst CuO and acid pre-treated biomass (BM-H3PO4), the hybrid material BM-H3PO4-(CuO) was used for the removal of azo dye Direct Red 89 (DR-89). The morphology, texture phase, composition of the samples was characterized with scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, elemental diffraction analysis X-ray (EDAX). That confirms the presence of CuO into the pretreated biomass BM-H3PO4. The results reveal that when the biomass was loaded with a proper CuO/BM-H3PO4 weight ratio of 60%, the biosorption capacity was enhanced to 5.5 times compared to BM-H3PO4. The maximum adsorption capacity of BM-H3PO4-(CuO)60% was 30.3 mg g−1 determined from the Langmuir isotherm. The pseudo-second-order kinetic model was more appropriate for describing dye biosorption. The hybrid material BM-H3PO4-(CuO)60% demonstrated a better photocatalytic activity under visible light irradiation then pure CuO. Incorporation of the CuO particles into the biosorbent, offers the possibility to harvest visible light for oxidative photodegradation. The prepared material also showed good reusability in the cyclic of biosorption–photocatalysis experiments and the biosorption efficiency was higher than 90% over four cycles. This study provides an eco-friendly way to fabricate self-regenerative biosorbents.