Design and development of Carissa edulis fruit extract mediated bimetallic CuO-NiO-HNT composites for photocatalytic removal of food dye and antibiotic drug

The current study demonstrates the synthesis of one dimensional halloysite nanotube (HNT) based CuO-NiO (CN) photocatalyst using green approach via non-conventional microwave and ultrasonication method. Structural, optical, electrochemical, morphological, stability, and surface area characteristics of the synthesised composite were investigated. From the optical studies, the composite exhibited the absorption band edge above 420 nm in the visible region. Electrochemical studies confirmed that 20CN-HNT composited had good charge carrier separation rate compared to CN. Morphological and elemental analysis revealed that the composite was in microsphere structure with even distribution of elements throughout the composite. Congo red (CR- a dye) and tetracycline (TC- a drug) were used to test the composites' photocatalytic efficacy by the irradiation of visible light. Amongst various synthesized composites, 20CN-HNT composite showed good removal efficiency around 82 % and 84 % against CR and TC respectively, in 90 min. The breakdown of CR and TC is caused by the active species( )OH and O-(2)- radicals which was identified using trapping studies. The reusability study demonstrated that the 20CN-HNT photocatalyst retained its high level of stability after being used for five times.