Visible light driven photocatalytic degradation of ofloxacin and malachite green dye using cadmium sulphide nanoparticles

This work demonstrates an effective approach for the degradation of persistent and mutagenic water pollutants under visible light illumination. Cadmium sulphide (CdS) was synthesized using a facile hydrothermal approach and its structural, morphological and optical properties were evaluated by various techniques such as XRD, FTIR, UV-DRS, TGA/DSC, HRTEM and EDX. The XRD spectrum indicated that the synthesized CdS was a crystal mixture of cubic and hexagonal phases. HRTEM images displayed the formation of well crystalline CdS nanoparticles, grown in high density. Further, the synthesized CdS nanoparticles were effectively used as photocatalyst for the degradation of fluoroquinolone antibiotic (ofloxacin) and mutagenic water pollutant (malachite green) under visible light irradiation. Role of hydroxyl radicals (center dot OH) in the photocatalytic process was confirmed by terephthalic acid photoluminescence (TA-PL) technique. Degradation efficiency of about 79.5% and 96% was obtained for ofloxacin and malachite green in the reaction time of 80 and 60 min, respectively. It was found that photocatalytic degradation of both compounds i.e. drug and dye followed pseudo first order reaction kinetics.