Alginate beads for photodegradation of dye under solar light irradiation

Abstract

Photocatalytic degradation of organic pollutants with the aids of semiconductor engrossed massive attention in wastewater treatment recently. Zinc oxide (ZnO) and titanium dioxide (TiO2) are the most utilized semiconductors during photocatalytic degradation due to their favorable characteristics such as wide band gap, good stability, biocompatibility, biologically inert, light absorption property, high photo-catalytic activity, relatively high chemical stability and insoluble in water. ZnO loaded alginate beads and ZnO/TiO2 loaded alginate beads were fabricated through spherification method and immersed into calcium chloride (CaCl2) to achieve stability into beads form. The excellent immobilization ability of alginate aids the formation of alginate beads which ease for handling and recycling of the photocatalyst in photodegradation process. The fabricated alginate beads were then characterized by scanning electron microscope (SEM), X-ray diffraction analysis (XRD) and brunauer-emmett-teller (BET) analysis to identify the morphology, chemical composition and surface porosity, respectively. Photodegradation ability of fabricated alginate beads were identified through the photodegradation efficiency of RG 19 dye solution by the study of the effect of initial dye concentration, effect of photocatalyst loading, effect of solar light irradiation and the effect of metal oxides coupling. According to the results obtained from photodegradation study of RG 19, 12 wt% ZnO loaded alginate beads is the most optimum photocatalyst as compared to others. Fabricated alginate beads also showed excellent reusability in photodegradation activity which up to 5 cycles.