Green Synthesis of ZnO Nanoparticles by an Alginate Mediated Ion-Exchange Process and a case study for Photocatalysis of Methylene Blue Dye

Photocatalytic degradation has been gaining attention in recent years and the role of Zinc Oxide nanoparticles as a photocatalyst has been investigated due to it wide availability, low cost and favourable gap energy. In this... [ view full abstract ]

Photocatalytic degradation has been gaining attention in recent years and the role of Zinc Oxide nanoparticles as a photocatalyst has been investigated due to it wide availability, low cost and favourable gap energy. In this study, ZnO beads were prepared via extrusion-dripping method through an ion exchange mediated process using Sodium alginate as the precursor before drying at 40oC for 24hr. The oven dried samples were calcined at 500 ˚C and 600 ˚C to study the effect of calcination temperature on the synthesized ZnO nanoparticles. The morphology, microstructure and optical activity of the calcined ZnO nanoparticles were analyzed by FESEM and XRD. It was found that ZnO nanoparticles synthesized at 600 ˚C was of higher purity with high crystallinity. To enhance the photocatalytic efficiency of zinc oxide, ZnO/NCC (Nanocrystalline Cellulose) films are synthesized at varying ZnO loading fractions of 10 wt%, 15 wt%, 20 wt% and 25 wt%. Photocatalytic activity of the prepared pure ZnO, ZnO/NCC films and NCC was evaluated by photodegradation of Methylene blue dye. It was observed that the removal efficiency of ZnO-NCC films is increased with higher loadings of ZnO particles. In the presence of UV light irradiation after 30 minutes, the degradation efficiency of ZnO-NCC films were obtained to be 87%, 90%, and 96% for films with ZnO loadings of 15 wt%, 20 wt% and 25 wt% respectively. It was also observed that the films exhibited a higher performance in the presence of UV light. The results of this study help to understand the links between the characteristics and photodegradation capabilities of ZnO nanoparticles in the modified film form with the support of NCC.