Photocatalytic degradation of Congo red using Carissa edulis extract capped zinc oxide nanoparticles.

The use of plant extract to synthesize nanoparticle has been considered as one of the eco-friendly method. Additionally, it is a strong alternate for conventional methods which includes chemical and physical approach. In this study, microwave assisted extraction of Carissa edulis (C. edulis) at 70°C and 400W was used to extract the secondary metabolites. Further, the metabolites were used as capping agent and Zn (NO3)2 as the metal precursor to synthesize ZnO nanoparticles (ZnO NPs). UV-Vis spectroscopy, FT-IR, XRD, SEM and HR-TEM were used for the characterization of nanoparticles. The Surface Plasmon Resonance around 358nm from the UV-Vis spectroscopy result represents the ZnO NPs formation. The FT-IR confirms the presence of functional groups that acts as the capping agent for the synthesis of ZnO NPs. The crystalline structure of nanoparticles is revealed in the XRD result, morphology showed by SEM results and the size of the ZnO NPs were predicted by HR-TEM. We have carried out the photocatalytic degradation of Congo red at 365nm in photo reactor using ZnO NPs. The result from the photocatalytic degradation Congo red showed rate constant is (-k) 0.4947 with 97% of degradation. This is our first attempt on the C. edulis extract on ZnO NPs preparation and Congo red dye degradation revels that ZnO NPs exhibit good photocatalytic property.