Chemistry
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Item PHOTOCATALYTIC DEGRADATION OF CRYSTAL VIOLET UNDER SOLAR IRRADIATION USING A BIOSYNTHESIZED ZnO BASED POLYANILINE(Hawassa University, 2024-06) BELAYNESH SIRIYE TALILAA morphologically modified PANI/ZnO Nanocomposite was synthesized using leaf extract from Solanecio gigas (S. gigas) a reducing and capping agent for the photocatalytic degradation of Crystal Violet (CV) under natural sunlight irradiation. Additionally, PANI and pure ZnO NPs were synthesized via a green route, and the nanomaterials were characterized using spectroscopic techniques such as UV-Vis, FT-IR, SEM, and XRD. The blue-shift in the absorption peak of PANI/ZnO NCs suggests a change in electronic structure, potentially due to a type-II heterojunction between PANI and ZnO. FTIR analysis revealed red-shifted peaks, indicating hydrogen bonding between ZnO and PANI. Morphologically, the composite material combines the roughness of ZnO NPs with the smoothness of PANI. XRD patterns showed overlapping peaks from the composite with a crystalline size of 5.577 nm, which is smaller than the crystalline size of ZnO NPs (9.455 nm). This reduction in size is likely due to the formation of a polymer-Zn complex on the nanoparticle surface. The photocatalytic activity of the polyaniline/ZnO nanocomposite in degrading CV in aqueous solution under natural sunlight irradiation was evaluated and compared with that of ZnO nanoparticles. The effects of experimental conditions such as pH, photocatalyst dosage, and CV concentration were investigated with 91.20% and 99.06% at pH 11, 99.47% and 99.97% at 0.12 g, and 94.93% and 96.20% at 20 ppm for both ZnO NPs and PANI/ZnO NCs. The ZnO/polyaniline nanocomposite exhibited higher photocatalytic activity at 98.25% compared to ZnO nanoparticles at 92.76% under optimal conditions after 60 minutes of sunlight exposure. Kinetics studies indicated that the degradation rate fit well with the pseudo-first-order kinetics model, showing an R2 value of 0.968 for PANI/ZnO NCs. The composite demonstrated good catalytic activity with four cycles of reusability time compared to non-coated ZnO NPs. These findings highlight the potential of S. gigas plant-assisted PANI/ZnO NCs as effective and sustainable nanocatalysts with promising applications in catalytic decomposition of organic contaminants for environmental remediation.