Photocatalytic reduction of hexavalent chromium with nickle-doped zinc oxide/polyaniline nanocomposites and sunlight

WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
Jennifer Paige Coleman (Creator)
Institution
Western Carolina University (WCU )
Web Site: http://library.wcu.edu/
Advisor
Channa De Silva

Abstract: The removal of hexavalent chromium (Cr(VI)) from aquatic systems is critical due to the extreme toxicity and high mobility of the contaminant in the environment. Semiconducting zinc oxide nanoparticles synthesized with a conducting polymer, such as polyaniline, have shown a high efficiency for the photocatalytic reduction of Cr(VI) to the less toxic form using visible light. Doping zinc oxide with nickel ions has also been shown to increase the photocatalytic efficiency of zinc oxide. I have synthesized zinc oxide-polyaniline and nickel-doped zinc oxide-polyaniline nanoparticles via microwave synthesis to determine the effect of nickel-doping on the photocatalytic reduction potential of the zinc oxide-polyaniline particles. XRD, FTIR, TEM, SEM, EDX and DLS measurements have confirmed the synthesis of zinc oxide and nickel-doped zinc oxide nanocrystals. The polymerization of the nanoparticles with polyaniline was confirmed with FTIR and TEM. Photocatalytic reduction experiments with hexavalent chromium (Cr(VI)) and a methanol hole scavenger were performed under an Atlas sunlight simulator. The remaining Cr(VI) concentrations were determined using the standard 1,5-diphenyl carbazide colorimetric method and UV-Vis spectroscopy. The Ni-ZnO-PANI nanocomposites showed a similar Cr(VI) removal efficiency to ZnO-PANI at 97.7% and 98.0%, respectively. The Ni-ZnO-PANI reduced about 5% more Cr(VI) in the first 90 minutes of sunlight exposure. Overall, there was not a significant difference between the Cr(VI) reduction efficiency of the ZnO-PANI and Ni-ZnO-PANI photocatalysts.

Additional Information

Publication
Thesis
Language: English
Date: 2019
Keywords
Chromium, Photocatalysis, Water remediation

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