Abstract
Polyaniline modified zinc oxide (PANI-ZnO) photocatalyst composites were synthesized by focusing on dissolution disadvantage of ZnO. In-Situ chemical oxidation polymerization method was performed under neutral conditions (PANI-ES) whereas in hybridization method physical blending was applied using emeraldine base of polyaniline (PANI-EB). PANI-ZnO composites were prepared in various ratios of aniline (ANI) to ZnO as 1%, 3%, 6% and 9%. The alterations on the structural and morphological properties of PANI-ZnO composites were compared by Fourier Transform Infrared (FT-IR), Raman Spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-ray Analysis Unit (SEM-EDAX) techniques. FT-IR and Raman spectroscopy confirmed the presence of PANI in all composites. SEM images revealed the morphological differences of PANI-ZnO composites based on PANI presence and preparation methods. Photocatalytic performances of PANI-ZnO specimens were investigated by following the degradation of methylene blue (MB) in aqueous medium under UVA irradiation. The effects of catalyst dose and initial dye concentration were also studied. MB degradation was followed by both decolorization extents and removal of aromatic fractions. PANI-ZnO composites expressed enhanced photocatalytic performance (~95% for both methods) as compared to sole ZnO (~87%). The hybridization method was found to be more efficient than the In-Situ chemical oxidation polymerization method emphasizing the significance of the neutral medium.
Highlights
Due to the continuous release of contaminants to the environment, application of photocatalysis as an alternative advanced oxidation treatment process is attracting the main focus of researchers
The yields of polyaniline emeraldine salt form (PANI-ES) and PANI-EB were found as 95% and 77%, respectively, and all PANI-zinc oxide (ZnO) composites were obtained in high yields as 95% ± 2.8 irrespective of the preparation methodology
All PANI-ZnO composites were obtained in high yields as 95% ± 2.8 irrespectiv preparation methodology
Summary
Due to the continuous release of contaminants to the environment, application of photocatalysis as an alternative advanced oxidation treatment process is attracting the main focus of researchers. Besides TiO2 , ZnO is the second most extensively used photocatalyst exhibiting excellent photocatalytic activity, stability and almost similar band gap energy The major advantage of ZnO is its broad band in ultraviolet-visible (UV-vis) region in the wavelength range of 350–470 nm enabling charge transfer from oxide. ZnO has more negative conduction band potential and has a higher exciton binding energy compared to TiO2. To overcome the disadvantages of n-type semiconductors expressing large band gaps, coupling with conducting polymers exhibiting small bandgaps and extended π–e− systems drew current interest. With respect to attained beneficial effect via “sensitization”, coupling of p-type conducting polymers with an n-type semiconductor opened a new area of research
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