Polymeric nanostructures for photocatalytic dye degradation: polyaniline for photocatalysis

Abstract

The motivation for the work presented in this paper comes from the need to explore novel and efficient photocatalysts for the degradation of contaminants from waste water. In this regard and in addition to the existing class of semiconductor photocatalysts, polymeric structures such as polyaniline, have emerged with the potential to degrade common water contaminants through photocatalysis. This paper elucidates the preparation of polyaniline (PANI) nanofibers and its implementation as a photocatalyst for the degradation of organic dyes such as Methylene Blue (MB) and Methyl Orange (MO). PANI was obtained using oxidative polymerisation and was examined for morphological and structural properties using XRD, SEM, TEM and FTIR which confirmed the formation of fibrous PANI sample. The chemical composition and the bonding states were studied using XPS. Subsequently, photo induced degradation of MB was performed in the presence of PANI as photocatalyst which indicated 42% degradation while MO was degraded by 97% in less than 3 h. Kinetic analysis by pseudo first order, second order and intra particle diffusion model, showed well-fit results for first order kinetic model with a rate constant of 0.0505 (g mg−1 min−1). The photocatalytic efficiency of PANI was assigned to the π–π* transition wherein the excited state electrons were transferred from the π to the π* orbital. Therefore, polyaniline was observed to be a promising photocatalyst for the degradation of environmental pollutants.