Hybrid functional Pani/TiO2 nanocomposites for dyes degradation treatment

Abstract

A calling need for environmental protection is not abating and high demands have been set for the current topic that deals with applied technologies for removal of organic pollutants. The AOPs appear to be one of the most effective processes, where heterogeneous photocatalysis using efficient UV light-harvesting TiO2 nanocrystals has unquestionably become one of the most commonly used process for dyes degradation treatment. Limited photocatalytic efficiency of TiO2 under sunlight illumination was overcame by coupling with polyaniline (PANI) as notably investigated conductive polymer. Reducing the level of e-/h+ recombination in TiO2 and photosensitized properties of PANI was the basis for creation of new functional PANI/TiO2 nanocomposites. Such hybrid functional nanomaterials consisting of conductive polymers and dissimilar nanocrystals manifest the unique properties, usually not characteristic of independent components but their synergistic effect. Series of developed functional nanocomposites based on PANI and colloidal TiO2 nanoparticles (NPs) (TP), carbonized PANI and colloidal TiO2 NPs (TPC) and carbonized PANI and TiO2 nanotubes (NTs) (TTPC) by the efficient and harmless synthesis pathways are presented. Differently shaped TiO2 nanocrystals are carefully prepared via sol-gel and hydrothermal synthesis and the influence of their size and shape on the photocatalytic efficiency of hybrid nanocomposites was evaluated. The non-carbonized PANI/TiO2 nanocomposites were synthesized by the chemical oxidative polymerization of aniline with ammonium peroxydisulfate, in the presence of selected TiO2 nanocrystals, while the carbonized class was obtained in the subsequent carbonization process, following the polymerization, in an inert atmosphere at 650 °C. The morphology and structure of these nano-based photocatalysts was determined by TEM analysis and Raman spectroscopy. Functionality of nanocomposites was evaluated following the photocatalytic degradation processes of model compounds Methylene blue and Rhodamine B and enhanced degradation efficiencies in the used dyes were observed.