Photoactive floating conducting polymers for water remediation

The chemical industry of the forthcoming years will be shaped by a number of emerging global megatrends strictly related to the demand of innovative materials able to solve new needs in different fields. Among them. environmental deterioration and the scarcity of fresh water have become imperative global issues to be solved nowadays. In the last three decades many efforts have been addressed to develop photoactive materials which could be suitable for real-world use in the field of water remediation. In this regard, water-floating photocatalysts could represent good alternatives to traditional materials thanks to their characteristics in terms of efficiency and reasonability including a high oxygenation of the photocatalyst surface, a fully irridiation, easy recovery and reuse. Thanks to its high photocatalytic activity and good stability TiO2 has been proved to be an excellent photocatalyst [1]. However, because of its wide band gap (3.2 eV) its efficiency under solar light is dramatically limited. Hence, much effort has been devoted to improve the utilization of solar light by extending the photoresponse of TiO2 to the visible region, such as metal ion doping, non-metal doping, noble metal deposition, narrow band-gap semiconductors coupling and dye sensitization [2]. Recently, conducting polymers, such as polyaniline (PANI) and polypyrrole (PPy) have been reported as promising sensitizers to extend the spectral response of TiO2 to visible light effectively in TiO2 photocatalysts. The photocatalytic activity of conducting polymers modified TiO2 under visible light irradiation resulted from the visible light absorption of conducting polymers and effective charge separation of photogenerated carriers owing to the heterojunction built between TiO2 and the conducting polymers [3]. In the present study, PANI/TiO2 and PPy/TiO2 modified floating materials were fabricated by inexpensive, ease and innovative environmentally friendly approaches, properly characterized and applied in the photodegradation of rhodamine and in the reduction of CrVI to CrIII under solar light. The role of the conducting polymers in the pollutants abatement on the basis of their chemical-physical characteristics were also investigated. The best materials were subjected to recycle tests in order to demonstrate their stability under the reaction conditions.