Floating Polyaniline/TiO2 Composites for Water Remediation Under Solar Light Irradiation: A New Life for an Old Polymer

Combining organic and inorganic compounds to obtain new materials that exhibit the properties of both components while adding new ones is a well-established technique that has produced extraordinary results over the years [1]. Organic–inorganic materials have multifunctional applications in several fields, such as gas sensors, tissue engineering, photovoltaic cells, and environmental decontamination [2, 3]. Concerning wastewater remediation, the photocatalytic degradation of organic pollutants represents an important example of green and sustainable technology. Although several conventional and commercially available semiconductors (mainly ZnO, TiO2, etc.) [4, 5] have been extensively investigated, their limited activity under solar light represents a significant downside for transitioning from fundamental study to practical applications. Recently, thanks to their extended -configuration system, conducting polymers (CPs) have been employed as excellent photosensitizers for traditional photocatalysts [1, 6]. For example, it has been demonstrated that CPs can extend the TiO2 activity to the visible region of the electromagnetic spectrum, paving the way to a new class of CPs-based photocatalysts for the photodegradation of different types of water pollutants [6, 7]. Moreover, for applications with sunlight as the irradiation source, the development of water-floating photocatalysts could be one of the best options due to their characteristics in terms of efficiency, thanks to high oxygenation of the photocatalyst’s surface, full sunlight irradiation, easy recovery, and reuse. Herein, the synthesis of innovative floating PANI-TiO2 composites supported on a low-cost commercial polyurethane (PU) foam (PT/PU) is described, as well as their ability to remove rhodamine B (model dye) from the water matrix. Moreover, the photodegradation pathway was identified based on the LC/MS analyses of the transformation products (TPs).