Abstract The aim of this investigation was to study the degradation of tributyl phosphate (TBP) in aqueous solution by heterogeneous photocatalysis (UV-C/TiO2). To perform the investigation, aqueous solutions containing the contaminant were exposed to UV radiation in the absence or presence of TiO2 in suspension or supported on a Fe-Cr metal alloy plate. TBP analyses before and after the treatment were performed by Ultra-Performance Liquid Chromatography (UPLC) in order to quantify the contaminant degradation. The results showed that the TiO2 photocatalytic system was able to remove TBP from the solution and the formation of some by-products was observed. TiO2 photocatalytic systems were able to reduce acute toxicity in an Artemia Salina bioassay according to the increase in LC50 from 10.2 ± 0.5%(v/v) to 16.9 ± 0.6 %(v/v) for the immobilized system and to levels which were not possible to detect by the applied method any more for the suspension system.

Abstract The present work aims to study the photocatalytic degradation of three organophosphate esters considered environmental emerging contaminants by the UV/H2O2 system with the use of 31P NMR spectroscopy to investigative their removal after the treatment. Results demonstrated the efficiency of the oxidation system in removing the esters tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP) and tri-butyl phosphate (TBP) from aqueous solutions when they were individually present and mixed. High levels of degradation of these chemicals were achieved, in addition to the good performance of the analytical technique applied in the study, which represents some advantages in comparison with other techniques reported in the literature. An increase in the 31P NMR signal removal could also be observed when the oxidizing agent concentration increases. Decreases in solution acute toxicity were also verified for both TBP and TBEP treated samples when compared with the samples before the treatment.

The purpose of this study was to synthesize TiO2-polymer composites able to act as photocatalyst membranes. TiO2 catalysts were prepared using the sol-gel method to contain 0.0, 0.5, 1.0, and 2.0 wt.% of embedded Ag particles, subsequently incorporated into natural rubber latex at a weight fraction of 15%. Samples of these ceramic powders were suspended in a latex emulsion (natural rubber), cast in Petri dishes and slowly dried in an oven. The resulting materials were evaluated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray, diffuse reflectance spectroscopy, differential scanning calorimetry, thermogravimetry, and photocatalytic assaying using methylene blue as an organic pollutant reference. All composite membranes exhibited good photoactivity conferred by TiO2 powder, with 98% dye fading after 300 min of ultraviolet irradiation.