Degradação fotocatalítica de poluentes emergentes empregando Tio2 imobilizado

Abstract

For a long time the studies on the treatment of residues were directed at certain groups of pollutants considered resistant and toxic. In recent years, species considered micropollutants, with concentrations of the order of μg L-1, have received attention, since many of them have pharmacological activity and due to their great use and the low removal efficiency presented by sewage treatment systems can contaminate surface waters and underground. In this way, several researches have been developed in search of new forms of treatment, with capacity for the removal of antibiotics, analgesics, anti-inflammatories, among others. The Advanced Oxidative Processes (POAs) have been recognized as important because they show an efficient degradation of these micropollutants, which in some cases allow their complete mineralization, that is, their conversion into carbon dioxide, water and inorganic ions. Due to its high use by the population and potential problems attributed to its presence in the environment there is a need for research on remediation methodologies for the drugs amoxicillin (AMX), fluoxetine (FLU) and simvastatin (SIN). Therefore, the potential of heterogeneous photocatalysis using titanium dioxide immobilized in cellulose acetate (TiO2/AC) assisted under ultraviolet (UV) radiation in relation to the remediation of aqueous matrices containing the AMX, FLU and SIN drugs was studied. The photocatalyst was characterized by thermogravimetry (TG) and differential thermal analysis (DTA), Quantitative Microanalysis with chemical mapping by X-ray Dispersive Energy Spectroscopy (EDS), X-ray Diffraction (XRD) and Infrared Spectroscopy (FTIR). The drug degradation assays were conducted in a photochemical reactor and the fractions obtained were analyzed by high performance liquid chromatography at the maximum absorption wavelength for each drug. Degradations of 99.1% (SIN in 30 minutes), 85% (FLU in 180 minutes) and 99.0% (AMX in 240 minutes) were obtained. Photolysis assays were performed proving the low photosensitivity of the drugs, thus, degradation is attributed as a result of the interaction between the TiO2 / AC photocatalyst and ultraviolet radiation. Analysis of Gas Chromatography coupled to the mass detector (GC / MS) allowed to quantify and identify the degradation products, with results of Total Organic Carbon (TOC), it was possible to determine the mineralization rate of 70, 43 and 15% for AMX, FLU and SIN, respectively. Ecotoxicological assays performed with the aquatic plant Lemna aequinoctials Welw have been shown to be effective in understanding how drugs and their degradation products can affect aquatic organisms.