The detection of the pharmaceutical compounds used in human and veterinary medicine is in several environmental matrices (surface waters, effluents, groundwater, soils, and sediments), and such presence promotes the resistance bacteria development, making them ineffective in some diseases treatment. The research project promotes the TiO 2 synthesis using yeast culture as biotemplate, the step followed by the microstructure characterization with surface area enhancement; such properties are responsible for the improvement of solar photodecomposition processes of the veterinary antibiotic oxytetracycline. In such simple and standard process conditions the system reaches about 84% of removal percentage with a better agreement with the pseudo-first-order with the Pearson coefficient in the range from 0.82 to 0.94 and K 1 = 0.035 M −1 •s −1. The degradation rate constant increased with the increasing initial Yeast-TiO 2 dosage until the maximum mass of 0.1 g or with the decreasing of initial oxytetracycline concentration. The solar light used as a sustainable irradiation source is abundant and low cost in tropical countries, perfect to be applied in water treatment to decompose the pharmaceuticals pollutants, as the veterinarian antibiotics. The study demonstrates that solar photodecomposition is an efficient treatment technology for the removal of antibiotics from polluted water and provides insightful information on the potential practical application of this technology to treat contaminated water, possibly also in rural, distant areas.

Reliable data of antibiotic use and environmental discharge as veterinary medicine are essential to help countries raise awareness of the appropriate use, control, and correct water release. The first approach is to change the regulatory framework based on consuming information, use policy, and discharge laws. The important research contribution is a novel water treatment process to treat, remove, and reduce antibiotic concentration in discharged water, mainly those used in the animal protein industry. The low particle biochar added during the titanium isopropoxide hydrolysis reduces the titanium dioxide (TiO 2) agglomerates and promotes the adsorption surface process. Such improved catalyst material enhances the solar decomposition efficiency to 93% from original oxytetracycline with better correspondence with the Elovich kinetics, intraparticle diffusion, R-P isotherm, and Langmuir-Hinshelwood model.

AZEVEDO, Izabela. R. C. L. Use of solar photodecomposition to remove oxytetracycline from water contaminated by livestock. 2020. 90 p. Dissertação (Mestrado em Tecnologia Nuclear) Instituto de Pesquisas Energéticas e Nucleares -IPEN-CNEN/SP.Since its discovery in 1953, oxytetracycline has become the most widely used and commercialized veterinary antibiotic in rural areas due to its high power of action against bacterial infections that affect animals. On farms, after metabolization, the antibiotic and its metabolites have been released as excreta directly into the soil or surface water resources. Such compound's presence compromises the water quality on surface resources and groundwater. The antibiotics presence in the environment have become a worldwide threat due to resistance genes in pathogenic bacteria. It is worth remembering that conventional water treatment methods do not remove these micropollutants. This study aimed to develop a water treatment process for the antibiotic oxytetracycline using solar photodecomposition as a renewable energy source, which is abundant and constant in many Brazilian regions. Moreover, it can possibly be applied in distant rural areas. The synthetic antibiotics solution prepared in the laboratory allowed the processes optimization; the chosen initial concentrations were equivalent to those found in the literature for contaminated effluents. The experiments also used different semiconductor mass proportions prepared from the titanium isopropoxide hydrolysis and biocarbon. The synthesized TiO2 was analyzed by scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersion spectroscopy (EDS). The micrography's obtained by SEM analyses showed a reduction of the agglomerate's presence with the biocarbon addition during the hydrolysis and promoted higher surface adsorption, increasing the pores' size. The EDS indicated that the sample has a preponderance for titanium and to a lesser extent for oxygen and carbon. The X-ray diffractogram of the crystalline structure of TiO2 prepared with the addition of biocarbon confirms high crystallinity, amorphous content, and possibly the development of high TiO2 surface area.Laboratory tests allowed the enhancement of photodecomposition process parameters and promoted the kinetic and thermodynamic calculation, intraparticle diffusion, and allowed the Elovic Model calculations, confirm the Langmuir-Hinshelwood model and perform the isotherms. The higher removal percentages systems confirmed the pseudo-second order kinetics as the most corresponded kinetics indicated by the Pearson coefficient (R 2 ) values. The calculations of the isotherm models of Langmuir, Freundlich, and Redlich-Peterson, confirmed the correspondence with the Langmuir model with the highest R 2 . Thermodynamic calculations enable reaction identification as endothermic, spontaneous, and presented the system disorder. The ideal mass of TiO2 with biocarbon for the photodecomposition development was 0.6 g. Based on these results, it is possible to achieve o...