Estudo da degradação do atenolol e do paracetamol em reator batelada por fotólise direta, peroxidação fotoassistida e fotocatálise heterogênea.

Abstract

concentrations of ng L-1 and µg L-1, wich can cause damage or even be fatal to some aquatic organisms. Conventional wastewater treatment methods are not efficient for removing these micropollutants, but new methods, such as those using Advanced Oxidation Processes, are emerging as an alternative to their degradation. Faced with this problem, this work aimed to study the degradation of atenolol and paracetamol drugs by direct photolysis, photo-assisted peroxidation (H2O2/UV) and heterogeneous photocatalysis in a photocatalytic batch reactor. The UV lamp power of 36 W, stirring of 180 rpm and initial concentration (25 mg L-1 atenolol and 15 mg L-1 paracetamol) were fixed as experimental parameters. For both drugs, a 23 factorial design without center points was applied, triplicate for atenolol and duplicate for paracetamol, through which the treatment time (60 and 120 minutes), TiO2 in suspension (absence and presence) and H2O2 (absence and presence) were studied. In addition, the temperature of the solution in the reactor was monitored and recorded, and the pH of the solutions before and after treatment was recorded as well. It was not possible to determine the atenolol degradation in the tests with absence of H2O2, because was an increase in absorbance in all of them, but in the tests with H2O2/UV, the maximum atenolol degradation (42.05%) was obtained in the 60 minutes test with TiO2 in suspension. There was maximum degradation of paracetamol (96.31%) in the 120 minutes experiment with TiO2 in suspension and presence of H2O2. Statistical analysis about paracetamol degratation showed that the influence of TiO2 was practically negligible, the time of treatment, to a lesser extent, positively influenced the process, and that H2O2 was the most influential variable on the treatment, being the only significant at a 95% confidence level. In all tests performed with both drugs, there was a decrease in the pH of the solutions after the treatment, being more accentuated in the H2O2/UV tests. From the results obtained from the experiments and statistical analyses, it was found that, in the experimental conditions of this work, the H2O2/UV method was the most efficient on the degradation of the drugs.