Estudo da cinética de degradação do propranolol por processos oxidativos avançados

Abstract

The significant increase in industrial activity coupled with population growth has worried the environmental agencies in several countries, especially about environmental pollution, especially to water pollution. Emerging micropollutants are one of the types of pollutants that have frequently been detected in the aquatic matrices of several countries. Among the most detected micropollutants is the drug propranolol. Due to their high chemical stability, the drugs are not completely degraded in conventional effluent treatments. For this reason, the Advanced Oxidative Processes (AOP) has shown to be a promising alternative to perform this degradation. The objective of this work was to study the kinetics of propranolol degradation by direct photolysis and photo-assisted peroxidation (H2O2/UV) in a bench-top reactor operating in batch mode. The experiments were performed in a reactor containing a 254 nm UV lamp, with a 20 mgL-1 propranolol solution under the conditions of temperature (25ºC and 35ºC) and the presence of hydrogen peroxide (H2O2) (0mL and 2.3mL). The results were evaluated in a UV-Visible spectrophotometer and demonstrated a decrease in the concentration of the drug in all assays, with the most significant decrease being 98.39%, operating in the conditions of 25ºC and 2.3 mL of H2O2. To evaluate the kinetics of degradation, assays were performed in duplicate of the experiment that showed maximum degradation (25ºC and 2.3 mL of H2O2) and calculated the reaction constant (k) and the reaction order (α) by the derivative and integral methods, obtaining the average values of k = 0.05645 min-1 and α = 1.2408, for the derivative method and k = 0.06250 min-1 α = 1, for the integral method. From the results obtained and the statistical analysis it is possible to state that photo-assisted peroxidation operating at a temperature of 25ºC is the most efficient method to degrade propranolol when compared to direct photolysis.