Degradação dos contaminantes emergentes triclosan e ibuprofeno em efluente sintético por via fotoquímica uv e uv/h2o2

Abstract

Ibuprofen (IBU) is a pharmaceutical compound widely used by people all over the world; it is a non-steroidal anti-inflammatory drug that does not require a prescription to be administered, increasing its consumption. Triclosan (TCS) is a broad-spectrum antimicrobial widely used in soaps and other personal care products. Both substances belong to the class of emerging contaminants, these compounds have no regulations for limits in water bodies and lead to various risks to the environment. Traditional treatment processes in wastewater treatment plants and water treatment plants have already shown difficulties in the removal of this class of contaminants, because of this, it is necessary to implement polishing treatments that result in the degradation of these pollutants. In this work, the implementation of an advanced oxidative system based on UV and UV/H2O2 radiation for degradation of TCS and IBU in synthetic effluent is evaluated. The assays took place in a 2L reactor, protected from the dark and equipped with a UV lamp (λ = 254nm). The effect of contaminant concentration, mineralization, and the fractions of chemical species present were evaluated. In the UV/H2O2 system different concentrations of H2O2 were studied for oxidation of the target contaminants. The assays occurred kinetically between 75 – 270 min of irradiation. Concentration analyses were performed by High Performance Liquid Chromatography. The results showed 100% oxidation of TCS in the direct photolysis system at pH 9.4 after 12 min. For IBU the UV/H2O2 system using 10 mg L-1 of H2O2 obtained 97.39% oxidation. We obtained k' values of 0.189 min-1 for TCS when it had its highest oxidation and k' of 0.0219 min-1 for IBU. The system was not able to completely mineralize the contaminants, presenting high values of TOC and COD after the treatment, thus suggesting the occurrence of phototransformation.