Degradation and mineralization of the emerging pharmaceutical pollutant sildenafil by ozone and UV radiation using response surface methodology

ABRILE, MARIANA GUADALUPE; CIUCIO, MARÍA MICHELA; DEMARCHI, LOURDES MARLÉN; BONO, VIRGINIA MARIEL; FIASCONARO, MARÍA LAURA; LOVATO, MARÍA EUGENIA

ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH

SPRINGER HEIDELBERG

Año: 2020

0944-1344

Pharmaceuticals and their degradation products which are present in wastewater and superficial waters are becoming anecological issue. This research investigated the degradation and mineralization of synthetic solutions of the pharmaceuticalcompound sildenafil citrate (SC) by single ozonation and ozonation jointed with UV radiation (O3/UV). The effects ofinitial drug concentration (50?125 mg L−1), inlet ozone concentration (35?125 g Nm−3), and UV radiation on SC degradationand decrease of total organic carbon (TOC) were investigated using response surface methodology based on a centralcomposite experimental design. Through the RSM analysis, it was possible to confirm the removal of SC for the entireexperimental range. Major intermediates of SC degradation were identified and a degradation pathway was proposed. Thekinetics of SC degradation was modeled as a pseudo-first-order reaction with a rate constant ranging between 0.072 and1.250 min−1. The SC degradation and TOC removal were strongly enhanced by increasing the concentration of gaseous ozoneat the inlet and incorporating UV radiation. The highest TOC removal reached at 60 min was 75%, in the O3/UV system, withinitial SC content of 50 mg L−1 and inlet ozone concentration of 125 g Nm−3. The degradation rate of SC was increased 3 to 9times in the presence of UV radiation. Ozone-based advanced oxidation processes appear as a suitable alternative for treatment ofthe emerging pollutant SC.