Uso de fotocatálise eletroassistida com diferentes fontes de radiação e material nanoestruturado para tratamento de um fármaco em água

Abstract

Drugs are inappropriately disposed in the environment leading to contamination of water bodies. Different effects on aquatic ecosystem have been related to the presence of these products in surface waters, causing damage not fully known to humans even at low concentrations. Most drugs are resistant to conventional treatment technologies (physical, chemical and biological) because they have limitations for treat recalcitrant compounds.Therefore is essencial the development of new technologies. In this context, the Advanced Oxidation Processes (AOP) may contribute for the degradation of recalcitrant compounds through the generation of highly reactive radicals. This study investigated the electrolytic, photocatalytic and electro-assisted photocatalytic processes to treat solutions containing different concentrations of the drug Sildenafil Citrate (S.C.) as known as Viagra © . The experiments were carried out in a reactor consisted by of cathode DSA © (Dimensionally Stable Anode) and nanostructured anode of TiO 2 . The system was irradiated with Ultraviolet Light Emitting Diode (UVLED), Black Light Lamp and a Solar Simulator. Solutions at the concentrations of 1.0, 5.0 and 10.0 mg L -1 of S.C. were treated. The conditions tested in experimental runs were: flowrate 400 and 1000 L h -1 (batch-recirculation mode); 1,0 M of Na 2 SO 4 as supporting electrolyte and 0,5; 1,0 and 1,5 Volts (potential bias). Absorbance readings were carried out between 190 and 800 nm in UV-Vis spectrophotometer. Additionally, pH, temperature and Total Organic Carbon (TOC) were monitored during the tests. The results showed that flowrate of 1000 L h -1 was the most favorable. By treating 1.0 mg L -1 the S.C. the results showed reductions lower than 1.0 %, regardless of the treatment process and the radiation source type used. By treating 10.0 mg L -1 of the S.C. the treatment type which shows a higher reduction of the concentration was the electrolytic (19.2%). The UV source more efficient for absorbance decay was 18.7% using UVLED in the electro-assisted photocatalytic process in 180 minutes.