Degradation of Antibiotics in Aqueous Solution by Photocatalytic Process: Comparing the Efficiency in the Use of ZnO or TiO2

Abstract

The study examined the photodegradative efficiency of ZnO and TiO 2 in degradation of antibiotics in aqueous matrices . Among several types of antibiotics , four antibiotics were chosen to feature the major classes of these compounds : amoxicillin , erythromycin , streptomycin and ciprofloxacin . Degradation of antibiotic solutions was carried out mainly under UV - light irradiation in a set time with the presence of small quantity of zinc oxide or titanium dioxide . Solutions were analyzed with HPLC chromatography and degradation percentages were calculated from ratio between pick area associated to no degraded drug solution and degraded drug solution ' s pick area . Meanwhile , toxicity of antibiotics and degrading compounds were investigated using a biosensor system , consisting of Clark ' s electrode associated with a portion of agar medium culture containing Saccharomyces Cerevisiae yeast cells . This way , it was possible to define the oxygen that was consumed by yeast cells . Toxicity associated to antibiotics and degrading products are related to decrease of oxygen concentration in solution . It is clear that zinc oxide is slower than titanium dioxide to degrade antibiotics , but zinc oxide shows better photodegradation efficiency than titanium dioxide in spite of its small specific superficial area .