DEGRADATION/MINERALIZATION OF ANTIBIOTICS FROM AQUEOUS SOLUTIONS BY THE ADVANCED OXIDATION PROCESSES

Maria GONȚA, Larisa MOCANU, Vera MATVEEVICI Universitatea de Stat din Moldova

Аннотация

Pharmaceutical compounds are mostly non-biodegradable drug residues that have a removal efficiency of 20.0-50.0% by applying conventional methods, in comparison to the high efficiency obtained after the application of advanced oxidation processes. The main objective of this research was to determine the optimal oxidation/mineralization conditions according to the physico-chemical parameters such as pH value, oxidant (H2O2) and catalyst concentrations (Fe2+ and TiO2) that influence the oxidation of AMX and the evaluation of the degradation process of AMX in Fenton reagent and titanium dioxide systems. Initial reactant concentrations ranged from 0.01 to 0.3 mM for Fe2+, 0.1 to 0.5 g for TiO2 and 1.0 to 5.0 mM for H2O2. Homogeneous and heterogeneous oxidation of AMX was performed at a pH of 2.2 for the AMX/ Fe2+/H2O2/UV system and 3.5 for the AMX/TiO2/H2O2/UV system in aqueous solutions. The research methodology includes the study of oxidation/mineralization processes by determining the variation of chemical oxygen demand and substrate concentration using spectrophotometric methods. As a result of the process of optimizing the physico-chemical parameters, it has obtained that the maximum rate of mineralization/oxidation by Fenton oxidation achieved 96.0%, and the degradation rate – 90.0%. In the presence of titanium dioxide, efficiency is lower for degradation rate – 65.0% and achieved 97.0% form oxidation/mineralization rate. Although a high rate of oxidation/mineralization has been obtained, the COD values are high (11.9-12.5 mgO/L), which indicates the presence of stable organic compounds. Keywords: amoxicillin, homogeneous Fenton reaction, heterogeneous titanium dioxide reaction, oxidation/mineralization, degradation.