Determing the fate of selected antibiotics during nitrogen recovery via urea-formaldehdye synthesis

Abstract

The work presented here focused on the determination of fate of four selected antibiot-ics: enrofloaxicin, oxytetracyline, sulfamethoxazole and tylosin during nitrogen recovery from source separated urine via urea formaldehyde synthesis. The experimental pH was at 2 and temperature at 25°C throughout the chemical reaction, preventing urea hydroly-sis. Five main chemical reactions: aqueous + antibiotics, Urine + formaldehyde + antibi-otics (UF synthesis experiment), urea-formaldehyde polymer + antibiotics (adsorption experiment), formaldehyde + antibiotics and dried Urea formaldehyde polymer dissolved in the nitric acid + antibiotics (absorption experiment) were sat up. The spiked antibiotics concentrations were analyzed for each reaction. Solid phase extraction (SPE), liquid chromatography and mass spectrometer (LC/MS) were used to extract and measure the antibiotics. According to the data obtained, enrofloxacin was not hydrolyzed, thus its degradation behavior was not analyzed in details. Oxytetracyline’s concentration fluctuated and indicated that at some point chemical reaction occurred with presences of alpha and beta epimers. The results for sulfamethoxazole showed that the antibiotic was very stable and did not under go any chemical reaction except during UF synthesis and adsorption experiment. Tylosin in all experimental chemical reactions showed vulnerability to hydrolysis due to its instability at pH 2 and it was completely degraded in each experiment. In addition two more chemical reactions: urine + antibiotics and selected urine (no Cl and Ca) + antibiotics were set up in order to determine the role of inorganic and organic compounds during the reaction and their effect on the fate of the antibiotics. The results showed that inorganic ion, absence or presence of Cl and Ca and organic compounds had no effect on the concentration decrease and the fate of the antibiotics. The results helped to validate and support the five main chemical reactions analysis.