Deteção do antibiótico minociclina em águas residuais

Miguel Martins Lamúria

Key information

Authors:

Miguel Martins Lamúria (Miguel Martins Lamúria)

Supervisors:

Ana Clara Lopes Marques (Ana Clara Lopes Marques); Susete Maria Martins Dias (Susete Maria Martins Dias)

Published in

07/07/2022

Abstract

The tetracyclines constitute the third most consumed antibiotic group. Their low cost and broad spectrum of activity make them an attractive choice for people, however, the low metabolization rate - for instance, around 60% of the minocycline (MC) intake is excreted - of these compounds lead to large quantities being discharged in urban and rural effluents. Therefore, it is urgent to develop treatment methods that allow their elimination before discharge. The stability of aqueous solutions at room temperature and at -20 oC was studied. The half-life of MC when exposed to solar radiation in water lines was determined. The influence of the exposure time to solar radiation on the degradation of MC in 10 mg/L solutions was initially evaluated using a solar simulator coupled to a batch reactor with recirculation. The effect of radiation was measured via the introduction of a filter and a collimator. The quantification of MC was performed by analysis of UV-Vis spectra and HPLC-DAD. The results obtained show that the photodegradation of MC in aqueous solution, with an initial pH between 5,4 and 5,7, occurs with kinetics varying between 0,03 and 0,115 min-1 and the half-life time between 21,9 and 6,1 minutes, for the 100 mL initial volume solution with filtrated and collimated light tests, respectively. In a 192-hour test using collimated light and with a real exposure time of the 10 mg/L solution of 18 min, the peak corresponding to MC disappeared and the MC suffered a change of its spectrum, evidencing the occurrence mineralization.