Photodegradation of amoxicillin in aqueous solution under simulated irradiation: influencing factors and mechanisms

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Courtesy of IWA Publishing

This paper investigated the effects of selected common chemical species in natural waters (HCO3, NO3 and humic acids (HA)) on the photodegradation of amoxicillin (AMO) under simulated irradiation using a 300 W xenon lamp. Quenching experiments were carried out to explore the mechanisms of AMO photodegradation. The results indicated that AMO photodegradation followed pseudo-first-order kinetics. Increasing AMO concentration from 100 to 1,000 μg L−1 led to the decrease in the photodegradation rate constant from 0.2411 to 0.1912 min−1. The presence of NO3 and HA obviously inhibited the photodegradation rate of AMO because they can compete for photons with AMO. Bicarbonate, as a hydroxyl radical (·OH) scavenger, also adversely affected AMO photodegradation. Quenching experiments in pure water suggested that AMO could undergo self-sensitized photooxidation via ·OH and singlet oxygen (1O2), accounting for AMO removal of 34.86 and 8.26%, respectively. In HA solutions, the indirect photodegradation of AMO was mostly attributed to the produced ·OH (22.37%), 1O2 (24.12%) and 3HA* (20.80%), whereas the contribution of direct photodegradation was to some extent decreased.

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