A Plug flow reactor model for UV-based oxidation of amoxicillin

Amoxicillin was treated with UV and UV/H2O2 processes, and the byproduct formation, mineralization and toxicity on Vibrio fischeri (a luminescent micro-organism) were monitored to satisfy environmental considerations. A plug flow cylindrical reactor (33 cm length and 1.75 cm radius) and a peristaltic pump (multifunctional speed pump) were used to perform the treatments. A UV lamp covered with a quartz protection was placed inside the reactor. The UV fluence rate was calculated with a chemical actinometry method, and its value was 2.3 W m−2. The maximum removal of amoxicillin with the UV and UV/H2O2 processes was achieved when the peristaltic pump speed was adjusted to 10 rpm and the H2O2 concentration to 588 mg L−1 (55 and 90%, respectively). In addition, under the above-mentioned optimal conditions, the mineralization was 11 and 43% for the UV and UV/H2O2 processes, respectively. A byproduct formation pathway was proposed for each process. When the flow reactor was operated in the presence of alkalinity (20.5 mg CaCO3 L−1) and humic acid (5 mg L−1), a 50% decrease in the removal performance was observed due to the applied matrix parameters. The EC50% value was 76 and 36% after the UV and UV/H2O2 treatments, which indicates the toxicity level of the effluents after 67 min of UV-based oxidation treatments.