Proposal of Pathway from the Electrodegradation of Amoxicillin and Paracetamol from Hemodialysis Wastewater using Electro-Oxidation, UVC and Electro-Oxidation-UVC Treatment

Amoxicillin (AMX) and paracetamol (PAR) do not have a synergistic effect, as they act through separate mechanisms and do not combine to enhance each other's effects (synergy), in fact, they are considered medications with no or clinically insignificant interactions, since they act independently, neither improving nor decreasing the efficacy of the other. However, both drugs are found in wastewater from hemodialysis. It is perfectly safe to take AMX with PAR; this is a common combination for treating infections (AMX) and associated symptoms such as pain or fever (PAR). For this reason, this study reports for the first time. Synthetic HD wastewater was treated via simple electro-oxidation (EO), simple ultraviolet radiation from 200 to 280 nm (UVC), and combined EO–UVC processes in the presence of 30 mg⋅L -1 AMX or PAR individually or together using the IrO 2 -Ta 2 O 5 |Ti electrode as the anode, with a Ti cathode, applying j = 5 mA⋅cm -2 . Electrochemical treatment enhanced the degradation efficiency of the pollutants present, due to the electro-generation of •OH radicals and active chlorine, resulting in decreases of 78% and 100% in AMX and PAR, respectively. Among the three systems compared, direct UVC radiation had the lowest performance in the degradation of pharmaceutical compounds and total organic carbon (TOC): 34.29% AMX and 41.98% PAR. The coupled EO-UVC system was noted to aid in the removal of AMX and PAR, as well as a decrease in TOC, with 55.40% AMX and 28.10% PAR removal, respectively. The degradation pathways of AMX and PAR were observed under operating conditions in synthetic HD water via three processes (EO, UVC, and EO–UVC). In AMX, 27 reaction products were identified (AM 1 – AM 23), of which 15 byproducts were identified in EO, and 19 were identified in UVC and combined EO–UVC. Notably, several of these reaction intermediates were identified in all three processes. During the degradation of PAR, 10 reaction products were identified (PC 1–PC 10), which were common to all three methods.