Insights into the efficient degradation of metformin - An emerging antidiabetic medicine by UV/Sulfite process

The growing utilization of metformin (MET) in diabetes treatment has resulted in its occurrence in wastewater treatment plants, where conventional techniques were proved inadequate in eliminating it. The present study evaluated the potential of UV/sulfite system in degrading MET and analyzed the influence of common factors (i.e UV intensity, dosage of reagent, the pH value of reaction solution) on the target contaminant removal. In comparison with both direct UV photolysis and merely sulfite reduction, the UV/sulfite process had a remarkable enhancement in MET removal, with 96.54% of MET (initial concentration of 15 mg/L) being degraded within 30 minutes. A strong linear relationship (R2 > 0.99) was observed between MET degradation kinetics and UV intensity. The increase of sulfite dosage and solution pH could promote MET degradation to a certain extent in the studied system. Additionally, the hydrated electron (eaq-) was found played the principle role in MET removal through scavenging reactions.