*2.4. ROS Generation*

It should be noted that O2· − was not detected with the XTT sodium salt (probe for O2· −) in this study; therefore, we only focused on the production of ·OH and 1O2. Free radical quenching experiments were first carried out with L-histidine and potassium iodide (KI) as radical quenchers to identify the contribution of 1O2 and ·OH, respectively [37,38]. The inhibition rate of SMZ degradation was determined after introducing free radical scavengers. In addition, 200 μM terephthalic acid (TPA) and 300 μM furfuryl alcohol (FFA) were used as indicators to quantify the amount of ROS [39,40]. TPA reacted with ·OH and produced 2-hydroxyterephthalic acid (HTPA), which could be measured by a fluorescence spectrophotometer (HITACHI, F-2500, Tokyo, Japan). The excitation and emission wavelengths were 315 nm and 425 nm, respectively [23,40]. FFA was analyzed by HPLC at 218 nm. The mobile phase was 30% acetonitrile and 70% phosphoric acid and run at 1.0 mL/min.
