Study On The Degradation Of Sulfamethoxazole And Its Mechanism By Peroxymonosulfate/Hydrogen Peroxide Activated By Iron Alginate Beads Under Ultraviolet Light

Sulfamethoxazole（SMX）is a very representative sulfonamide antibiotic.It is widely used in the clinical treatment of urinary tract infections,respiratory tract infections,otitis media,digestive tract infections and other diseases.It is also often used as a feed additive,agriculture,animal husbandry,aquaculture,etc.Sulfamethoxazole is widely detected in soil and water environments worldwide due to its stable chemical properties and the"pseudo-persistence"generally possessed by antibiotics.At the same time,sulfamethoxazole also accumulates in organisms through environmental media and food chain,inhibits its growth,and causes the formation of drug-resistant genes in certain microorganisms and animals,posing a potential threat to the ecological environment.Both Fenton and peroxymonosulfate oxidation have the characteristics of low cost and strong environmental friendliness.However,they also have low catalyst efficiency and too harsh reaction conditions,which limits their application scope and prospect.In this experiment,iron alginate beads（Fe-SA）,a heterogeneous catalyst,used as a catalyst for both under ultraviolet light,the degradation effect and mechanism of sulfamethoxazole were systematically studied.The specific content includes:Fe-SA catalytically activated permonosulfate（PMS）under ultraviolet light to degrade sulfamethoxazole in water removal effect and degradation mechanism,and extended the application of other antibiotics;Fe-SA catalytically activated under ultraviolet light The removal effect and degradation mechanism of sulfamethoxazole in water by hydrogen oxide（H₂O₂）.The conclusions of this experiment are as follows:1)Fe-SA effectively activate peroxymonosulfate（PMS）and hydrogen peroxide（H₂O₂） to generate oxygen-containing free radicals accounting for the degradation of sulfamethoxazole under ultraviolet light2)The performance in SMX degradation is positively correlated with the amount of Fe-SA,the initial concentration of PMS,also H₂O₂.However,due to the limitation of surface reaction sites,excessively elevating the amount of one of Fe-SA,PMS and H₂O₂does not significantly increase the degradation rate.Acidic conditions are beneficial to the activation process of Fe-SA.Specifically,when PMS is activated,the initial pH value is 7,and the degradation rate of SMX can still reach 89%within 20 minutes;and when H₂O₂ is activated,the initial pH value is 4 to achieve the best degradation rate.3)Fe-SA has a good recycling capacity.Degradation rate of SMX can still reach 78.7% after five consecutive cycles,within 20 minutes4)The combination of quenching experiments with electron paramagnetic resonance technology（EPR）verify that·OH is the dominant species responsible for SMX degradation during Fe-SA/H₂O₂ process,whereas,·OH,SO₄^·-and Fe（IV）is the main reactive species attributing to SMX decay in Fe-SA/PMS system.5)Degradation pathway of SMX was analyzed by liquid chromatography-mass spectrometry（LC-MS）.Attacking the S-N in the SMX molecular structure via SO₄^·- results in the degradation of SMX.