Degadation Of Sulfamethoxazole In Water By Ultraviolet Irradiation

Since the 1990s,drugs and personal care products have been listed as new environmental pollutants,which have been frequently detected in surface water,underground water and other water environmental media.The long-term residual accumulation of this kind of pollutants in the water environment will seriously affect and destroy human health and the stability of water ecosystem.Therefore,this kind of pollution has become an inevitable environmental problem faced by every country in the world,which has attracted more and more attention of environmental protection workers.In this paper,a typical antibiotic-sulfamethoxazole?SMX?simulated wastewater was used to study the degradation of SMX by three kinds of ultraviolet irradiation systems,and the effects of various environmental factors on the degradation of SMX were discussed.The degradation mechanism of different reaction systems was studied.The main findings are as follows:1.The degradation process of SMX by UV alone accords with the first-order reaction kinetics model.The degradation efficiency of SMX,decreases with the increase of initial concentration of SMX,significantly affected by the initial pH,and the degradation efficiency of SMX decreases with the increase of initial concentration of SMX.The degradation efficiency of SMX was acid>neutral>alkaline.Different concentrations of Cl^-,SO₄^2-,Cu²⁺and Fe³⁺have little effect on the degradation of SMX,but different concentrations of NO₃^-promote the degradation of SMX.The higher the concentration of NO₃^-the faster the degradation efficiency of SMX.FA has a significant inhibitory effect on the degradation of SMX.The higher the concentration of FA was,the more significant the inhibitory effect was.2.When 10mmol/L methanol was added into the system of UV/NO₃^-,the degradation of SMX was obviously inhibited,and the degradation effect of SMX was almost identical to that of UV alone.This proves that the degradation of SMX in UV/NO₃^-system is the function of HO^·.The degradation process of SMX by UV/NO₃^-system accords with the first order reaction kinetics model.The degradation efficiency of SMX decreases with the increase of the initial concentration of SMX.The degradation of SMX was significantly affected by the initial pH,acidity was beneficial to the degradation of SMX,followed by alkalinity,and finally neutral.Different concentrations of Cl^-,SO₄^2-,Cu²⁺and Fe³⁺had little effect on the degradation of SMX,but different concentrations of HCO₃^-promoted the degradation of SMX.FA significantly inhibited the degradation of SMX,and the higher the concentration of FA,the more significant the inhibition.3.The introduction of HCO₃^-alone has little effect on the degradation of SMX;The introduction of NO₃^-can significantly accelerate the degradation of SMX,while the introduction of HCO₃^-and NO₃^-can further promote the degradation of SMX,which is due to the formation of CO₃^·by the reaction of HO^·and HCO₃^-.The degradation process of SMX by UV/NO₃^-/HCO₃^-system accords with the first order reaction kinetics model.The degradation efficiency of SMX decreased with the increase of initial concentration of SMX.Different concentrations of Cl^-,SO₄^2-and Fe³⁺have little effect on the degradation of SMX,high concentration of NO₃^-has a significant effect on the degradation of SMX,and different concentrations of Cu²⁺can inhibit the degradation of SMX.