Adsorption And Photolysis Of Sulfanamidesby Ferrihydrite/Humic Acid

Sulfanamides are widely used in the treatment of human diseases. livestock and aquaculture for the prevention of various bacterial diseases. As iron oxides and humic acids are the main active substances in soil and sediment, the adsorption and photolysis performance of sulfanamidesin ferrihydrite and humic acid were studied by static adsorption and photolysis experiments, acute toxicity test and reactive oxygen species on quenching experiment, XRD,FTIR and other characterization methods were used to characterize the adsorbens before and after adsorption, and the main results are as follows:1. The adsorption kinetics of sulfanamides on ferrihydriteor humic acid follows pseudo-second-order kinetics. The adsorption of sulfanamideson ferrihydriteand humic acid are a spontaneous endothermic process. With the increase of pH, the adsorption capacity of ferrihydrite for sulfanamides showed a trend of"V" shape, decreasing first and then increasing,while the adsorption capacity of humic acid for sulfanamides decreased gradually. With the increase of ionic strength, the adsorption capacity of sulfanamides in ferrihydrite or humic acid were decreased; When the mole ratio of sulfonamides to lead nitrate was 2:1. the adsorption capacity of sulfanamides to ferrihydrite or humic acid was the maximum, the adsorption capacity of SD,SMland SM2 on the ferrihydrite was 8.90 mg/g, 8.86 mg/g and 7.55 mg/g, respectively;the adsorption capacity of SD.SM1and SM2 on the humic acid was 2.24 mg/g, 2.64 mg/g and 2.30 mg/g, respectively; and when the mole ratio of sulfonamides to cadmium nitrate was 2:1,the adsorption capacity was also the maximum,the adsorption capacity of SD,SM1and SM2 on the ferrihydrite was 9.60 mg/g, 10.72 mg/g and 10.10 mg/g, respectively; the adsorption capacity of SD.SM1and SM2 on the humic acid was 2.68 mg/g, 2.37 mg/g and 2.16 mg/g, respectively.2. The ferrihydrite or humic acid promoted the photolysis of sulfanamides. Under illumination, with the increase of initial concentration, the photolysis rate of sulfanamides decreased and the pH impacted the photolysis rate of sulfanamides significantly. Ionic strength could promote the photolysis of sulfanamideson ferrihydrite. and inhibit the photolysis of sulfanamideson humic acid. When the mole ratio of sulfonamides to lead nitrate was 2:1.photolysiseffect ofSD,SM1 and SM2 in ferrihydrite was the maximum,the photolysis rate was 47.39%,45.84% and 23.81%,respectively: and photolysiseffect ofSD.SM1 and SM2 in humic acid was also the maximum.the photolysis rate was45.33%. 57.25% and 58.32%.respectively.And when the mole ratio of sulfonamides to cadmium nitrate was 2:1, photolysiseffect ofSD,SM1 and SM2 in ferrihydrite was themaximum,the photolysis rate was 44,63%, 50.84%and 26.89%,respectively,and photolysiseffect ofSD,SM1 and SM2 in humic acid was also themaximum,the photolysis rate was56.15%, 58.96% and 59.31%,respectively.3. In their photolysis process, the sulfonamides generated more toxic intermediate products,which harmed to environment in a certain degree.