The Adsorption/desorption And Leaching Properties Of 2 Sulfa Antibiotics In Meadow Black Soil

For a long time, antibiotics have play a role of prevention and treatment of bacterial infections, are widely used in livestock production. Sulfa antibiotics as a kind of synthetic antibacterial drug, is widely used in the livestock industry. After poultry eating sulfa antibiotics, about 60 to 90 percent of the original drug or metabolite form excreted with animal feces and urine. With the agricultural cycle operations, sulfa antibiotic eventually enter the soil, water and other environment.Through a series of transformation processes, they are widely distributed in the environment and impact on the environment. To evaluate the potential risks of veterinary drug sulfa antibiotics on the ecological environment, this study selected two common sulfa antibiotics : Sulfadiazine(referred to as SD) and sulfamethazine(SM2). To study the environment behavior like adsorption, desorption and vertical migration in meadow black soil which can provide a theoretical basis and experimental date for Sulfa antibiotics on environmental pollution and method to treatment. The results of the study are as follows :The adsorption kinetics process of SD and SM2 can be divided into fast and slow two stages and reach adsorption equilibrium after 24 hours. Quasi-two kinetic equation is closet to the experimental results above five kinds of dynamics model. Adsorption and desorption isotherms of SD and SM2 were both well fitted by Freundlich and Langmuir thermodynamic models. The correlation coefficients were highly significant correlation(p<0.01).Thermodynamic fitting correlation coefficient suggests, the adsorption coefficient of SD and SM2 respectively between 2.4860 to 6.4032 and 3.1268 to 8.4081 under different conditions in meadow black soil. 1/n respectively between 0.5094 to 0.8418 and 0.6470 to 0.7299. Adsorption curves are “L” type. It is generally believed that 1/n is between 0.1 to 0.5 easy adsorption. So SD and SM2 are not easily adsorbed by meadow black soil. The factors analysis showed that adsorption capacity of SD and SM2 decreased along with the increase of ion valence in meadow black soil, decreased along with the increase of pH values, increased along with more and more organic matter added in meadow black soil. Desorption hysteresis coefficient(HI) of SD and SM2 are both less than 0.7 which mean a significant lag. Calculations of adsorption free energy of SD and SM2 were less than 40 KJ · mol-1. It showed that two kinds of adsorption sulfa antibiotics of physical adsorption in meadow black meadow.Using soil column leaching method to investigate the effects of different application rates, leaching solutions ang leaching solution pH on vertical migration of SD and SM2 in meadow black soil. The result showed that migration of SD and SM2 in strong in meadow black soil and the SD > SM2. The content of SD and SM2 in leaching solution decreased along with increase of application rate; increased along with increased of pH values; The amount of SD and SM2 in leaching solution is less than distilled water with Ca2+ as background. The trend of two kinds antibiotics are both fist increased and then declined under different factor conditions.