Research On Adsorption Behavior Of Sulfonamides And Copper In Soils And Impact Of Factors On Their Adsorption

With the booming of intensive livestock and the development of industry and agriculture, there has been an increase concentration of antibiotics in soil. This has gradually posed a threat on the ecological environment and human health. Sorption of contaminants in soil and sediment will influence their migration, degradation and bioavailability in the environment. Research on the sorption behavior of antibiotics and its sorption behavior with heavy metal has important scientific value and practical significance for the ecological risk prediction of these pollutants, evaluation of soil quality and remediation of the contaminated soil.In this dissertation, research on the sorption behavior of antibiotics and heavy metal in two soils with different physicochemical properties and their main mineral components was conducted, and the main influence factors on sorption of sulfadiazine were studied. Interactions of sorption between antibiotics (sulfadiazine) and the typical heavy metal (copper) in soils and their main mineral components (montmorillonite and kaolinite) were also investigated. The main results are summarized as following:1. The sorption experiments of sulfadiazine in black soil and red soil were conducted using batch equilibrium methods. Results showed that the sorption isotherms of sulfadiazine in black soil and red soil could be well described by the Freundlich model, correlation coefficient R2>0.997, the values of 1/n were less than 1, which illustrated that the sorption of sulfadiazine in these two kinds of soil were non-linear adsorption. Sorption capacity of sulfadiazine in black soil and red soil increased with the increase of the temperature, which showed that low temperature was against the sorption of sulfadiazine. The value of Gibbs free energy function change was less than 40 kJ·mol^-1, which showed that the sorption of sulfadiazine in black soil and red soil all belong to physical adsorption.2. With the increase of equilibrium concentration, the sorption amount of sulfadiazine in black soil and its different particle size component increased. With the decrease of the particle size, organic matter content of component increased, accordingly, the sorption amount of sulfadiazine also increased. It could be inferred that the content of soil organic matter was the main influence on the sorption of sulfadiazine in black soil and its different particle size component.3. Under the tested pH values, with the increase of pH, the sorption capacity of sulfadiazine decreased firstly and then increased slightly. This was mainly because sulfadiazine showed different existing form under different pH. With the increase of concentration of cations (Na⁺,Ca²⁺) in solution, the equilibrium sorption amount of sulfadiazine in black soil and red soil increased. The existence of Ca²⁺ in solution reduced the sorption capacity of sulfadiazine, but increased the sorption capacity of sulfadiazine.4. The sorption ability of the black soil treated with H2O2 decreased greatly, which clearly suggested that organic matter was the dominant factor affecting the sorption of sulfadiazine in soil. High-temperature incineration can remove soil organic matter, it can also change the physical structure of soil inorganic mineral, which can affect the sorption of sulfadiazine.5. The existence of sulfadiazine significantly increased the sorption capacity of Cu²⁺ in black soil, red soil and montmorillonite, but decreased the sorption capacity of Cu²⁺ in kaolinite. The existence of Cu²⁺ increased the sorption capacity of sulfadiazine in black soil, montmorillonite and kaolinite, but reduced the sorption capacity of sulfadiazine in red soil and humic acid.