Adsorption Behavior of Sulfadiazine on Black Soil and Its Different Particle Sizes

The adsorption of sulfadiazine on the black soil and its different particle sizes was tested by batch equilibrium experiments.The results showed that the adsorption data were well fitted for the Freundlich and Langmuir model,but deviated different degrees from the linear model.The Freundlich model parameter Kf values of the bulk soil(0.2 mm) and different particle sizes(clay:0.002 mm,fine:0.002~0.02 mm,sand:0.02~0.2 mm) were 29.6,53.1,32.9 L·kg-1 and 21.6 L·kg-1,respectively,which showed that there was some difference in the sorption behaviors of sulfadiazine in different soil sizes.After treated with organic carbon normalized equation on the Kf,the resulting Koc values showed some consistentance except for the silt particle.With the increase of the solution pH(1.0~10.0),the lgKf values of sulfadiazine presented a trend that greatly decreased and then slightly increased.It could be deduced that the cation exchange might be the predominant sorption mechanism of sulfadiazine on the tested soils.After dealt with H2O2,the Kd value of the bulk soil decreased from 1.92 L·kg-1 to 1.22 L·kg-1,and the sorption amount of sulfadiazine decreased from 16.5 mg·kg-1 to 11.2 mg·kg-1.It suggested that organic matter amount was also an important factor which affected the sorption of sulfadiazine on soils.