Study Of Adsorption Of Tetracycline On Soils Affected By Phosphate

Adsorption of P and Tetracycline(TC;H₃L) on soils(minerals) were studied and their sorption mechanisms were explored.The main results are summarized as following:1) TC adsorption on the Wushan soil(WS),Red soil(RS),γ-Al₂O₃ increased with the increasing TC concentration in the equilibrium solution.Adsorption quantity of TC on the RS was higher than that on the WS.Freundlich equation simulated the adsorption isotherms of TC on the soils well.Adsorption of TC on the soils and minerals was significantly affected by equilibrium solution pH.2) The presence of phosphate decreased the adsorption of TC on the soils significantly, which can be ascribed to the increase of negative charges of soils and the competition of phosphate,onγ-Al₂O₃,When the concentration of tetracycline was low,all the tetracycline were adsorbed on the surface ofγ-Al₂O₃,phosphate did not affect its adsorption,but when the concentration of tetracycline was high,the presence of phosphate increased the adsorption of tetracycline onγ-Al₂O₃.3) On the RS,The presence of phosphate increased the adsorption of TC on the RS when the pH was below 4,while decreased at pH＞4.But on the WS,the presence of phosphate did not significantly affect the adsorption of TC when the pH was belowe6;while pH was above 6, the presence of phosphate slightly decreased the adsorption of TC,which may be ascribed to the increase of electrostatic repulsion when phosphate was added to the soil solution.The presence of phosphate decreased the adsorption of TC onγ-Al₂O₃ when the pH was below 4 and above 7,while at 4＜pH＜7,the presence of phosphate increased the adsorption quantity of TC.We studied the impact of the adsorption of tetracycline affecting zeta potentials of equilibrium solution,andγ-Al₂O₃ by infrared spectral analysis,found that phosphorus is by changing the electrostatic to affect adsorption of tetracycline.4) Different Fertilization system can affect the adsorption of tetracycline on the soil. Studies have shown that organic matter can restrict organic pollutants in the soil of the migration,transformation,degradation and other chemical and biological processes,can promote the adsorption of pollutants on the soil.