Adsorption Characteristics and Influencing Factors of Oxy tetracycline in Red Soil
In this study,the adsorption ability and mechanism of oxytetracycline in red soil were investigated using the batch equilibrium method and ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-MS/MS).Oxytetracycline(OTC),a commonly used veterinary antibiotic,was chosen as the target pollutant.The silty red soil collected from Yichun pig farm in Jiangxi Province was used to study the adsorp-tion-desorption characteristics and influencing factors of OTC in red soil.The results revealed that the adsorption of OTC in the red soil occurred rapidly reaching equilibrium in approximately 6 hours.The pseudo-first-order kinetic model only adequately described the adsorption process within the first hour,while the pseudo-second-order kinetic model provided a much better fit for the entire adsorption process.The desorption process exhibited significant hysteresis.The Freundlich model proved more effective in representing the isothermal adsorption process of OTC in the tested soil.Additionally,the adsorption amount of OTC on the tested soil exhibited a negative correlation with pH.Among coexisting cations,the adsorption capacity decreased gradually with increasing ionic strength,and cations with higher valence state with larger ionic radius showed stronger adsorption inhibition.Among the coexisting anions,only HCO3-was found to affect the adsorption and this effect was pH dependent.This study demonstrates that oxytetracycline residues in red soil can lead to persistent and significant environmental pollution,posing a high degree of soil contamination.
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