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磺胺嘧啶在土壤及土壤组分中的吸附/解吸动力学
张步迪, 林 青, 曹东平, 徐绍辉
青岛大学环境科学与工程学院
摘要:
抗生素在土壤中的吸附/解吸及迁移过程受其理化性质的强烈影响,其中土壤中的矿物成分,如高岭石、蒙脱石及腐殖酸等是重要控制因素。本文主要研究了磺胺嘧啶在土壤、高岭石、蒙脱石和腐殖酸中的吸附/解吸动力学过程,并对反应前后的高岭石、蒙脱石和腐殖酸进行傅里叶红外光谱(Fourier transform infrared, FTIR)表征,探讨其可能的吸附机理。结果表明:磺胺嘧啶的吸附(解吸)动力学过程,可以分为快速吸附(解吸)、吸附解吸动态平衡和吸附(解吸)平衡3个阶段;磺胺嘧啶在土壤及其3种组分中的吸附(解吸)均可在24 h内达到平衡,其浓度高低会导致土壤及其组分的吸附差异,不同土壤组分中的官能团含量、带电性质及氢键是造成吸附差异的主要原因;分别用伪一级动力学模型、伪二级动力学模型和Elovich模型对其吸附过程进行拟合,其动力学吸附过程更符合伪二级动力学模型,R2>0.99,主要受控于物理化学吸附;FTIR图谱表明磺胺嘧啶与高岭石以物理吸附为主,并有少量氢键作用,与蒙脱石之间主要以氢键作用完成吸附,而在腐殖酸中存在表面络合和π–π共轭作用。
关键词:  磺胺嘧啶  吸附解吸  动力学  土壤组分
DOI:10.13758/j.cnki.tr.2018.05.014
分类号:X53
基金项目:山东省自然科学基金青年基金项目(ZR2014DQ021)资助。
Sorption and Desorption of Sulfadiazine by Soil and Its Components
ZHANG Budi, LIN Qing, CAO Dongping, XU Shaohui
College of Environment Science & Engineering, Qingdao University
Abstract:
The adsorption, desorption and migration of antibiotics in soil are seriously affected by soil physical and chemical properties. Soil humic acid and mineral components, such as kaolinite and montmorillonite, are important controlling factors. This paper mainly studied on adsorption and desorption kinetics of sulfadiazine (SDZ) onto soil, kaolinite, montmorillonite and humic acid. Fourier Transform Infrared Spectroscopy (FTIR) was utilized to investigate the changes of kaolinite, montmorillonite and humic acid before and after adsorption, and adsorption mechanism was explained. The results showed that adsorption (desorption) kinetics of SDZ could be divided into three stages: fast adsorption (desorption) stage, dynamic equilibrium of sorption and desorption stage and adsorption (desorption) equilibrium stage. The extent of adsorption (desorption) was determined at the end of 24 hours of adsorption (desorption) period in soil and its three components. SDZ concentration affected adsorption difference of soil and its components. Functional group content, electric property and hydrogen bond are the main causes of differences in adsorption. The pseudo-first-order kinetics model, pseudo-second-order kinetics model and Elovich model were used to fit the adsorption process. It was found that pseudo-second-order mechanism is predominant and the overall rate of SDZ adsorption process appears to be controlled by physical and chemical adsorption. FTIR hinted that SDZ was adsorbed by kaolinite mainly consists of physical adsorption with somewhat H-bonding. Montmorillonite adsorbed SDZ mainly by hydrogen bonding. Surface complexation and π-π EDA might be important factors in the sorption of SDZ with humic acid.
Key words:  Sulfadiazine  Sorption and desorption  Kinetics  Soil components

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