聚苯乙烯微塑料对土壤吸附泰乐菌素的影响过程和机制

    Effect of Polystyrene Micro-particles on Sorption Behaviors of Tylosin onto Typical Chinese Farmland Soils

    • 摘要: 以聚苯乙烯(PS)微粒和泰乐菌素(TYL)为研究对象,选取我国不同地区、不同性质农田土壤,通过吸附动力学和热力学试验研究微塑料添加对土壤吸附TYL的影响。结果表明,添加PS条件下4种土壤吸附TYL的能力显著提高,其中,PS对黏质土壤吸附TYL能力的提高作用大于壤土;土壤中w=1%的PS没有明显改变4种土壤对TYL的吸附过程,吸附过程能较好地用准二级动力学模型(R2>0.97)拟合,通过颗粒内扩散模型判断原土壤和含PS土壤对TYL的吸附过程分为外部扩散、颗粒内扩散和吸附平衡3个阶段。土壤对TYL的吸附等温线可以用Freundlich和Langmuir方程进行较好的拟合(R2>0.97)。添加PS后土壤吸附TYL的能力随pH值和离子强度的增加均有一定程度减弱,且达到显著性差异,其吸附机制为以疏水作用和静电作用为主导的多相吸附。

       

      Abstract: Taking polystyrene micro-particles (PS) and tylosin (TYL) as experimental objects, the effect of the application of PS on adsorption kinetics and thermodynamics characteristics of TYL onto four typical Chinese farmland soils with different physicochemical properties was studied. The results show that PS could enhance the adsorption capacity of those four soils towards TYL. The enhancement was more significant on clay soils than that on loam soils. Soils added with 1% PS had little impact on the adsorption process of TYL, which could be well fitted with the pseudo-second-order kinetic model (R2>0.97). The sorption process was divided into three stages as external diffusion, intra-particle diffusion and adsorption equilibrium according to the intraparticle diffusion model. The adsorption isotherm was close to the Freundlich or Langmuir model (R2>0.97). The adsorption capacity of TYL onto soil with PS was apparently weakened along with the increase of pH or ionic strength. The adsorption was a multiphase process with hydrophobic and electrostatic interactions playing the dominant roles.

       

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