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

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.