Microscopic investigation on the adsorption of lubrication oil on microplastics

Abstract

Abstract The different size of microplastic in the environments may affect the fate and effects of traditional hydrophilic chemicals. The effect of reaction time, pH, salinity and concentration on the adsorption of lubrication oil on the 20–140 μm sized polystyrene (micro-PS) and 50 nm polyethylene (nano-PE) were presented. The adsorption kinetics and isotherms of nano-PE and micro-PS can be satisfactorily fitted by pseudo-second-order kinetic model and Langmuir, respectively. The adsorption of lubrication oil on nano-PE and micro-PS significantly increased with increasing concentration of salinity, indicating that the outer-sphere surface complexation dominated lubricating oil sorption on nano-PE and micro-PS. The maximum adsorption capacity of lubricating oil on nano-PE and micro-PS was 6.8 and 5.2 g/g at pH 5.0 and 293 K, respectively. These results are of crucial importance to the application of microplastics as the promising adsorbent in natural environments.