Application of two modified kaolin materials in removing micro-plastics from water

Abstract

Some modified kaolin materials have the potential as adsorbents for the removal of numerous pollutants. In view of this, we developed two modified kaolin named Fe–kaolin and Co/Mn–kaolin, respectively, and studied the adsorption properties and mechanism of two materials for micro-plastics. The results showed that the adsorption of micro-plastics on these two modified kaolin materials reached equilibrium basically after 72 h. The adsorption capacity of Co/Mn–kaolin for micro-plastics was about 22.00 mg·g⁻¹ while the adsorption capacity of Fe–kaolin for micro-plastics was about 13.68 mg·g⁻¹. The adsorption of micro-plastics by these two adsorbents may follow the pseudo-first-order kinetic model and the Freundlich isotherm model. The adsorption behavior of micro-plastics on Co/Mn–kaolin was an exothermic adsorption process while the adsorption behavior of micro-plastics on Fe–kaolin was an endothermic adsorption process. This work provides two low-cost, environmentally friendly and reusable adsorbents for the extraction of multiple micro-plastics in water simultaneously, which means that these two modified kaolin materials have the application chance of the lab-scale experiments. Besides, this work provides another new idea for the recycling and reuse of kaolin tailings and some heavy metal ions in the environment, which is very beneficial to the comprehensive treatment of the environment.