Preparation and performance study of recyclable microsphere soil conditioner based on magnetic metal organic framework structure

Abstract

The soil environment affects agroecology and the soil environment; however, there are no reports on recyclable, waste-free soil conditioners that can both improve fertilizer utilization and remove soil contaminants. In the present work, a magnetic metal-organic framework material, Fe3O4 @ZnO@ZIF-8, with porous structure, was hydrothermally prepared. Fe3O4 @ZnO@ZIF-8 exhibited high loading and slow release performance under different pH conditions for a soil conditioner fulvic acid (FA), and showed high adsorption capacity for pollutants such as heavy metal ions and organic dyes. The slow release process can be described by the Ritger-Peppas models. Adsorption thermodynamic parameters displayed that the adsorption was an exothermic, spontaneous and more ordered arrangement process. The kinetic model and isothermal adsorption model can be described by the pseudo-second-order kinetic and Langmuir adsorption model, respectively. The organic dyes were physically adsorbed on the adsorbent surface of the magnetic microspheres through the synergistic effect of strong electrostatic attraction, hydrogen bonding and π⋯π stacking interactions. In addition, Fe3O4 @ZnO@ZIF-8 absorber exhibited good recyclability, and was reused three times by simple cleaning with less impact on its retardation and adsorption efficiency. Thus, Fe3O4 @ZnO@ZIF-8 is an effective substance for improving the physicochemical properties of soil.