Effects of porous guest sizes of magnetic porous liquids on lead ion adsorption from the aqueous solution

Abstract

This study synthesized magnetic-loaded nanomaterials using three different sizes of porous guests (165 nm, 200 nm, and 310 nm), subsequently converting them into porous liquids (PLs) using polyetheramine M2070 and (3-glycidoxypropyl) trimethoxysilane (KH560) as a steric hindrance solvent. M2070 imparted excellent fluidity to the PLs at room temperature, which were employed in the extraction of Pb(II) ions from wastewater. The physicochemical properties of the adsorbents were characterized using SEM, TEM, FTIR, XPS, BET, and TGA analyses. The adsorption behavior of PLs with different guest sizes for Pb(II) was studied and compared. The adsorption capacities (Qe) of Fe3O4@HS(165nm)-M2070, Fe3O4@HS(200nm)-M2070, and Fe3O4@HS(310nm)-M2070 for Pb(II) were 160.12, 211.47, and 173.10 mg·g-1, respectively. This confirms that the guest size is essential in influencing the adsorption performance. All three adsorption materials were found to better fit the pseudo-first-order kinetic model and the Freundlich isotherm model, indicating that physisorption and multilayer adsorption are the prevailing mechanisms, with the process tending toward heterogeneous multilayer adsorption. Thermodynamic analysis further revealed the spontaneous and endothermic characteristics of the adsorption process, highlighting the thermodynamic feasibility and effectiveness of these materials for the removal of Pb(II). Additionally, the adsorbents exhibited a rich mesoporous structure, abundant surface functional groups, and excellent recyclability, all contributing to the effective elimination of Pb(II) ions from wastewater. Overall, this study elucidates the intrinsic correlation between porous guest size and Pb(II) adsorption efficiency, offering valuable insights for preparation of high-performance magnetic PL adsorbents. It also facilitates the practical utilization of PLs for heavy metal pollution remediation.