A novel magnetic loading porous liquid absorbent for removal of Cu(II) and Pb(II) from the aqueous solution

The first example of a magnetic loading functional porous liquid (PL) by employing hollow silicon dioxide (HS) loaded with Fe3O4 as the porous guest, (3-glycidyloxypropyl) trimethoxysilane (KH560) and polyetheramine M2070 as hindered sterically solvents was demonstrated in this paper. This nanoadsorbent (Fe3O4@HS-PL) was prepared for the decontamination of aqueous solutions from Cu(II) and Pb(II) heavy metals. The hindered sterically solvents (i.e., the flexible oligomer chains) endow the Fe3O4@HS porous guest with a superior flowing behavior at ambient temperature. Various approaches were applied to confirm the morphology, structure and properties of the resultant Fe3O4@HS-PL. More significantly, the adsorption behavior of Cu(II) and Pb(II) in aqueous solution by Fe3O4@HS-PL was studied in detail. As expected, combined with the cavity structure from porous guest and amine groups from flexible organic flow layer, Fe3O4@HS-PL exhibited excellent adsorption capacities of 322.58 and 357.14 mg·g−1 for Cu(II) and Pb(II), respectively, at 298 K, pH 8 and initial concentration of 20 mg·L-1. The obtained HS and Fe3O4 in Fe3O4@HS-PL magnetic nanoadsorbent presented average particles size ascertained to be ca.200 nm and 30 nm, respectively. Moreover, the Freundlich model and pseudo-first-order model has described the adsorption process and adsorption kinetics. The parameters in thermodynamic experiment signified the spontaneity and endothermic properties of the adsorption. Moreover, magnetic loading endowed the Fe3O4@HS-PL with a superior regeneration performance. A variety of mechanisms containing coordination interaction, porous guest absorption, electrostatic interaction, steric effect and entropy are simultaneously realized in this novel adsorption system. Therefore, the introduction of PLs adsorbents into heavy metal adsorption systems through the construction of PLs materials by magnetic loading and surface amination is of great significance in the field of heavy metal adsorption, eventually starting a new time of pushing forward the development of novel adsorbents for decontamination of aqueous solutions from heavy metal ions.