Biopolymer-Coated Magnetite Nanoparticles and Metal–Organic Framework Ternary Composites for Cooperative Pb(II) Adsorption

Abstract

The imperfection instability, recyclability, and separation factors of metal−organic frameworks (MOFs) limit their practical applications in the field of catalysis and water purification. Designing MOFs that are benign, flexible, and separable is still a critical challenge. Up to now, most of MOFs have been coated with conventional synthetic polymers, which are undegradable and carcinogenic. However, no studies have reported the stepwise growth of biocompatible polymer-capped Fe 3 O 4 (PFe 3 O 4 ) nanoparticles (NPs) onto the NH 2 -MIL-125 (Ti) surface (ternary composite). In this study, a simple stepwise embedding of PFe 3 O 4 NPs onto NH 2 -MIL-125 (Ti) was successfully employed and used for efficient aquatic scavenging, which can allow synergetic cooperative adsorption with functionality on both the biopolymer and MOF surface. The obtained transmission electron microscopy (TEM) and high-resolution TEM images illustrate that the PFe 3 O 4 NPs were uniformly embedded onto the surface of the MOF. The composite was employed for the quick and significant removal of Pb(II) from aqueous solution. The effects of various parameters like the pH, contact time, initial metal-ion concentration, interfering ions, and temperature on the adsorption capacity of the nanoporous composite were examined. The Langmuir model presented the best fitting with a maximum adsorption capacity of 561.7 mg g −1 at pH 5 and 298 K. Moreover, increasing the PFe 3 O 4 precursor on nanoporous NH 2 -MIL-125 (Ti) decreased the recovery time (21 s) and enhanced the adsorption process because the same MOF can be recycled six times without obvious loss of the adsorption capacity of Pb(II) in water. Therefore, we can finally conclude that, due to the coating of Fe 3 O 4 with a biopolymer, the composite showed not only highly efficiency in metal-ion adsorption but also high stability for recycling of the material, which is significant for its future practical use in the treatment of industrial waste discharge.

A Three-Dimensional Porous Organic Framework for Highly Selective Capture of Mercury and Copper Ions

“…The peaks for nitrogen-containing functional groups shift toward lower binding energies after adsorbing Hg(II)/Cu(II) ions, reflecting the binding force between the two ions and nitrogencontaining groups. 41 3.3. Adsorption Selectivity.…”

“…The N 1s high-resolution XPS spectra of POFct-1 before and after adsorbing Hg­(II) and Cu­(II) ions are shown in Figure f. The peaks for nitrogen-containing functional groups shift toward lower binding energies after adsorbing Hg­(II)/Cu­(II) ions, reflecting the binding force between the two ions and nitrogen-containing groups …”

Design Considerations for Next‐Generation Polymer Sorbents: From Polymer Chemistry to Device Configurations

“…Likewise, coordinating bonds have been formed to adsorb Hg(II) (e.g., coordinating sulfur and triazole moieties), [104][105][106][107] and form chelating bonds with Pb(II) (chelating bonds between lead and amine, hydroxyl or sulfur groups). [108][109][110] These case studies exemplify how the weaker adsorptive interactions (e.g., ion exchange) can be overcome through the synergistic interplay between multiple moieties, an effect that relies on analytes possessing multiple complexation modes (e.g., heavy metals form up to six coordination bonds and organic molecules may interact through hydrogen bonding and molecular orbital interactions). [111][112][113][114][115][116] In turn, nanoscale manipulations that position moieties adjacent to one another can tailor the kinetics [10] and strength [117] of solute-ligand interactions.…”

Magnetically Recyclable Wool Keratin Modified Magnetite Powders for Efficient Removal of Cu2+ Ions from Aqueous Solutions

“…The typical nanomaterial sorbents with magnetic features have been widely studied for the removal of heavy metal species because they have high surface area and are easy to separate from aqueous solutions by applying external magnetic fields [18]. Recently, many magnetite (Fe 3 O 4 ) based adsorbents have been developed by incorporation of chitosan [19], chitosan and calcium alginate [20], chitosan and polyether sulfone [21], polyacrylamidoxime [22], asparagine [23], polyethylenimine [24], ethylenediamine coupled with graphene oxide and chitosan-g-poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid) copolymer [25], TiO 2 and graphene [26], graphene oxide [27], amino acid and graphene oxide [28], carbon [29], polydopamine or polyamidoamine [30], NH 2 -MIL-125 (Ti) [31], organodisulfide [32], curcumin [33], alginate [34], zeolite and cellulose nanofibers [35], and selective adsorbents ethylene diamine tetraacetic acid [36] and N-(trimethoxysilylpropyl) ethylenediamine triacetic acid [37]. For example, the catechol groups of dopamine can integrate with metal ions and increase the hydrophilic ability of asprepared adsorbents [38].…”