Hyperbranched Polyethylenimine-Tethered Multiple Emulsion-Templated Hierarchically Macroporous Poly(acrylic acid)–Al₂O₃ Nanocomposite Beads for Water Purification

Abstract

Emulsion template-guided strategy has been used to produce porous architectures with exquisite structure, tailored morphology, and exclusive features for ubiquitous applications. Notwithstanding, the practical water remediation is often marred by their transport-limited behavior and fragility. To circumvent these conundrums, we prepared hierarchically porous poly(acrylic acid)−alumina nanocomposite beads by solidifying the droplets of emulsions jointly stabilized by the organic surfactants and alumina nanoparticles. By virtue of their positive charge, the alumina nanoparticles got entrapped within the poly(acrylic acid) scaffolds that excluded the risk of secondary contamination typically observed with conventional nanocomposites. Being amenable to surface modification, the carboxyl moieties of the beaded polymer were further exploited to covalently tether branched polyethylenimine throughout the exterior and interior surface of the porous matrix via a grafting-to approach. The macropores expedite an active fluid flow and easier adsorbate transport throughout the functionalized nanocomposites whose overall higher density of positive charge over a certain pH range electrostatically attracts and effectively adsorbs the negatively charged Cr(VI) complexes and anionic congo red ions/molecules from water. This proof-of-concept synthetic approach and postsynthetic modification offer an improved mechanical robustness to these macrosized multifunctional nanocomposite beads for their easier processing, thereby paving the way for the point-of-use water purification technology development.

Fundamentals and Design‐Led Synthesis of Emulsion‐Templated Porous Materials for Environmental Applications

“…The resultant PAA−AO−PEI beads exhibited hierarchical pores in the size range of 0.09–4.24 µm and a BET surface area of 5.42 m 2 g −1 (Figure 10g ). [ 201 ]…”

“…Reproduced with. [201] Copyright 2021, American Chemical Society. soaked a PAMPS polyHIPE in aqueous FeCl 3 solution and the swollen polyHIPE was then immersed in NaOH/NaCl solution, leading to the precipitation of Fe(OH) 3 .…”

“…The interaction of AO NPs with PAA excluded the risk of secondary contamination while the mechanical robustness of PAA-AO-PEI beads paved their way for practical applications. [201] Arsenic Ions: The word arsenic was derived from the Greek arsenikon that means bold, valiant, or potent. As is the heavy metal found everywhere in the earth's crust.…”

“…Reproduced with permission. [ 201 ] Copyright 2021, American Chemical Society. d) Schematic illustrates the plausible mechanism of arsenate adsorption by hydrated ferric oxides NPs‐embedded porous AMPS‐based polyHIPE monoliths.…”

“…g) Schematic view of the preparation of the PAA-AO-PEI (AO = alumina) NC beads. Reproduced with [201]. Copyright 2021, American Chemical Society.…”