Phytic acid-engineered TiO₂/cellulose composite hydrogels featuring multidentate phosphate sites for efficient...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Polysaccharide hydrogels face challenges in stability and functional site organization for metal recovery.
• Competitive aqueous environments further limit the efficiency of existing materials.

Purpose of the Study:

• To develop a stable and spatially organized composite hydrogel for selective metal ion capture.
• To engineer robust, accessible, and well-dispersed binding sites within a polysaccharide scaffold.

Main Methods:

• In situ embedding of phytic acid-modified TiO2 hybrid nanoparticles into a carboxymethyl cellulose/poly(acrylic acid) network.
• Characterization using spectroscopic analyses and density functional theory (DFT) calculations.
• Evaluation of adsorption capacity, selectivity, and reusability for metal ions.

Main Results:

• The composite hydrogel (CAPT-gel) exhibits high adsorption capacities for Cu(II) (223.25 mg/g) and La(III) (313.52 mg/g).
• CAPT-gel shows pronounced selectivity for La(III) in coexisting-ion systems and maintains over 80% capacity after five cycles.
• Adsorption mechanisms involve multidentate phosphate coordination, electrostatic effects, and surface complexation facilitated by interconnected transport pathways.

Conclusions:

• The inorganic-anchored site-engineering strategy successfully created phosphate-rich binding environments in cellulose-based hydrogels.
• CAPT-gel offers a green and effective route for selective heavy-metal and rare-earth ion recovery.
• This approach expands the application of polysaccharide-derived materials in environmental remediation and resource recycling.