Phosphate uptake studies of cross-linked chitosan bead materials.
A systematic experimental study is reported that provides a molecular based understanding of cross-linked chitosan beads and their adsorption properties in aqueous solution containing phosphate dianion (HPO42-) species. Synthetically modified chitosan using epichlorohydrin and glutaraldehyde cross-linkers result in surface modified beads with variable hydrophile-lipophile character and tunable HPO42-uptake properties. The kinetic and thermodynamic adsorption properties of cross-linked chitosan beads with HPO42-species were studied in aqueous solution. Complementary structure and physicochemical characterization of chitosan beads via potentiometry, Raman spectroscopy, DSC, and dye adsorption measurements was carried out to establish structure-property relationships. The maximum uptake (Qm) of bead systems with HPO42-at equilibrium was 52.1mgg-1; whereas, kinetic uptake results for chitosan bead/phosphate systems are relatively rapid (0.111-0.113min-1) with an intraparticle diffusion rate-limiting step. The adsorption process follows a multi-step pathway involving inner- and outer-sphere complexes with significant changes in hydration. Phosphate uptake strongly depends on the composition and type of cross-linker used for preparation of chitosan beads. The adsorption isotherms and structural characterization of bead systems illustrate the role of surface charge, hydrophile-lipophile balance, adsorption site accessibility, and hydration properties of the chitosan bead surface.
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada.
Mohammad H
MH
Mahaninia
Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada. Electronic address: lee.wilson@usask.ca.
Lee D
LD
Wilson
D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004058:Diffusion; D004811:Epichlorohydrin / Q000737:chemistry*; D005976:Glutaral / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D010710:Phosphates / Q000302:isolation & purification*; D055672:Static Electricity; D013329:Structure-Activity Relationship; D013816:Thermodynamics; D062065:Wastewater / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods
D048271:Chitosan; D003432:Cross-Linking Reagents; D004811:Epichlorohydrin; D005976:Glutaral; D010710:Phosphates; D062065:Wastewater; D014874:Water Pollutants, Chemical
Adsorption; Chitosan beads; Cross-linking; Hydration processes; Phosphate dianion