title: Ion-imprinted chitosan gel beads for selective adsorption of Ag⁺ from aqueous solutions.
abstract: In this study, the Ag(+)-imprinted chitosan gel beads were synthesized to selectively adsorb Ag(+) from bimetallic aqueous solutions containing the same molar concentration of Ag(+) and Cu(2+). The Ag(+)-imprinting not only helps to achieve extremely high selectivity of Ag(+), but also enhances the uptake capacity of the target Ag(+) by protecting some amine groups, the primary binding sites of metal ions from cross-linking. The maximum uptake of Ag(+) by the ion-imprinted chitosan beads was found to be 89.20 mg g(-1) at 25.0°C with an initial Ag(+) concentration of 352.95 mg L(-1) and the biosorbent dosage of 1.0 g L(-1). The adsorption equilibrium and kinetics of Ag(+) by the ion-imprinted chitosan beads can be better described by Langmuir isotherm and the intraparticle diffusion model. FTIR and XPS analyses suggested that amine functional groups involve the binding of Ag(+) via complexation at higher solution pH (3.0 ≤ pH ≤ 5.0) and ion exchange at lower solution pH (1.0 ≤ pH < 3.0).
authors.affiliation: Department of Process Engineering, Memorial University of Newfoundland, St. John's, NF, Canada.
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Memorial University of Newfoundland, St. John's, NF, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Helleur
authors.affiliation: Department of Process Engineering, Memorial University of Newfoundland, St. John's, NF, Canada. Electronic address: yanz@mun.ca.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D048271:Chitosan / Q000737:chemistry*; D003300:Copper / Q000302:isolation & purification*; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D008962:Models, Theoretical; D012834:Silver / Q000302:isolation & purification*; D012996:Solutions; D018508:Water Purification / Q000379:methods*
chemical_list: D007477:Ions; D012996:Solutions; D012834:Silver; D003300:Copper; D048271:Chitosan
keywords: Chitosan; Cross-linking; Ion-imprinting; Selective adsorption; Silver