Phosphate uptake studies of cross-linked chitosan bead materials

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• 作者：Mohammad H. Mahaninia ; Lee D. Wilson ; ^{lee.wilson@usask.ca" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Chitosan beads ; Cross-linking ; Phosphate dianion ; Adsorption ; Hydration processes
• 刊名：Journal of Colloid and Interface Science
• 出版年：2017
• 出版时间：1 January 2017
• 年：2017
• 卷：485
• 期：Complete
• 页码：201-212
• 全文大小：2637 K

文摘

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 (Q_m) of bead systems with HPO₄²⁻ at equilibrium was 52.1 mg g⁻¹; whereas, kinetic uptake results for chitosan bead/phosphate systems are relatively rapid (0.111–0.113 min⁻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.