Abstract The aim of this paper is to enhance the knowledge on the behaviour and thermodynamic properties of natural and synthetic biopolymers in aqueous solutions. The acid-base properties of Carrageenan (Car), Xanthan gum (XG), Hydroxyethyl cellulose (HEC), Carboxymethyl cellulose (CMC), Acusol 445™ (Sol), Monopropylene glycol (MPG) and Polyethylene glycol (PEG) have been studied by potentiometric technique in NaNO3(aq), at I = 0.15 mol dm−3 and T = 298.15 K. In some cases, the protonation constants have been determined at different ionic strengths, and the dependence on ionic strength has been modelled by a Debye-Huckel type equation. The binding ability of the different polymers has been investigated towards Ca2+, Zn2+ and Sn2+ and, different speciation models have been obtained. For Acusol 445™, the weak interactions with Na+ and K+ have been determined. The effect on the complexing ability of a secondary inorganic ligand, the fluoride, has been evaluated on Carboxymethyl cellulose and Acusol systems; the formation of ternary mixed complexes with a significant increasing stability with respect the binary species has been obtained. The sequestering ability of the polymers towards the metal cations has been evaluated by means the empirical parameter pL0.5.

中文翻译：

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作为资源的自然。天然和合成聚合物的热力学表征及其对某些二价金属阳离子的螯合能力

摘要 本文的目的是增强对天然和合成生物聚合物在水溶液中的行为和热力学性质的认识。研究了角叉菜胶 (Car)、黄原胶 (XG)、羟乙基纤维素 (HEC)、羧甲基纤维素 (CMC)、Acusol 445™ (Sol)、单丙二醇 (MPG) 和聚乙二醇 (PEG) 的酸碱特性通过 NaNO3(aq) 中的电位技术，在 I = 0.15 mol dm-3 和 T = 298.15 K。在某些情况下，质子化常数已在不同离子强度下确定，并且对离子强度的依赖性已由 Debye 建模- 休克尔类型方程。研究了不同聚合物对 Ca2+、Zn2+ 和 Sn2+ 的结合能力，并获得了不同的形态模型。对于 Acusol 445™，已确定与 Na+ 和 K+ 的弱相互作用。已在羧甲基纤维素和 Acusol 系统上评估了对二级无机配体氟化物络合能力的影响；已经获得了关于二元物种稳定性显着增加的三元混合复合物的形成。聚合物对金属阳离子的螯合能力已通过经验参数 pL0.5 进行评估。