van den Hoop M A, van Leeuwen H P, Benegas J C
Department of Physical and Colloid Chemistry, Wageningen Agricultural University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands.
Biophys Chem. 1995 Mar;54(1):35-42. doi: 10.1016/0301-4622(94)00125-4.
Voltammetric speciation data for the potassium/zinc/polymethacrylate system, recently obtained for various charge densities of the polyelectrolyte (Díaz-Cruz et al., Anal. Chim. Acta, 264 (1992) 163) and for different concentrations of monovalent counterions (van den Hoop and van Leeuwen, Anal. Chim. Acta, 273 (1993) 275), are compared with theoretical predictions computed according to a new thermodynamic model developed by Paoletti et al. (Biophys. Chem., 41 (1991) 73) and recently extended by Benegas and Paoletti (in preparation). The model allows: (i) the simultaneous condensation of both monovalent and divalent counterions and (ii) can account for a certain specific affinity of the polyelectrolyte for one type of the counterion over the other. For various charge densities of the polyelectrolyte, experimentally obtained speciation data for the K/Zn/PMA system agree well with theoretical predictions by considering an extra reduced molar affinity energy of -4RT for the Zn(2+) polyelectrolyte binding. The agreement between experimental and theoretical values for the distribution of Zn(2+) ions over the free and bound state becomes less perfect for relatively high concentrations of monovalent counterions.
最近针对聚电解质的各种电荷密度（迪亚斯 - 克鲁兹等人，《分析化学学报》，264 (1992) 163）以及不同浓度的单价抗衡离子（范登霍普和范李文，《分析化学学报》，273 (1993) 275）获得的钾/锌/聚甲基丙烯酸酯体系的伏安形态数据，与根据保莱蒂等人（《生物物理化学》，41 (1991) 73）开发并由贝内加斯和保莱蒂（正在准备中）最近扩展的新热力学模型计算出的理论预测值进行了比较。该模型允许：(i) 单价和二价抗衡离子同时凝聚，以及 (ii) 能够解释聚电解质对一种抗衡离子比对另一种抗衡离子具有一定的特异性亲和力。对于聚电解质的各种电荷密度，通过考虑锌（2+）与聚电解质结合时额外的 -4RT 降低摩尔亲和能，实验获得的钾/锌/聚甲基丙烯酸甲酯体系的形态数据与理论预测值吻合良好。对于相对较高浓度的单价抗衡离子，锌（2+）离子在自由态和结合态之间分布的实验值与理论值之间的一致性变得不那么完美。
