Commercial resin microbeads are widely applied in ion exchange and extraction. Here, a single anion-selective and phosphate binding resin microbead (FerrIX™) is mounted into an epoxy membrane and investigated by 4-electrode membrane voltammetry and membrane impedance spectroscopy. Anion transport properties are observed to dominate associated with three distinct potential domains: (I) a low bias ohmic potential domain (dominant at high electrolyte concentration), (II) a concentration polarisation potential domain, and (III) an over-limiting potential domain. Voltammetric responses show transient diffusion-migration features at higher scan rates and quasi-steady state features at lower scan rates. Inherent microbead conductivity is shown to be linked to two resistive elements, electrolyte concentration dependent and independent, in series. The effects of phosphate binding are revealed as transient pattern in impedance spectroscopy data. Preliminary data suggest phosphate concentration-dependent peak features in the imaginary impedance versus frequency plot due to phosphate binding into the microbead.

Graphical abstract

中文翻译：

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使用安装在环氧树脂膜中的单个磷酸盐结合树脂 (FerrIX™) 微珠进行电分析

商业树脂微珠广泛应用于离子交换和萃取。在这里，将单个阴离子选择性和磷酸盐结合树脂微珠 (FerrIX™) 安装到环氧树脂膜中，并通过 4 电极膜伏安法和膜阻抗谱进行研究。观察到阴离子传输特性与三个不同的电位域相关联：（I）低偏置欧姆电位域（在高电解质浓度下占主导地位），（II）浓差极化电位域，以及（III）超限电位域. 伏安响应在较高扫描速率下显示瞬态扩散迁移特征，在较低扫描速率下显示准稳态特征。固有的微珠电导率显示与两个串联的电阻元件有关，电解质浓度依赖和独立。磷酸盐结合的影响显示为阻抗谱数据中的瞬态模式。初步数据表明，由于磷酸盐结合到微珠中，假想阻抗与频率图中的磷酸盐浓度依赖性峰值特征。

图形概要