Piasecki Wojciech, Lament Karolina
Department of Physical Education and Health, Józef Piłsudski University of Physical Education in Warsaw, Akademicka 2, 21-500 Biała Podlaska, Poland.
Molecules. 2024 Jan 23;29(3):0. doi: 10.3390/molecules29030555.
The adsorption of divalent ions on metal oxides is controlled by the pH of a solution. It is commonly assumed that this is a reversible process for pH changes. However, there are reports that the sorption of ions on oxides may not be reversible. To verify this, we used potentiometric titration, ion-selective electrodes (ISEs), and electrokinetic measurements to examine the reversibility of the adsorption of hydrogen ions and three metal ions (Ca, Cu, and Fe) on TiO. The ferrous ion was used as a reference because its adsorption is entirely irreversible. The surface charge determined by potentiometric titration and the adsorption edges measured using ISE indicate that the adsorption of copper ions is reversible with changes in pH. In the case of calcium ions, the results suggest a certain degree of irreversibility. There are apparent differences in the electrokinetic potential data obtained during titration with base and acid, which suggests that the adsorption is irreversible. We have explained this contradiction by considering the complex and dynamic nature of electrophoretic mobility. In our opinion, potentiometric titration may be the simplest and most reliable method for assessing the reversibility of multivalent ion adsorption.
二价离子在金属氧化物上的吸附受溶液pH值控制。通常认为，对于pH变化而言，这是一个可逆过程。然而，有报道称离子在氧化物上的吸附可能不可逆。为了验证这一点，我们使用电位滴定法、离子选择性电极（ISE）和电动测量法来研究氢离子和三种金属离子（Ca、Cu和Fe）在TiO上吸附的可逆性。亚铁离子用作参考，因为其吸附完全不可逆。通过电位滴定确定的表面电荷以及使用ISE测量的吸附边界表明，铜离子的吸附随pH变化是可逆的。对于钙离子，结果表明存在一定程度的不可逆性。在用碱和酸滴定过程中获得的电动电位数据存在明显差异，这表明吸附是不可逆的。我们通过考虑电泳迁移率的复杂和动态性质来解释这种矛盾。我们认为，电位滴定可能是评估多价离子吸附可逆性的最简单、最可靠的方法。
