Hydrogen ions in interfacial processe

ROLE OF HYDROGEN IONS IN THE INTERFACIAL AND DISSOLUTION PROCESSES OF MONTMORILLONITE... 

A simple and effective way of incorporating such a cation-exchange material into the interfacial region would be to apply it to the metal surface as a final pretreatment process. This way the released hydrogen ions would be present in the immediate vicinity of the hydroxide ion generation sites. Therefore, the hydroxide ions could be promptly neutralized and the hydrolysis of the epoxy coating by strong alkali minimized 91>. 

The other interfacial process involving hydrogen ion is the cation-exchange process in the interlayer space. When montmorillonite is suspended in water or in an electrolyte solution, a part of exchangeable cations can be dissolved. In Table 2.7, the relative quantity of calcium ions dissolved in water or in acidic solutions is shown. 

The dipolar relaxation (TSDC) is observed at temperatures (90 molecular mobility causing the dc relaxation (TSDC) appears at higher temperatures (T> 210-230 K) than FMM (NMR) and both processes depend (but differently) on the confined space effects. These results are due to the influence of surface electrostatic fields on the structure of the hydrogen bond network in interfacial water (i.e., the average number of these bonds per molecule and their strength and geometry) and due to additional conditions necessary for the dc relaxation (ion percolation) in comparison with the FMM. An increase in the content of an adsorbent (and, therefore, contribution of interfacial... 

Proposed intermediates in the above reaction include atomic hydrogen [27, 28], hydride ions [29, 30], metal hydroxides [31], metaphosphites [32, 33], and excitons [34]. In general, the postulated mechanisms are not supported by direct independent evidence for these intermediates. Some authors [35] maintain that the mechanism is entirely electrochemical (i.e. it is controlled by electron transfer across the metal-electrolyte interface), but others [26] advocate a process involving a surface-catalyzed redox reaction without interfacial electron transfer. 

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