Thermodynamically stable colloidal system temperature

A definite prediction of DLVO theory is that charge-stabilized colloids can only be kinetically, as opposed to thermodynamically, stable. The theory does not mean anything at all if we cannot identify the crystalline clay state (d 20 A) with the primary minimum and the clay gel state (d 100 to 1000 A) with the secondary minimum in a well-defined model experimental system. We were therefore amazed to discover a reversible phase transition of clear thermodynamic character in the n-butylammonium vermiculite system, both with respect to temperature T and pressure P. These results rock the foundations of colloid science to their roots and... 

As emphasized earlier, similarity in the composition of contacting phases in the vicinity of the critical temperature leads to a decrease in the interfacial tension to very small values, at which the spontaneous formation of thermodynamically stable liophilic colloidal systems is possible (see Chapter VI). 

Redox potentials for various different Feu/Fem couples are shown in Table 3 and although [Fe(OH)2] is thermodynamically capable of reducing water to hydrogen and does so at elevated temperatures,39 the rate of the reaction is low. It can, however, be increased by the addition of suitable catalysts, eg. Ni salts,39,40 excess [FeSOJ,40 metals such as Ni,40 Cu,40 Pd,18,41 or colloidal Pt.40 Nevertheless, cyclic water cleavage based on this system is unlikely since [Fe(OH)3] is a. highly stable material. 

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