This work studied the determination of the hydrogen fugacity during electrolytic charging. With a virgin surface, there were irregular permeation transients, attributed to irreproducible surface conditions. Cathodic pre-charging conditioned the entry side to a stable state. Permeability transients were used to measure the critical parameters in the thermodynamic relationship between hydrogen activity and electrochemical potential. At the same overpotenial, the hydrogen fugacity in the pH 12.6 0.1 M NaOH solution was higher than that in the pH 2 0.1M Na 2 SO 4 solution, attributed to differences in (i) the hydrogen evolution reaction, (ii) the surface state, and (iii) the true surface area.

The colloidal size and rod morphology of nanocrystalline cellulose (NCC) lead to suspensions with useful phase and gelation behaviours as well as complex rheologies. However, these have not been comprehensively evaluated previously. Here we report the detailed phase behaviour of sulphonated NCC aqueous suspensions as a function of concentration and salinity. Four phases - liquid, viscoelastic, repulsive glass and attractive glass/gel - are identified in terms of their distinct rheological behaviours. The liquid-solid transitions (LSTs) are determined rheologically, and these are supported by a simplified model based on the DLVO theory that indicates the importance of charge in determining the phase behaviour. Rheology is also used to investigate the solid-solid transition from a repulsive glass to an attractive gel with increasing salt at high NCC concentrations. A time-dependent aging phenomenon is observed in suspensions with a composition just below the LSTs, and the implications of this on the dynamics occurring during gelation processes are discussed. This work can be directly applied to the development of structure-function relationships and the expanding utilisation of NCC suspensions, whilst also providing a basis for the study of charged colloidal rods more generally and evaluation of theoretical models.

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A phase diagram is developed based on the structure-rheology measurements showing various states of NCC that form as a function of salt and NCC concentration, which go well beyond those previously reported. This extended range of conditions reveals regions where the suspension is a viscous fluid and viscoelastic soft solid, as well as regions of instability that is suggested to arise when there is sufficient salt to reduce the electrical double layer (as explained qualitatively using DLVO theory) but insufficient NCC to form a load bearing network.

The Mg corrosion reaction sequence was considered in terms of possible elementary reaction steps, and their plausibility in relation to their thermodynamic status. The uni-positive Mg + reaction sequence is thermodynamically favoured, and can occur by a number of elementary steps. There are a number of possible dissolution reactions (which are defined are reactions which contribute no electrons to the corroding Mg electrode). It is impossible at this stage to conclusively determine the reaction mechanism without knowledge of the species present at the magnesium-water interface.

Liquid crystal hydroglass: under a specific solution environment, aqueous suspensions of cellulose colloidal rods phase separate into a colloid-rich attractive glass matrix and a coexisting liquid crystal phase. This structure allows control over reversibly orientating the colloidal rods through shear forces, which achieves a persistent flow-programmable directional order to the liquid crystal phase.

CO 2 -based enhanced geothermal systems (EGSs) have been examined from a reservoir-oriented perspective, and as a result thermodynamic performance is well explored. Economics of the system are still not well understood, however. In this study, the economics of the CO 2 -based EGS technology is explored for an optimized power plant design and best-available cost estimation data. We demonstrate that near-optimum turbine exhaust pressure can be estimated from surface temperature. We identify that achievable cooling temperature is an important economic site consideration alongside resource temperature. The impact of time required to sufficiently dry the reservoir prior to power generation is also addressed. The role of sequestration as part of CO 2 -based EGS is also examined, and we conclude that if fluid losses occur, the economic viability of the concept depends strongly on the price associated with CO 2 .