Mining and Materials Engineering

Inverse gas chromatography (IGC) is a versatile, powerful, sensitive and relatively fast technique for characterizing
the physicochemical properties of materials. Due to its applicability in determining surface properties of
solids in any form such as films, fibres and powders of both crystalline and amorphous structures, IGC became
a popular technique for surface characterization, used extensively soon after its development. One of the most
appealing features of IGC that led to its popularity among analytical scientists in early years was its similarity
in principle to analytical gas chromatography (GC). The main aspect which distinguishes IGC experiments
from conventional GC is the role of mobile and stationary phases. Contrary to conventional GC, the material
under investigation is placed in the chromatographic columnand a known probe vapour is used to provide information
on the surface.
In this review, information concerning the history, instrumentation and applications is discussed. Examples of
the many experiments developed for IGC method are selected and described. Materials that have been analysed
include polymers, pharmaceuticals, minerals, surfactants, and nanomaterials. The properties that can be determined
using the IGC technique include enthalpy and entropy of sorption, surface energy (dispersive and specific
components), work of co/adhesion, miscibility and solubility parameters, surface heterogeneity, glass transition
temperature, and specific surface area.

Inverse gas chromatography (IGC) is a versatile and powerful technique for characterizing physicochemical
properties of materials. One such property, the surface energy, plays an important role in the adhesiveness,
wettability, and consequently flotation of minerals. In this work, quartz was chosen as a
naturally hydrophilic mineral, and dodecylamine was used to hydrophobise the surface. To study the correlation
between the surface properties as measured from IGC experiments and flotation, microflotation
experiments were also conducted. It was shown that with treatment by dodecylamine, the surface energy
decreased, as did the work of adhesion to water. The recovery of quartz increased after the treatment,
indicating a correlation between surface energy and flotation response.
The results indicate that IGC has the capability to determine the thermodynamic properties of quartz,
pre- and post-conditioning. Relating the hydrophobicity and flotation of minerals to the surface energy
can be observed from combining the results of IGC and microflotation experiments.

All the possible parallelism conditions associated with low-index crystallographic planes and directions in face-and body-centred cubic crystals are enumerated in terms of their minimum angle-axis misorientations. These include the Kurdjumov-Sachs (K-S), Nishiyama-Wassermann (N-W) and Pitsch orientation relationships, which are expressed in terms of close-packed (and near-close-packed) planes, close-packed directions, or both in the two crystal systems. By classifying these into either coplanar or codirectional relationships, it is possible to specify intermediate relations with either high-index directions or planes. In such a way, the Greninger-Troiano (G-T) relationship is approximated as a coplanar relation lying between the K-S and N-W relations. Based on geometric symmetry, a further correspondence relationship, which falls into the codirectional category and is located between the K-S and Pitsch relations, is represented both in pole-figure form and in Rodrigues-Frank space. It is referred to here as the inverse G-T, or G-T 0 . Experimental evidence from the plessite regions of the Gibeon meteorite is presented to support the validity of this relationship. It is shown that, in plessite, all the well known models, as well as their intermediates, are applicable to the -totransformation. By contrast, in the Widmansta ¨tten portions, the misorientations are largely limited to the K-S, G-T and N-W relations.