The ammonia electrode serves as the basis of a simple, accurate method for determination of cation exchange capacity of small (ca. 50 mg) samples of clays. The technique is also capable of accurate measurement of CEC values on the order of 0·01 m-equiv/100 g if larger (ca. 500 mg) samples are used. The procedure, which requires saturation of the exchange sites with ammonium as in the usual methods, utilizes the electrode in the determination of ammonia released by treatment of the ammonium clay by strong base. For a Wyoming bentonite, the technique gave a CEC of 86 m-equiv/100 g with an S.D. (four determinations) of 0·83 m-equiv/100 g. Duplicate runs on the same sample by the conventional Kjeldahl method gave results of 86·0 and 85·5 m-equiv/100 g.

The effects of Na-citrate-dithionite (NaCD), ammonium oxalate in the dark (NH4Ox-D), and photolytic reaction under ultraviolet radiation (NH4Ox-P) on the mineralogy of <2-µm fractions of selected soils from Virginia were investigated. The NH4Ox-D treatment removed the smallest amounts of Al (<0.22%) and Fe (<0.50%) from all soils, indicating low levels of noncrystalline material in these materials. From the six soils examined, NH4Ox-P treatment extracted 5–62% more Fe and 12–300% more Al than the NaCD treatment. The NH4Ox-D and NaCD treatments revealed no X-ray diffraction detectable alterations to mineral phases present in <2-µm fractions of these soils. The NH4Ox-P treatment, on the other hand, produced considerable degradation of hydroxy-interlayered vermiculites in these soils, as evidenced by a shift of the 14-Å X-ray diffraction maxima to lower spacings with heat treatment of the sample. The NH4Ox-P treatment removed variable amounts of hydroxy-Al material from the interlayers of 2:1 layer silicates, depending on their stability and degree of development.

In 2010, Turaev introduced knotoids as a variation on knots that replaces the embedding of a circle with the embedding of a closed interval with two endpoints which here we call poles. We define generalised knotoids to allow arbitrarily many poles, intervals and circles, each pole corresponding to any number of interval endpoints, including zero. This theory subsumes a variety of other related topological objects and introduces some particularly interesting new cases. We explore various analogs of knotoid invariants, including height, index polynomials, bracket polynomials and hyperbolicity. We further generalise to knotoidal graphs, which are a natural extension of spatial graphs that allow both poles and vertices.

A study of the thermal transformation of alkylammonium cations adsorbed on the surface of a montmorillonite in various conditions of hydration has been carried out. The experimental conditions were: inert atmosphere, temperatures below 250°C and time periods up to 270 days. The reactions observed are mainly transalkylations, for which a mechanism of acid catalysis is proposed. A high degree of dissociation of the water remaining on the surface of the clay is required and is attained for an optimal, and rather low, water content of the clay.

The immobilization of soluble Cs from spent fuel elements by ion exchange and direct chemical reaction with clay minerals or shales was investigated under hydrothermal conditions. Various clay minerals or shales were reacted with likely Cs sources and water at 300 bars pressure and 100°, 200°, and 300°C for 4, 2, and 1 months, respectively. Pollucite was the principal product, but CsAlSiO4 was also observed, along with unreacted or hydrothermally altered aluminosilicates. From Cs concentrations of the product solutions partition of Cs between liquid and solids was found to vary depending on the Cs source, the clay or shale phase, temperature, and run duration. For example, illite-Cs2MoO4 interactions resulted in 19, 32, and 95% fixation of added Cs at 100°, 200°, and 300°C respectively. Fixation of as much as 97% of the Cs in some solids was observed. In addition to Cs-aluminosilicates, Cs was fixed on cation-exchange sites by interlayer collapse in montmorillonite. Reactions with Cs2MoO4 also produced powellite because Ca was available in the reaction mixture. The U6+ from β-Cs2U2O7 was reduced to form uraninite by sulfide- and/or organic-rich shales. (Cs,Na)2(UO2)(Si2O5)3·4H2O, an analog of weeksite, was produced in reactions with β-Cs2U2O7. The reaction products pollucite and uraninite can immobilize much of the Cs and U from spent fuel elements because Cs in pollucite is extremely difficult to exchange and U in uraninite is insoluble.

Dimensional changes in kaolinite pellets as a function of temperature show two sharp shrinkage “steps,” at about 450–550°C and 900–980°C, which are roughly comparable in magnitude. Isothermal heat-soaking tests confirm that the rates for both are kinetically controlled. Water vapor inhibits shrinkage at low temperature but promotes shrinkage at high temperature. Both the former reaction, related to dehydroxylation, and the latter reaction, related to “mullitization,” take place at temperatures well below those observed in DTA, TG, and other measurements, indicating that bond-breaking is a necessary prelude to transitions at higher temperatures.

Bonding energy changes, as measured by X-ray fluorescence shifts, were used in interpreting the phenomena involved. The relative absence of bonding energy changes in the aluminum until the range 950–1100°C, and the presence of such changes in the silicon, suggest that high-temperature energy release is probably related to segregation or crystallization of silica, rather than of an aluminum-containing phase. Caution must be used in interpreting bonding energy changes, and in distinguishing kinetic and thermodynamic contributions to dynamic phenomena.

Based on X-ray powder diffraction measurements of swelling, thermodynamic analysis of adsorption and kinetics, a mechanism of interaction between xylene isomers and two organoclay complexes was derived. The work is intended to resolve the factors which make possible the chromatographic separation of the xylene isomers with organoclays. Significant differences between the behavior of fresh organoclays and xylene vapor-conditioned organoclays were noted. Only small differences were apparent between the montmorillonite and the hectorite organoclays. Force constants, enthalpy changes, entropy changes, free energy changes and two specific rate constants were derived from the information obtained from this study.

The new genus Imsharria is proposed for a crustose species found on or near mountain summits on the Falkland Islands. It is separated from other genera of Lecideaceae by a combination of Porpidia-type asci, halonate ascospores, immersed apothecia and a hyaline hypothecium, and forms a distinct branch in the phylogenetic analysis using the markers nrITS and mtSSU. The single species, I. orangei, is characterized by its innate apothecia with a brown disc and a thallus containing norstictic acid and an amyloid (I+ violet) medulla. In addition, Porpidia imshaugii is described for a species from the Falkland Islands resembling P. skottsbergiana but with larger ascospores, and Porpidia navarina is shown to belong in the genus Poeltiaria, with the new combination Poeltiaria navarina being made. A key to the Lecideaceae on the Falkland Islands is provided.

An X-ray spectrochemical method is compared with the flame photometer determination of potassium in a series of sixty-five soil clay fractions. Two methods of preparing the clay samples for the X-ray determination were used. In one case a 20 mg sample of clay in suspension was dried onto a plastic disc as a thin film. Potassium was determined by comparing the fluorescence intensity of the unknown with a sample of known composition which was prepared for analysis by the same technique. For the second method a 100 mg sample of dried clay was pressed into a pellet using methyl cellulose as a backing. In this case a National Bureau of Standards sample (NBS-98) was prepared in an identical manner and used as a standard for determining the potassium in the unknown. The results for both techniques were highly significantly correlated with the values as determined by flame photometric analysis. The pellet technique gave a more accurate measure of the potassium content. With the thin films the same sample may be used for X-ray diffraction analysis. In either case the X-ray spectrochemical technique provides a fairly rapid and simple procedure that can be useful for handling large numbers of samples.

For very small crystallites diffraction theory shows not only broadening of powder lines, but generally also a shift of the line position, depending on the change of the structure factor over the range of broadening. For decreasing thickness of kaolinite crystals (less than 50 layers) an increasing shift of reflections is found: the lines (001), (002), (004) and (006) are shifted to apparently larger spacings, the lines (003) and (005) to smaller spacings, resulting in a nonintegral series. Presuming a known crystallite size, tables are given for evaluating true spacings from measured values of 2θ.

The crystallization of calcium zeolites was carried out in an open hydrothermal system at 100°–250°C, using reactants that in nature are known to alter to calcium zeolites and 0.1 N CaCl2, 0.01 N CaCl2, and 0.01 N CaCl2 + 0.01 N NaOH (1:1) solutions. The following calcium zeolites were identified by X-ray powder diffraction:

• Rhyolitic glass: heulandite, phillipsite, epistilbite, wairakite;

• Basaltic glass: phillipsite, scolecite, wairakite, levynite;

• Nepheline: thomsonite, wairakite, gismondine;

• Oligoclase: heulandite, phillipsite, wairakite.

Factors that influenced the type of zeolite formed were: Si/Al ratio of the starting material, calcium/alkali ratio of the starting material, calcium activity of the reacting solution, presence of an open alteration system, and temperature. The Si/Al ratio of the starting material was of special importance in that zeolites formed with Si/Al ratios similar to or smaller than that of the parent material. The calcium/alkali ratio of the starting material also influenced the kind of the early alteration products in the open system. As alteration progressed, the importance of the starting material decreased. The importance of the calcium activity of the reacting solution and the influence of the open system increased as alteration proceeded. Because of mass transfer during alteration in the open system, the calcium content of the minerals formed increased, while their Si/Al ratio decreased. Temperature was especially effective during prolonged alteration, in that the higher the alteration temperature the smaller was the H2O content of the alteration product. Initially, H2O-rich zeolites formed transitorily at higher temperatures.

The structure and behavior of homoionic bentonites was markedly affected by a grinding procedure often applied to clays. The main changes observed on clay powders were the breakage of weakly bound large aggregates, the reduction in the tactoids’ thickness by delamination, the reduction in the plates’ area, and the formation of colloidal matter. The tendency of clays to form secondary aggregates in aqueous suspensions is probably due to the exposure of active broken edges following grinding.

The mild mechanical stress applied increased both the rate and the amounts of parathion sorbed by clays from an apolar solvent. The effect of grinding on parathion adsorption in aqueous clay suspensions seems to be a rate effect.

The interactions of clay minerals with organic compounds which give rise to the formation of colored complexes, are discussed. The color reactions of clays can be ascribed to a charge transfer between the mineral and the adsorbed species. The active sites on the clay are aluminums exposed at crystal edges and/or transition metal cations in the higher valency state at planar surfaces both of which can act as electron acceptors. The pH of the system, the nature of the solvent and that of the exchangeable cation, influence the rate of color development and the final intensity and quality of the color produced. Steric factors also play a part in reactions involving bulky organics. Some practical applications based on color reactions of clays with electron-donating organic substances are described.