The optical spectra of Cu2+ and Ni2+ on Camp Berteau montmorillonite after lyophilization and evacuation at room temperature are characteristic for the presence of Cu(H2O)42+ and Ni(H2O)62+ in the interlamellar space. The most probable ligand field parameters for Cu(H2O)2+4 are Dqxy = 1310 cm−1, Ds = 1807 cm−1 and Dt = 664cm−1. The covalent character of the Cu2+-OH2 bond is not negligible as indicated by the orbital reduction factors k∣∣2 = 0.66 and k⊥2 = 0.76. This is also the case for Ni(H2O)62+ which is characterized by a ligand field strength, Dq = 850 cm−1 and an electronic repulsion parameter B = 920 cm−1. After desorption in vacuum the optical spectra of Cu2+ were poorly resolved, while Ni2+ was present partially as (Ol)3Ni2+, partially as (Ol)3Ni-OH2 where Ol means an oxygen of the hexagonal rings in the tetrahedral layers.

Previous studies by Electron Spin Resonance (ESR) have established the substitution of Fe3+ and Mg2+ in the kaolinite structure. It is shown that Fe2+ can substitute in kaolinite and stabilize defects which are detectable by ESR in a manner identical to Mg2+. The development of methods of preparing a synthetic kaolinite doped with Fe2+ is described in detail. It is shown that the main ESR signals, which occur at g = 2.0 in natural kaolinites and which previously have been interpreted in terms of iron and magnesium, can be attributed to iron alone.

The hydrolysis of aluminum-tri-(sec-butoxide), ASB, in ionic and nonionic media is shown to be a useful method for the synthesis of aluminum minerals. Infrared and X-ray analysis were used to identify the reaction products. Pseudoboehmite is formed at low water to aluminum ratios. At higher water content, transformation of pseudoboehmite occurs with bayerite as the final phase. Dawsonite-type minerals are produced when ASB is hydrolyzed in the presence of sodium, potassium, or ammonium bicarbonate. Infrared evidence suggests that the carbonate group is more perturbed than indicated by the proposed crystal structure. A compound with a structure like the pyoaurite-sjögrenite group was obtained when ASB reacted with a lithium carbonate solution. The infrared spectrum indicates the possible existence of bicarbonate and carbonate ions between the brucite-like layers.

While studying the retention of additives used in tertiary recovery of petroleum (waterflooding) on minerals present in a rock reservoir, an investigation has been undertaken into the adsorption mechanism of Polyacrylamides on to clays. The adsorption of amides and Polyacrylamides takes place exclusively on the external surfaces of the clay particles. The organic molecules are protonated on the surface and adsorbed by ionic forces. There is a linear relationship between the adsorption ratio and the polarizing power of the exchangeable cations of the clay mineral. The adsorption isotherms and the thermal analyses reveal the existence of two adsorption mechanisms: (i) a strong, irreversible adsorption, which corresponds to the formation of a monolayer of chemisorbed molecules, (ii) a more important adsorption of molecules retained by hydrogen bonding, which can be eliminated by heating at low temperature. The retention ratio in the irreversible process, which is practically identical both for acetamide and Polyacrylamide, is low (3 mg/g). It depends on the external cation exchange capacity (CEC) of the mineral and increases with the surface area. The Polyacrylamide adsorption depends on the physico-chemical characteristics of the macromolecule, more particularly on the CONH2/COO−ratio, which determines the extent of the carbon chain, and the molecular weight. The accessibility of the organic macromolecule to the clay particle is controlled by the preceding factors. The quantity of Polyacrylamide irreversibly adsorbed by clay minerals is important in the context of the use of the polymer on a petroleum field. It may be reduced to a minimum by working at low concentrations with a weakly hydrolyzed Polyacrylamide solution.

Organic solvent soluble organosilicate compounds retaining silicate backbone were obtained by the reaction between biotite and trimethylsilylating reagent. The soluble product which was formed at room temperature or at reflux temperature was a viscous liquid and was soluble in a wide range of organic solvents, but insoluble in water. Molecular weights of the soluble products and their thinlayer chromatograms made it clear that the soluble products consisted of several trimethylsilylated derivatives of silicic acids which were mainly the derivatives of mono- and disilicic acid. The influence of reaction temperature for the trimethylsilylation reaction also was discussed.

The standard method of assessing the available portion of the nutrient reservoir of a forest soil is to use a neutral salt solution, such as NH4OAc, to extract the exchangeable plus dissolved ions, which are analyzed and considered available. This approach, designed for evaluating nutrients available for the short growth term of agricultural crops, is inadequate for assessing the nutrient pool of forests where tree growth term may reach 100 yr or more.

Soil nutrient reservoirs were evaluated in two forest soils for K, Na, Ca, Mg and Fe, using an approach based on continuous extraction of the elements and kinetic analyses of the extraction rate curves. The analyses of the curves indicate that K, Na, Ca and Fe are each released at four separateconstant rates, and Mg is released at three separate constant rates. By analogy with similar kinetic studies done on monomineralic layer silicate samples, each separate extraction rate is thought to correspond to a single type of bond site in the soil. Higher extraction rates indicate greater ease of removal and are interpreted as indicating a higher degree of availability relative to the extractant.

The available K reserves of the Everett soil evaluated by standard methods, compared with annual net K uptake rates of its forest system, indicates growth limiting K deficiency in 12–17 yr. K availability assessed by kinetic analyses indicates about 100 yr supply of K is available.

The surface charge characteristics of a range of synthetic amorphous aluminosilicates, hydrous alumina, hydrous silica and two allophanic soil clays were determined by the retention of Na+ and Cl− as counter-ions from 0.1 M NaCl solution. In the pH range investigated (3–9), only negative charges could be detected in the hydrous silica and the most siliceous aluminosilicate [Al/(Al + Si) = 0.29], and only positive charges were detected in the hydrous alumina; whereas both positive and negative charges were detected in the more aluminous aluminosilicates and the soil allo-phanes. In all cases, the surface charges were pH-dependent and in the aluminosilicate series negative charge decreased and positive charge increased with Al/(Al + Si). Consequently, the point of zero charge increased with Al/(Al + Si).

The charge characteristics of the amorphous aluminosilicates could be explained by current models of their structure. Negative charge can be attributed to isomorphous substitution of Al for Si in the silicate structure and to the dissociation of silanol groups in structural and adsorbed silicate. Positive charge is attributed to protonation of hydroxy-aluminum species occupying cation exchange sites.

Artificial stacking faults can be created within a well-crystallized kaolinite by intercalating and removing hydrazine. X-ray powder patterns with electron microscopy show that the created defects are ±b/3 translations with a proportion 0.30. The infrared spectrum of the treated kaolinite is not modified with respect to the starting one. On the other hand, a natural kaolinite containing defects by displacement of Al vacancies in a similar proportion shows an infrared spectrum significantly different from that of a well-crystallized kaolinite. The modification of the infrared spectra of natural disordered kaolinites is then related to the presence of defects by change of Al vacancy positions

This paper describes the calculation of the diffracted intensity for models of powdered minerals with lamellar structure, in order to compare experimental and theoretical X-ray diagrams. The calculation takes into account at the same time (i) the possibility of coexistence of different kinds of layers in the stackings, (ii) the possibility of stacking faults between the layers (translative or rotative ones) and (iii) the unavoidable orientation of particles in the powder sample (the method of determination of the orientation is described).

Until now, the different attempts to describe the defects of kaolinites were based on the ideas that (i) the hkl reflections with k = 3n are Bragg reflections, while (ii) the hkl reflections with k ≠ 3n are affected by ±b/3 translations or ±2π/3 rotations. With regard to this conception, this work provides several important precisions: (i) The h, 3n, l′ reflections are true continuous diffraction bands, more or less modulated, and disturbed by the existence, in the stacking, of random shifts parallel to the layer plane. (ii) The major defect in natural kaolinites is not the ±b/3 translation, but the displacement from one layer to the other (or from one domain to another in the same layer) of the Al vacancies. (iii) The model containing true rotation of layers should be rejected because it does not allow us to interpret all the different parts of the experimental diagrams. Such a concept of defects in kaolinites is in agreement with the existence of polytypes of kaolinite, with the presence of twins, and allows us to interpret some physico-chemical properties such as the infrared spectra.

Effects of particle size, crystallinity and the amount of the structural water in kaolinites on their infrared spectra, were studied. The samples were ground in a vibrating ball-mill, and infrared and X-ray spectra, as well as thermal and specific surface area measurements, were taken on the initial and ground samples. Changes of the 3705-cm−1 infrared band intensity and of the absorbance ratio of the A 3630/A 3705-cm−1 bands were determined as a function of the grinding time. Correlation functions between the absorption ratio, calculated from the infrared spectra, and the average particle size, as well as between the amorphism, calculated from the X-ray spectra, and the average particle size, were obtained.

The adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray photoelectron spectroscopy (XPS) has been carried out. Comparison of the binding energies for metal ions in octahedral sites in selected minerals (reference minerals) and in simple nickel and copper containing compounds with values for Ni(II) and Cu(II) adsorbed on chlorite indicate that nickel(II) is probably bound as the aquo ion while copper(II) may be adsorbed as Cu(OH)+.

The physical and chemical interactions between organic amines and mineral surfaces are of considerable importance in many industrial applications. For example, the preparation of organophilic minerals often involves the adsorption of organic amines, or the ion exchange of the minerals with quaternary ammonium salts (Jordon, 1951; Miller and Faust, 1972). Chemical interactions occurring in these systems have been studied because of their relevance to an understanding of the chemical nature of the clay surface. A number of these studies have reported on the decomposition of adsorbed amines and alkylammonium-mineral complexes at elevated temperatures, usually in excess of 100°C (Chaussidon and Calvet, 1965; Weiss and Roloff, 1963; Durand, Pellet and Fripiat, 1972; Chou and McAtee, 1969). It is now well established that under these conditions the mineral may have potential strong-acidity, and these reactions have been explained in terms of acid-induced decomposition or rearrangement of the adsorbed amines or their derivatives. However, there have been few studies of the reactions of organo-mineral complexes at temperatures below 100°C, under conditions where retention of adsorbed water could be expected to moderate the mineral surface acidity.