Phillipsite was crystallized from a high siliceous aluminosilicate mixture containing Zn cations and methylene blue (MB). The presence of MB did not affect the crystallization, but it resulted in a substantial amount of dye being anchored to the zeolite, despite its narrow channels. Dye-free synthetic phillipsite modified with MB solution showed markedly lower dye content, which, however was considerably higher than those in the MB-treated natural phillipsite and mordenite. The ultra violet/visible (UV-vis) spectra of the dye-modified synthetic phillipsites indicated the presence of MB monomers and oligomers, whereas the spectra of the modified natural zeolites showed protonated MB also. The electron spin resonance spectra of samples crystallized with MB indicated the presence of paramagnetic species.

In this study, aluminium fluoride trihydrate (AlF3⋅3H2O) was used to inhibit the sintering of calcined coal-series kaolin (CCSK). In addition, the oil absorption properties of CCSK were studied. The particle-size distribution, specific surface area and porosity of the samples were investigated as a function of calcination temperature and the addition of AlF3⋅3H2O. Moreover, the ability of AlF3⋅3H2O to improve the oil absorption of CCSK was explored. The morphology, structure and phase composition of the specimens were investigated using scanning electron microscopy and X-ray diffraction. The phase transition during heating of the samples was studied using thermogravimetric analysis. The preparation with 10 wt.% AlF3⋅3H2O had the optimal sintering inhibition effect on CCSK at 1000°C. The release of SiF4 gas during heating and the formation of mullite whiskers on the particle surface caused by AlF3⋅3H2O moderated the formation of molten-phase liquid bridges between particles and inhibited sintering of the raw material powder. Furthermore, the formation of submicron mullite whiskers on the surface of the CCSK particles enhanced the oil-absorption properties of the sample significantly.

The mineral present in most clays used in the fine ceramics industries is kaolinite. Both china clays and ball clays consist essentially of this mineral in association with quartz and some form of mica. There is some evidence for the presence of traces of montmorillonite in certain of the Cornish china clays (Clark, 1950) and a method of estimating this has been reported (Parker, Warren and Morcom, 1951). Work at the British Ceramic Research Association has shown that many Dorset ball clays are largely composed of a disordered kaolinite similar to Brindley and Robinson's fireclay mineral (1947); such clays are frequently more plastic than other ball clays and show high mechanical strength. Other ball clays contain normal kaolinite of finer particle size than the average china clay and in exceptional cases may show strengths equalling those of the disordered kaolinite.

Bentonite-based tablets offer multiple advantages over other types of formulated tablets, including being biocompatible and cost-effective, and they can be used to develop gel-like matrices that have potential for use in sustained-release formulations. Developing a high-load sustained-release formulation has been reported to be challenging; therefore, the aim of this study was to develop systematically bentonite-based sustained-release tablets for a high-load active agent (ibuprofen) and investigate their release kinetics. Ibuprofen-loaded tablets (800 mg) were prepared using wet and dry granulation followed by enteric coating of the tablets. Fourier-transform infrared spectroscopy, differential scanning calorimetry and X-ray powder diffraction were used to evaluate the compatibility of ibuprofen with bentonite. The results show that these tablets comply with compendial requirements. In addition, the release profile of the formulations reveals that the drug follows a non-Fickian release model. The present formulation demonstrates a new use of bentonite as a safe and cost-effective excipient with adequate binding and compaction for preparing sustained-release tablets.

This study investigates two clayey facies from the Bomkoul area in the littoral region of Cameroon for their suitability as fired clay building products. The field study consisted of a geological survey and a geotechnical mission (G0). Assessment of the raw clayey materials included their mineralogy, particle size, determination of Atterberg limits, density and shear stress. Firing properties (shrinkage, water absorption and flexural strength) at 900−1100°C were also determined. The two main facies observed in the field are the mottled red/yellow grey clays from surface ‘A’ with a thickness of 2.0–2.5 m and the deep blackish fossiliferous schisteous grey clays ‘B’ with a thickness of 8−10 m. Estimation based on boreholes revealed a minimum of 1,400,000 tons of clayey materials. These reserves will supply a small brick-manufacturing unit for a minimum period of 25 years at an extraction rate of 50,000 tons per year. The main clay minerals of both samples are kaolinite (35% and 49%) and illite (1–11%). Both samples contain quartz (47% and 49%) as non-clay minerals, associated with a small amount of anatase (0.5–2.6%) and trace hematite (<1%). The major oxides are SiO2 (71–76%) and Al2O3 (14%). The raw clayey material ‘A’ was finer and more plastic than the ‘B’ facies. The technological properties of the fired bricks obtained from the ‘A’ facies showed greater potential than the ‘B’ facies in terms of sonority and flexural strength. A mixture made of 40% ‘A’ and 60% ‘B’ yielded satisfactory brick properties at 1050°C.

The pyroclastic carbonatitic rocks from the Catanda volcanic area (Angola) contain annite and phlogopite grains which have been affected to a significant extent by vermiculitization. A mineralogical study of these micas has revealed that the annite was altered to K-vermiculite while vermiculitization of phlogopite generated Ca-vermiculite. Intermediate alteration products such as intergrowths of phlogopite/Ca-vermiculite were also found, but interstratified crystals of phlogopite/ vermiculite, a common intermediate product during vermiculitization processes, are not reported in the Catanda rocks. The two types of vermiculitized micas show ‘accordion’ textures, related to the expansion of vermiculite. To the authors’ knowledge, the present study is the first report of expanded vermiculites described in natural rocks and not generated as a consequence of industrial processing.

The clayey sludge resulting from aggregate washing in quarries of the Marrakech region generates significant environmental impacts and adds an economic burden to the industry. This study aims to characterize these clayey sludges in order to explore their potential for ceramic applications. Fifteen samples were collected from various quarries along the major waterways of the Marrakech region. The physical properties of the clayey materials were analysed according to particle-size distribution and plasticity limits. The mineralogical composition was determined using X-ray diffraction and Fourier-transform infrared spectroscopy. The chemical composition was determined using X-ray fluorescence spectroscopy. The carbonate and volatile contents were determined by calcimetry and loss on ignition at 500°C and 950°C, respectively. SiO2 and Al2O3 are main constituents, while quartz, feldspars and clay minerals are the main phases, along with minor calcite and hematite. Illite is the dominant clay mineral, followed by kaolinite and chlorite. The clayey material exhibits low to medium plasticity and variable particle-size distributions. The chemical composition of these sludges confirms their potential for red ceramic applications. However, their low plasticity, variable particle-size distribution and mineralogical composition, characterized by a low clay mineral content, limit their direct applicability. To improve their suitability for ceramic production, adding clay-rich tempers is essential to enhancing their mineralogical composition, granulometry and plasticity. Furthermore, the results provide a valuable guide for selecting local materials for Marrakech pottery and can serve as a model for other regions.

The Weissenberg method has been used to study crystalline fragments of hydrobiotites from Stupná near Křemže, Czechoslovakia. The intensity distribution for basal reflections recorded in zero-level photographs indicates that most ‘single crystals’ are nearly regular interstratifications of vermiculite and biotite. Proportions of vermiculite in these interstratifications lie between 12 and 60%.

Two clays of the kaolinite type, one from Bihar and the other from Kerala, were each separated into particle-size fractions greater than and smaller than 1·4 µ.e.s.d. X-ray diffraction, differential thermal analysis, cation-exchange capacity and moisture absorption determinations and chemical analysis of the fractions showed that the micaceous mineral was concentrated in the fine fraction of one whereas it was mostly in the coarse fraction of the other. The evidence suggests that the mineral in the former belongs to the illite group and in the latter to the mica group.

Clay minerals possess the peculiar characteristic that they normally occuras very small crystals. We cannot, therefore, afford to ignore thecontribution that colloid science can make to the study of clay minerals.Many colloidal systems are stable because the particles are electricallycharged. There is, of course, electrical neutrality of the system as awhole, but there is an electric separation within the system wherebyelectricity of one kind (it may be a positive or negative, depending on thesystem) is anchored for the time being to the particles while thecomplementary charge exists as ions (counter ions they are often called).Some of the counter ions must be regarded as in solution in the suspendingmedium (normally water) for it is their mobility relative to the particleswhich gives rise to electrical conductivity and to electrophoresis,electro-endosmosis and streaming potential.

Laterite could play a crucial role in soil stabilization and environmental remediation, but its internal particle interaction mechanism remains unclear. This study, based on molecular dynamics simulations, used umbrella sampling methods to measure the interaction strength between amorphous alumina and montmorillonite particles in laterite. The mechanisms were explored using differential charge density analysis and bond energy analysis. The results show that the interaction process between alumina and montmorillonite exhibited initial repulsion, then attraction, followed again by repulsion. Calcium ion-induced polarization, the negative charge on the alumina surface and the bonding strength during adsorption played key roles in this interaction. Notably, the bond energy measurement results in this study are consistent with data from other related research, validating the data’s accuracy. These findings improve our understanding of the microscopic mechanisms of laterite particle interactions, providing a scientific basis for its application in soil stabilization and environmental remediation.

A genetic classification of clay rocks is given in which five main types are recognized. In this classification minerals of the kaolin group formed directly from hydrothermal solutions, along with sulphides, sulphates, and pneumatogenic minerals, are separated from the same minerals formed by the hydrothermal-metasomatic action of gases and vapours on aluminosilicate rocks. Some data on the occurrence of these two types in Azerbaijan are recorded. The origin of the bentonitic clays (“gilabi”) of Azerbaljan is also discussed; the geology of the deposits indicates cycles of volcanic activity and long-range transport of volcanic ash.