In the Upper Cretaceous-Danian North Sea chalk, silica composed of nano-size quartz spheres is dispersed in the chalk matrix, and quartz is present in bands and nodules of flint. In the present investigation of the North Sea Danian chalk the nano-quartz in the chalk matrix is compared with the silica in the flint. Samples of chalk and flint layers from four North Sea wells have been investigated. Atomic Force Microscopy (AFM) has been applied to image the quartz in the chalk and in the flint. X-ray diffraction (XRD), including analysis of the positions and profiles of hkl reflections in powder diffraction patterns, has been applied to characterize the lattice of the quartz in both the chalk matrix and in the flint. The quartz in the chalk matrix and in the flint is composed of nano-quartz spheres having identical cell parameters. Based on the results we propose a new model for formation of flint in North Sea chalk: (1) The nano-quartz in the flint, like the nano-quartz in the chalk matrix, has crystallized in the marine Chalk Sea environment. The colloidal quartz particles flocculated and were deposited on the sea floor mixed with calcitic bioclastic material. (2) Regional variations in the concentration of nano-quartz particles in the sediment reflect different degrees of acidification of the Chalk Sea. (3) This resulted in areas where practically all the calcite bioclasts were dissolved leaving a high concentration of nano-quartz particles to form flint layers; where there was less dissolution, indurated chalk with abundant nano-quartz particles is now preserved. (4) The acidification could have been caused by the effects of enhanced atmospheric CO2 linked to massive short-lived volcanic eruptions in the British Tertiary Igneous Province.

Various physical and analytical techniques (XRD, XRF, SEM, FTIR and EPR) have been used to investigate the effects of chemical and/or physical modification of Ranong kaolin, which has been proposed as a potential bleaching clay for vegetable oils. Acid treatment after grinding resulted in major changes compared with acid treatment of the original mineral sample or mechanical treatment alone. Previous work has shown that the combined treatments produce increases in surface area and new porous structures, and the present measurements show reductions in Al:Si ratios. These are accompanied by a major reduction in O–H stretching vibrations as a result of grinding, although acid treatment produced little subsequent effect on the O–H bands in the FTIR spectra. However, acid treatment resulted in a reduction in the Al–OH–Al bending vibrations and the appearance of Si–O bands associated with newly synthesized material; these effects were much greater with samples that had been ground prior to the acid treatment. There were appreciable qualitative differences in the way in which the EPR spectra of Fe and Mn were affected; the Fe signal was sensitive to mechanical treatment, but little subsequent change was induced by acid extraction, whereas the Mn peaks were sensitive to the both the pH and the chemical nature of the acid used. These results therefore indicate that the Fe and Mn are in different types of site in the kaolin structure. Little change was observed in the main oxygen-based free radical centre associated with Si atoms, but that associated with Al was lost as a result of the treatments. Such mineral characterization is of fundamental importance to understanding the modification of kaolins and their uses as adsorbents in the food and environmental sciences.

The evolution of the nitrogen and boron content of shales during diagenesis and anchimetamorphism was studied in the Carboniferous rocks of Donbas by means of the bulk rock chemical analysis and the XRD quantification of mineral composition, aided by CEC and EGME sorption measurements. The contributions of the organic-bound N and B were taken into account, based on the literature data (B) and on the relationship established in the course of this study (N). 28–98% of the total N and 80–100% of the total B are contained in the mineral fraction of the investigated shales.

The mineral nitrogen is located mostly in illite and accounts for 3 to 64% of the sites available for its fixation in 1Md illite. The fixation of N by illite seems to diminish in the course of diagenesis, but additional fixation occurs in newly formed 2M1 illite during the anchimetamorphic stage. The volume of N contained in illite in most samples greatly surpasses the N available locally from the organic matter contained in shale. Modelling indicates that the measured level of N for K substitution in illite corresponds to the capture in 30 vol.% of shale of all N released in a basin containing 5 vol.% of coal.

Boron is held predominantly by the 1Md fraction (illite+smectite). During diagenesis boron is redistributed into the 1Md illite, and during anchimetamorphism it is released from the 1Md illite and incorporated into new 2M1 illite. No indication of the net enrichment of pore water in B due to the clay alteration process was found.

Suspensions of thirty six bentonites were equilibrated for 24 h and then adjusted to pH 3. After an hour, pH titrations up to pH 12 at varying ionic strengths were performed within 4.5 h. The titration data were recalculated into proton affinity distributions (PAD) using the condensed approximation. In spite of widely varying chemical compositions, all bentonites showed a protonation reaction between pK 4 and 5, which could be assigned to aluminol groups at the edge surfaces of the smectites. The average pK is 4.73±80.31. A second prominent peak in the PAD at pK = 10.43±80.13 could be assigned to exchangeable Mg2+ in the interlayer space. The possibility to constrain both pK values at a fixed average value will decrease the number of parameters in surface complexation modelling and thus enhance its convergence.

Micrometric and nanometric illite-rich size fractions of claystones, bentonites and shales were exchanged with alkylammonium cations that have the specificity of stoichiometrically replacing K in trioctahedral mica interlayers. The purpose of the study was a separate evaluation of the K-Ar ages of potentially dioctahedral residual particles not affected by alkylammonium leaching and of potentially trioctahedral illites that were exchanged by the organic molecules.

The K-Ar ages of micrometric size fractions from an Estonian Blue Clay sample collected next to another studied previously show that, even if identical in their mineralogical characteristics, the fractions contain variable amounts of trioctahedral particles that are of different origins. The alkylammonium treatment modifies slightly, within analytical uncertainty, the K-Ar ages of the <0.1 and 0.1–0.4 mm size fractions from, respectively, 464±13 and 530±14 Ma before organic exchange to 480 ± 11 and 546±12 Ma after. The K-Ar ages of alkylammonium exchanged nanometric size fractions from the rim and centre of a thick Upper Cretaceous bentonite bed in Montana suggest that trioctahedral illite-rich particles mineralogically and chemically homogeneous and about 30 Ma old precipitated next to older dioctahedral particles of ∼60–65 Ma. The untreated mixtures consist of two generations of authigenic illite having apparently different di/trioctahedral layerings. The same type of authigenic di/trioctahedral illite layering could be demonstrated for nanometric illite particles of a bentonite bed from the East Slovak Basin, one size fraction appearing to even consist of a pure trioctahedral illite as the alkylammonium exchange emptied completely the illite interlayers. The nearby shale level consisted of detrital illite particles that were found to be of different ages, di/trioctahedral layerings and therefore varied origin.

K-Ar ages of alkylammonium exchanged micrometric to nanometric illite and illite-smectite mixed layers, either increasing or decreasing, appear to outline variable di/trioctahedral layering assemblages or independent particle mixtures resulting from a more complex smectite illitization process than the conventionally assumed homogeneous reaction. It could record changing chemical compositions of the interacting pore fluid during crystallization, even when illitization progressed slowly. Similar ages before and after alkylammonium exchange suggest a constant chemical composition and therefore an homogeneous dioctahedral crystal structure. Alternatively, a changing chemical composition of the fluids during illitization is potentially recorded by variable K-Ar ages of the alkylammonium-leached illite resulting from differentiated ion exchanges.

This investigation was carried out to determine whether the adsorptive and ion-exchange properties of faujasite (FAU) could be used to delivery locally the anticancer drugs gemcitanine hydrochloride (dFdU.HCl) and oxaliplatin (DACH-Pt). A soaking procedure was used for the determination of the maximum adsorption capacity of FAU and the mechanism described here was achieved. 274 mg dFdU.HCl/g FAU were adsorbed in 16 h, while 48 h were needed for the adsorption of 79.7 mg DACH-Pt/g FAU. Drug release studies were carried out by soaking the samples of loaded FAU in simulation body fluids (SBF). After only one hour 76% of dFdU.HCl was released while the release of DACH-Pt from the FAU was more normal since 38% of DACH-Pt was released in the first 24 h.

Lime-based mortars with admixtures of metakaolin (10, 20 and 30 wt.%) and fine sepiolite (5 wt.%) were prepared with the aim of facilitating their use as repair mortars in low-humidity conditions. The mechanical properties and the dynamic modulus of elasticity were studied after 28, 90 and 180 days of curing. With an increasing amount of metakaolin in lime mortars, improved mechanical strength was observed mainly after 90 days. Addition of fine sepiolite, due to its adsorption properties for storing water for later supply to the mortar system and its microfibrous morphology, led to an improvement of compressive and flexural strength of blended air lime/air lime-metakaolin mortars, espec ially at later ages of curing. Incorporation of fine sepiolite into air lime-metakaolin mortars resulted in comprehensive densification of the core of the mortars. Air lime mortar containing 5 wt.% of fine sepiolite and 20 wt.% of metakaolin appears to be an optimal admixture.

Polycondensation reactions between amino acids and phenols are one of the pathways for the formation of humic substances, and clay minerals are able to catalyse these reactions. To investigate the catalytic power of allophane, an allophane fraction (ALF) was separated from weathered pumice (WP) that contained imogolite as an impurity by taking advantage of differences in sedimentation velocity. The iron content in the separated ALF was increased by up to 3.0% compared to that in the starting WP (1.3%), and the ALF was further treated with sodium dithionate and citric acid (ALF-DC) to remove the iron. The catalytic powers of WP, ALF and ALF-DC were evaluated, based on the degree of darkening of reaction mixtures from polycondensation reactions between catechol and tryptophan, model compounds for precursors of humic substances. The catalytic power for ALF was significantly higher than the corresponding values for WP and ALF-DC. This can be attributed to the high iron content of the ALF, which serves as a Lewis acid that can enhance nucleophilic reactions which occur during the polycondensation reactions.

Clay mineralogy and its palaeoclimatic interpretation of the early-Eocene (∼53.3–49.70 Ma) sediments at Lulehe, Qaidam basin, northwest China, were investigated using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The interval of ∼53.3–49.70 Ma, including the early-Eocene climate optimum (EECO) with isotopic events, was the transition period of “greenhouse” to “icehouse”. Climate changes during the episode were documented in the sediments and were expressed by the proportion of clay species and clay indices, as well as by the proportion of non-clay minerals, gypsum, halite and calcite. Our results suggest that a warm and humid climate prevailed over the period ∼53.3–52.90 Ma, followed by a warm and seasonally dry and humid climate in the period ∼52.90–51.0 Ma and a subsequently warm and humid climate in the period ∼51.0–49.70 Ma. Three warmer and more humid intervals were observed at 52.7, 51.0 and 50.5 Ma based on clay indices. The climate evolution in the Qaidam Basin during the period derived from the clay mineralogical study is in good agreement with the early Eocene global climate change, and the warm and seasonally dry and humid episode in the early Eocene in Qaidam basin is a regional response to the global early-Eocene climate optimum.