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.

Cement mortars and concretes incorporating clinoptilolite, silica fume and fly ash were investigated for changes in their physical and mechanical properties. It was found that additions of 10% clinoptilolite and 10% Pozzolite (1:1 mixture of silica fume and fly ash) were optimal for improvement of the quality of the hardened products, giving 8% and 13% increases in flexural and compressive strength respectively. The specific pore volume of the mortars incorporating zeolite decreased between the 28th and 180th day to levels below the values for the control composition due to the fact that clinoptilolite exhibits its pozzolanic activity later in the hydration. In these later stages, pores with radii below 500 nm increased at the expense of larger pores. The change in the pore-size distribution between the first and sixth months of hydration occurs mostly in the mortars with added zeolite.

The Cu-triethylenetetramine-complex (Cutrien) is one of the commonly used index cations for CEC determination in clay science. Cutrien-exchanged smectites show basal spacings between 13.0 and 13.5 Å after correction for the Lorentz and polarization factors. The full width at half maximum (FWHM) of the d001 reflection is today related to the percentage of tetrahedral charge (beidellitic character) and/or to the Fe content of the smectites. The structural Fe content and the tetrahedral charge correlate, so their individual influence on d001 cannot be resolved. Nevertheless, the FWHM of Cutrien smectites should depend on the charge distribution rather than the Fe content.

X-ray diffraction (XRD) and water uptake capacity measurements showed that the interlayer of Cutrien-exchanged smectites does not swell any more, but can take up a few water molecules. Accordingly, the water uptake capacity of the external surface area can be determined independently from the interlayer water uptake capacity. Adjusting the pH of Cutrien-bentonite dispersion to different values allows for the determination of the variable charge.

In conclusion, Cutrien exchange of smectites appears to be suitable for the study of external surfaces area related phenomena (e.g. edge adsorption processes) without any influence of the interlayer region.

Bentonite is composed primarily of montmorillonite and is useful in a wide range of applications. This paper presents the results of an experimental investigation carried out to evaluate the possibility of using a Pakistani bentonite (from Jehangira, Swabi District) as a cement replacement material in mortar and concrete. The cement in mortar and concrete was replaced with the bentonite at 0%, 20%, 30%, 40% and 50% by cement mass. The strength activity index of bentonite was determined ‘as received’ (20ºC) and ‘heated’ (treatment at 500ºC and 900ºC). The test results indicated that the strength activity index of bentonite conformed to the ASTM Standard C618 specifications, except for the ‘900ºC heated’ bentonite. The water absorption decreased for mortar containing up to 30% bentonite and then steadily increased at higher bentonite loadings. When immersed in 5% Na2SO4 and 2% MgSO4 solution, the greatest compressive strength was observed for mortar containing 30% bentonite. The water demand of concrete increased with increasing bentonite content. Although the compressive strength of concrete decreased progressively as the substitution level of bentonite was increased, the compressive strength of concrete containing 30% ‘as received’ bentonite was found to be 70% of the control concrete, whereas for concrete containing 30% ‘500ºC heated’ bentonite, the strength was found to be 79% of the control concrete. It can be concluded that this Pakistani bentonite can be used to replace up to 30% of cement to produce concrete with sufficient compressive strength for low-cost construction resistant to sulphate attack.

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.

Rheological, porosimetric, and SEM studies of cements with additions of natural zeolites (chabazite, mordenite and clinoptilolite) were investigated. The addition of 5% zeolite to cement pastes had a plastifying effect. The increase in the rheological parameters of aqueous cement–zeolite suspensions began after additions of more than 10% zeolite. At a water/solid ratio (w/s) = 0.5 all compositions exhibited similar rheological behaviour for yield stress and maximum shear stress values. At lower w/s values the rheology depended on the zeolite used, decreasing in the order Sl (clinoptilolite, Nižny Hrabovec deposit, Slovakia), M (mordenite, Philipines), Bp (clinoptilolite, Beli Plast deposit, Bulgaria), NM (clinoptilolite, Saint Cloud deposit, New Mexico) and Ch (chabazite, Nasm Yan deposit, Korea).

After 28 days of hydration the mixtures containing 10% Bp clinoptilolite, mordenite, and Sl clinoptilolite (up to 30%) had unchanged specific pore volumes but additions of 10% and 30% of chabazite and NM clinoptilolite and of 30% mordenite and Bp clinoptilolite lead to increases in the total specific pore volume compared to the neat cement paste. Between the 28th and 180th days of hydration the specific volume of the pores in all the cement-zeolite pastes decreased due to the filling of the pores with products from the pozzolanic reaction between the zeolites and the hydration products of the cement.

The pozzolanic reaction between zeolite and the hydration products of cement is enhanced by the zeolite content in the samples and depends on the Si/Al ratio (clinoptilolite (Si/Al >4.5), mordenite (Si/Al >5), chabazite (Si/Al <2.5)) and the surface area (clinoptilolite from Slovakia has the smallest crystallites and, hence, the greatest reactive surface area).

The Hallaçlar kaolinite deposit of the Uşak Province (western Turkey) is hosted by dacite, andesite and siliceous materials of the Miocene Karaboldere volcanites. Mineralogical zonation, such as the prevalence of kaolinite at the centre of the deposit, coexisting with silica polymorphs such as quartz and cristobalite along with feldspar and hornblende, and a relative increase of smectite, illite, chlorite, and Fe-oxide/-hydroxide phases outward and upward, demonstrate that hydrothermal-alteration processes resulted in kaolinization. Micromorphologically, kaolinite occurs as pseudohexagonal blocky kaolinite with coarse-grained quartz in microfractures, and the presence of relatively fine-grained vermiform kaolinite that edges volcanic materials indicates that kaolinite developed in several phases coexisting with goethite, lepidocrocite, hematite, pyrite, jarosite, alunite, and gypsum/anhydrite with smectite in fractures. The highly crystallized Hallaçlar kaolinite is identified by: (1) sharp reflections at 7.23 and 3.57 Å, with triplet and doublet non-basal reflections; (2) sharp infrared spectral bands at 3687, 3651 and 3620 cm-1; (3) well defined, pseudohexagonal and hexagonal kaolinite crystal growth; (4) a chemical index of weathering of 98.6-100; and (5) SiO2/Al2O3 ratios between 1.04 and 1.45. Enrichment of Sr and depletion of Rb+Ba, Ti, and HREE relative to LREE, with a distinct negative Eu anomaly, are responses to the fractionation of feldspar and hornblende by the hydrothermal fluid; these results are also supported by the O- and H-isotopic character and formation temperatures of the Hallaçlar kaolinite and smectite; namely, 134.1-183.4°C and 65.6°C, respectively. The negative δ34S (-20.7‰) value of gypsum/anhydrite reflects its formation from geothermal-water-derived sulphur. Under the influence of a tectonically controlled hydrothermal process, feldspar, hornblende and volcanic glass were altered, resulting in the conservation of Al and depletion of Si, Na, Ca, K, Mg and Fe in an open hydrological system such that formation of kaolinite in the central part of the deposit under acidic conditions and development of smectite and illite upward and outward under basic conditions were favoured.

The aggregation of three cationic dyes (CD), crystal violet (CV), Nile blue (NB) and rhodamine B (RB) in aqueous solution was studied by visible absorption spectrophotometry and compared with methylene blue (MB). The distribution of the dye species (monomers, dimers, trimers, and tetramers) in aqueous solutions with different concentrations of dye was calculated using equilibrium stepwise aggregation constants Kn. These cationic dyes were intercalated into montmorillonite (SAz-1) and its reduced charge form (RC-SAz(210)) prepared by heating lithium montmorillonite (Li/SAz-1) at 210ºC. The fluorescence of fully saturated CD/SAz and low-CD loaded CD/RC-SAz(210) complexes was studied. Visible absorption spectra of CD aqueous solutions and visible absorption spectra and X-ray diffraction patterns (d001) of the CD/SAz and CD/RC-SAz( 210) solid complexes were obtained and evaluated. Large fluorescence intensities were found for CV/RC-SAz(210) and NB/RC-SAz(210) complexes in the same way as for the complex of methylene blue with reduced-charge montmorillonite MB/RCM(210) described previously.

The origin and distribution of late Maastrichtian–early Palaeocene clay mineral associations were investigated in the Tremp-Graus basin (South Pyrenees, Spain) to assess palaeoclimate changes during that period. The studied succession is made up of expanded continental and transitional terrigeneous and carbonate deposits accumulated in a coastal plain setting. X-ray diffraction, SEM-EDX and TEM-AEM analysis reveal that the main clay components are illite and smectite, but kaolinite, chlorite and illite-smectite mixed layers are present, although irregularly distributed, all of them showing a platy morphology typical of a detrital origin. Persistence of the chemical features of the Al-dioctahedral smectites throughout the whole succession demonstrates the persistence of the same source area during the interval studied. Palygorskite occurs in the late Danian and Selandian, within carbonate tidal flats as sabkha-like facies. In SEM images, the palygorskite displays straight fibre morphologies, both coating and branched curling out, a clear proof of authigenic origin.

Physical or chemical weathering (PhW/ChW) determined as illite + chlorite/smectite + kaolinite ratio, smectite/kaolinite ratio and palygorskite distribution have been used as clay proxies for palaeoclimate reconstructions. Such data suggest a shift from temperate subhumid (perennial) conditions in late Maastrichtian times to a warm seasonal climate during early Palaeocene times. This trend, however, was dramatically altered during the late Danian–Selandian interval, when prevailing warm and semi-arid to arid climatic conditions caused intense evaporation and the development of an alkaline environment in which the palygorskite authigenesis took place.

The proposed climatic trend partly concurs with that established for earliest Danian time by Domingo et al. (2007), also in the Tremp-Graus basin, from isotopic and geochemical proxies, as well as with the reconstruction of Cojan & Moreau (2006), in which a semiarid Danian phase for the near continental basin of Aix-en-Provence is postulated. However, it is at odds with the notion of a humid Danian state in the Pyrenees, as inferred by Gawenda et al. (1999) from clay mineral proxies of deep marine successions.

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.

The anthropogenic accidents in the world (including the underground emergency nuclear explosion at the site “Kraton-3” (Yakutiya) and also the recent Fukushima accident) resulted in significant environmental pollution by radionuclides, mainly long-lived 90Sr and 137Cs. One of the ways to solve this problem is the creation of “permeable reactive barriers” (PRBs). High selectivity of clinoptilolite-containing tuffs (CLT) towards Sr2+ and Cs+ radionuclides, together with their availability and reasonable cost, make possible their use as PRBs. The scales of the ion-exchange processes taking place on PRBs indicate the necessity of mathematical modelling. In this connection, Sr2+ and Cs+ ion-exchange sorption on Khonguruu CLT (Yakutiya) from solutions of various mineralizations was studied under equilibrium and non-equilibrium conditions. The physicochemical and mathematical models of the dynamic ion-exchange process and also the computer program considering both structural features of CLT (two-stage particle diffusion kinetics) and possible periodic interruptions of the process were developed. The breakthrough time of CLT as a geochemical barrier was calculated by such mathematical modelling.

Bentonite mixed with varying quantities of sand is currently of widespread interest as engineering liners for water containment and waste disposal. However, the alternative use of pumice, widespread in many volcanic regions, has been less studied and requires further characterization of geotechnical properties and performance prior to its extensive use. The objective of this study was to determine and compare the compaction and swelling characteristics of sandbentonite and pumice-bentonite mixtures using available geo-materials from Turkey. Standard Proctor compaction tests and constant volume swell tests were carried out using mixtures with four different bentonite contents (15, 20, 25, 30%) and three different sand and pumice grain size ranges (2.00–1.00; 1.00–0.50; 0.50–0.25 mm). The results indicate that pumice-bentonite mixtures have lower maximum dry unit weights, higher optimum moisture contents and greater swelling potentials than equivalent sand-bentonite mixtures. Important differences occur in the swelling potentials of the sand and pumice mixtures with respect to grain size whereby sand-bentonite mixtures show increased swelling with coarsening grain size, in contrast to the pumice–bentonite mixtures which showed a decrease. These differences are attributed to the amount of grain-size-dependent connected pore space that can be filled during bentonite expansion and the presence of dissolvable salts in the pumice. It is concluded that locally available pumice material could be used to replace sand in engineering bentonite seals, despite some differences in their geotechnical properties.

Production of kaolin for the paper-coating industry in the Brazilian Amazon region generates large amounts of waste, most of which is kaolinite. It is known that such materials can be used to synthesize zeolites. The use of kaolin waste for zeolite synthesis could, in principle, help social and economic development while providing valuable materials for industry. Additionally, there is a significant environmental appeal if such wastes could be used instead of new raw materials.

This study focused on the production of zeolite A. Samples of the raw material were first calcined (700ºC/2 h) to obtain metakaolinite for further reaction with NaOH solution. Different parameters were evaluated to optimize the synthesis conditions of zeolite A. The results showed that zeolite A with a large degree of structural order was generally obtained as the only zeolitic product. The following synthesis conditions were used: temperature 110ºC, time 24 h and a Na/Al ratio of 1.36. Hydroxysodalite was also obtained under specific conditions.

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.

The adsorption of methylene blue (MB) on montmorillonite from acid solutions has not yet been studied in detail. In this paper the adsorption of this dye on Ca/SAz montmorillonite from 0.32, 0.80 and 1.60 M HCl solutions at ambient temperature and after 2 hours leaching was carefully studied and evaluated. Under the above conditions the MB/SAz intercalates formed are practically insoluble. In contrast to the adsorption of methylene blue on montmorillonite from aqueous solutions, the adsorption from acid solutions consists of two adsorption waves. The intercalated samples from the first and second waves were studied using X-ray powder diffraction (XRD), FTIR, Vis spectroscopy, and scanning electron microscopy (SEM) equipped with a microprobe system. The adsorption of MB in the first wave is attributed to ion exchange of the dye cationic species (MB+, MB22+, H-aggregates, MBH2+ and H+) for the original interlayer cations of montmorillonite. The percentages of MBH2+ and H+ based on total adsorbed MB were estimated for varying HCl concentrations. The second adsorption wave is linked to the precipitation of MB species on the outer MB/SAz surface.

This paper presents results from comparative thermogravimetric, calorimetric and pozzolanic activity analyses of five natural zeolite samples from Bulgaria, Slovakia, Philippines, USA and North Korea. The zeolites actively participate in the hydration processes of cement. Their activity in the early stage of hydration is based mainly on the large surface area of the particles while, in the later stages of activation, chemical reactions occur between the products of the hydration of cement and the soluble SiO2 that is present in the bulk of the zeolites. It has been shown that in all cement pastes which contain zeolite additives, the quantity of portlandite is lower than that in pure cement paste or is even totally absent. The amounts of hydration products are greater when 30% zeolite is used than when 10% zeolite is added (excluding the sample with chabazite). The lowest pozzolanic activity is shown by chabazite, which possessed the lowest SiO2/Al2O2 ratio.

The Alto dos Quintos Mine, Rio Grande do Norte, northeast region of Brazil, is one of the few mines where a LCT (Li-Cs-Ta-enriched) pegmatite is exploited for the deep blue gemstone called “Paraiba Tourmaline (PT)”. Blue cuprian elbaite, a fault-bound pink montmorillonite bearing some relict apatite and newly-formed Ca-Al-phosphate of the Al-P-sulphate group (APS minerals) also occur in the underground mine. The montmorillonite was studied using extended clay mineralogical tools (XRD, IR spectroscopy, XRF, SEM-EDX, cation exchange capacity (CEC), DTA). The structural formula method for calculation of the smectite formula based on EDX data yielded an extremely Fe-poor montmorillonite: (Ca0.22+)(Al1.7Fe0.0Mg0.4)(Si3.8Al0.2). The charge on the tetrahedral sheets accounts for approximately 30% of the total permanent negative charge. However, based on the more precise Hofmann & Klemen test, tetrahedral charge values of 11% to 13% were calculated. This is indicative of the dominance of montmorillonite rather than beidellite among the smectite minerals, which is independently proved by a pronounced IR band at 630 cm-1. The formation of pink montmorillonite is not directly related to the emplacement of the Li-bearing PT pegmatite. The sheet silicate developed after a considerable hiatus (Mesozoic?), when the Neoproterozoic pegmatites had already undergone different stages of hypogene (cookeite) and supergene (illite, kaolinite) alteration, during which Li was flushed out to a degree that formation conditions of expandable Li-bearing phyllosilicates were no longer favoured. The nature of the pinkish tint is not yet clarified. The montmorillonite formed in a temperature regime close to 250°C, when apatite was transformed into Ca-bearing APS minerals under acidic conditions. Cainozoic volcanic activity and the reactivation of deep-seated fault zones are considered to be responsible for the formation of this pink P-bearing montmorillonitic clay.

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.

A binary ion exchange of cationic pairs involving K, Na, Ba and Ca in clinoptilolite was investigated calorimetrically. The selected cations included two pairs equal in charge and two pairs similar in size. The heats of ion exchange and the degrees of exchange were determined at 30 and 95°C. The data obtained are discussed with respect to cationic interactions in the clinoptilolite structure and hydration characteristics (heats of hydration and hydration numbers) of competing cations in the solution. No correlation was found between the heat effects and the degree of exchange. The heat of exchange depends mainly on the difference between the hydration heats of the cations in the solution, whereas the degree of exchange depends on their positioning over the extraframework sites in the clinoptilolite structure. The heats of ion exchange are lower at 95°C than those measured at 30°C, which is due to a decrease of the hydration number with increasing temperature. In all cases the degree of exchange increases with increasing temperature.

Hematite exists ubiquitously in soils and sediments, and is commonly aluminium (Al)-substituted. This study investigated systematically the effects of Al substitution on the visible diffuse reflectance spectrum (DRS) of hematite by using several sets of synthetic samples. We found that the position and amplitude of the characteristic absorption band of hematite (estimated from the first- and second-order derivative curves of the Kubelka-Munk remission function spectrum derived from the DRS) was significantly affected by the degree of Al substitution as well as by sample grain morphology. Therefore, there are ambiguities in quantifying the degree of Al substitution and the mass concentration of hematite using DRS. Nevertheless, if hematite forms under similar environmental conditions, it is possible to establish a transfer function between the DRS parameters and hematite concentration as discussed here for a Chinese loess-palaeosol sequence.