Kaolinite is a common gangue mineral in iron ore and sodium silicate has been used widely as a dispersant of silicate gangue minerals including kaolinite in various iron-ore flotation methods over a wide range of pH. Its actual dispersive effect on kaolinite under iron-ore flotation conditions has received very limited attention, however. The presence of hydrolyzable metal cations in process water further complicates sodium silicate—kaolinite interactions. In the present study, the dispersive effect of sodium silicate on kaolinite particles in distilled water as well as in CaCl2 and MgCl2 solutions was investigated systematically through electrophoretic mobility and colloid-stability studies. The studies were based on controlled pH, which eliminated the dispersive effect of sodium silicate induced by increasingpulp pH, in order to simulate the conditions of iron-ore processing. With pH controlled at constant levels, sodium silicate dispersed kaolinite only when positively charged sites were present on kaolinite surfaces and the zeta potential of kaolinite was more negative than ~−30 mV. Over the pH range from 5 to 10.5, a significant dispersive effect of sodium silicate was only observed at pH 7. In process water, when Ca and Mgwere present, the strong coagulation of kaolinite particles caused by the hydrolyzable metal cations could not be dispersed effectively with sodium silicate.

This research boarded on a novel initiative to replace the error-prone and labour-intensive process of converting Paper Nautical Chart (PNC) symbols to Electronic Navigational Chart (ENC) symbols with a more efficient and automated manner using Artificial Intelligence (AI). The proposed method applies the Convolutional Neural Network and YOLOv5 model to recognise and convert symbols from PNC into their corresponding ENC formats. The model's competence was evaluated with performance metrics including Precision, Recall, Average Precision, and mean Average Precision. Among the different variations of the YOLOv5 models tested, the YOLOv5m version revealed the best performance achieving a mean Average Precision of 0 ⋅ 837 for all features. A confusion matrix was used to visualise the model's classification accuracy for various chart symbols, underlining strengths and identifying areas for improvements. While the model has demonstrated high ability in identifying symbols like ‘Obstruction’ and ‘Major/Minor Lights’, it exhibited lesser accuracy with ‘Visible Wreck’ and ‘Background’ categories. Further, the developed graphical user interface (GUI) allowed users to interact with the artificial neural network model without demanding detailed knowledge of the underlying programming or model architecture.

Syntheses of Fe-, Co-, and Ni-containing Mg-Al-layered double hydroxides (LDHs) are described here because Fe, Co, and Ni represent the major constituents in steel containers used for storing spent nuclear fuel. Much evidence exists for the formation of LDHs during the corrosion of such containers under repository-relevant conditions. Because of their anion-exchange properties, LDHs can be considered as materials with the potential to retain and immobilize anionic radionuclides. Evaluation of the thermodynamic properties of LDHs is essential for reliable prediction of their behavior (solubility, anion exchange properties) in geochemical environments. The impact on the thermodynamic properties of the isostructural incorporation of divalent cations into the LDH was the main focus of the present study.

Mg-Al-Cl-LDH and the Fe-, Co-, and Ni-doped LDHs were synthesized by the co-precipitation method and then characterized (using powder X-ray diffraction (PXRD), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy energy-dispersive X-ray spectroscopy (SEM-EDX), and thermogravimetric analyses (TGA)).

The PXRD and EXAFS analyses indicated that all synthesized samples were pure LDHs where Co, Ni, and Fe were incorporated isostructurally. The EXAFS and XANES results demonstrated that Ni and Co were incorporated as divalent cations and Fe as a trivalent cation. Thermodynamic calculations were performed assuming an equilibrium state between aqueous solutions and corresponding precipitates after synthesis. The first estimates of the molar Gibbs free energies for Fe-, Co-, and Ni-containing LDHs at 70ºC were provided. The calculated Gibbs free energy of the pure Mg-Al-LDH (-3629 kJ/mol) was slightly less than those for Fe-, Co-, and Ni-containing compositions (-3612±50, -3604±50, -3593±50kJ/mol).

The purpose of this report is to describe the appropriate use of indices relating to crystallinity, such as the ‘crystallinity index’, the ‘Hinckley index’, the ‘Kübler index’, and the ‘Árkai index’. A ‘crystalline’ solid is defined as a solid consisting of atoms, ions or molecules packed together in a periodic arrangement. A ‘crystallinity index’ is purported to be a measure of crystallinity, although there is uncertainty about what this means (see below). This report discusses briefly the nature of order, disorder and crystallinity in phyllosilicates and discusses why the use of a ‘crystallinity index’ should be avoided. If possible, it is suggested that indices be referred to using the name of the author who originally described the parameter, e.g. ‘Hinckley index’ or ‘Kübler index’, or in honor of a researcher who investigated the importance of the parameter extensively, e.g. ‘Árkai index’.

Sticta canariensis is a lichen which is rare in all parts of its range in Atlantic Europe and Macaronesia, where it occurs in laurisilva forests, a habitat highly threatened by global change. Thus, this species is of high priority for inclusion in conservation programmes where genetic diversity should be considered. We have established new microsatellite loci and generated a dataset that demonstrates the genetic diversity of the lichen-forming fungus S. canariensis from eight locations across its disjunct range, in Macaronesia, Norway and England. We genotyped 25 microsatellite loci for 65 specimens and detected five genetic clusters which resemble major geographical divisions, specifically among the Macaronesian archipelagos. The total number of observed alleles ranged from 2 to 22. These are the first microsatellite markers developed for S. canariensis and they will be useful for population genetic studies and for conservation assessments.

Micaceous layer silicate clay minerals are attractive materials for applications involving non-linear optics because of their low cost and ability to form well ordered, platy aggregates, but such applications require precise knowledge of the dielectric behavior of the clay. The purpose of the present study was to use Terahertz time-domain spectroscopy (THz-TDS) to determine the dielectric properties of certain cleavable layered clay minerals, including muscovite, vermiculite, phlogopite, and biotite. The samples were characterized by X-ray diffraction and Fourier transform infrared spectroscopy as well as chemical analysis by Energy dispersive X-ray spectroscopy. The THz frequency window investigated was the far-infrared region of 3.3 to ∼40.0 cm−1 corresponding to 0.1 and 1.2 THz, respectively. The samples were selected so that the hydrated form of the interlayer cation, e.g. Mg2+ present in the interlayer gallery of vermiculite, could be compared to species such as phlogopite, biotite, and muscovite with the dehydrated form of interlayer cations such as K+ or Na+. The frequency-dependent complex index of refraction of these natural materials was determined to vary between 2.50 and 2.80. The presence of water in the interlayer space of vermiculite was reflected in the detection of increased values of the absorption index in comparison with the muscovite, phlogopite, and biotite.

The spatial distribution of the dominant matrix minerals present in the middle-Proterozoic Athabasca Group sandstone (kaolin, illite, sudoite, dravite, hematite) was studied at a regional scale in the Shea Creek region (Saskatchewan, Canada), in which two epigenetic unconformity-type uranium deposits have been discovered. 3D models of matrix mineral distribution were derived from normative mineral calculations and 3D interpolation using whole-rock geochemical analyses of sandstone samples collected from both mineralized and barren areas. The calculations were constrained by information obtained from petrographic and crystal-chemical clay mineralogical studies on representative samples. The 3D mineral distribution models were compared to the lithostratigraphy and structural features of the Athabasca Group sandstone to ascertain the source and mobility of the main elements involved in the sandstone host-rock alteration processes related to the U mineralization. The distribution of Al is conformable with the lithostratigraphy throughout the studied area, regardless of proximity to basement-rooted structures and U ore bodies. The distribution of illite displays similar features, but the intensity of the illitization of kaolin decreases with increasing distance from the structures and U ore bodies. Hematite bleaching and neoformation of sudoite and dravite were restricted to the vicinity of the fault zones above the U ore bodies. The spatial configurations of the mineral anomalies show that syn-ore fluids flowed from the basement towards the sandstone cover via the fault zones, as described in current metallogenic models. Although Al remained immobile (mass transfer), the anomalous K, B and Mg present in the host-rock alteration haloes were probably imported from the basement rocks (mass transport). Unlike B and Mg, K migrated laterally at least several kilometers from the basement-rooted faults. The mineral distribution models were used to quantify the volume of altered sandstone (10−2−10−1 km3) and the amounts of K, Mg and B which were imported to the alteration haloes above the Shea Creek U ore bodies: 186,000 t of K, 66,000 t of Mg, and 11,000 t of B above the Anne ore body, and 24,000 t of K, 185,000 t of Mg, and a similar 11,000 t of B above the Colette ore body.

Water is essential for humans, animals, and plants; pollutants, usually derived from anthropogenic activities, can have a serious effect on its quality. Heavy metals are significant pollutants and are often highly toxic to living organisms, even at very low concentrations. Among the numerous removal techniques proposed, adsorption onto suitable adsorbent materials is considered to be one of the most promising. The objective of the current study was to determine the effectiveness of halloysite nanotubes (HNT) functionalized with organic amino or thiol groups as adsorbent materials to decontaminate polluted waters, using the removal of Hg2+ ions, one of the most dangerous heavy metals, as the test case. The effects of pH, ionic strength (I), and temperature of the metal ion solution on the adsorption ability and affinity of both materials were evaluated. To this end, adsorption experiments were carried out with no ionic medium and in NaNO3 and NaCl at I = 0.1 mol L−1, in the pH range 3–5 and in the temperature range 283.15–313.15 K. Kinetic and thermodynamic aspects of adsorption were considered by measuring the metal ion concentrations in aqueous solution. Various equations were used to fit experimental data, and the results obtained were explained on the basis of both the adsorbent’s characterization and the Hg2+ speciation under the given experimental conditions. Thiol and amino groups enhanced the adsorption capability of halloysite for Hg2+ ions in the pH range 3–5. The pH, the ionic medium, and the ionic strength of aqueous solution all play an important role in the adsorption process. A physical adsorption mechanism enhanced by ion exchange is proposed for both functionalized materials.

Bentonite, biotite, illite, kaolin, vermiculite and zeolite were acidified or alkalized with hydrochloric acid or sodium hydroxide at concentrations of 0.1, 1.0 and 5.0 mole dm−3 at room temperature for two weeks. In acid treatments, dissolution of Al prevailed over Si and the opposite was observed in alkali treatments. The XRD patterns showed severe alteration of the crystal structure after acid treatments, whereas sharpening of the XRD peaks after alkali treatments was observed. Illite and kaolin were most resistant to acid attack. with a few exceptions, the surface areas of the minerals computed from both water and nitrogen adsorption isotherms increased with acid and alkali treatments. with increasing reagent concentration, the nitrogen surface area increased faster than the water surface area. well-defined trends were not noted in either changes of average water or nitrogen adsorption energies or in relative amounts of adsorption sites, indicating that the effects of acid and alkali attack are controlled by the individual character of the minerals.

Dioctahedral phyllosilicates from an altered rhyolitic hyaloclastite located at Ponza Island, Italy, were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The samples are from a sequence previously characterized by X-ray diffraction (XRD) methods, indicating that a complete range of illitization accompanies alteration. Backscattered electron (BSE) images, obtained from ion-milled samples, show that samples partly retain the original textures since clay minerals pseudomorph lapilli fragments and preserve vesicular texture. The lowest-grade sample studied contains obsidian clasts partially replaced by smectite. As the alteration grade increases, illitization proceeds with formation of interstratified illite-smectite (I-S), zeolites, illitic phases, feldspars and quartz. The most altered sample contains illite, mica and quartz. Lattice-fringe images show that following the formation of smectite, illitization takes place through the formation of (R=1) I-S, highly illitic I-S and illite with mica; (R=1) I-S is the only ordered interstratified I-S. The BSE and TEM images of Ponza samples show irregular cavities filled with euhedral dioctahedral clay minerals and the zeolite mordenite, providing direct evidence for neocrystallization from a fluid. Chemical compositions by analytical electron microscopy (AEM) support the sequence described. Selected area electron diffraction (SAED) patterns indicate the predominance of 1 Md polytypism both in I-S and illitic phases, and the coexistence in the more altered samples of 1Md illite and a 2-layer mica polytype (probably 2M1), without the intermediate 1M polytype generally assumed to exist in prograde sequences. Previous XRD studies indicated progressive change from cis-vacant, turbostratically stacked smectite, to interstratified cis- and trans-vacant, 1Md I-S, to trans-vacant, 1M illite, and then to 2M1 illite in Ponza Island samples. We observed a clear correlation between the chemical compositions as determined by AEM and the proportion of cis-vacant determined by XRD, suggesting that the octahedral cation distributions change in the studied samples with increasing degree of illitization.

The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informally known as grit) of the mined Georgia kaolins are potential and significant sources of the rare-earth elements (REE). The abundances and provenance of the REE signature have not been studied extensively for the Georgia kaolins. The objective of the present study was, therefore, to define the contribution of these heavy minerals (e.g. zircon) to the REE inventory of the coarse fractions of Georgia kaolins. Heavy-mineral subfractions separated from the coarse fractions contained 1647 mg/kg REE from the Jeffersonville Member of the Lower Tertiary Huber Formation and 5012 mg/kg REE from the Buffalo Creek Kaolin Member of the Upper Cretaceous Galliard Formation, respectively. These heavy-mineral subfractions were enriched 10–100 times in the heavy rare-earth elements (HREE, Gd—Lu,), Hf, and Zr relative to the concentrations of these elements in Upper Continental Crust. The heavy-mineral subfractions comprised 5% of the coarse fractions (grit) of these two kaolin-producing formations. The heavy-mineral subfractions consisted of zircon, anatase, rutile, kaolinite, and minor amounts of muscovite, trace ilmenite, and staurolite. The large concentrations of REE were obtained by separating the dense heavy minerals from the coarse fraction (grit) obtained during the typical production of kaolin-group minerals (kaolinite) from kaolin ore. The amount of zircon (estimated from the 6–11 wt.% Zr) and the absence of monazite did not explain the high concentrations of REE in the heavy-mineral subfractions. The large amounts of REE could have resulted from the sorption of REE released during weathering reactions, or from the presence of small amounts (0.025 wt.%) each of monazite and xenotime in addition to the presence of zircon. This heavymineral subfraction represented a novel domestic resource of extractable REE, especially the HREE, of a grade as high as 0.50 wt.% total REE.

Ruthenium compounds are highly toxic and carcinogenic. In the present study, clinoptilolite was used in the removal of Ru species from aqueous solutions. Clinoptilolite is a good choice of sorbents because it is naturally abundant and therefore cheap. After the process where Ru was removed from the aqueous solution, the clinoptilolite was characterized by X-ray diffraction, X-ray fluorescence, thermogravimetric analysis, and Fourier-transform infrared spectroscopy techniques. The influence of pH, contact time, and temperature on the adsorption of Ru was investigated and the optimum conditions were found to be 2 h of contact time and pH = 2. Pseudo first-order, pseudo second-order, Elovich, and intra-particle diffusion models were used to analyze the adsorption-rate data. The pseudo second-order model was found to be the best kinetics model in terms of matching the experimental results obtained. Adsorption isotherms were constructed to assess the maximum adsorption capacity of clinoptilolite. The Langmuir model fitted the data reasonably well in terms of regression coefficients. Adsorption studies were also performed at different temperatures to calculate the thermodynamic parameters. The numerical value of ΔG0 decreased with increasing temperature, indicating that adsorption is favored at higher temperatures. The positive values of ΔH0 corresponded to the endothermic nature of the adsorption processes. The proposed method of removal is applicable at an industrial scale.

Most of the world's sepiolite-palyg orskite precipitates in lacustrine and perimarine environments. Although these minerals can transform from precursor minerals, the most common formation mechanism involves crystallization from solution. In this study, equilibrium activity diagrams are calculated for sepiolite-palygorskite in the seven component system MgO-CaO-Al2O3-SiO2-H2O-CO2-HCl, employing available thermodynamic data for related minerals, aqueous species and water. Stability fields are illustrated graphically on plots of log $[a_{{\text{Mg}}^{2+}}\text{/}{(a_{{\text{H}}^{+}})}^2]$vs. log $[a_{{\text{H}}_{\text{4}}{\text{SiO}}_{\text{4}}}{}^{\text{o}}]$, using the activities for log $[a_{{\text{Al}}^{3+}}\text{/}{(a_{{\text{H}}^{+}})}^3]$ defined by an arbitrarily chosen value and the approximate saturation limits of pyrophyllite + amorphous silica, kaolinite + amorphous silica, kaolinite + pyrophyllite, pyrophyllite + quartz and gibbsite. The formation of sepiolite-palygorskite from solution is more favored in the presence of amorphous silica than quartz. Lower aqueous aluminum activities favor the non-aluminum phases sepiolite and kerolite relative to the aluminum-containing phases palygorskite and saponite. The stability ranges of worldwide associations of magnesite and dolomite with sepiolite and palygorskite are also illustrated as a function of aluminum activity.

Salt solutions have complex effects on the swelling characteristics of compacted bentonite; these effects are caused by the inhibitory action of salinity and the ion-exchange reaction between the solution and bentonite. In order to characterize the swelling properties of compacted bentonite in a salt solution, swelling deformation tests were carried out for Gao-Miao-Zi (GMZ) bentonite specimens in NaCl and CaCl2 solutions. Swelling characteristics decreased with increasing salt concentration. Swelling strains in NaCl solution were larger than those in CaCl2 solution, even though the ionic concentration of 1.0 mol/L (M) NaCl solution is larger than that of 0.5 M CaCl2. According to the exchangeable cations tests, cation exchange was different for specimens immersed in different salt solutions. The swelling fractal model was used to predict the swelling strains of compacted bentonite in a concentrated salt solution. In this model, the effective stress incorporating osmotic suction was applied to take the effect of salinity into consideration, and the swelling coefficient, K, was employed to describe the swelling properties affected by the variation in exchangeable cations. In the model, fractal dimension was measured by nitrogen adsorption, and the salt solution had little effect on fractal dimension. K was estimated by the diffuse double layer (DDL) model for osmotic swelling in distilled water. Comparison of fractal model estimations with experimental data demonstrated that the new model performed well in predicting swelling characteristics affected by a salt solution.

The adsorption and photolysis of the herbicide bensulfuron-methyl [2-(4, 6-dimethoxypyrimidm-2-carbamoylsulfamoyl)-o-toluic acid methyl ester] on homoionic Na+-, Ca2+- and Fe3+-montmorillonite and kaolinite clays were studied. The Freundlich adsorption coefficient, Kf, measured from isotherms on clays followed the order Na+ < Ca2+ < Fe3+. Montmorillonite showed a greater adsorptive capacity than kaolinite. Analysis of Fourier transform infrared spectra of bensulfuron-methyl adsorbed on clay suggested probable bonding interactions between bensulfuron-methyl and homoionic clays. The photolysis rate of herbicide adsorbed on homoionic clay surfaces was quite slow to its free state and decreased in the order Na+ > Ca2+ > Fe3+, indicating that adsorption may have prevented photolysis.

This work presents Atomistic Topology Operations in MATLAB (atom), an open source library of modular MATLAB routines which comprise a general and flexible framework for manipulation of atomistic systems. The purpose of the atom library is simply to facilitate common operations performed for construction, manipulation, or structural analysis. Due to the data structure used, atoms and molecules can be operated upon based on different chemical names or attributes, such as atom- or molecule-ID, name, residue name, charge, positions, etc. Furthermore, the Bond Valence Method and a neighbor-distance analysis can be performed to assign many chemical properties of inorganic molecules. Apart from reading and writing common coordinate files (.pdb, .xyz, .gro, .cif) and trajectories (.dcd, .trr, .xtc; binary formats are parsed via third-party packages), the atom library can also be used to generate topology files with bonding and angle information taking the periodic boundary conditions into account, and supports basic Gromacs, NAMD, LAMMPS, and RASPA2 topology file formats. Focusing on clay-mineral systems, the library supports CLAYFF (Cygan, 2004) but can also generate topology files for the INTERFACE forcefield (Heinz, 2005, 2013) for Gromacs and NAMD.

Fired bricks were valued as essential building materials in the central tradition of Byzantine architecture in Constantinople (İstanbul), Anatolia, and the Balkans. In this study, Byzantine bricks from three construction periods, covering nearly nine centuries (fifth–fourteenth centuries), of Anaia Church (Kadıkalesi) in Western Anatolia were investigated to determine their characteristics, raw material properties, and production technologies. The characteristics of the bricks were evaluated and compared in order to identify similarities and differences between the periods and to investigate the continuity of the tradition of brick production over centuries. Basic physical and colorimetric properties, chemical and mineralogical compositions, thermal behavior, and microstructural and mechanical properties of bricks were determined by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (SEM–EDS), Fourier-transform infrared spectrometry (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and mechanical tests. The results indicated that all the bricks in the Anaia Church were brown-beige colored, highly porous, low-density materials with low mechanical strength. They were produced from Ca-rich clays, probably obtained from two different sources used during all construction periods. The mineralogical composition and thermal properties revealed that the bricks from the first and second periods were fired at between 800 and 900°C and the bricks from the third period were fired at < 850°C. Greater calcium content and firing temperatures were found to reduce the total porosity and the number of small pores (< 10 μm) and increase the mechanical strength of the bricks. The results of the study revealed no significant differences in the production of bricks, including raw material sources and kiln conditions, for the different construction periods of the church.