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A kind of layered Li2MSiO4 material, Fe saponite with Na+ pillaring (Na+-FSAP) was developed as a low-cost and environment-friendly lithium-ion storage material. The Na+-FSAP follows the insertion/deinsertion working mechanism accompanied by valence change of Fe from Fe1.86+ to Fe2.71+ (average value) after stabilization, and displays a specific capacity of 125 mAh g–1 at 50 mA g–1 with retention ratio of 80.8% after 75 cycles. The Na+-pillaring effect and abundant structural water in the gallery urge Li+ migrate rapidly, resulting in a large Li+ diffusion coefficient within a range of 10−6.5–10−7.5 cm2 s−1. Thus, the Na+-FSAP provides a model material to design electrode materials with rapid lithium-ion migration and has great potential to take place of polyanionic-type Li2MSiO4 (M = Mn, Fe, Co) cathode materials.

The presence of hydrous minerals in carbonaceous chondrites has been considered as an important evidence for the former presence of liquid water in parent asteroids. However, the evolution of water–rock reactions in hydrous asteroids remains not well constrained. Here, we conduct water–rock type experiments and chemical equilibria calculations under low-temperature hydrothermal and reducing conditions to investigate the alteration process and secondary mineral assemblages of chondritic rock in the earliest alteration stage. Using synthetic chondrite (mixtures of olivine (forsterite95), orthopyroxene (enstatite95), silicate glass, troilite and Femetal) as a starting material, our experiments were conducted at temperatures of 25°C–80°C for time periods between 1 to 460 days at a water-to-rock mass ratio of 10. A combination of X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses revealed that the primary secondary phases consisted of pyrrhotite, an amorphous SiO2-rich phase and saponite at 80°C, while the secondary phase consisted of an amorphous SiO2-rich phase and saponite at 25°C. At both temperatures, the SiO2-rich phases and saponite densely covered the surface of the primary phases. The Fe/Mg ratios of saponite and amorphous SiO2-rich phases showed clear difference between 80°C and 25°C. Saponite that was formed at 80°C was richer in Fe than the initial silicate phases, and the highest Fe/Mg ratios were obtained in the saponite encrusting the troilite and Femetal. These results suggest that the Fe distributed from the troilite and Femetal induced the formation of Fe-rich saponite. Some of the secondary minerals observed from our alteration experiments were consistent with those expected by chemical equilibria calculations. However, the formation of serpentine, the dominant secondary mineral expected from chemical equilibria calculations, was not observed in our experiments up to 460 days, probably because the preferential dissolution of SiO2-rich silicate glass in the earliest stage of alteration induced the formation of saponite rather than serpentine. The secondary mineral assemblage and its morphological characteristics, as observed by our alteration experiments, showed similarities with carbonaceous chondrites such as CM2 and CO3 chondrites. This alteration might be explained by water–rock reactions at low temperatures and by the short time alteration. These findings better constrain the temperatures and timescales of aqueous alterations in hydrous asteroids, as well as the role of water in the early solar system bodies.

Surface-fixation induced emission is a fluorescence enhancement phenomenon, which is expressed when dye molecules satisfy a specific adsorption condition on the anionic clay surface. The photophysical behaviors of two types of cationic acridinium derivatives [10-methylacridinium perchlorate (Acr+) and 10-methyl-9-phenylacridinium perchlorate (PhAcr+)] on the synthetic saponites with different anionic charge densities were investigated. Under the suitable conditions, the fluorescence quantum yield (Φf) of PhAcr+ was enhanced 22.3 times by the complex formation with saponite compared to that in water without saponite. As the inter-negative charge distance of saponite increased from 1.04 to 1.54 nm, the Φf of PhAcr+ increased 1.25 times. In addition, the increase in the negative charge distance caused the increase in the integral value of the extinction coefficient and the radiative deactivation rate constant (kf) and the decrease in the nonradiative deactivation rate constant. It should be noted that the 2.3 times increase in kf is the highest among the reported values for the effect of clay. From these results, it was concluded that the photophysical properties of dyes can be modulated by changing the charge density of clay minerals.

Their drawback can be explained by the high cost and regeneration complexity. That is why the usage of natural sorbents (Tashkiv saponite deposits, Khmelnitsky region). They are able to clean contaminated water from colloidal, molecular and ionic substances. Exploring the specified topic, physicochemical properties of various forms of saponites are studied; the area of their usage is defined. The paste for cleaning contaminated surfaces is developed on their basis. The research results have shown that the most effective method is to use natural saponite. The author of the article advises to conduct preliminary acid activation of clay minerals and modification of its surface multivalent metal salts. Saponite clay granulate is obtained with different time and sintering temperature. Granulation is shown to improve the strength and filtration characteristics of natural sorbents, increasing the filtration rate and the duration of the filter cycle. The influence of the granulation process on the sorption properties of the obtained granulated aluminasilicates is investigated. A detailed hydrocarbon analysis of the A-92 starting gasoline is carried out. The composition of the purified samples of the hydrocarbon mixture is evaluated with gas chromatography using saponite granulate (Octane rating = 94,013 according to the method of research) under static conditions. The structure changes of raw and acid activated saponite clay has been investigated by nitrogen adsorption method and scanning electron microscopy. Established that the porous structure of saponite clay mineral represented by micro-meso porous system with domination of micropores. Acid modification promotes the development of specific surface area (from 47,7 m2/g to 177,9 m2/g) and increase the total volume of pores (from 0,134 cm3/g to 0,201 cm3/g).

Immobilization of poly[8-methacroyloxy-quinoline] on a natural saponite surface immediately after polymer formation has been performed. The adsorption properties of the modified adsorbent with resp...

The influence of increasing the waste loading of Ca- and Zn-containing MW high-level-waste glass, from 20 to 35 wt%, on the chemical durability was investigated using 112-day PCT-B tests at 90 °C in ultra-high-quality water. During the initial stage of dissolution, from 0 to 3 days, increased waste loadings corresponded to reduced boron dissolution rates. By 112 days, however, there was no difference in the normalised mass loss of boron as a function of waste loading, within experimental uncertainty. In comparison to literature values obtained for traditional MW high-level-waste glasses, containing no Ca and Zn, the boron dissolution rates of CaZn MW glasses in the residual stage of dissolution, > 28 days, were greater by at least an order of magnitude. Analysis of secondary phases, combined with geochemical modelling of the solutions, indicate that the dual formation of Mg- and Zn-smectite phyllosilicate clays, potentially saponite (Ca0.2Mg3(Si,Al)4O10(OH)2·4H2O) and sauconite (Na0.3Zn3(Si, Al)4O10(OH)2·nH2O), respectively, may be the cause of this enhanced dissolution.

We provide the first detailed analysis of the carbonaceous chondrite Dhofar (Dho) 1988. This meteorite find was recovered in 2011 from the Zufar desert region of Oman and initially classified as a C2 ungrouped chondrite. Dho 1988 is a monomict breccia composed of millimetre-sized clasts, between which large (∼50–250 µm) intermixed sulphide-Ca-carbonate veins formed. It has high sulphide abundances (∼14 vol%), medium-sized chondrules (avg. 530 µm, N = 33), relatively low chondrule/CAI abundances ( Dho 1988 experienced advanced aqueous alteration [petrologic subtype 1.3 in the scheme of Howard et al. (2015)]. Alteration style and extent are similar to the CM chondrite group, with the matrix having been replaced by tochilinite-cronstedtite intergrowths and chondrules progressively pseudomorphed by phyllosilicates, sulphides and in one instance Ca-carbonates. However, departures from CM-like alteration include the replacement of chondrule cores with Al-rich, Na-saponite and upon which Cr-spinel and Mg-ilmenite grains precipitated. These late-stage aqueous alteration features are common among the CY chondrites. Fractures in Dho 1988 that are infilled by phyllosilicates, sulphides and carbonates attest to post-brecciation aqueous alteration. However, whether aqueous alteration was also active prior to brecciation remains unclear. Veins are polymineralic with a layered structure, allowing their relative chronology to be reconstructed: intermixed phyllosilicate-sulphide growth transitioned to sulphide-carbonate deposition. We estimate temperatures during aqueous alteration to have been between 110 °C Dho 1988 was later overprinted by thermal metamorphism. Peak temperatures are estimated between 700 °C and 770 °C, based on the thermal decomposition of phyllosilicates (both serpentine and saponite) combined with the survival of calcite. As temperatures rose during metamorphism the thermal decomposition of pyrrhotite produced troilite. Sulphur gas was liberated in this reaction and flowed through the chondrite reacting with magnetite (previously formed during aqueous alteration) to form a second generation of troilite grains. The presence of both troilite and Ni-rich metal in Dho 1988 (and other CY chondrites) demonstrate that conditions were constrained at the iron-troilite buffer.

The fine fraction of clay from Tagaran (TC) was characterized with X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Fourier-Transform Infrared Spectroscopy (FT-IR) and compared with the fine fraction of Topkhana clay (TPC). Both, TC and TPC were dominated by a trioctahedral swelling clay mineral (saponite). The use of TC was investigated for the adsorptive removal of methylene blue (MB) from blood film preparation washing waste of medical laboratory and undergraduate microbiology laboratory wastewater of the University of Sulaimani. The effect of initial pH of the dye solution was negligible at the studied range of dye concentration. The optimum adsorbent (TC) dose was 5 g/L for 50 mg/L of MB with an optimum equilibration time of 120 minutes. Adsorption isotherms were fitted to Langmuir and Redlich-Peterson isotherms by non-linear regression method. Pseudo-second-order kinetics best describe the analytical results. The thermodynamic parameters confirmed spontaneous endothermic adsorption. The study showed that local clays can be used to clean MB contaminated wastewaters.

The effect of copper on various acid saponite supported Ni–Cu bimetallic catalysts, prepared with different Ni : Cu ratios, was studied for the liquid phase hydrogenolysis of glycidol on a batch reactor at 393 and 453 K. Characterization of the catalysts showed that Ni and Cu are in close contact as the XRD measurements evidenced the formation of an alloy. H2 chemisorption results revealed that the measured metallic area progressively decreased with an increase in the wt% of copper. In the presence of high metal activity (higher Ni wt%), the formation of 1,2-propanediol (1,2-PD) outweighed, while acid activity led to the formation of dimerization and oligomerization products. The addition of Cu and the increase of the reaction temperature decreased the diol formation but boosted the 1,3-PD/1,2-PD ratio. This could be explained by an improvement of the collaborative effect between the metal Ni and the H+ of the saponite. Therefore, the presence of an appropriate amount of Cu allowed the control of the hydrogenation capacity of Ni and enhanced the collaborative effect of Ni and H+ favouring the formation of 1,3-propanediol with respect to 1,2-propanediol.

The adsorption properties of electrochemically and thermally modified saponite relative to heavy metals are analyzed. The tests have found the efficient use and regeneration parameters of the sorbent to ensure maximized adsorption of cations of heavy metals and to enable production of pregnant solutions with high concentrations of heavy metals.

The issue of grinding saponite–titanium composites has not been considered in the machine building industry yet. The reason is that the chips are stuck on the working surfaces of abrasive tools made of silicon carbide and electrocorundum. This is due to the high adhesive activity at operating cutting temperatures between the composite and traditional abrasives. The article aims at studying the grinding of saponite–titanium composites using abrasive tools in various cutting modes based on parametric and non-parametric statistical methods. To solve this problem, high porous wheels (HPW) made of cubic boron nitride CBN30 with 100 % concentration on a bond V (K27), a pore-forming KF40, varied grains: B76, B126, B151 (ISO 6106:2013) – and hardness: M and O (ISO 525:2013) were used to grind saponite–titanium composites. Additionally, the Norton wheels from green silicon carbide with a normal porosity 39C (46; 60) K8 VK and with different grain size were tested. Norton wheels provide reduction of roughness height by 1.4–1.5 times in comparison with boron nitride HPW. These are recommended for the finishing grinding stage and HPW CBN30 – the preliminary to reduce the thermal effects on composites. By processing stability, the Norton wheels with grain 46 rank first, and among boron nitride HPW – CBN30 B76 100 OV K27–KF40.

The article presents the results of diamond prospecting studies in the Subotska structure of the Inhulskyi megablock of Ukrainian Shield. For the results, it is indicated that the Subotska structure is mimicked by crater rocks and in some cases by manifestations of the vent facies with signs of kimberlitic-lamproitic magmatism. The typical local features of manifestations of explosive structures from maar volcanism in Subotska area are determined. The article presents the results of petrographic and mineralogical study of the core material from exploratory wells on the Subotska structure, the results of study of material composition of the clay fraction, X-ray diffraction analysis of the pellet fraction. Data of the X-ray structural analysis of the pellet fraction of samples taken from the core material from exploratory wells on the Subotska structure indicates the obvious mechanical sum, the head folder of such is calciferous montmorilonite, and also saponite, nontronite, hydromica and kaolinit. The availability of the nontronite and saponite is confirmed by the results of electronic-microscopic reports. Also the article presents the results of studying the secondary lithochemical halos of Cr, Ni, Mg, Co, Ti, V, Fe, covering the geochemical spectrum inherent in alkaline-ultrabasic rocks and their weathering crust. These halos are combined with negative gravitational anomalies associated with the explosive structures in the Subotska area. The structural control of the great part of the detected geochemical anomalies, geochemical halos are determined. According to the degree of manifestation of the complex of criteria five potential diamond-prospective structures are discovered on the Subotska area. There were developed recommendations for further research on the Subotska area.

Several procedures for hydrothermal synthesis of saponite can be found in the literature. They differ in terms of the preparation conditions of the precursor and of the synthesis temperature. The objective of the present study was to investigate how these two parameters influence the structure of the final synthesis product. The precursor was prepared from Mg(NO3)2, Al(NO3)3, and Na4SiO4 in three different ways: as a gel, a dried gel, and a calcined gel. The influence of the synthesis temperature on the structure of saponite was investigated in the range 90–200°C. The results showed that the use of a calcined precursor yielded a single mineral phase, saponite, with up to 90% aluminum in tetrahedral configuration. In comparison, the use of a gel precursor resulted in a product with only 60% aluminum in the tetrahedral configuration. The synthesis temperature had no significant effect on the saponite structure. The reported synthesis method showed the possibility of obtaining saponite with superior characteristics, in terms of crystallinity, surface acidity, and thermal stability compared to the natural mineral, even at 90°C, and thus with greater potential for industrial application.

Advanced water supply systems for industrial enterprises represent complex facilities that include the supply of fresh water and its preparation for the process, treatment, decontamination and disposal of waste water, disposal of the resulting residue, and often the organization of a closed water cycle. Designing and operating such facilities is a complex technical and environmental task, which must be solved using the best available technologies. The management system for the drainage waters generated in diamond mining at the Lomonosov GOK of PJSC Severalmaz in the Arkhangelsk Region is a typical example. The precipitation indicators for the suspension in the drainage water were established using the traditional coagulants of aluminum sulfate and hydroxochloride, as well as an experimental sample of a calcium-aluminosilicate inorganic precipitator. The results of experiments with different coagulant dosages were used to establish the average and effective precipitation rate, the residual aluminum content in the water, acidity and turbidity of the clarified drainage water. The results obtained allow substantiating the higher efficiency of the experimental coagulant in terms of the water clarification rate and the possibility of meeting the sanitary standards for water discharge into natural water bodies envisaged by SanPiN 2.1.5.980-00. The work was carried out with the financial support of the Russian Science Foundation under Agreement No. 18-19-00577 dated April 26, 2018, on the provision of a grant for fundamental and exploratory research.

Because they are so widespread, the use of saponites is significant in many industries. The modification of saponite-rich clay minerals is known to improve their existing characteristics and may provide new functional properties. The objective of the present paper was to characterize the effects of adding nanosized graphene-like molybdenum (Mo) and tungsten (W) sulfides on the textural and surface characteristics of composites based on native saponite and saponite pre-modified with nanoscale magnetite. The textural characteristics were investigated by the nitrogen adsorption-desorption method and scanning electron microscopy. The total acidity, Hammett Bronsted centers, and Quasi-Equilibrium Thermo Desorption (QE-TD) Lewis centers were characteristics used to probe the acid-base properties of the modified composites. In all cases, modification proved to have a significant effect on both the surface and textural properties of the clay matrix. Modification of the native saponite by graphene-like Mo and W sulfides resulted in a decrease in the specific surface area, except a slight increase in the surface area of the magnetite-containing saponite was observed. Analysis of the acid-base characteristics of native and magnetite-modified saponite (MMS) indicated the ability of modified MoS2 and WS2 additives to alter the acid-base state of the surface. The addition of graphene-like Mo and W sulfides increased the total acidity of native and MMS, with MoS2 modification being more promising because, in almost all the samples, saponite composite materials increased the number of both Bronsted and Lewis active centers compared with WS2, which was determined by the corresponding methods. The acid-base characteristics of the saponite-containing samples, which were studied in an aqueous medium by various methods, are in good correlation with each other, and are consistent with the sorption activity of cationic and anionic dyes.

The cultivation of Bacillus subtilis ІМV B-7023 in Spizizen medium, containing 1 g/L of bentonite or saponite stimulated the growth of these bacteria. The addition of 0.1–1 mM of Mn2+ ions to this medium resulted in increasing the number of bacteria. The cultivation of bacilli in the medium with similar concentrations of ferrum ions without NP`s had insignificant impact on their growth. However, the addition of 1 g/L of saponite to this medium led to considerable biomass increase, whereas bentonite had almost no impact on this value. The cultivation of B. subtilis bacteria in the medium, containing Mn2+ ions, resulted in nigligible increase in superoxide dismutase (SOD) activity. The addition of saponite and especially bentonite led to the considerable stimulation of SOD activity. The introduction of ferrum ions to the medium stimulated SOD activity of this strain, which maximum values amounted at the concentration of 1.5 mM Fe2+.

This study investigated the adsorption of a non-ionic water-insoluble organic molecule (meso-tetraphenylporphyrin, TPP) on a trioctahedral layered aluminosilicate (saponite, SP) in organic solvents...

the paper shows the possibility of producing a thermal insulating composite based on basalt fibers and sapo-nite-containing mining waste. A method for manufacturing thermal insulating composites from hydro-mass with different contents of the mixture components is proposed. Basalt fibers were used as a filler, and pre-mechanoactivated saponite-containing material (SCM) was used as a binder. It was found experimentally that depending on the composition of composites, the coefficient of thermal conductivity varies from 0.1109 to 0.1342 W/(m•K), and the compressive strength – from 0.45 to 0.93 MPa. In addition, it was found that thermal modification of composites at temperatures up to 1200°C significantly (up to 3 times) increases the compressive strength of composites, while not affecting the coefficient of thermal conductivity. The ex-periments to determine the conductivity of the composite “basalt fiber – SСM” depending on its moisture content showed that the obtained composite is characterized by intense and linear increase in the values of conductivity when the humidity of the sample to 12% and further increase in humidity practically does not change the values of the coefficient of thermal conductivity. Comparison of the studied thermal insulation composite with known structural thermal insulation materials in terms of its thermal insulation and strength characteristics showed that it is comparable to gas and foam blocks. It should also be noted that this material is environmentally safe and can withstand high temperatures without collapsing.

Although clays are crucial mineral phases in Earth's weathering engine, it is unclear how they form in surface environments under (near-)ambient pressures and temperature. Most synthesis routes, attempting to give insights into the plausible mechanisms, rely on hydrothermal conditions, yet many geological studies showed that clays may actually form at moderate temperatures (< 100 deg. C) in most terrestrial settings. Here, we present the mechanism of the low-temperature (25-95 deg. C) crystallization of a synthetic Mg-clay, saponite. We describe the pathway at the various sub-stages of the reaction, as we derived from high-energy X-ray diffraction, infrared spectroscopy and transmission electron microscopy data. Our results reveal that saponite crystallizes via a two stage process: 1) a rapid (several minutes) co-precipitation where ~20% of the available magnesium becomes incorporated into an aluminosilicate network followed by 2) a much slower crystallization mechanism (many hours to days) where the remaining magnesium becomes gradually incorporated into the growing saponite sheet structure., manuscript + supporting information

Green conversion in organic synthesis is one of the interesting and important topics in green chemistry. The use of heterogeneous catalysis instead of homogeneous catalysis offers some advantages, such as easy separation and reusability. In this research, a heterogeneous acid catalyst was prepared from saponite by immobilizing ZnO in the form of a pillared clay (Zn/PILS) and Zn supported on porous clay heterostructure (Zn/PCH). Physicochemical studies involving X-ray diffraction measurement, surface analysis using a gas sorption analyzer, and surface acidity measurement were performed. Results indicated that the increasing surface acidity and the high specific surface area of the material were the relevant physicochemical properties that facilitate environment-friendly citronellal cyclization. The higher values for both parameters in Zn/PCH than in Zn/PILS linearly affected citronellal conversion and the selectivity for isopulegol production. Zn/PCH demonstrated a conversion rate of 98.9% for a 3-hour reaction and a selectivity of 100% for isopulegol production, and it exhibited reusability properties. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The paper describes the results of vibrational molding and proposes a process for producing a gradient filtering material from stainless steel and saponite powders by vibrational segregation. Methods of theoretical and analytical mechanics, oscillation theory, vibrational mechanics, experimental design theory, and computer simulation were used. The surface and microstructure of the samples were examined and their density across the thickness was determined by metallographic analysis using a Micro Optic MMP-4 microscope with the Smart-Eye software. The structural properties and the concentration of the key mixture component were examined throughout the sample height with the ImageJ2x software package. The vibrational amplitude and frequency inducing gradient segregation were determined. An approach was proposed for producing porous gradient filtering materials using an industrial UVM-60/60 vibrating machine. The C++ Builder environment was applied to develop a second-order mathematical regression model by processing the experimental data obtained from a symmetric rotatable uniform design.

Ferrous saponite is a secondary mineral that can be used to reveal the redox state of past aqueous environments on Mars. In mineralogical analyses for ferrous saponite formed in laboratory simulations or contained in future returned samples from Mars, its oxidation by the Earth’s air could be problematic due to the high redox sensitivity. Here, we performed micro X-ray diffraction and scanning transmission X-ray microscopy analyses for a single particle of synthesized ferrous saponite without any exposure to air. The sample was reanalyzed after air exposure for 10–18 h to assess the adequacy of our anoxic preparation/measurement methods and the impacts of air on the sample. We found that the crystal structures agreed with ferrous saponite, both before and after air exposure, however, ferrous iron in saponite was partially oxidized, at least until 0.1–1 μm from the surface, after air exposure at the submicron scale, forming micro-vein-like Fe(III)-rich features. Together with our results of infrared spectroscopy of ferrous saponite, we showed that oxidation of octahedral iron occurred rapidly and heterogeneously, even in a short time of air exposure without any structural rearrangement. Since ferrous saponite is expected to exist on carbonaceous asteroids and icy dwarf planets, our methodology is also applicable to mineralogical studies of samples returned from these bodies.

Synthetic saponites were successfully used to prepare phase change materials (PCMs) based on paraffin/synthetic saponite. Paraffin/synthetic saponites PCMs were prepared by a solution intercalation process. The PCMs were characterized by powder X-ray diffraction, FT-IR spectroscopy, thermal analyses and nitrogen adsorption. The thermal properties and the stability of PCMs were measured by DSC analysis and from heating–cooling curves. The results showed that the prepared PCMs have a higher heating rate and a lower cooling speed than paraffin because the heat storage was improved with the synthetic saponite. A one-pot synthesis method for obtaining PCM has been successfully developed in this work. The material thus obtained had better results for heat storage applications.

The object of this study is magnesian clay minerals present in carbonate rocks of the post-rift phase of the pre-salt in the Santos Basin. These rocks developed in an Aptian-age alkaline lacustrine environment. This study summarizes the formation of clay minerals associated with different lithotypes in a range of 19 m and a depth of more than 5100 m. They were characterized from petrographic analysis by optical microscopy, X-ray diffraction (total sample and clay fraction), and modeling by Newmod®, and examined and analyzed by scanning electron microscopy. An approach based on identifying lithotypes and characterization of microsites allowed us to understand the occurrence of different clay minerals. Kerolite was the most abundant mineral in the sampled range. It occurs in lamellar aggregates under greater preservation of the original rock lamination and in association with spherulites and shrubs. The Stv/Ker mixed layers occurs in the same association, and formed finer unlaminated aggregates associated with the more intense dolomitization and silicification processes. Saponite occurs associated with detrital minerals forming clayey levels intercalated with microcrystalline carbonates. Fluids with a high Mg/Si and pH &lt, 9 favor the precipitation of kerolite. The increase in pH during diagenesis may be responsible for the formation of Stv/Ker mixed layers.

An ultrathin film was prepared by hybridizing a cationic Ir(III) complex with exfoliated nanosheets of clay minerals such as natural montmorillonite (denoted by MON) or synthetic saponite (denoted ...

International audience; Lacustrine carbonates formed in rift settings are increasingly studied not only as archives of Earth chemical and climatic history but also as potential hydrocarbon source rocks and/or reservoirs. The role of magmatic gases in their formation and diagenetic evolution, hence in their reservoir properties, remains unclear. We studied the first meter of carbonate sediment of the Dziani Dzaha volcanic crater lake (Mayotte Island) and developed a reactive-transport model with CrunchFlow software that allows the quantification of diagenetic reactions by considering depth-dependent burial rates and sediment compaction. The model is constrained by the previously documented solid-phase compositions of the lake sediment and new data consisting of 14C dating of plant macroremains to characterize the sediment age model, chemical composition of sediment pore waters, and chemical and isotopic composition of gases dissolved and bubbling through the lake. These new data reveal a massive magmatic CO2 contribution to the dissolved inorganic carbon of the lake, which fuels the primary productivity and carbonate formation. A pH value of 9 in the surface sediment pore waters induces supersaturation relative to aragonite, hydromagnesite, and saponite. At 1 m depth in the sediment, our model predicts that magmatic CO2 inflows and organic matter degradation account for 22 and 2 mol % dissolved inorganic carbon, respectively. The magmatic CO2 inflows result in a pH decrease at depth, leading to the destabilization of hydromagnesite, while saponite and aragonite remain stable. These results demonstrate the role of magmatic CO2 in fueling carbonate production and controlling the diagenetic evolution of sediment mineralogy.

Positively charged Gd(III) and Y(III) complexes were intercalated in the gallery of a synthetic saponite. A combination of solid-state NMR and 1H NMR relaxometric investigations has been employed to characterize these hybrid systems. This enabled us to gain atomic level insights into the local environment of the chelates and to evaluate the interactions of the metal species with the co-intercalated water molecules.

Based on experimental studies, the possibility and efficiency of usage of montmorillonite, saponite, and clinoptilolite as separation membranes during electroosmotic fractionation of hydrogen isotopes in an aqueous electrolyte solution was evaluated. For the experiments, the following samples were used: bentonite (Cherkasy deposit) with a content of montmorillonite of 75% (hereinafter referred to as montmorillonite), saponite (Varvariv deposit) and clinoptilolite (Sokyrnytsya deposit). It was found that under the influence of an electric field, electroosmotic filtration of the tritiated electrolyte occurs through weakly permeable membranes. Depending on the structural features of the mineral substance, various proton conductivity of the membranes was recorded, which determines the different intensity of the redistribution of ions of dissociated HTO molecules between the anode and cathode chambers. The largest difference between the specific activity of tritium in the anolyte and catholyte was obtained in the system where the mineral membrane was made of saponite (11% and 26% of the specific activity of tritium in the initial HTO, respectively). The least was the stability of the montmorillonite membrane. Its destruction upon interaction with a Na2CO3 solution led to electrolyte leakage and a decrease in the extraction of tritium from the filtrate (catholyte). The use of clinoptilolite when creating a composite with montmorillonite made it possible to increase the stability of the membrane and additional possibilities for fractionating hydrogen isotopes in an electrolyte. Electroosmotic filtration of the electrolyte was accompanied by fractionation of hydrogen isotopes in the mineral membranes of the experimental systems. The largest isotope effect was obtained in montmorillonite and composite montmorillonite-zeolite membranes, where the fractionation coefficient α in the fraction extracted from the interlayer space was 1.16 and 1.12, respectively. In a composite membrane, where the amount of clinoptilolite was 67.5%, isotopic hydrogen fractionation was also observed in the surface-adsorbed fraction (α = 1.5) and in a structurally bound form (α = 1.1). The use of saponite as an electroosmotic membrane leads to a smaller isotope effect than in a montmorillonite membrane, and is manifested in surface-adsorbed water (α = 1.08) and in the interlayer space (α = 1.02). The addition of quartz sand to montmorillonite reduces the efficiency of fractionation of hydrogen isotopes detected only in the surface-adsorbed fraction (α = 1.02).

Tb3+ and Eu3+ ions were encapsulated for the first time in the inorganic layers of a synthetic saponite clay following a one-pot synthetic approach. The co-presence of the two metal ions led to tuneable light-emitting properties, promoted by an efficient Tb3+ → Eu3+ energy transfer and enhanced Stokes shift character. To our knowledge, the so-prepared luminescent material was tested for the first time as an optical sensor for the detection of chromate anions in water.

NiFe saponite (NF-SAP) with Na+ pillaring was investigated for the first time, as a new anode material for high-performance lithium-ion batteries (LIBs). In this material, non-metallic element Si and metallic elements Fe and Ni all act as active components (providing capacity) and undergo valence state changes during electrochemical progress. Si changes between Si2+ and Si4+, while Fe and Ni transform between a nearly metallic state and Fex+ and Niy+ (0 < x < 3, 0 < y < 2). In the fully lithiated state, Ni–Ni bonds appear but only Fe–O bonds can be observed in NF-SAP. The NF-SAP/Li half cell delivers a gradually increasing specific capacity in the initial hundreds of cycles (maximum capacity of 815 mA h g−1 at the 350th cycle) and maintains a capacity of 646 mA h g−1 after 1000 cycles at 500 mA g−1. The pre-pillaring effect of Na+ is responsible for the good Li+ storage performance, which leads to the decrease of Li+ transport hindrance and high contribution of pseudocapacitance. Furthermore, a full cell of LiMn2O4/NF-SAP was assembled, which shows an initial specific capacity of 104 mA h g−1 at 100 mA g−1 and maintains a capacity of 68% after 50 cycles, demonstrating the bright application prospects of NF-SAP as a promising anode material. This work shows a new kind of anode for LIBs and provides an in-depth understanding of its energy-storage mechanism. Considering the easy preparation, low cost and environment-friendly characteristics of NF-SAP, this kind of material is applicable to large-scale energy storage.

The use of clay minerals has ancient origin and nowadays natural clays are extensively employed for a large number of applications, including in building, packaging, cosmetics, pharmaceutics and foundries. The major advantages of the use of natural clays are associated with their large availability and low price. However, when clays have a natural origin, extensive purification steps are required to remove inorganic and organic contaminants. In addition, depending on the genesis process and on the provenance site, the chemical composition of natural materials can be extremely variable. This variability represents a strong limitation for their application, especially when surface properties have to be strictly controlled. These reasons have stimulated scientists to develop synthetic materials whose structure and properties mimic those of natural layered materials. Synthetic saponite clays have largely been investigated in this scenario and, through designed synthesis procedures, it was possible to obtain solids with controlled chemical compositions, tuneable layer dimensions and enhanced physico-chemical features. The purpose of this concise review is to give an overview of the physico-chemical properties of saponite clays and of the strategies that in recent years have been adopted for their preparation and functionalization. In this respect, a number of papers are related to the modification of saponites by substitution of cations in the interlayer space by organic surfactants, ions or hybrid compounds, thus extending their application. Moreover, a few examples concerning the insertion of specific ions (i.e. transition metal species) in the tetrahedral sheets of the clay through one-pot methods have also been reported recently. These materials, prepared through less time consuming methods, are characterized by the presence of well-defined metal sites that can be effectively exploited for several applications, such as heterogeneous catalysis. In this overview, after a summary on the most common intercalation compounds based on saponite clays, attention was focused on the one-pot methods for the production of functional saponite clays.

In the article, the process of water purification mainly from suspended particles of clay mineral saponite is considered. Those particles are formed during the process of diamond mining in the quarry water of M.V. Lomonosov Mining and Processing Plant owned by PJSC «Severalmaz». The scheme of the existing technology of sedimentation of suspended particles using the acoustic method is shown. Using the granulometry method the size of suspended particles in free volume was studied, and the sedimentation rate of suspended substances was calculated using Stokes' formula. The mineral composition of suspended particles in the quarry water is determined using Х-ray phase analysis. Calculations of the sedimentation rates of suspended particles are given for aluminum sulfate – traditionally used in water clarification – and for calcium-aluminosilicate reagent developed when taking into account the mineral composition. The results of measurements of pH of the clarified water, the content of residual aluminum, and the indicator of turbidity of the water are shown

The fine fraction of the Tagaran natural clay (TC) from the Kurdistan region of Iraq-Sulaimani was characterized and used to remove Cd ions from industrial swage. Using XRF, XRD, SEM, and FTIR, the dominant clay mineral of the Tagaran clay mineral was identified as saponite, with minor amounts of chlorite. The clay was examined for its efficiency to adsorb and remove (Cd2+) in the presence of other heavy metal contaminants from Sulaimani industrial zone sewage by a batch method. The effect of initial pH, equilibrium time, temperature, clay dosage, and Cd2+ concentration was studied. Results were evaluated using Langmuir, Freundlich, Temkin, and Redlich-Peterson isotherms. The kinetics could be best fitted to pseudo-second-order reaction kinetic model. In addition, the activation energy and the amount of calculated and experimentally determined heavy metal loads were consistent. The thermodynamic studies showed spontaneous endothermic adsorption. The trioctahedral smectite (saponite) showed a good efficiency for the adsorption of Cd2+ from the real sample (up to 100%) which at least partly can be explained by cation exchange. Tagaran clay is a candidate material for the production of an adsorber material for removing Cd2+ from aqueous solutions.

To identify the mechanisms for and to estimate the photochemical reaction efficiency of molecules in solid-state host materials is difficult. The objective of the present research was to measure the photogeneration efficiency of the methylviologen cation radical (MV+•) hosted in a semi-transparent hybrid film composed of MV2+ and saponite, a 2:1 clay mineral. MV+• is the one-electron reduced species of MV2+. MV+• was generated by UV irradiation of these films. The fluorescence intensity of MV2+ and the photogeneration efficiency of MV+• depended on the loading level of MV2+. When the loading level of MV2+ was high (75% of the cation exchange capacity (abbreviated as % CEC) of saponite), its fluorescence was reduced considerably because of the self-fluorescence quenching reaction, and the photogeneration efficiency of MV+• was relatively high (quantum yield φ = 3.5×10–2) compared to that of films with low adsorption density (10% CEC, φ = 1.1×10–2). Furthermore, when the loading level of MV2+ was very low (0.13% CEC), a self-fluorescence quenching reaction was not observed and MV+• was not generated. From these observations, one of the principal mechanisms of the self-quenching reaction and MV+• formation in saponite is the electron transfer reaction between excited MV2+ and adjacent MV2+ molecules in the ground state.

In this article, a novel method, amidation, was used to modify saponite. Amidated ammonium citrate intercalated saponite (Aa-saponite) was synthesized by amidation reaction. The structure of Aa-sap...

The physical and compositional properties of some common opals from Eastern Rhodopes, Bulgaria have been investigated through several methodologies such as optical and gemological equipments, X-Ray Powder Diffraction (XRPD), Scanning Electron Microscopy (SEM), Raman Spectroscopy and Laser Ablation Microprobe (LA-ICP-MS). The investigated opals show different colors such as light-apple and yellowish green; the diaphaneity is opaque or opaque/translucent with luster waxy/dull/greasy. They are inert to the long and short wavelength UV radiation (366–254 nm). Refractive index and specific gravity values are between 1.445–1.470 and 1.96–2.09 g/cm3, respectively. XRPD analyses show the opals are CT type and in some cases contain quartz and clay minerals (saponite). Fe and, subordinately, V appear the main chromophores that determine the green-yellowish color, while Ni is responsible for the apple and light green. Other detected trace elements are Al, Ca, K, Mg, Na, B, Zn, Rb. SEM analysis shows three types of structures already observed in the CT opals like randomly distributed nanograins and lepispheres, mammillary structure, channels structure made up by bundles of fibers. Raman spectra confirm the samples are made up by para-crystalline CT-opal, generally considered of volcanic origin, with significative content of saponite.

Conversion of hydrotalcite (Ht) to saponite was observed by hydrothermal alkaline alteration of metal oxides. The conversion was through a pathway of hydration-dissolution-precipitation. It involved several critical steps, including the construction of Ht from metal oxides, dissolution of Al3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of saponite. The condensation was favored by relatively low Mg/Al ratios of Ht, along with high concentrations of Al3+ and silicate oligomers in the environment, resulting in highly crystalline saponite. The latter conversion was greatly accelerated by the isomorphous substitution of Al3+ for Si4+ in silicate oligomers. The substitution generated the extra negative charge and led to the aforementioned condensation with Ht surface, thereby promoting the formation of saponite TOT layers. During the process, CO2 is an indispensable component. Initially intercalated as CO32− to form Ht, CO2 was subsequently eliminated from the solid phase, and saponite formed when the layer charge was reversed. Thus, this study presents a novel formation mechanism of saponite from metal oxides via hydrotalcite and contributes to a better understanding of the crystallization, chemical stability, and transformation of Ht to saponite. The results are also relevant to evaluating metal availability and carbon cycling on the surface of the Earth.

A simple method for preparing AgNPs/clay nanocomposites using an adsorption process without any reducing agent was developed in which saponite iron-rich clay was both the solid inorganic support and reducing agent. Silver adsorption by ion exchange of silver ions and saponite ferrous ions resulted in simultaneous silver reduction and silver nanoparticle formation. The maximum loading of silver was determined as 48 mg/g (4.8 mass %). Microscopy showed a homogeneous distribution of sphere-like silver nanoparticles which are composed from smaller crystallites in the form of twinned triangular prisms. The silver particle sizes ranged from 1 nm to 50 nm but predominantly between 8 and 10 nm. The optimum pH range for silver immobilization on saponite support was between 4 and 8. Characterization of the clay samples and synthesized AgNPs/saponite nanocomposites was performed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), porosimetry (low temperature nitrogen adsorption-desorption) and zeta potential measurements. The antibacterial activities of raw saponite and AgNPs/saponite nanocomposite samples were tested against clinical relevant Gram-positive Staphylococcus aureus, Staphylococcus epidermidis, and Gram-negative Escherichia coli, Pseudomonas aeruginosa and Proteus mirabilis bacteria by the well diffusion method.

Carbon capture using amine-modified porous sorbents is one of the main proposed technologies to reduce the CO2 atmospheric concentration. In this work, a wide series of inexpensive clays have been selected to assess their role as supports of amine-containing sorbents for CO2 capture. Montmorillonite, bentonite, saponite, sepiolite and palygorskite have been hydrated and functionalized by three routes: (a) grafting with aminopropyl (AP) and diethylenetriamine (DT) organosilanes; (b) impregnation with polyethyleneimine (PEI); and (c) double functionalization by impregnating previously grafted samples. XRD, FTIR and N2 adsorption-desorption analyses along with nitrogen content and CO2 adsorption properties (thermogravimetry and fixed bed) have been evaluated for bare and functionalized clays. Under dry conditions (45 °C, 1 bar), grafted and impregnated samples yielded CO2 uptakes as high as 61.3 and 67.1 mg CO2/g ads (for Sepi-DT and Paly-PEI, respectively), with the latter being the best-performing sample in terms of CO2 uptake. On the contrary, double-functionalized samples displayed poor CO2 adsorption properties, probably due to pore-blocking problems related to their high organic loading. The presence of 5% H2O in the feed gas resulted in CO2 uptake increments from 17 to 27%. The adsorption performance of AP, DT and PEI-containing samples was maintained after three adsorption-desorption cycles.

Local natural clay from Topkhana (Sulaimani district, Kurdistan region of Iraq) was characterized with XRD, XRF, FT-IR, and gas adsorption analyzer. The clay sample was dominated by saponite with minor amounts of chlorite. The clay was examined for its efficiency to adsorb and remove methylene blue (MB) from clinical laboratory wastewater by a batch method. The effects of pH, temperature, clay dosage, and initial MB concentration on the adsorption efficiency were investigated. The equilibrium experimental data were analyzed using Langmuir, Freundlich, Temkin, and Redlich-Peterson (R-P) isotherms. Most of the MB adsorption could be explained by cation exchange. The saponite, therefore, was the most important component in the clay. The rate of the adsorption process was found to follow pseudo-second-order kinetics. The conventional linear least squares method was compared with the more accurate method of non-linear curve fitting for the determination of isotherm and kinetic model parameters. Two error functions (the sum of the squared residuals and the correlation of determination) were used to evaluate the linear and non-linear regression analysis applied to the experimental data. Equilibrium thermodynamic parameters indicated a spontaneous and endothermic adsorption process.

The versatile structure of smectites can exhibit large variations in chemical compositions and cationic substitutions in different crystallographic sites, resulting in various locations of layer charge. Natural smectites can contain various amounts of structural iron, the chemical form of which can influence the reactivity of these minerals. The variety of Fe crystal chemistry in smectite was explored for eight natural smectites of distinct chemical compositions and charge locations, together with two synthetic ferric saponites used as reference compounds for tetrahedral Fe(III). All samples were identified as dioctahedral or trioctahedral smectite by X-ray diffraction and Fourier-transform infrared spectroscopy. The extent of [4]Al for [4]Si substitution was determined by 27Al and 29Si magic angle spinning nuclear magnetic resonance spectroscopy. The Fe local chemical environment was probed by polarized X-ray absorption spectroscopy. Only Fe(III) could be detected in all samples, with no evidence of cluster formation. The O shell at 1.86 A in synthetic saponites suggests Fe insertion in tetrahedral sites, and the absence of detected octahedral Fe implies quantitative substitution of [4]Fe3+ for [4]Si4+. In natural smectites, Fe(III) is bound to six O atoms at ~ 2.00 A, suggesting insertion in octahedral sites. This inference is also supported by the detection of in-plane Mg/Al/Fe atoms at ~ 3.05 A and out-of-plane Si/Al atoms at ~ 3.25 A. In one Fe-rich nontronite, the detection of an O subshell at ~ 1.88 A suggests a concomitant insertion of Fe(III) in tetrahedral sites. Low numbers of octahedral neighbors were detected in natural saponite and hectorite, presumably because of the presence of vacancies and/or Li(I) in adjacent octahedral sites balancing the local charge excess originating from the substitution of Fe(III) for Mg(II). The substitution of [4]Fe3+ for [4]Si4+ can be readily obtained under defined conditions in the laboratory, but seems more rare in natural samples, or present in amounts below the detection limit of spectroscopic methods used in this study.

Citral and citronellal are important chemicals in the pharmaceutical and chemical industries, since they can be converted into other more valuable chemicals that are needed in many pathways. From the perspective of green catalysis, the present investigation examines the preparation of a recyclable heterogeneous catalyst of ruthenium-supported saponite clay for microwave assisted catalytic hydrogen transfer. Catalysts were prepared by supporting ruthenium bipyridine cations within saponite interlayers at various ruthenium contents, and the catalysts were then characterized by x-ray diffraction (XRD), gas sorption measurements, and scanning electron microscopy-energy dispersive x-ray spectrometry (SEMEDX) analyses. The catalytic activity was determined using microwave-assisted conversion of citral and citronellal. The prepared catalysts exhibited significant activity in the microwave-assisted catalytic hydrogen transfer of citral and citronellal. The catalytic activity was related to the content of the supported ruthenium in the catalysts, which also contributed to the increased specific surface area and external surface area of the materials.

In a detailed investigation of three active geothermal systems from Greece (Milos), from El Salvador (Chipilapa) and from Japan (Nigorikawa), it was found that smectites are common minerals in vapor dominated reservoirs. These smectites are formed in response to local discharge of boiling fluids in permeable horizons; they can crystallize also in pipelines of powerplants. According to the varying composition of the fluids involved in these geothermal systems (i. e. meteoric waters or sea water), beidellite, saponite and stevensite have been identified at temperature between 180 and 300°C. Montmorillonite has not been observed for these thermal conditions. The association of variable amounts of smectite rich mixed layers including illite/smectite, chlorite/smectite or stevensite/talc with pure smectites suggests that smectites are metastable phases which rapidly evolve toward illite, chlorite or talc via conversion series of mixed layers. These smectites are a potential guide for the recent evolution of vapor dominated geothermal reservoirs.

The solution of the sludge utilization problem and yield increase at processing plants have great importance today all over the world. Disasters associated with the tailings dams failures have madeus develop technologies of tailings sludge utilization as a commercial product, reducing the environmental damage on the regions of mineral extraction. This research aimed to provide new data, methods and an analytical approach to solve the saponite sludge accumulation problem on mining enterprises with silicate coagulant to increase the rate of cycle water clarification for the enrichment process and the recycling of sludge to reduce its hazardous effect. Samples were taken in the deposit located in the north of the European part of Russia, where diamond bearing ore contain montmorillonite minerals, mostly saponite, which is considered to be a perspective secondary product. The content of this mineral in the sludge is above 20 wt.%. Saponite is a clay mineral with the general chemical formula (Ca,Na)0.3(Mg, Fe2+)3(Si, Al)4O10(OH)2·4H2O. The mineral has high adsorption, ion exchange, and catalytic and filtration properties, due to the developed diffuse layer, saponite particles are highly stable in an aqueous medium—the resulting suspension is highly stable and has slow sedimentation. During the research, a positive effect on the sedimentation process of clay saponite particles was established, due to the introduction of a coagulant containing 70% tricalcium silicate, at a dosage of 2 g/dm3 coagulant, the degree of purification of water containing the saponite clay suspension is 99%. The condensed sediment after the thermal drying and with the limestone addition can be used again as a coagulant or secondary product with enhanced properties, therefore, the sludge will be processed, and not stored.

The fit of the smectite structural formula is reviewed. In addition, a group of samples, both dioctahedral and trioctahedral, are studied, demonstrating the influence of interlaminar Mg that can lead to the erroneous classification of smectite if it is not considered., The understanding of the structural formula of smectite minerals is basic to predicting their physicochemical properties, which depend on the location of the cation substitutions within their 2:1 layer. This implies knowing the correct distribution and structural positions of the cations, which allows assigning the source of the layer charge of the tetrahedral or octahedral sheet, determining the total number of octahedral cations and, consequently, knowing the type of smectite. However, sometimes the structural formula obtained is not accurate. A key reason for the complexity of obtaining the correct structural formula is the presence of different exchangeable cations, especially Mg. Most smectites, to some extent, contain Mg2+ that can be on both octahedral and interlayer positions. This indeterminacy can lead to errors when constructing the structural formula. To estimate the correct position of the Mg2+ ions, that is their distribution over the octahedral and interlayer positions, it is necessary to substitute the interlayer Mg2+ and work with samples saturated with a known cation (homoionic samples). Seven smectites of the dioctahedral and trioctahedral types were homoionized with Ca2+, substituting the natural exchangeable cations. Several differences were found between the formulae obtained for the natural and Ca2+ homoionic samples. Both layer and interlayer charges increased, and the calculated numbers of octahedral cations in the homoionic samples were closer to four and six in the dioctahedral and trioctahedral smectites, respectively, with respect to the values calculated in the non-homoionic samples. This change was not limited to the octahedral sheet and interlayer, because the tetrahedral content also changed. For both dioctahedral and trioctahedral samples, the structural formulae improved considerably after homoionization of the samples, although higher accuracy was obtained the more magnesic and trioctahedral the smectites were. Additionally, the changes in the structural formulae sometimes resulted in changing the classification of the smectite.

Summary We detected large values of the complex electrical conductivity of four kimberlite samples based on laboratory measurements carried out when saturating the samples with brines with the electrical conductivity ranging between 200 and 30 000 S/cm. Both the real surface conductivity and the quadrature conductivity were found much larger than that of common volcanic rocks and sediments. Based on measurements of petrophysical properties of these cores as well as on optical microscopic images we argued that this anomalous conductivity is explained by highly conductive and polarizable clayey matrix, which shows an abundance of the saponite, a mineral of smectite group. These new data confirms usability of electrical (resistivity, and especially Induced Polarization) and electromagnetic methods in kimberlite exploration.