Aluminosilicate Surfaces Research Articles

Flotation of Li Pegmatite with a Soybean Oil-Based Collector: Fundamental Studies

ABSTRACT In this work, the effect of a soybean oil-based collector on the surface properties of spodumene, feldspar, quartz, and muscovite was characterized and evaluated. By means of gas chromatography, it was determined that the reagent was composed of a mixture of carboxylic acids: linoleic (48%), oleic (28%), palmitic (13.3%), stearic (3.6%), α-linolenic (3.4%), and elaidic (3.2%). The reagent contained ~14 ppm Ca (determined by inductively coupled plasma optical emission spectroscopy – ICP-OES) and a critical micellar concentration (CMC) of 100 mg/L. At pH 6, the spodumene recovery was 50–60% higher than the other mineral recoveries, ascribed to chemical adsorption of the collector ionic-molecular species, which has high hydrophobicity power, on Al3+ sites on the spodumene surface. For pH values >10, the recoveries of feldspar and quartz were higher than spodumene, due to their activation by hydroxyl and hydroxide of Ca and subsequent adsorption of ionic specimen of the collector. The electrokinetic potential curves of spodumene, feldspar, and muscovite with collector were shifted toward more negative values compared to their electrokinetic potential curves without reagent. Fourier transform infrared spectroscopy (FT-IR) showed chemical adsorption of the anionic species of the collector at pH 6 with the Al3+, Fe3+, and Ca sites on the surface of aluminosilicates and Ca for quartz.

Investigation on the compressive strength of desulfurization gypsum binary cementitious materials with low energy consumption: the utilization enhancement of industrial wastes

Geopolymer, a new low carbon green cementing binder, has widely been used as an alternative to Ordinary Portland cement (OPC), which effectively reduces carbon emissions and industrial solid waste stockpiles on land, also improving solid waste utilization. To raise the utilization of sulphate solid waste and decrease energy consumption, desulphurization gypsum (DG)-based binary cementitious materials were synthesized, and the effects of DG dosage and alkali exciter components on the compressive strength of binary cementitious materials were investigated. In addition, the improvement mechanism of the mechanical properties of binary cementitious materials was revealed by microstructure characterization tools. The results prove that the optimum compressive strength of 52.5 ± 0.5MPa is achieved with a DG dosage of 20%, SiO2/Na2O of 1, water glass dosage of 10% and water-cement ratio of 0.5. Due to the continuous reaction of sulphate in DG with Ca2+ and reactive silicates/aluminosilicates during the curing process, the crystals of ettringite (AFt) are generated and filled the pores of binary cementitious materials and thus furtherly enhancing its compressive strength. And the gel products wrap the AFt that has been filled in the inter-vacancy space on the surface of aluminosilicates already formed at an earlier stage. In summary, ground granulated blast-furnace slag (GGBS) and DG work synergistically to reduce the negative effects of delayed AFt and increase the compressive strength of the geopolymer.

Atomistic simulations of calcium aluminosilicate interfaced with liquid water.

The dissolution behavior of calcium aluminosilicate based glass fibers, such as stone wool fibers, is an important consideration in mineral wool applications for both the longevity of the mineral wool products in humid environments and limiting the health impacts of released and inhaled fibers from the mineral wool product. Balancing these factors requires a molecular-level understanding of calcium aluminosilicate glass dissolution mechanisms, details that are challenging to resolve with experiment alone. Molecular dynamics simulations are a powerful tool capable of providing complementary atomistic insights regarding dissolution; however, they require force fields capable of describing not-only the calcium aluminosilicate surface structure but also the interactions relevant to dissolution phenomena. Here, a new force field capable of describing amorphous calcium aluminosilicate surfaces interfaced with liquid water is developed by fitting parameters to experimental and first principles simulation data of the relevant oxide-water interfaces, including abinitio molecular dynamics simulations performed for this work for the wüstite and periclase interfaces. Simulations of a calcium aluminosilicate surface interfaced with liquid water were used to test this new force field, suggesting moderate ingress of water into the porous glass interface. This design of the force field opens a new avenue for the further study of calcium and network-modifier dissolution phenomena in calcium aluminosilicate glasses and stone wool fibers at liquid water interfaces.

Photoinduced Antibacterial Activity and Cytotoxicity of CdS Stabilized on Mesoporous Aluminosilicates and Silicates.

Inactivation of bacteria under the influence of visible light in presence of nanostructured materials is an alternative approach to overcome the serious problem of the growing resistance of pathogenic bacteria to antibiotics. Cadmium sulfide quantum dots are superefficient photocatalytic material suitable for visible light transformation. In this work, CdS nanoparticles with size of less than 10 nm (QDs) were synthesized on the surface of natural and synthetic mesoporous aluminosilicates and silicates (halloysite nanotubes, MCM-41, MCM-41/Halloysite, SBA-15). Materials containing 5–7 wt.% of CdS were characterized and tested as agents for photocatalytic bacteria degradation of Gram-positive S. aureus and Gram-negative E. coli with multiple antibiotic resistance. Eukaryotic cell viability tests were also conducted on the model cancer cells A 459. We found that the carrier affects prokaryotic and eukaryotic toxicity of CdS quantum dots. CdS/MCM-41/HNTs were assumed to be less toxic to eukaryotic cells and possess the most prominent photocatalytic antibacterial efficiency. Under visible light irradiation, it induced 100% bacterial growth inhibition at the concentration of 125 μg/mL and the bacteriostatic effect at the concentration of 63 μg/mL. CdS/MCM-41/HNTs showed 100% E. coli growth inhibition in the concentration of 1000 μg/mL under visible light irradiation.

Characteristic Features of the Change in the Zeta-Potential of the Surface of Synthetic Aluminosilicates of a Kaolinite Group with Different Morphologies

Characteristic Features of the Change in the Zeta-Potential of the Surface of Synthetic Aluminosilicates of a Kaolinite Group with Different Morphologies

Comparison of lead(II) ions accumulation and bioavailability on the montmorillonite and kaolinite surfaces in the presence of polyacrylamide soil flocculant

Heavy metals, such as Pb(II), Cd(II), Hg(II), do not degrade like organic compounds and remain in soil for a long time. The presence of organic, mineral or polymeric substances (such as polyacrylamides) may contribute to the accumulation and immobilization of toxic metals in poorly absorbable form for living organisms. The main aim of the study was to compare the effectiveness of lead(II) ions immobilization on the layered aluminosilicate surfaces in the anionic polyacrylamide presence. The effectiveness of Pb(II) adsorption was tested depending on metal cation concentration, content of dissociable groups in added flocculant as well as internal structure of clay mineral. The desorption tests of heavy metal ions were performed by the use of water and EDTA (ethylenediaminetetraacetic acid). By means of measurements of suspension stability and aggregate size formed in the studied systems, the flocculating ability of anionic polyacrylamide was checked. The electrokinetic parameters of mineral particles, i.e. surface charge density and electrokinetic potential, without and with individual adsorbates were also determined. It has been shown that the Pb cations adsorbed amount and the effectiveness of their immobilization strongly depends on the polyacrylamide presence in the system and the internal structure of aluminosilicate.

Effect of activation temperature on surface basicity of natural aluminosilicates

Montmorillonite and nontronite are layered aluminosilicates of smectite group minerals widely demanded in many industries owing to their unique physical-chemical and other properties. By thermal activation of raw clays there are variations in their porosity, surface area and physical-chemical properties, including formation and redistribution of surface active site of acid-base or redox character. The aim of present studies included investigation of the effect of thermal activation on the character of distribution and a number of basic sites on the surface of natural layered aluminosilicates by means of the new method of inverse thermoprogrammed desorption of СО2.
 Samples of natural aluminosilicates rich in montmorillonite (Montmorillonite 67%, illite 5%, quartz 5%, feldspars 21%) and nontronite (nontronite 70%, illite 10%, kaolinite 5%, quartz 10%, feldspars 8%) were characterized by XRD, XRF, BET N2 adsorption techniques. To probe surface basicity and determine the number of basic sites a new iTPD-CO2 was used. Prior the iTPD-CO2 measurement 100 mg of a sample was activated at 200, 300, 400oC, then cooled down and loaded with CO2 (3ml/min flow rate of CO2 for30 min). Next, the reactor was flushed by 5 ml/min N2-flow to desorb weakly sorbed CO2. The iTPD-CO2 profiles were recorded within 20-800oC at a 20oC/min heating rate and treated using ChemStation software.
 The experimental profiles of CO2 desorption for Mt and Nt samples observed two temperature regions. Low temperature peaks evolved around 80-90oC for Mt and between 110-127oC for Nt were most likely related to the weak basic sites, whereas high temperature peaks around 510 and 620oC for Mt and above 320oC for Nt testified to stronger ones. The reasoning of the obtained iTPD-profiles was done considering thermal behavior of layered aluminosilicates.
 The total basicity of Nt and Mt samples was 359.2 and 209.9 mmol/g respectively. The 1.6 times higher basicity of Nt was, obviously, caused by its phase and chemical composition and developed surface area and porosity. At higher activation temperatures the number of weak basic sites related to hydroxyl groups of adsorbed water molecules gradually decreased, namely, by 21 times for Mt and by 2.8 times for Nt.
 Dehydroxylation of structural Al-OH, Fe-OH, Mg-OH above 200oC, which becomes irreversible above 300oC, provided formation of residual oxygen atoms and their contribution to population of stronger basic sites. In accordance with thermal behavior of dioctahedral smectites, is assumed that strong basic sites of Mt are trans- and cis-vacant Al-OH groups dehydroxylating correspondingly at ~550 and 650oC. Fe-rich sample of Nt rapidly lost hydroxyls at rather lower temperatures that resulted in more heterogeneous distribution of strong basic sites of varying strength. At higher activation temperatures the ratio of stronger sites number to weak sites increased from 23 to 200 for Mt, whereas for Nt this ratio varied between 54-67 times. In general, total basicity of Mt and Nt decreased by 2.2-2.3 times as a result of their dehydration and dehydroxylation by thermal activation. The normalized values of basicity per unit surface area (BΣ/S, mmol/m2) were 1,5 times higher for Mt surface, testifying to higher occupancy and density of active sites for Mt than that of Nt.

SYNTHESIS AND PHYSICOCHEMICAL CHARACTERISTICS OF MESOPOROUS ALUMINOSILICATES

In the article, the synthesis of mesoporous aluminosilicates was carried out according to the developed methods, in which tetraethylorthosilicate Si(OC2H5)4 was used as a source of silicon, secondary aluminum butoxide (sec-BuO)3Al and aluminum triisopropoxide Al(i-OPr)3 were used as aluminum's sources. The synthesis of mesostructured aluminosilicate is based on the method of copolycondensation of silicon and aluminum sources in the presence of alcohol. Hexadecylamine (HDA, C16H33NH2) was used as a template for the formation of a porous structure. The physicochemical characteristics of the synthesized structured mesoporous aluminosilicates have been studied. It was found that the synthesized materials MAS-1 and MAS-2 possess high specific surface area from 511 to 1170.0 m2/g. The presence of a mesoporous and ordered structure in the synthesized aluminosilicates is confirmed by the data of low-temperature nitrogen adsorption/desorption, X-ray diffraction and FT-IR. To determine the relative strength of Brønsted and Lewis acid sites on the surface of mesoporous aluminosilicates, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of adsorbed pyridine samples was carried out. DRIFT analysis data demonstrated a majority of Lewis acid sites on the surface of the synthesized materials. We are currently studying the possibility of applying these materials as acidic components of bifunctional catalysts for petrochemical N E W S OF THE NATIONAL ACADEMY OF SCIENCES OF THE REPUBLIC OF KAZAKHSTAN SERIES CHEMISTRY AND TECHNOLOGY ISSN 2224-5286 https://doi.org/10.32014/2020.2518-1491.94 Volume 6, Number 444 (2020), 22 – 29 UDC 665.64.097.3 MRNTI 61.51.17, 61.51.19 К.M. Umbetkaliyeva1,2, G.K. Vassilina1,2, А.К. Abdrassilova1 , А.R. Khaiyrgeldinova2, Т.К. Vassilina2,3, Zh.Y. Zakirov1, М.Kh. Taliyeva2 , А.К. Kaldybayeva2 1al-Farabi Kazakh National University, Almaty, Kazakhstan; 2SRIfor New Chemical Technologies and Materials, Almaty, Kazakhstan; 3Кazakh National Agrarian University, Almaty, Kazakhstan. E-mail: kamilla.u.m21@mail.ru, v_gulzira@mail.ru, albina06.07@mail.ru, asyltas_2008@mail.ru, v_tursunai@mail.ru, abuzhassulan@gmail.com, taliyevamadina@gmail.com, kaldybayeva.assylai@gmail.com SYNTHESIS AND PHYSICOCHEMICAL CHARACTERISTICS OF MESOPOROUS ALUMINOSILICATES Abstract. In the article, the synthesis of mesoporous aluminosilicates was carried out according to the developed methods, in which tetraethylorthosilicate Si(OC2H5)4 was used as a source of silicon, secondary aluminum butoxide (sec-BuO)3Al and aluminum triisopropoxide Al(i-OPr)3 were used as aluminum's sources. The synthesis of mesostructured aluminosilicate is based on the method of copolycondensation of silicon and aluminum sources in the presence of alcohol. Hexadecylamine (HDA, C16H33NH2) was used as a template for the formation of a porous structure. The physicochemical characteristics of the synthesized structured mesoporous aluminosilicates have been studied. It was found that the synthesized materials MAS-1 and MAS-2 possess high specific surface area from 511 to 1170.0 m2/g. The presence of a mesoporous and ordered structure in the synthesized aluminosilicates is confirmed by the data of low-temperature nitrogen adsorption/desorption, X-ray diffraction and FT-IR. To determine the relative strength of Brønsted and Lewis acid sites on the surface of mesoporous aluminosilicates, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of adsorbed pyridine samples was carried out. DRIFT analysis data demonstrated a majority of Lewis acid sites on the surface of the synthesized materials. We are currently studying the possibility of applying these materials as acidic components of bifunctional catalysts for petrochemical processes.

Study of the functioning time of aluminosilicates for the formation of hydrophobic surfaces

The modification of surfaces for the creation of hydrophobic materials has grown in recent years due to the wettability properties that can be obtained, in this process the chemical environment of the surface is modified. In the case of aluminosilicates, surfaces are generally considered polar, so it is of great interest to create hydrophobic surfaces through the functionalization process, obtaining low wettability; hydrophobicity is determined when a surface comes in contact with a drop of an organic component and contact angles greater than 90 ° are obtained. The present work describes the results of the study of the contact time between aluminosilicate surfaces and a siloxane as a functionalizing agent, to determine the optimal time in which hydrophobic surfaces are obtained. The results show that after 3 hours of contact between the surface and the functionalizing agent, a surface with a contact angle of 106° is generated, due to the heterogeneous surface of the functionalizing agent that is generated in the aluminosilicate because of the polymerization reaction.

Acid-base properties of aluminosilicates from rice husk and straw

We obtained aluminosilicates of sodium and potassium from alkaline hydrolysate of rice straw and husk. Chemical, phase composition of the samples was determined, and nature of the functional groups was studied. We presented results of studying acid-base properties of aluminosilicates’ surface by pH-metry and Hammett methods. We built distribution curves of a number of acid-base centers of the samples from pКa indicators. It was found that the surface of the as-prepared aluminosilicates is characterized by a wider spectrum of Bronsted acid centers (pKa + 2.5; + 3.46; + 6.4), presence of Lewis acid centers (pKa + 16.8) and main Bronsted centers (pKa + 9.45). The largest number of Lewis acid centers was recorded on the surface of sodium aluminosilicates with a narrow ratio of Al2O3:SiO2 = 1:2, the smallest—on the surface of potassium aluminosilicate with a wide ratio of Al2O3:SiO2 = 1:5. The maximum number of Bronsted acid centers was present on the surface of sodium aluminosilicates from rice straw, the minimum—on the surface of potassium aluminosilicate with the amount of SiO2 equal to 41%.

Characterization of mesoporous aluminosilicate materials by means of inverse liquid chromatography

Estimation of the properties of mesoporous aluminosilicates in various environments is important when assessing their sorption capacity. Using inverse liquid chromatography (ILC), Hansen solubility parameters (HSP) and linear free energy relationship (LFER) parameters were calculated to determine the properties of aluminosilicates in a protic and an aprotic system, using water and acetonitrile as the mobile phase, respectively. The calculated Hansen parameters, reflecting the ability of the material under investigation to different types of intermolecular interactions, slightly differ depending on the mobile phase used. It was found that in the presence of water the surface of aluminosilicates shows a weaker ability to interact, as evidenced by negative or near-zero e, s, a, b, v coefficients. Additionally, it was found that the Si/Al ratio in aluminosilicates structure has little effect on the determined parameters.

Sorption of cesium by aluminosilicate sorbents from rice straw

Using rice straw of various varieties of the Far Eastern selection as a source of silicon, a number of samples of sodium aluminosilicates with a Si:Al ratio from 1.02 to 1.56 were synthesized. For the obtained samples, the elemental and phase composition was found, the thermal properties were investigated. The morphology of aluminosilicates was studied: the particle size varies from 0.2 to 50 μm with a maximum distribution of about 10 μm, the specific surface area is 364 m2/g. The acid-base properties of the surface of aluminosilicates are characterized by pH-metry methods and the Hammett indicator method, the nature of the distribution of adsorption centers on the surface is established. The sorption capacity of the obtained samples, determined with respect to methylene blue (MB), is from 31.9 to 103.9 mg/g. By varying the synthesis conditions, it was shown that the greatest sorption capacity with respect to MB is achieved at the time of hydrolysis of the original rice straw for 60 minutes. It is shown that the sorption of Cs+ ions in the obtained samples is described by the Langmuir model. The sorption properties with respect to Cs+ ions from aqueous solutions with different salt background were studied.

Adsorption of Crude Oil Components on Mineral Surfaces Followed by Quartz Crystal Microbalance and Contact Angle Measurements: The Effect of Oil Composition, Simulated Weathering and Dispersants

Improved knowledge of interactions between crude oil and solid surfaces is of great importance for understanding oil spill responses as well as oil spill behavior on land and in the near-shore environment. Here, the goal was to study how crude oils with various physicochemical properties interacted with model shoreline surfaces. In addition, the influence of simulated weathering and addition of dispersants was investigated for selected crude oils. A quartz crystal microbalance was used to follow the adsorption from 13 different crude oils on silica, aluminosilicate, and calcium carbonate surfaces, whereas the corresponding wettability alterations were followed by contact angle measurements. The polar crude oil components adsorbed in considerably higher amounts on the calcium carbonate surfaces than on the silica and aluminosilicate surfaces. The simulated weathering of oils resulted in increased adsorption onto both the silica and aluminosilicate surfaces, whereas it had a little effect on the calcium carbonate surface. The presence of dispersants generally reduced the amounts adsorbed on the surfaces. In the presence of seawater, the crude oil with a higher total acid number interacted strongest with the calcium carbonate surface.

Synthesis and application of hierarchical zeolites prepared using amino-acid mesoporogens

Amino-acid-templating is a newly developed versatile synthetic strategy for the effective construction of hierarchically porous architectures in zeolites. Although the role of amino acid polymerization on dealuminated zeolites has been well perceived in biochemical evolution as possible origin of life, the use of amino acids to tailor pore architectures in zeolites has merely merged. The present work provides an overview from the early studies on aluminosilicate surfaces as promoters in probiotic chemistry to our recent endeavours on designing hierarchically porous zeolites using various amino acids. The power of amino acids is depicted through assessing their multi-functional roles and the differences to that of surfactant templates. The key advantages using amino acids as mesoporogens include wide availability and rich diversity offering cost efficiency and unparalleled control of zeolite architecture, minimal interference on the 3D continuous zeolite crystallization, easy removal through washing with water, and amino acid recyclability. Finally, the application of amino-acid-mediated hierarchical zeolites and potential industrial usage are highlighted.

APPLICATION OF ADSORPTION MODELS FOR DESCRIPTION OF BALANCES IN THE SYSTEMS «CATIONS OF COPPER (II) AND LEAD (II) – NATURAL MATERIALS OF ASTRAKHAN REGION »

I
 In the work there were studied the regularities of extracting copper (II) and lead (II) cations from aqueous solutions with the help of natural sorbents from the Astrakhan region such as the marl of the Baskunchak deposit, the Kamennyy yar deposit and the clay of the Volzhsky deposit. A comparative study was made of the applicability of the adsorption models of Langmuir, Freindlich, Temkin, and Dubinin-Radushkevich to describe the experimental adsorption isotherms of these cations on the surface of aluminosilicates. The constants and parameters of the equations corresponding to these models are determined. A comparison of the regression coefficients shows that the Temkin model is suitable for describing the adsorption equilibria in the "M2+ -clay" systems. The Freundlich model most adequately describes the experimental data on adsorption in the "M2+ -marl/opoka" systems, which reveals the heterogeneous surface of both of these materials with a large number of energetically dissimilar active centers. The regression coefficients found in this case by the Langmuir model are small; the boundary conditions for the description of systems with a monomolecular coating are not observed. The Dubinin-Radushkevich model was also used to describe the process of concentrating lead (II) compounds on the marl surface of the Baskunchak deposit and the Kamennyy Yar deposit. The calculated values of the free energy of adsorption were 11.2 (opoka) and 4.17 kJ/mol (marl). The process of fixing lead cations on these natural sorbents in the Astrakhan region proceeds according to the ion-exchange mechanism. The adsorption activity of Cu2+, Pb2+ ions on the surface of sorbents is confirmed by the calculated values of Gibbs energy and entropy. The endothermic nature of the processes taking place with the participation of the clay of the Volzhsky deposit and the Kamennyy Yar deposit is explained by the considerable energy expenditure for the dehydration of the surface groups of sorbents.
 For citation:
 Dzhigola L.A., Sadomtseva O.S., Shakirova V.V., Kargina K.V., Syutova E.A., Razgovorov P.B., Nagornov R.S. Application of adsorption models for description of equilibria in systems cations of copper (II) and lead (II) – natural materials of Astrakhan region. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 105-112

Water chemistry on two-dimensional silicates studied by density functional theory and temperature-programmed desorption

The interactions of water with two-dimensional (2D) silica and aluminosilicate bilayers were studied using density functional theory (DFT) and temperature-programmed desorption (TPD). The DFT calculations encompassed a systematic investigation of the impacts of silanol groups, Si:Al ratio, and the proximity of a Pd(111) growth substrate on water adsorption, permeation, and dissociation, as well as the thermal stability of charge balancing protons at the 2D aluminosilicate surface. Water adsorption on pure, defect-free 2D SiO2 was weak; however, the barrier for water penetration to the Pd(111) substrate was small. Water adsorption at the 2D SiO2/Pd(111) surface was slightly weaker than bare Pd(111) but once at the metal surface water dissociation energetics were scarcely affected by the SiO2 overlayer. Silanol groups at 2D SiO2 edges substantially strengthened water adsorption but by only roughly half as much as hydroxyls bridging Al and Si atoms in 2D aluminosilicates. The metal substrate did not fundamentally alter the surface chemistry of the outer 2D aluminosilicate surface; water adsorption energies on the bridging hydroxyls differed by only a few meV for freestanding versus Pd-supported bilayers. Removal of the charge balancing proton via a dehydration process that produces an oxygen vacancy was favored over a dehydrogenation pathway irrespective of the presence of the metal. The dehydration pathway is uphill by at least 3.37 eV suggesting that temperatures in excess of 1100 K would be required to remove charge balancing protons as neutral species. In contrast, chemical bonds between the 2D aluminosilicate and the metal substrate make it difficult to protonate the metal side of the 2D aluminosilicate bilayer via water dissociation. The TPD experiments for pure 2D SiO2/Pd(111) revealed desorption curves consistent with adsorption at the metal surface, supporting weak adsorption on a defect-free bilayer and permeation through and around the silica overlayer to the metal. Incorporating Al into the bilayer shifted the water TPD peak to higher temperatures but not as much as would be expected based on the computed adsorption strength at bridging hydroxyls on 2D aluminosilicate surfaces. No water or hydrogen desorption consistent with removal of charging balancing protons from 2D aluminosilicate surfaces via dehydration or dehydrogenation was observed. The results suggest thermally robust Brønsted acid sites on the surface of 2D aluminosilicates supported on Pd(111).

Investigations of the possibility of lithium acquisition from geothermal water using natural and synthetic zeolites applying poly(acrylic acid)

Abstract The purpose of the paper was to investigate the possibility of obtaining lithium from geothermal water using natural and synthetic zeolites applying poly(acrylic acid). The efficiency of lithium ion sorption was determined depending on the type of tested zeolite, pH of the solution and the presence of anionic poly(acrylic acid). It was shown that the adsorption amount on the surface of aluminosilicates depends on their structure (size of specific surface area and porosity). Moreover, it was proved that the amount of adsorbed lithium ions increases with the increasing pH value of the solution. This is due to an increase in the concentration of negatively charged groups on the zeolite surface that capture the lithium cations from the solution effectively. In general, the addition of anionic polymer increases lithium ions sorption from the LiCl solution at pH 9, at which about 100% recovery of Li cations by Na-X zeolite was obtained. Under these conditions the poly(acrylic acid) carboxyl groups are completely dissociated which guarantees effective formation of polymer-metal complexes and results in the increase of amount of adsorbed lithium ions. The important parameter affecting lithium ions sorption amount is the order of adsorbates addition to the system since the polymer adsorption modifies surface properties of the solid thus influencing the ion exchange process of metal cations. The maximum recovery of lithium cations from geothermal water (at the natural pH 5.5) was obtained in the system containing natural clinoptilolite and anionic polymer. It amounted to almost 5 mg/L (with the initial content of Li+ ions in water about 10 mg/L).

Water Dissociative Adsorption on α-Al2O3(112̅0) Is Controlled by Surface Site Undercoordination, Density, and Topology

α-Al2O3 surfaces are common in a wide variety of applications and useful models of more complicated, environmentally abundant, alumino-silicate surfaces. While decades of work have clarified that all properties of these surfaces depend sensitively on the crystal face and the presence of even small amounts of water, quantitative insight into this dependence has proven challenging. Overcoming this challenge requires systematic study of the mechanism by which water interacts with various α-Al2O3 surfaces. Such insight is most easily gained for the interaction of small amounts of water with surfaces in ultra high vacuum. In this study, we continue our combined theoretical and experimental approach to this problem, previously applied to water interaction with the α-Al2O3 (0001) and (11̅02) surfaces, now to water interaction with the third most stable surface, that is, the (112̅0). Because we characterize all three surfaces using similar tools, it is straightforward to conclude that the (112̅0) is most reactive with water. The most important factor explaining its increased reactivity is that the high density of undercoordinated surface Al atoms on the (112̅0) surface allows the bidentate adsorption of OH fragments originating from dissociatively adsorbed water, while only monodentate adsorption is possible on the (0001) and (11̅02) surfaces: the reactivity of α-Al2O3 surfaces with water depends strongly, and nonlinearly, on the density of undercoordinated surface Al atoms.

Surface active properties of silicate and aluminosilicate surfaces

Liquid heat-insulation based on hollow microspheres and polymer compounds become more and more popular in the construction industry. This material enjoys indisputable technological advantages easiness of application, low mass, flexibility, good adhesion to different materials. Traditional non-organic heat insulating materials, widely presented on modern construction market, have some disadvantages. Foam concrete and gas silicate have relatively high average density, which enables obtaining items and materials with a fairly low thermal conductivity coefficient. These materials have high saturation coefficient and low values of cold endurance. Inside the mineral-wool plates, which are quite popular on the modern market, the hyperfine fibers transform into dust particles by time, and agglutinative compounds destruct, releasing toxic substances. The aluminosilicate microspheres have a high potential as a commercial product, but their market has just started forming. According to rough calculations, the cost of the product is next lower order to the hollow microspheres, obtained by industrial methods.

A molecular zoom into soil Humeome by a direct sequential chemical fractionation of soil

A Humeomics sequential chemical fractionation coupled to advanced analytical identification was applied directly to soil for the first time. Humeomics extracted ~235% more soil organic carbon (SOC) than by the total alkaline extraction traditionally employed to solubilise soil humic molecules (soil Humeome). Seven fractions of either hydro- or organo-soluble components and a final unextractable humic residue were separated from soil. These materials enabled an unprecedented structural identification of solubilised heterogeneous humic molecules by combining NMR, GC–MS, and ESI-Orbitrap-MS. Identified molecules and their relative abundance were used to build up structure-based van Krevelen plots to show the specific contribution of each fraction to SOC. The stepwise isolation of mostly hydrophobic and unsaturated molecules of progressive structural complexity suggests that humic suprastructures in soil are arranged in multi-molecular layers. These comprised molecules either hydrophobically adsorbed on soil aluminosilicate surfaces in less stable fractions, or covalently bound in amorphous organo-iron complexes in more recalcitrant fractions. Moreover, most lipid molecules of the soil Humeome appeared to derive from plant polyesters rather than bacterial metabolism. An advanced understanding of soil humic molecular composition by Humeomics may enable control of the bio-organic dynamics and reactivity in soil.