Silica Clay Research Articles

Silica clay (opoka) as a promising raw material for unfired wall products by compression molding

The article is devoted to the actual problem of producing unburnt wall products of compression molding with improved and high efficiency in terms of thermal and engineering properties. The article notes the relevance, attractiveness, and wide use of unburnt pressed products in modern civil engineering. The raw material composition and production technology of unburnt wall products of compression molding are described. The traditionally used aggregates for unburnt wall products of compression molding are reviewed and their properties are analyzed. High average density and high thermal conductivity are noted in these products. The objective is to improve the thermal characteristics of these products while ensuring their strength properties. For this purpose, it is proposed to introduce a porous component of siliceous rock called opoka (silica clay) into the raw material composition of products as a mineral filler. Opoka collected from three different deposits was reviewed, its characteristics given, and the raw material analyzed. It is noted that the porosity and average density of opoka depend on its deposit. The effect of porosity and average density of opoka on the average density, compressive strength, and water absorption of unburnt wall products of compression molding based on opoka with different porosities from different deposits is described. The effect of the properties of opoka on the properties of unburnt wall products of compression molding is explained. It is confirmed that the use of opoka in the production of unburnt wall products reduces the average density of the products and improves their thermal and engineering properties. The appropriateness of manufacturing large-sized hollow wall blocks based on opoka is substantiated.

Immobilization of Lipases on Modified Silica Clay for Bio-Diesel Production: The Effect of Surface Hydrophobicity on Performance

The hydrophobicity of a support plays a critical role in the catalytic efficiency of immobilized lipases. 3-aminopropyltriethoxysilane (APTES)-modified silica clay (A-SC) was coupled with silane coupling agents of different alkyl chains (methyl triethoxysilane, vinyl triethoxysilane, octyl triethoxysilane, and dodecyl triethoxysilane) to prepare a series of hydrophobic support for lipase immobilization. The lipases were immobilized onto the support by conducting glutaraldehyde cross-linking processes. The results showed that the activity of the immobilized biocatalyst increased with hydrophobicity. The hydrolytic activity of Lip-Glu-C12-SC (contact angle 119.8°) can reach 5900 U/g, which was about three times that of Lip-Glu-A-SC (contact angle 46.5°). The immobilized lipase was applied as a biocatalyst for biodiesel production. The results showed that the catalytic yield of biodiesel with highly hydrophobic Lip-Glu-C12-SC could be as high as 96%, which is about 30% higher than that of Lip-Glu-A-SC. After being recycled five times, the immobilized lipase still maintained good catalytic activity and stability. This study provides a good strategy to improve the efficiency of immobilized lipases, showing great potential for future industrial application on biodiesel production.

Experimental study of the possibility of using a silica clay as a source of silicon in the production of glass in the Turkestan region of Kazakhstan

Three series of experiments were carried out to study the possibility of replacing quartz sand in the initial charge for the production of glass with a silica clay. The experiments were carried out at atmospheric pressure and temperatures of 900–1200 С. It is shown that the complete replacement of quartz sand with a silica clay and the use of the presented initial compositions based on silica clay in the glass industry will lead to an increase in the temperature in the technological scheme of production, an increase in energy consumption and is economically unprofitable.Production schemes are promising, in which, along with the silica clay, the original charge contains cullet. It is shown that the disappearance of crystalline phases in this case in the samples with the addition of the silica clay occurs at a lower temperature than in the samples without the silica clay.

Surface ion-imprinted silica clay for adsorption of chromium(III) ions from aqueous with high selectivity

Surface ion-imprinted silica clay for adsorption of chromium(III) ions from aqueous with high selectivity

Influence of silane functionalized nanoclay on the barrier, mechanical and hydrophobic properties by clay nanocomposite films in an aggressive chloride medium

The surface alteration of silica clay by a silane coupling agent was done to improve the compatibility with epoxy polymer matrix. It can be attained with ethoxy based silanes namely (3-mercaptopropyl) triethoxysilane (MPTES), propyltriethoxysilane (PTES) and 3-aminopropyl(diethoxy)methylsilane (APDES) in order to enhance the anticorrosion potential of epoxy coatings on mild steel. The structural and thermal properties of the functionalized clay nanoparticles are studied by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The morphological features of the functional nanoclay were also described by employing field emission scanning electron microscopy with energy dispersive x-ray analysis (FE-SEM/ EDX) and TEM (Transmission electron microscopy) analysis. These analyses showed the well functionalization of nanoclay by silanes. The well dispersion of functionalized nanoclay in the epoxy resin produces better nanocomposites which are coated on the mild steel. The coated steel samples were analyzed in terms of microstructure and corrosion resistant properties in 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SECM), salt spray analysis, and analysis of oxygen and water permeability were applied to assess the barrier properties against water permeation, oxygen penetration and protectiveness of silane-modified epoxy coatings. It was found that all the modified coatings showed higher barrier resistance and superior corrosion resistance than pure epoxy coating, which were described by higher charge transfer resistance (Rct) 6815.36 kΩcm2 and lower double-layer capacitance (Cdl) 405.51 µF at the electrolyte/metal interface. The tensile strength was found to be 113 MPa for EP-MPTES/clay nanocomposite while the value of pure epoxy coated specimen was 41 MPa. Therefore, the silane grafted clay nanoparticles results in slower diffusion processes, which specifically slow down the anodic reaction, thus blocking the overall corrosion path. Modified clay-epoxy nanocomposite displays good thermostability, better dispersion, outstanding mechanical property and superior water resistance property. Among the examined silanes, MPTES shows an effective functionalization of nanoclay, followed by the APDES and PTES. A possible mechanism has also been proposed.

Effect of nanofillers on radiation crosslinked natural rubber latex vulcanisates

Radiation vulcanised natural rubber latex (RVNRL) nano composites were prepared by incorporating aqueous dispersions of fumed silica and nano clay (fluorohectorite) in the RVNRL. Properties of the nanocomposites were compared with vulcanisates containing inert filler were used. RVNRL/nano silica composites showed superior tensile properties. TGA analysis indicated that the thermal stability of RVNRL/nano composites is higher than that of micro composites. Theoretica lmoduli of nano and micro composites were computed using different composite models and compared with experimental data. A good agreement between experimental and theoretical values was observed in the case of RVNRL/nano silica composites. The transparency of the composites was quantified using UV-Visible spectrophotometer. The morphology analysis of the composites using scanning electron microscopy indicated that the nanoparticles were homogeneously distributed in NR matrix.

КОММУНАЛЬНЫЕ СТОКИ В ОПЫТАХ ПО РЕКУЛЬТИВАЦИИ ОТХОДОВ ОБОГАЩЕНИЯ ЛОПАРИТОВЫХ РУД

Introduction. This paper discusses the effectiveness of using clarified municipal wastewater (CMW) and wastewater sludge (WS) to form stable phytocenoses at the waste storage facilities of the rare metal industry in Murmansk Region. The restoration of the vegetation cover at tailing dumps is limited by the low content of organic matter and associated nitrogen, and the low bioavailability of plant nutrients (K, Ca, Mg, P). The use of WS and other ameliorants of organic nature is a type of chemical amelioration aimed primarily at improving the edaphic properties of man-made soils. Methods. We examined the loparite ore dressing tailings sampled in the operating field of the tailing dump of a rare metal industry enterprise in the center of the Kola Peninsula. In the course of the study, we determined the suitability of the man-made soil for reclamation. To form seeded phytocenosis in a laboratory experiment, seeds of meadow fescue (Festuca pratensis Huds.) were used. The laboratory experiment involved the introduction of CMW, WS, a mixture of WS with silica clay into the soil, and a check. Analysis of the soil and plants was performed using inductively coupled plasma mass spectrometry. The quality of seeded cenosis was assessed according to the following parameters: green biomass, plant height, and projective cover. Results. The preliminary assessment of the man-made soil suitability for reclamation showed the following: the loparite ore dressing tailings have unfavorable characteristics both for the natural regeneration of the vegetation cover and biological reclamation. The introduction of ameliorants had a stimulating effect on the growth of terrestrial biomass during the formation of phytocenosis under laboratory conditions. The results of leaf analysis confirmed the effectiveness of the surface application of organic additives with regard to the loparite ore dressing tailings. Conclusion. In the laboratory experiment with the simulation of surface application, the stimulating effect of unconventional ameliorants (clarified municipal wastewater, wastewater sludge, and its mixture with silica clay) on the supply of nutrients to the reclaimed loparite ore dressing tailings was confirmed. The investigated ameliorants can be recognized as suitable for the biological reclamation of the dressing tailings of the rare metal industry, which does not require costly earthing and the application of protective polymer coatings.

Influence of Fillers on Silicate Compositions Porization

The article is devoted to the problem of raw material base expanding and improving construction and technical properties of porous granular materials. The results of experimental studies of silicate compositions based on liquid glass and technogenic fillers containing burnable or gas-forming components are presented. Influence of molding mixtures’ composition on thermal expansion nature of granular compositions was established. Preference of a filler combined, containing glass cullet, silica clay and mineral additives was revealed. Multicomponent composition of a filler helps to intensify composition’s expansion. Electron microscopy studies of porous silicate granules have confirmed the advantages of combined fillers using. Effectiveness of sodium additive introduction to regulate technological properties of the raw material and the process of pores formation has been proven. Expediency of mechanical activation of a raw mixture to reduce the temperature of expansion and obtain granules with a bulk density of not more than 300 kg/m3 has been determined.

Defluidization Investigation into Bubbling Fluidized Bed Particles with Alkaline Addition during Pyrolysis

Some unwanted inorganic materials, such as alkaline compounds contained in biomass, have the potential to create slagging formations with oxide compounds from either inside or outside the bubbling fluidized bed (BFB). The process involved 88-125 µm silica sand and clay (bentonite) as bed particles during pyrolysis with KCl addition at 700°C to represent biomass under superficialN2-velocity operation. Agglomeration formation was confirmed by the decrease in the average ΔP of the experiment, which theoretically should take place during the addition of KCl, while the defluidization condition was confirmed by a consistent average ΔP particle deviation, even after further KCl additions. Investigation of 0.005 and 1 g encapsulated KCl periodical addition showed that the silica sand has a tendency to form agglomeration faster than bentonite, specifically after 0.0211 g of KCl addition (0.0032% of total silica sand mass). Meanwhile, the bentonite has a tendency to achieve defluidization formation more easily than silica sand according to deviation analysis. The ability of silica sand to maintain fluidization longer than bentonite indicates that silica sand is the better particle for this process.

Synthesis of efficient stable dendrimer-modified carbon for cleaner drilling shale inhibition

Shale hydration is a major hurdle in oil well drilling with water-based drilling fluids (WBDFs) in oil and gas which could greatly increase the gross cost of production due to well collapse. Shale hydration inhibitors must be added to the WBDFs to prevent such occurrence. Attention has been drawn currently to the design of eco-friendly and low-cost shale inhibitors having excellent compatibility with WBDFs for effective wellbore drilling operations. Herein we report the efficient enhancement of shale inhibition of polyvinylpyrrolidone (PVP) by incorporating activated carbon modified dendrimer (ACD) represented as ACD/PVP with a low environmental footprint. The characterization of the composite material, as well as the sodium bentonite (Na-BT) treated with it via various spectroscopic and imaging instruments including FTIR, NMR, TGA, and SEM, was established. The result of the TGA revealed that the materials could withstand high temperatures. SEM images proved that it has the tendency to successfully inhibiting shale swelling. The prepared material shale preventive ability was further assessed through an anti-swelling ratio, recovery test, and free swelling test. The 2 wt% AC-D/PVP solution reflected outstanding shale inhibition and tolerance to high temperature. This could be ascribed to the synergetic activity of the composite in which the dendrimer acted as a cation, which brings the clay silica sheets together while the PVP participated in sealing the surface of the clay mineral via the large volume of hydrogen bond formation with the dendrimer to form a shield against water penetration. The plugging potential of AC and the hydrophobic character of the PVP polymer chain also contributed greatly to this effect. The PVP which is the major component of the materials is environmentally compatible likewise the AC-D to some extent. In view of this, the AC-D/PVP composite could be a suitable substitute for the present less efficient and unsustainable shale inhibitors that are being used in the oil and gas industry.

Preparation of Immobilized Lipase on Silica Clay as a Potential Biocatalyst on Synthesis of Biodiesel

Biodiesel offers an important alternative to fossil fuel. In this work, Eversa Transform 2.0 lipase was immobilized onto 3-aminopropyltriethoxysilane (APTES) modified silica clay (SC) by glutaraldehyde. The characteristics of the functionalized supports and the immobilized lipase were investigated by FTIR, TEM, BET, and XRD. The results show that the optimal conditions of lipase immobilization are as follows: 2% glutaraldehyde concentration, 15 mg/mL lipase concentration and incubating at 25 °C for 60 min. The immobilized lipase showed a high tolerance to temperature and pH variation in comparison to the free lipase. The immobilized lipase on SC was applied as a biocatalyst for the synthesis of biodiesel from methanol and canola oil. A biodiesel yield of 86% was obtained at a temperature of 45 °C via a three-step methanol addition. A conversion yield of 67% was maintained after reusing the immobilized lipase for five cycles. This work provides a strategy for the preparation of an efficient biocatalyst for the synthesis of biodiesel.

Strength and deformability of cement stone, mortar and concrete during loading

The article analyzes the structural strength and the main provisions of the mechanical behavior of cement systems under short-term loading. It presents the results of the research into concrete’s strength and deformability at the structural levels of the cement stone, mortar and concrete in general during loading. To fabricate concretes, manufacturable binders, quarry sands and rock – silica clay of the Penza region were used. The following materials were considered: cement stone with different W/C, cement mortar with different sands and with its addition in different proportions, and concrete with the use of a light aggregate – thermolith. It was found that when the W/C increases from 0.25 to 0.31, the ultimate compressibility and ultimate extensibility of cement stone increases to 9% and 29.5%, respectively. The introduction of various types of sand into the composition caused the reduced compressibility and extensibility of materials, despite the fact that the mortars became more plastic. The authors describe the fabrication technology and properties of a light aggregate based on a silica clay - thermolith. Tests of thermolith concrete showed the character of immediate elastic and rapidly increasing creep deformations development in the context of longitudinal compression and transverse expansion.

Removal of Basic Violet from Wool Dyeing Effluent Using Nanoparticles

ABSTRACT In the reported study, nano silica and nano clay were used to remove the residual color from effluent generated during the dyeing of wool fabric with basic violet. Various concentrations (0.1%, 0.25%, 0.5%, and 1.0%) of the nanoparticles were treated with dye effluent for different durations and the results are compared with the color removal of commercial activated carbon. The nanoparticles were characterized for their physical properties including particle size, FTIR, and TEM. Freundlich isotherm was used for the dye adsorption studies. The FTIR and TEM analysis depicted the characteristic peaks and crystal geometry for the selected nanoparticles. The treated effluent showed a significant reduction in color, biological, and chemical oxygen demand (more than 99%). The treatment was optimized for 1.0% adsorbent concentration for 60 minutes. The color removal efficiency of nano silica was found to be higher at low concentration; however, the efficiency of nano clay exceeded at a higher concentration of adsorbents.

The study of the silica clay dust elemental composition in building materials’ production

The paper discusses the physical properties of the silica clay used as building material and mineral. During crushing, pouring, packing and other processes the dust which enters the storage bunkers of dust removal systems, is formed; it is emitted from the dust collecting devices into the atmosphere, and a part of the dust enters the working area. The paper compares the elemental composition of the silica clay before the crushing operation; the dust collected in bunkers of dust removal systems; in the air emissions; the dust after using the dust collectors and working area air dust. The study was conducted using a Versa 3D Dual Beam scanning electron microscope. The dust characteristics’ comparative studies were carried out in three intake zones for three types of dust collectors used in dust removal systems: fabric filters, cyclones and swirling approach flows (SAF). The homogeneity hypothesis was tested using the Kolmogorov-Smirnov criterion. Based on the measurement results, it was concluded that the dust from the dust bunkers for all the dust collector options has a close elemental composition and can be returned to the additives’ production process. It is shown that the dust entering the working area air and in emissions into the atmosphere are close in their characteristics. The results of measuring the random distribution functions of the elemental composition and molecular weight are obtained, which allow calculating particle weight and other characteristics with 95% certainty, as well as evaluating the aerodynamic characteristics of dust particles, etc.

Heat insulators based on silica clay raw materials

The paper presents the results of laboratory studies and pilot tests of the production of foamed glass based on the silica clay from Shipovo field (Republic of Kazakhstan). It is shown that the granulated foamed glass can be commercially produced from widespread siliceous raw material, using home equipment.

Creating and Studying of Enterosorbent with Harsh-Fixed Antioxidants which Have Enzymatic Properties

The enterosorbent-antioxidant is created on the basis the silica clay of the Astrakhan region as a result of theoretical and experimental studies. The antioxidant properties enterosorbent SV-1-AO were studied. The studies to elucidate the possible deactivation of hydrogen peroxide in the gastrointestinal tract of animals in the application of enterosorbent SV-1-AO were carried out. The practical application of the product of the sorption concentration of antioxidant enzymes to ensure the safety of life is shown

Moisture Diffusion in Silica/Clay/Natural Rubber Hybrid Composites

This study investigated moisture diffusion in natural rubber (NR) hybrid composites filled with silica and bentonite clay. Natural bentonite (BNT) was treated with tetradecyldimethylammonium chloride and coco diethanolamide to produce modified bentonite (M-BNT). Varied proportions of silica, M-BNT, and BNT fillers were added to raw NR according to a third-degree simplex lattice mixture design of experiment. The addition of fillers affects the vulcanization characteristics, mechanical properties, and hardness of NR hybrid composites. Moisture diffusion behavior was studied by monitoring the water uptake of NR composites during immersion in deionized water at 80°C. Data from sorption experiments were fitted on the classical Fickian and Langmuir-type diffusion models. The Fickian model overestimates and underestimates the water uptake of NR composites in the early and later stages of moisture diffusion, respectively. On the other hand, the Langmuir-type model adequately captures the anomalous diffusion behavior of moisture in NR composites. Parameters of the Langmuir model (equilibrium water uptake and diffusion coefficient) vary with the composition of hybrid fillers. Optimum proportions of silica, M-BNT, and BNT in rubber composites were obtained by considering the effect of fillers on mechanical properties and moisture diffusion characteristics of NR.

Precambrian Si isotope mass balance, weathering, and the significance of the authigenic clay silica sink

The geological cycles of carbon and silicon are linked via the silicate weathering feedback, but growing understanding of reverse weathering—the formation of authigenic clay minerals via back reaction of silica with cations—indicates that the nature of the connection between these two elemental cycles may be more complex than previously assumed. Recent carbon cycle modeling has suggested that enhanced reverse weathering during Precambrian time could have played an important role in regulating climate. The topology of the Precambrian silica cycle, including the size of the authigenic clay sink and its influence on the carbon cycle, is challenging to reconstruct due to inherent preservation biases in the rock record. Here we used an alternative approach using Si isotope values to invert for the magnitudes of Precambrian silica fluxes, by assuming that the silica cycle must be in mass balance with the bulk silicate Earth over geological time scales with respect to Si isotopes. To estimate uncertainties associated with these flux reconstructions, we used Monte Carlo simulations based on the natural variation exhibited in Si isotope ratio data from the Precambrian sedimentary record (n = 2118, spanning ~3.8 Ga to ~525 Ma) and modern authigenic clays (n = 123). The perspective of Si isotope mass balance shows that the previously observed increase in chert δ30Si values across Precambrian time is a signal of an evolving silica cycle rather than a secular change in seawater temperature. Results yielded a secular increase in the relative contribution of the authigenic clay sink across most of Precambrian time—this view is consistent with previous interpretations of a concomitant decrease in the concentration of dissolved silica in seawater. This result is consistent among a variety of model versions incorporating different assumptions about the abundance of iron formations and possible relationships between authigenic clay formation and concepts that invoke slow growth in the absolute amount of the continental crust. This approach also highlights key areas where improving Si isotope records could further enhance our constraints on the Precambrian silica cycle, and its relationship with the carbon cycle and climate stability.

Alkali-Activated Material Based on Red Clay and Silica Gel Waste

Industrial by-products such as silica gel waste and red clay based on natural illite, have been used as precursors for the preparation of alkali activated materials (AAM). Raw materials, precursors and the alkali-activated materials were examined using X-ray diffraction, XRFA and SEM analysis. The reactive concentrations of Si and Al were determined using the colorimetric method. The compressive strength of alkali-activated samples was also evaluated. The precursors were made from Lithuanian red clay (Ukmergė deposit) and silica gel waste. The clay and silica gel waste were first mixed together and then calcined at 900 °C or 600 °C to obtain the precursors. The results show that during the calcination process, new phase CaF2 formed in the precursors. It is possible that fluoride compound which forms during the calcination process, acts as a flux (at a temperature of 900 °C), and for this reason, the reactive amorphous phase is transformed into mullite and cristobalite (crystalline phases), which are not reactive. According to the XRD diffractogram, calcination at a temperature of 600 °C was sufficient to convert the crystalline structure of kaolinite into an amorphous phase. In this case, at a calcination temperature of 600 °C, it was recommended to use up to 25% of silica gel waste. The maximal compressive strength (7 MPa) was achieved by using 5% of silicagel waste. It was concluded that red clay–silica gel waste AAM can be considered for the production of green composite materials.

Hydrophobic Sorbent of Silica Clay

The paper presents the results of a study of the physicochemical and sorption characteristics of the modified silica clay. It is established that the modification of the silica clay provides an increase in the hydrophobicity, specific surface, and porosity of the sorbent, and also increases its capacity in petroleum absorption. It was found out that the modified silica clay is a highly effective sorbent with respect to emulsified petroleum products. The sorption activity of the modified silica clay on petroleum products was estimated using sorption isotherms.