Showing papers on "Vermiculite published in 2023"

Investigation of the use of ground raw vermiculite as a supplementary cement materials in self-compacting mortars: Comparison with class C fly ash

Abstract: A significant part of the global CO2 emission comes from the production of Ordinary Portland Cement (OPC). Supplementary cement materials (fly ash, silica fume, blast furnace slag, natural pozzolans, etc.) have been used in concrete and mortar production for decades. Due to the limited resources of these supplementary cementitious materials, there was no significant reduction in CO2 emissions. Therefore, the search for new materials and methods continues. In recent years, the use of clay types such as kaolin, metakaolin and bentonite in mortar has become widespread. However, no information has been found in the literature regarding the use of finely ground raw vermiculite as a supplementary cement material. In this study, the effects of ground raw vermiculite (RV) replaced for cement on self-compacting mortar (SCM) were investigated. In this context, 5%, 10%, 15% and 20% ground RV was used in SCM mixtures. SCM mixes was tested for fresh concrete such as slump-flowing and V-funnel times. The pozzolanic activity of fly ash and ground raw vermiculite have been using the strength activity index test. Prism specimens of 40 × 40 × 160 mm3 were produced in order to determine their mechanical properties. These samples were subjected to the flexural strength test at the end of 7, 28 and 90 days and the compressive strength test was performed on the parts obtained from the flexural test. In addition, the durability properties of SCM mixes such as capillary water absorption, sorptivity and porosity were determined. The fresh concrete, mechanical and durability results of RV replacement mortars were compared with Class C fly ash (FA), which is commonly used in SCM mixtures. The results showed that the presence of 5% RV gives the highest compressive strength value at all ages. The presence of 5% and 10% RV improved the 90 days compressive strength value by 3.68% and 2.91%, respectively, compared to the FA substituted series at the same rate. The lowest sorptivity coefficient of 90 days was calculated in the RV5 series with 0.037 mm/min1/2. The results showed that the presence of ground RV in the range of 10–15% in SCM mixtures did not adversely affect the mechanical and durability properties of the mixtures. However, 20% RV use negatively affected the properties of SCM.

Light Intensity and Growth Media Influence Growth, Nutrition, and Phytochemical Content in Trachyandra divaricata Kunth

Abstract: Trachyandra divaricata (Sandkool) is one of the most abundant wild edible inflorescence vegetables in South Africa. The dearth of literature on its edibility, nutrient composition, and conservation has contributed to its underutilisation. This study investigated mineral and proximate content, phytochemical compositions, and growth response of T. divaricata to light intensity and soilless media. Treatments comprised four media (LECA clay, silica sand, peat, and vermiculite) which were subjected to different shade levels (no shade, 20, 40, 60, and 80%) created from a factory-made 20% density net by doubling (40%), tripling (60%), and quadrupling (80%). All treatments were irrigated with a standard nutrient solution. The results showed that the treatments impacted the yield of T. divaricata significantly in terms of biomass and flower buds, especially in plants cultivated in peat under normal greenhouse lighting (no shade). Conversely, plants developed significantly more specific leaf size and total chlorophyll content under shade levels (20, 40, 60, and 80%) in different growth media, even though the values were comparable among treatments. The highest Ca, Mg, Cu, Fe, and Mn levels were consistently recorded in flowers of T. divaricata grown in LECA clay under 80% shade level, while other minerals varied in tested treatments. The peat medium under 20% shade optimised the neutral detergent fibre (NDF) and acid detergent fibre (ADF) content of the flowers, whereas both fat and protein contents were greatly enhanced by peat and vermiculite, respectively, under the 80% shade. Consistently, the lowest phytochemical contents were recorded in LECA clay subjected to 80% shade, whereas the highest polyphenols and DPPH antioxidants were produced by silica sand medium treated with 20% shade. Both TEAC and FRAP antioxidants were improved significantly in LECA clay under no shade and the 60% shade level. However, both 20% and 60% shade levels enhanced the flavonol content significantly. On the basis of these findings, T. divaricata is a promising inflorescent vegetable that may be considered for domestication and further research due to its potential pharmacological and nutraceutical values.

Preparation of nanocarbon modified vermiculite ceramics with excellent adsorption capacity

Abstract: Nanocarbon modified vermiculite porous ceramics with hydrophobicity were prepared using vermiculite as the starting materials and polyethylene terephthalate (PET) as the carbon precursor via the catalytic reaction method. The microstructures, hydrophobicity, and adsorption capacity of as-prepared porous ceramics were characterized by scanning electron microscope, water contact angle testing, and weight gaining, respectively. The results revealed that the nano-carbon generated from the pyrolysis of PET formed on the surface of the pores in ceramics. The water contact angle of as-prepared modified porous ceramics with 82% porosity was up to 123 °. The as-prepared porous ceramics showed highly efficient adsorption to oils and were very durable, and would be excellent candidate materials to separate the oil from the water/oil mixture.

Light Weight Plasters Containing Vermiculite and FGD Gypsum Wastes for Sustainable and Energy Efficient Building Construction Material

Abstract: Abstract Development of lightweight plasters for mortar rendering utilizing Flue gas desulfurization (FGD) gypsum have been reported here. Lightweight plasters prepared using FGD gypsum and exfoliated vermiculite were characterized and studied in detail for interior wall applications. Different gypsum vermiculite plasters (GVP) with variable amounts of vermiculite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal gravimetric analysis (TG-DTG). The physicochemical and mechanical properties of all the samples are determined and considered to be efficient for interior applications. An optimum mix composition was selected based on its compressive strength, water absorption and porosity. Water absorption and porosity studies restrict the usage of GVP only to interior wall purposes. The acoustic performance of the materials revealed good sound absorption (α = 0.65). Plasters exhibit satisfactory durability under severe conditions of winter and summer weather. GVP shows excellent fire resistance under BS 476-1997 fire resistance classification with thermal conductivities (< 0.161 W/mK) much lower than standard building materials, which makes them fit for energy efficient insulation materials. These studies depict the efficient utilization of thermal power plant waste, FGD gypsum in interior wall insulation for mortar rendering and can be further extended to exterior construction applications by reducing water absorption.

Properties of Sound Absorption Composite Materials Developed Using Flax Fiber, Sphagnum Moss, Vermiculite, and Sapropel

Abstract: To address the need to reduce consumption and pollution in the industrial sector, composite materials were created using a new type of raw materials—organic lake sediments (sapropel) as a binder; sphagnum moss, flax fiber, and vermiculite as a filler. The main application of these composite materials is for sound absorption and moisture buffering, but since they contain bio-based binders and fillers, they also work as carbon storage. Within the framework of this work, a total of 100 samples of composite materials were created. Fungicides—a biocide quaternary ammonium compound and its natural substitute montmorillonite mineral material were also added to the materials to improve microbiological stability. The mechanical sound absorption and microbiological properties of materials were investigated and compared to similar environmentally friendly materials, such as hemp-lime concrete (FHL), hemp magnesium oxychloride composite (MOC), and hemp magnesium phosphate cement (MPC). The results showed that sound absorption and mechanical and microbial properties of the created composite materials are sufficient for their intended use, with flax fiber and vermiculite composites showing more stable mechanical, sound absorbing, and microbiological stability properties than materials containing flax fiber and moss.

Investigation on Long-Term Stability of Vermiculite Seals for Reversible Solid Oxide Cell

Abstract: A reversible solid oxide cell (RSOC) integrating solid oxide fuel (SOFC) and a solid oxide electrolysis cell (SOEC) usually utilizes compressive seals. In this work, the vermiculite seals of various thickness and compressive load during thermal cycles and long-term operation were investigated. The leakage rates of seals were gradually increased with increasing thickness and input gas pressure. The thinner seals had good sealing performance. The compressive load was carried out at thinner seals, the possible holes were squeezed, and finally the leakage rates were lower. With a fixed input gas pressure of 1 psi, 2 psi, and 3 psi, the leakage rates of 0.50 mm vermiculite remained at around 0.009 sccm/cm, 0.017 sccm/cm and 0.028 sccm/cm during twenty thermal cycles, while the leakage rates remained at around 0.011 sccm/cm for about 240 h. Simultaneously, elemental diffusions between seals and components were limited, implying good compatibility. Furthermore, the open circuit voltage (OCV) remained at around 1.04 V during 17 thermal cycles, which is close to Nernst potentials. The stack performance confirmed that the vermiculite seals can meet the structural support and sealing requirements. Therefore, the vermiculite shows good promise for application in stacks during thermal cycles and long-term operation.

High-efficiency removal of Cs (I) by vermiculite/zinc hexacyanoferrate (II) composite from aqueous solutions

Abstract: Aimed to solve the problems of low adsorption capacity, complex preparation and difficult recovery for reported cesium ion adsorbents, a novel high-efficiency Cs+ adsorbent of vermiculite/zinc hexacyanoferrate (II) (VMT/ZnHCF) composite was prepared via in situ synthetic method. The structure and properties of this composite were comprehensively characterized using XRD, FTIR, SEM, TEM, and TG-DTA. The maximum Cs+ adsorption capacity was recorded to be 378.79 mg/g, and this value was significantly higher than the values recorded for other absorbents. This spontaneous and exothermic adsorption behavior could be explained by the Langmuir isotherm model and the pseudo-second-order kinetic model. In addition, this composite exhibited excellent selective adsorption ability towards Cs+ even in solutions containing high concentrations of Na+, K+, Ca2+, and Mg2+. The Cs+ adsorption mechanism was analyzed by conducting ion exchange experiments and using XRD, SEM, and XPS techniques. The Cs+ adsorption of the VMT/ZnHCF composite was synergistically achieved through the ion exchange of Na+ in vermiculite interlayers and Zn2+ in zinc hexacyanoferrate (II) lattices. A high-efficiency and simple preparation of cesium ion adsorbent has been developed in application of cesium ion wastewater treatment. This work can provide theoretical guidance to realize the non-hazardous treatment of radioactive wastewater.

Zeolite Composite Materials from Fly Ash: An Assessment of Physicochemical and Adsorption Properties

Abstract: Waste fly ash, with both low (with the addition of vermiculite) and high contents of unburned coal, were subjected to hydrothermal syntheses aiming to obtain zeolite composite materials—zeolite + vermiculite (NaX–Ver) and zeolite + unburned carbon (NaX–C). The composites were compared with parent zeolite obtained from waste fly ash with a low content of unburned carbon (NaX–FA). In this study, the physicochemical characteristics of the obtained materials were evaluated. The potential application of the investigated zeolites for the adsorption of ammonium ions from aqueous solutions was determined. Composite NaX–Ver and parent zeolite NaX–FA were characterized by comparable adsorption capacities toward ammonium ions of 38.46 and 40.00 mg (NH4+) g−1, respectively. The nearly 2-fold lower adsorption capacity of composite NaX–C (21.05 mg (NH4+) g−1) was probably a result of the lower availability of ion exchange sites within the material. Adsorbents were also regenerated using 1 M NaCl solution at a pH of 10 and subjected to 3 cycles of adsorption–desorption experiments, which proved only a small reduction in adsorption properties. This study follows the current trend of waste utilization (fly ash) and the removal of pollutants from aqueous solutions with respect to their reuse, which remains in line with the goals of the circular economy.

Experimental investigation and optimization of lightweight concrete bricks developed using vermiculite

Abstract: Concrete production requires a wealth of resources, including cement, aggregate, and water. Therefore, in terms of maintaining the Earth’s natural ecosystems and resources, researchers need to find sustainable and green methods for producing concrete. The focus of the current research was the use of potentially harmful alternative aggregates to manufacture lightweight concrete bricks. In this study, cement, fine aggregates, and vermiculite were the concrete brick mix components. Three trail mixes were followed by a replacement ratio of 60:40, 50:50, and 40:60 for fine aggregates in bricks. Statistical techniques were exerted to compare all the experimental results. Initially, regression analysis was employed to determine the precise relationship between the dependent and independent variables of the study. Furthermore, the compressive strength of the concrete brick was investigated. As a result of the research, vermiculite concrete bricks with the compressive strengths ranging from 3.2 to 5.9 N/mm2 and densities ranging from 1,780 to 2,142 kg/m3 were obtained. The regression model captured the variability of the data, as evidenced by the suitable R 2 threshold (R 2 > 0.9935). Subsequently, every property of the concrete bricks was predicted using regression, surface plots, main plots, and a heatmap. The conclusion of the study demonstrated that the models generated very effective results.

Do mycorrhizal symbiosis affect wastewater purification in constructed wetlands with different substrates?

Abstract: Arbuscular mycorrhizal fungi (AMF) can play important roles in pollutant removal in the terrestrial system. However, the functional role of AMF in wetland systems is still unclear. This study evaluated the effects of AMF on the purification of the pharmaceuticals and personal care products (PPCPs) containing wastewater in constructed wetlands (CWs) filled with different substrate types (sand, perlite, vermiculite or biochar). Results indicated that the removal efficiencies of total organic carbon (TOC), phosphate (PO43−-P), and total nitrogen (TN) in CWs with different substrates were in the following order: biochar > vermiculite > perlite > sand. Compared with sand systems, the removal efficiencies of TOC, PO43−-P, ammonium (NH4+-N), and TN in CWs filled with adsorptive substrates (biochar, vermiculite, or perlite) were enhanced by 3.8–11.4 %, 11.6–30.6 %, 16.5–31.2 %, and 6.2–34.6 %, respectively. AM symbiosis increased TOC, TN, and PO43−-P removal in CWs but the adsorptive substrates showed more significant influences on wastewater purification than AMF symbiosis. Besides, plant (Glyceria maxima) presence also improved the performance of CWs on wastewater purification. Overall, all the findings indicated that the interaction effects of AM symbiosis and adsorptive substrates (e.g., biochar, vermiculite, or perlite) could enhance the removal performance of pollutants from wastewater in planted CWs.

Baccharis vulneraria (Asteraceae) cuttings in different substrates

Abstract: Abstract The objective of the study was to identify the most suitable substrate and type of cutting to obtain seedlings from Baccharis vulneraria Baker cuttings. Apical and stem cuttings were collected from stock plants grown in a greenhouse. After collection, the cuttings were grown in the following substrates: commercial peat-based substrate (CPS); Vermiculite (VM); carbonized rice husk (CRH); Coconut fiber (CF); VM and CRH (1:1) (VM + CRH); VM and CF (1:1) (VM + CF); and CRH and CF (1:1) (CRH + CF) mixtures. The experiment used a completely randomized factorial design and, after 60 days, the percentage of survival and rooting (% SR), aerial part length (APL) and roots length (RSL), number of shoots (SN) and new leaves (LN), root volume (RSV), aerial part dry mass (APDM), and roots dry mass (RSDM) were evaluated. An interaction was found between the type of substrate and cutting for APL, RSL, LN, RSV, and RSM. On the other hand, %SR, SN and APDM differed only by cutting type. Apical cuttings showed higher APL, while internode cuttings showed higher SN, LN, RSV, and APDM. CPS promoted higher RSL in both types of cuttings, being a suitable option for the propagation of Baccharis vulneraria, particularly in internode cuttings.

Analysis of the Impact of Vermiculite on Hematite-Based Cement Systems

Abstract: Heavyweight oil-well cement systems are designed for isolating intervals and supporting the casing at deeper depths where high temperatures and pressures are encountered. The cement slurry should have adequate rheology to ensure efficient placement. Additionally, the hardened cement sheath should be homogeneous with lower porosity and permeability, higher strength, and sufficient flexibility. The effect of vermiculite on hematite-based cement samples has been investigated. The methodology and testing were based on the American Petroleum Institute standards and other recognized recommendations. Fluid properties were characterized by their rheology, while petrophysical and mechanical properties were used to analyze the properties of hardened cement specimens. The vermiculite was used in concentrations of 0.25, 0.5, 1, and 2% by weight of cement (BWOC). The slurries were cured at 3000 psi and 292 °F in cubic and cylindrical molds for 24 h. The results indicate that using 1% BWOC of vermiculite yields the best cement properties. It minimizes the settling of hematite particles to a very low value compared to the base cement as shown by the method of density variation and confirmed by nuclear magnetic resonance. Compared to the base cement slurry, the slurry of 1% BWOC of vermiculite has desirable rheology in terms of plastic viscosity and gel strength. The incorporation of 1% BWOC improves the strength of the cement sheath by 50.7% for the compressive strength and 65% for the tensile strength. Adding 1% vermiculite reduces the permeability and porosity of the cement by 45.8 and 43.5% compared to the control cement. In addition, the 0.7% vermiculite cement is more flexible than the control cement in terms of the elastic properties represented by lower Young’s modulus (a reduction of 33%) and higher Poisson’s ratio (an increase of 2%).

Layered Clay Minerals in Cancer Therapy: Recent Progress and Prospects.

Abstract: Cancer is one of the deadliest diseases, and current treatment regimens suffer from limited efficacy, nonspecific toxicity, and chemoresistance. With the advantages of good biocompatibility, large specific surface area, excellent cation exchange capacity, and easy availability, clay minerals have been receiving ever-increasing interests in cancer treatment. They can act as carriers to reduce the toxic side effects of chemotherapeutic drugs, and some of their own properties can kill cancer cells, etc. Compared with other morphologies clays, layered clay minerals (LCM) have attracted more and more attention due to adjustable interlayer spacing, easier ion exchange, and stronger adsorption capacity. In this review, the structure, classification, physicochemical properties, and functionalization methods of LCM are summarized. The state-of-the-art progress of LCM in antitumor therapy is systematically described, with emphasis on the application of montmorillonite, kaolinite, and vermiculite. Furthermore, the property-function relationships of LCM are comprehensively illustrated to reveal the design principles of clay-based antitumor systems. Finally, foreseeable challenges and outlook in this field are discussed.

The Expanded Vermiculite Was Quickly Prepared by the Catalytic Action of Manganese Dioxide on Hydrogen Peroxide and Its Adsorption Properties to Cd

Abstract: The structure and activity of vermiculite can be maintained by expanding vermiculite (Vrm) with hydrogen peroxide. However, it is time-consuming. In past studies, little attention has been paid to the catalytic properties of manganese dioxide on hydrogen peroxide to improve the swelling efficiency of vermiculite. In this experiment, this catalytic effect was utilized to swell Vrm in a short time. The samples were then used to adsorb Cd from the solution. Through a series of characterization tests. The results showed that the exothermic rate was 1960.42–2089.164 J/min and the total exothermic heat was 39,208.4–41,783.28 J when expanding 10 gVrm, which could have a good expansion effect. The expansion was completed in about 40 min. Compared with Vrm, the adsorption of Cd is enhanced by about 30%. It is consistent with the proposed secondary kinetic adsorption model. This study provides a new perspective and theoretical guidance for improving the efficiency of Vrm stripping by hydrogen peroxide. A kind of expanded Vrm with better Cd adsorption efficiency was also prepared.

The development of premix technology with vermiculite filler

Abstract: In achieving a high level of biological usefulness of feeding poultry, the enrichment of compound feed with a complex of biologically active additives – premixes is of decisive importance. The organization of the production of high-quality premixes is an important direction in the development of the domestic feed industry. Vermiculite is one of the mineral raw materials mined on the territory of the Republic of Kazakhstan, suitable for use in agriculture, in the production of premixes. Kazakhstan has large resources of vermiculites. The aim of the study is to determine the feasibility of using the natural mineral vermiculite from the Kulantau deposit as a filler in the production of premixes and a component in the production of animal feed. The physicochemical parameters of the natural mineral vermiculite have been determined. The analyzes of the study were carried out in the research laboratory for assessing the quality and safety of food products of the Almaty Technological University. Studies have been carried out on the use of vermiculite from the Kulantau deposit as a filler-diluent in the production of premixes. It was found that the natural mineral vermiculite has good flowability, low humidity, does not cake, so the use of vermiculite in the production of premixes helps to increase the safety of biologically active substances. The optimal time for preliminary mixing of microcomponents with vermiculite filler has been determined. With the addition of vermiculite after the third minute of mixing, the coefficient of variation is 6,63%. The introduction of the vermiculite mineral into the premix has a positive effect on the mixing process and the uniformity of the finished product. The mineral vermiculite reduces the humidity of the premix, has good flowability, and prevents the separation of the premix components during transportation. The total mixing time of the premixes is reduced to 4 minutes. The study of the vermiculite mineral in the composition of the premix, the improvement of the technological scheme for the production of the premix, will allow the production of high-quality domestic premix.