Clay Composites Research Articles

Evaluation of CO2 attack in wellbore class G cement: influence of epoxy resins, composites and minerals as additives

AbstractCarbon dioxide (CO2) injection into geological formations is pointed out as one of the most effective alternatives to reduce anthropogenic CO2 emissions to the atmosphere. To promote long‐term CO2 storage, wellbore integrity is a critical issue to be considered. Portland cement is commonly used for cementing wells, and considered chemically unstable in CO2‐rich media. In this context, this study investigated the CO2 chemical resistance of class G Portland cement modified with novel additives (epoxy resins, epoxy–clay composites, and clay minerals) at 1 and 2.5 wt% contents. Reaction times of 7 and 30 days of exposure to CO2 in supercritical conditions were evaluated. Samples were characterized by mechanical compression tests and phenolphthalein indicator as well as field emission scanning electron microscopy in order to determine the depth of carbonation in cement. Our results indicate that although there is slight reduction in the initial compressive strength, the addition of tested additives to cement paste offers improvements in terms of chemical resistance. The optimum content of different additives was 1 wt% in order to maintain compressive strength properties and improve chemical resistance to CO2. The best result was achieved with an epoxy resin blend as an additive, decreasing carbonation by up to 60% (7 days of exposure to CO2) and 52% (30 days of exposure to CO2). Addition of montmorillonite to the epoxy blend tends to improve chemical resistance of cement paste when compared to the neat epoxy blend. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

Electrical properties speculation of contamination by water and gasoline on sand and clay composite

Effects of temperature, frequency, and molarity on electrical conductivity have been studied for sand-clay samples contaminated by water and gasoline. Electrical properties change according to frequency, contaminant type, and structure of components at the sample. A comparison was performed for these contaminated sand-clay samples. Changes of dielectric constant (∈′), conductivity (σ), and complex impedance with frequency (0.1 Hz 2×107 Hz), with different contaminant concentration (at constant room temperature ~ 21 °C), have been studied. The sand-clay samples were mutually wetted gradually using gasoline and distilled water. Then, electrical properties were measured sequentially. Water is 30a conductive liquid and the contaminant gasoline is an insulator. The experimental results indicate that conductivity of samples increases with increase of water concentration while with the additions of the contaminant gasoline, the sample conductivity decreases. The permittivity decreases with reduction of conductive links between grains and with the progressive increase of frequency. The conduction of electrical conductivity, commonly, increases with increase of connectivity between different links between grains. Also, conduction increases with progressive increase of frequency. Comparison of both outcomes from lab electrical measurements gives 30a speculation about the picture in the field.

Efficient arsenic(V) removal from contaminated water using natural clay and clay composite adsorbents.

The natural clay is an abundant, accessible, and low-cost material that has the potential for use in the water and wastewater industry. In this paper, Iranian natural clay and clay/Fe-Mn composite were used to remove toxic arsenic from the liquid environment. The natural clay and clay/Fe-Mn composite were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX), X-ray diffractometry (XRD), thermo-gravimetric analysis (TGA), and atomic force microscopy (AFM) techniques. The effects of parameters (initial pH, temperature, sorption dose, and contact time) on the efficiency and behavior of the arsenic(V) adsorption process were studied. Freundlich (R2 = 0.945 and 0.989), Langmuir (R2 = 0.922 and 0.931), modified Langmuir (R2 = 0.921 and 0.929), and Dubinin-Radushkevich (R2 = 0.706 and 0.723) models were fitted to evaluate the equilibrium data of arsenic(V) adsorption process by natural clay and clay/Fe-Mn composite, respectively. The Langmuir adsorption capacity of arsenic(V) by the natural clay and clay/Fe-Mn composite was determined to be 86.86 mg/g and 120.70 mg/g, respectively. The arsenic(V) adsorption process followed the pseudo-second-order model. Negative values of ΔG° and ΔH° showed that the arsenic(V) sorption by the studied materials is thermodynamically spontaneous and exothermic. According to the findings, the natural clay and clay/Fe-Mn are suitable and recyclable sorbents for arsenic(V) adsorption from aqueous solutions. Also, the composite of clay with iron and manganese can improve the efficiency of clay in the removal of arsenic.

Organic-Inorganic Hybrid Films Fabricated from Cellulose Fibers and Imogolite Nanotubes.

Owing to the increasing environmental awareness, nanocellulose/natural clay composites with improved mechanical performance have attracted growing interest due to their eco-friendly properties. In this study, hybrid films composed of cellulose fibers (CFs) and imogolite nanotubes (natural aluminosilicate nanotubes) were fabricated. We mainly studied the structure, density, and properties of the hybrid materials. Specifically, the hybrid materials were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), a rheological test, and wide-angle X-ray diffraction (WAXD). The mechanical properties of the hybrid materials were measured by a tensile test, which demonstrated that the mechanical properties of the hybrid films were considerably improved by the addition of imogolite up to 1 wt %; meanwhile, the thermal-mechanical properties of the hybrid film were also enhanced.

Effect of phase change material integration in clay hollow brick composite in building envelope for thermal management of energy efficient buildings

The present trend in building research is to improve sustainability in building construction and operation. The development of new renewable technologies is essential to improve the sustainability and to reduce emissions. The incorporation of phase change materials in buildings is an effective way to reduce the room temperature fluctuations and cooling loads/heating loads. Although several works have been carried out in this field, a novel phase change material clay hollow-brick composite has been used in this work. This article discusses the research on investigating the thermal performance of phase change material integration in building walls. Two identical test rooms (3 m × 3 m × 3.65 m) were constructed to study the effect of phase change material integration in buildings. The experimental buildings were constructed for the warm and humid weather conditions of Chennai city, India. Phase change material integration in the building wall is beneficial for reduction of room temperature and provides passive cooling of the building. The temperature drop in a phase change material room compared with a non-phase change material room varies from 6°C to 2°C, during various months of the year. DESIGNBUILDER simulation was carried out for phase change material and non-phase change material buildings during the months of January, March, May, and July. The simulated room temperature variation follows the same pattern in these months.

The SO3H-functionalized carbonaceous@montmorillonite efficient heterogeneous catalyst for synthesis of trimethylolpropane from long-chain fatty acid

Abstract As the increasing demand of bio-lubricants in industries, the new “green” synthetic method to polyolesters has attracted lots of attention. Herein, we report a novel efficient heterocatalyst contained sulfonic acid group, which was assembled through hydrothermal carbonization with the mixture carbon source of chitosan and furaldehyde, the hydroxyethylsulfonic acid aqueous solution was added as SO3H source. The obtained carbonaceous intercalated clay composites conserved regular layered and enlarged specific surface areas and pore volumes, which were proved by small-angle XRD, SEM and N2 sorption isotherms. The FT-IR, XPS, 13C CP/MAS NMR spectrum, Raman spectra and elemental analysis were employed to confirm the SO3H groups and its loading level. As an acidic heterogeneous catalyst for esterification between trimethylolpropane and oleic acid, synthesized SO3H-loaded carbonaceous intercalated montmorillonite composite exhibits high catalytic activity under the solvent-free conditions. The yield of the desired bio-lubricant is as high as 91% in 3 h. With little loss of catalytic activity after be reused five times, the SO3H-functionalized carbonaceous intercalated montmorillonite composite shows good reusability.

Ni(2,2′-bipy)3]Cl2 activated sepiolite clay with high photocatalytic and oil–water separation abilities

Novel [Ni(2,2′-bipy)3]Cl2 activated sepiolite clay composites have been successfully synthesized by a hydrothermal reaction method. The activated clays are endowed with much higher photocatalytic abilities than the raw one. Degradation ratios of rhodamine B and methyl orange under UV light were found up to 99.8% and 95.4% within 120min. Beside efficient dye degradations, a high H2 evolution rate of 12.5 umol/g/h was reached by using the [Ni(2,2′-bipy)3]Cl2/sepiolite composite as the catalyst. Coating the as-synthesized material on surfaces leads to extraordinary superhydrophobic and superoleophilic properties. The cheap materials can be widely used in photocatalytic water purification and/or oil-water mixture separations.

Cured cuttlebone/chitosan-heated clay composites: Microstructural characterization and practical performances

Clay-based materials composed of geopolymers and natural fibbers, among others, could be suitable composites for building construction. So, in this study, composites of a heated kaolinitic-illitic clay and cuttlebone or chitosan (up to 10 mass%) were etched with a NaOH solution (6 M), shaped as briquettes and cured at 83 °C for up to 30 days. The microstructure of the cured composites was investigated, and some of their practical performances were evaluated. The results showed that metakaolinite and illite - to some extent-, and a portion of Na+ ions were involved in the formation of zeolite (chabazite) and Na-carbonate respectively. Moreover, layers of cuttlebone or chitosan were built up around the clay particles, and the thick layers developed in the cuttlebone- and in the chitosan-rich composites affected differently the zeolization process. Chitosan versus cuttlebone favoured zeolization by facilitating the ions mobility, and the illite reactivity. By referring to the mechanical/physical properties of the cured NaOH-etched heated clay, the bending and the compressive strengths of the cured composites as well as their water absorption increased by two-to three times. The strengthening of the composites was related mainly to the reduction of porosity (up to 40% for the cuttlebone-rich composite).

Adsorption studies of Ce(III) and Zr(IV) from aqueous solution using clay and humic acid—clay materials

Adsorption features onto clay and modified surface clay with humic acid (clay-HA) is investigated. Natural clay material and clay-HA composite were characterized using FTIR, TGA, and DTA. Performance adsorption for Ce(III) and Zr(IV) onto clay and clay-coated by HA are comparable. Adsorptive removal of 83.6 and 73.8% onto clay-HA for Ce and Zr, respectively, from aqueous solution, was carried out at pH 3. The results are revealed that the clay or clay-HA materials have an economic and a promising adsorbent for high potential decontamination of the minor lanthanides radioisotopes and Zr isotopes rather than Cs isotopes from nuclear site waste or environmental wastewater onto clay and clay-HA materials. This study concluded that the nature of clay material and modified clay-HA are capable of retention of radioisotopes and could be used as an effective barrier in the disposal, nuclear site to inhibit any leakage and/or migration of radioisotopes to the environment.

Non-toxic poly(vinyl alcohol)/clay composites as electrode material for detection of 4-chlorophenol and 4-nitrophenol

Development of new electrode materials is necessary for the fabrication of sensors with low detection limits, high sensitivity and broad concentration range. Beside analytical parameters, the ability to replace rare and expensive metals, without additional pollution, is also expected from new materials. Materials based on non-toxic raw materials are presented in this paper. Clay-polymer nanocomposites consisting of Wyoming clay rich in montmorillonite and different loadings of poly(vinyl alcohol) (PVA) (10wt% and 20wt%, i.e. PVA10-W and PVA20-W samples) were synthesized. The intercalation of PVA into montmorillonite was confirmed by elemental, XRD and SEM analysis. The electrochemical behavior of synthesized electrode materials was tested using the electrochemical impedance spectroscopy and cyclic voltammetry. It was found that PVA/montmorillonite ratio influenced the performance of the composite-modified electrode. The detection of 4-chlorophenol and 4-nitrophenol on the investigated electrodes was tested using the square wave voltammetry. The analytical application of the electrodes was evaluated on a river water sample.

PHB and Montmorillonite Clay Composites as KNO3 and NPK Support for a Controlled Release

In order to improve nutrient uptake by plants and at the same time decrease losses by leaching, polymeric compounds based on biodegradable poly(3-hydroxybutyrate) (PHB) and montmorillonite clay (MMt) were melt processed with KNO3 and NPK fertilizers (Fert). We present a comprehensive analysis of releasing profile of the potassium (K+), nitrogen (NH4+ and NO3−) and phosphorous (PO43−) from PHB/MMt/fertilizer at 90/0/10, 50/0/50, 80/10/10, 40/10/50, 25/25/50 formulation. The amount and type of the fertilizer and the presence of clay delineated the release of the cations and anions from the matrix. Cations released faster than anions through MMt composites due to cations–MMt interactions and its diffusion through MMt phase. The nutrients delivery from composites was lower than pure fertilizer. Composites formulations with smaller amount of PHB and MMt (25 wt%) were enough to encapsulate the fertilizer and delay the ions releasing. Further, the simple method of preparation also attains the sustainability of the whole process.

Cucurbit[6]uril Glued Magnetic Clay Hybrid as a Catalyst for Nitrophenol Reduction

Cucurbit[6]uril (CB6) was used as a molecular glue for preparation of a new hybrid material using exfoliated montmorillonite clay and copper ferrite magnetic nanoparticles. Hybrid material was prepared by ultra-sonication method and characterised by FTIR, DR UV–Vis, XRD, FE-SEM, TEM, TGA and BET surface area measurements. The catalytic activity of the hybrid was examined for reduction of a potential industrial pollutant, 4-nitrophenol. The hybrid exhibited good catalytic activity (kapp 0.026 s−1) with low catalyst loading (∼0.05 mg/ml) and was found suitable for large scale application. The hybrid catalyst was successfully recycled and reused up to eight reaction cycles without any loss in catalytic activity. Here, CB6 acted like a molecular glue stabilising the hybrid catalyst. This greatly improved reusability in comparison with bare nanoparticles and clay composite. This approach where CB6 was used as a molecular glue can be conveniently utilised for stabilising nanoparticles on various solid support materials to develop better quality catalysts, composites and hybrid materials.

Thermal and rheological properties of polyamide 6/layered double hydroxide clay composites

Thermal and rheological properties of polyamide 6/layered double hydroxide (PA6/LDH) composites were studied. Pristine (U-LDH) and organically modified (M-LDH) clays were used in this study. Some evidence of intercalation was observed on the microstructure of PA6/M-LDH samples, while PA6/U-LDH was characterised by microcomposite morphology as shown by the transmission electron microscopy results. The scanning electron microscopy results showed a complete delamination of the M-LDH in the PA6 matrix while U-LDH was evenly dispersed as immiscible tactoids. In the melt state, the M-LDH had a significant influence on the melt microstructure of PA6 matrix when compared to U-LDH. Differential scanning calorimetry results, both dynamic and isothermal experiments, showed that LDH had a heterogeneous nucleating effect on the PA6 matrix, with the U-LDH showing better nucleating effect when compared to M-LDH. The thermogravimetric analysis results showed that M-LDH had a negative influence on the thermal stability of the composites, while U-LDH improved their thermal stability. The X-ray diffraction and dynamic mechanical analysis results showed that the presence of M-LDH promoted the formation of γ-crystallites in the PA6 matrix, while U-LDH composites were dominated by the α-crystallites. This phenomenon had a positive correlation with increasing content of both LDH clays. An overall improved dynamic mechanical properties were observed for PA6/U-LDH when compared to PA6/M-LDH composites.

Adsorption recovery of Ag(I) and Au(III) from an electronics industry wastewater on a clay mineral composite

The aim of this work is to investigate the ability of an adsorbent of a clay mineral composite to remove and recover gold and silver ions from wastewater. The composite was prepared by mixing phosphogypsum (PG), obtained from an industrial waste, and a natural clay mineral. The materials were characterized before and after use in adsorption by several techniques. Batch adsorption experiments were carried out, and the effects of the contact time and the pH and temperature of solution on the removal processes were investigated. The optimum pH for the adsorption was found to be 4. The adsorption of these metal ions reached equilibrium after 2 h of contact. The pseudo-first- and the pseudo-second-order kinetic models, as well as the Freundlich and the Langmuir isotherm equations, were considered to describe the adsorption results. The maximum adsorbed amount of 85 mg·g−1 Ag(I) and 108.3 mg·g−1 Au(III) was found. The recovery of the adsorbed gold and silver ions from the adsorbent was also analyzed. Strong acids appeared to be the best desorption agents to recover gold and silver ions. The use of aqua regia gave regeneration rates close to 95.3% and 94.3% for Ag(I) and Au(III), respectively. Finally, the removal of gold and silver ions from an industrial wastewater was tested in batch experiments, and percentage recoveries of 76.5% and 79.9% for Ag(I) and Au(III), respectively, were obtained. To carry out the industrial application of the proposed methodology, an economic viability study is required.

Large-Scale Experimental Investigation of Strength Properties of Composite Clay

Composite clay is a mixture of clay and coarse-grained materials which can particularly be applied in practice as the core of earth dams and the platform for construction of buildings and roads. They are especially used when the appropriate materials are not available or the present mixed soils have not the required properties. The soil strength measurement for various types of soils including the cohesive and gravelly soils is an important issue in geotechnical engineering. Therefore, this paper is intended to compare the resistance of samples with different percentages of clay and gravel with a maximum grain size of 19 mm by performing large-scale direct shear tests. The samples consisted of clay and gravel with the gravel content of 30%, 50%, 70% (by dry weight of clay), respectively. First, to ensure the required compaction, modified Proctor compaction tests were performed. Then, large scale direct shear tests were conducted on the samples to measure the shear strength properties of soil. The results clearly reveal that by increasing the percentage of gravel in the mixture, the maximum dry density increased and the optimum moisture content decreased. It was also observed that increasing the gravel content leads to an increase in the soil internal friction angle and shear strength.

Adsorption and reduction of chromium(VI) from aqueous solution using polypyrrole/calcium rectorite composite adsorbent

Chromate is considered to be a toxic contaminant because of its potential to harm animal and human health. In this study, polypyrrole/calcium rectorite clay composites (PPy/Ca-REC composites) were prepared as a potential adsorbent, via in situ polymerization of pyrrole monomer for adsorption of Cr(VI) from aqueous solution. The XRD results indicated that the clay sheets were exfoliated in the prepared composites. SEM results showed good dispersion of the PPy on the clay sheets. The adsorption of Cr(VI) onto the PPy/Ca-REC adsorbent was highly pH-dependent, and the removal efficiency by PPy/Ca-REC composites was much higher than the PPy homopolymer. Adsorption kinetics followed a pseudo-second-order kinetic model with an equilibrium reached within 30–180 min. The adsorption isotherm data were fitted well by the Langmuir isotherm model with the maximum adsorption capacity of 714.29–833.33 mg/g at 25–45 °C. The PPy/Ca-REC composites could be regenerated and reused for three consecutive adsorption-desorption cycles without loss of the original removal efficiency for Cr(VI) removal. Furthermore, the selective adsorption of Cr(VI) was demonstrated in binary adsorption systems with coexisting ions. The mechanisms of Cr(VI) removal containing electrostatic interactions, ionic interaction as well as reduction of Cr(VI) to Cr(III), which could be observed by the XPS results.

Antimicrobial Applications of Clay Nanotube-Based Composites.

Halloysite nanotubes with different outer surface/inner lumen chemistry (SiO2/Al2O3) are natural objects with a 50 nm diameter hollow cylindrical structure, which are able to carry functional compounds both inside and outside. They are promising for biological applications where their drug loading capacity combined with a low toxicity ensures the safe interaction of these nanomaterials with living cells. In this paper, the antimicrobial properties of the clay nanotube-based composites are reviewed, including applications in microbe-resistant biocidal textile, paints, filters, and medical formulations (wound dressings, drug delivery systems, antiseptic sprays, and tissue engineering scaffolds). Though halloysite-based antimicrobial materials have been widely investigated, their application in medicine needs clinical studies. This review suggests the scalable antimicrobial nano/micro composites based on natural tubule clays and outlines research and development perspectives in the field.

Synergy of Magnetite Intercalated Bentonite for Enhanced Adsorption of Congo Red Dye

Recently, magnetic separation of adsorbent materials has attracted much attention for abatement of water pollutants. Due to the strong magnetic property and environmental beneficial behavior Fe3O4 NPs were used to modify local bentonite clay. The prepared magnetite intercalated Bentonite clay composite (Fe3O4-AC) structure and magnetic property were confirmed by powder X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FTIR), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM). The prepared Fe3O4-AC composite has shown a superior adsorption efficiency to Congo red (CR) dye over acid activated bentonite clay (AC). The enhanced adsorption of the Fe3O4 NPs intercalated in the layer of bentonite could be ascribed to the enhanced surface area and the prevention of the activated clay agglomeration. The optimum removal efficiency was analyzed using Response Surface Methodology (RSM) based Box-Benhken Design (BBD). The optimum conditions for maximum adsorption % removal were found to 94.9% at 105 min, 0.6 g Fe3O4-AC composite, 10 mg. L−1, and pH =4. The adsorption isotherms and Kinetics process were indicated that the experimental data are well fitted to Langmuir and pseudo-second-order models.

Understanding the electrical, thermal and mechanical properties of LDPE‐clay nanocomposites

The performance of low-density polyethylene (LDPE) clay nanocomposites was analysed. The inclusion of nano montmorillonite (MMT) clay in LDPE material has significantly increased the contact angle, corona ageing resistance, water droplet initiated corona inception voltage and surface discharge inception voltage of the composites. The surface charge decay rate of the samples significantly reduced on the inclusion of clay indicating modified trap distribution characteristics due to the inclusion of the filler. Dynamical mechanical analysis indicates increased storage modulus and reduced tan (δ) due to nanofillers inclusion. Laser-induced breakdown spectroscopy indicates that on inclusion of nanofillers the plasma temperature increases and crater depth decreases. In particular, increased discharge resistance, improved thermomechanical properties are observed with LDPE–MMT clay composites compared to pure LDPE.

Study on intercalation in layered structure of halloysite nanotubes (HNTs)

The organic-intercalated clay composites have aroused attractable interest due to their tremendous application in industry. As a new type of the layered-structure material, halloysite nanotubes (HNTs) were employed to explore the intercalation relationship between the interlayer property and intercalating agents, which were more significant for the potential application. For this purpose, this work systematically studied the intercalation behaviours of dimethyl sulphoxide, potassium acetate, N -methylformamide, methanol, and acrylamide in the layered-structure HNTs, respectively. The organics-intercalated HNT composites were determined by a series of characterisations.