Montmorillonite Layers Research Articles

Design and development of a biocompatible montmorillonite PLGA nanocomposites to evaluate in vitro oral delivery of insulin

We are introducing design, development and preliminary feasibility study of nanocomposites (made of Food and drug administration approved layered montmorillonite (Mt) and biodegradable polymer Poly lactic-co-glycolic acid (PLGA)), as a vehicle for oral administration of insulin. A systematic study on the variation of Mt-PLGA ratio was focused to reduce particles to the submicron size range while maintaining insulin's bioactivity. The synthesized Insulin-Mt-PLGA nanocomposites were successfully characterized with various techniques and compared with the Insulin-PLGA nanoparticles for their drug content, physico-chemical properties, in-vitro insulin release profile and cytotoxicity. High encapsulation efficiency, desirable particle size, prolonged gastric residence time, extended release of insulin in simulated gastrointestinal fluid and biocompatibility indicated the effectiveness of presence of Mt in the synthesized Mt-PLGA nanocomposites for the oral delivery of insulin. Thus, on the basis of our preliminary research findings, it could be concluded that the developed biocompatible Insulin-Mt-PLGA nanocomposites with double functionality of low pH stability and mucoadhesivity may offers promise to overcome the difficulties associated with the oral drug delivery of insulin.

Salt-controlled self-healing nanogel composite embedded with epoxy as environmentally friendly organic coating

Smart nanogel capsules are attracting great attention to act as self-healing materials for polymers and epoxy coating and as anticorrosion materials. The present work aimed at incorporating nanogel among silicate layers of sodium montmorillonite (Na-MMT) to increase its dispersibility into an epoxy matrix so as to be used as self-healing nanocomposites. For this purpose, N-isopropyl acrylamide (NIPAm) as a salt-sensitive monomer was selected to prepare smart nanogels to disperse the Na-MMT layers. The chemical structure, surface morphology, particle size distribution, surface charge, and degree of exfoliation of Na-MMT with NIPAm nanogel were investigated. The ability of Na-MMT/NIPAm to modify the mechanical, surface, and self-healing characteristics of epoxy matrix was studied. The corrosion inhibition and self-healing mechanism were discussed in light of salt spray resistance of epoxy nanocomposites to protect steel from corrosive environments.

Water-based synthesis of TiO2/CeO2 composites supported on plasma-treated montmorillonite for parathion methyl degradation

The undemanding water-based synthesis was employed for the preparation of TiO2/CeO2 composites supported on Montmorillonite (MT). The prior plasma treatment of Montmorillonite led to significantly faster dispergation in water during the synthesis. The composites were used as reactive adsorbents against toxic organophosphorus pesticide parathion methyl. Efficient pillaring of the Montmorillonite layers by surface deposition of TiO2/CeO2 composites reflected in a substantially improved degradation activity towards parathion methyl in non-polar (heptane) and polar solvents (acetonitrile) investigated by HPLC/DAD. Moreover, the use of plasma treated Montmorillonite in the composites resulted in a higher degradation rate than with use of pristine MT. The formation of composites and their physicochemical properties were studied by XRD, XPS, FTIR, nitrogen physisorption, SEM and HRTEM/EDS mapping. Prior plasma treatment of the MT in a simple arrangement led to an easier formation of the composites and caused further improvement of the samples activity.

Clay Minerals Variations in Quaternary Sediments of Basrah City-Iraq

Mineralogical and chemical analysis of two well cutting in quaternary sediments at Basrah city. This study have been focused on the quaternary clay minerals variations which give a clear indication to marine transgression and or / regression in Hammar formation. Kaolinite, Illite, Palygoreskite, Illite-Palygorestike mixed layer, Chlorite, Montmorillonite, Vermiculte, and mixed layers of Illite- Smectite are the most quantitatively important phyllosilicates in soil studies in both boreholes. The mineralogical composition of cutting sediments shows significant variability in the different size fractions and depth distribution. Chlorite and kaolinite minerals were increase in the fine grain size especially in the clayey silt, whereas montmoriolllinite and vermiculite minerals were increase in coarse grains especially in silty sand texture. Kaolinite decrease in abundance with depth, which give indicative of a transition from non-marine in quaternary recent sediment ( fresh or brackish water silt) to marine facies in quaternary Hammar formation ( marine shelly silt) during last transgression of quaternary. Palygoreskite mineral percentages increasing at depths 27 and 28 meter , after decreased at 30, 32, 35 , and 40 m respectively , which give data indication that early quaternary marine transgression happened in 32m , and center of quaternary marine transgression detected in 27 and 28 meters , while late marine transgression detected in 17 m , and all of these represent by Hammar formation. Soil ageing also caused to downward increase of montmorillonite suggest to climate became more arid during the early quaternary. Variations ratio of montmorillonite versus kaolinite can be indicated to climatic fluctuation. Illite-Semectite featured indicates changes in both sediment source and paleoclimate. Illite transformation for Illite-Palygoreskite mixed layers with ageing. Vermiculite has strong susceptibility to increase with age. SiO₂, Al₂O₃, CaO, MgO, K₂O, and Fe₂O₃ were the major oxides that identified in present study and used as indicated of clay minerals in studied sediments.

Influences of salt solutions and salinization-desalinization processes on the volume change of compacted GMZ01 bentonite

Investigation on influences of cyclic salinization-desalinization processes on clay is of great importance for evaluation of the behavior of engineering barrier in deep geological repository for disposal of high-level radioactive waste. In this study, one-dimensional free swelling tests were conducted on densely compacted GMZ01 bentonite specimens, which has an initial dry density of 1.7Mg/m3, with cyclically infiltration of NaCl, CaCl2 or KCl solution at different concentrations and de-ionized water. Results show that the volume change of the compacted clay could be influenced by concentrations and cation types of solutions, as well as number of salinization-desalinization cycles during the salinization-desalinization processes. The total swelling strain of GMZ01 bentonite specimens measured on the first salinization with salt solutions at a same concentration follows an order: NaCl>CaCl2>KCl. This observation could be explained by the influences of basal space, DDL theory and K-linkage. A cation with higher replacing power can be replaced by another cation with lower replacing capacity when it has a higher concentration in the pore solution. The concentration effect on the swelling behavior of GMZ01 bentonite was explained using the concept of osmotic suction for specimens initially infiltrated with NaCl solutions. For specimens initially infiltrated with CaCl2 solutions, in addition to the osmotic suction effect, the distance between the unit layers of montmorillonite also played a role in explaining the swelling behavior. The swelling behavior of specimens initially infiltrated with KCl solutions could be explained by the strong K-linkage.

Nanocomposite of ZnO with montmorillonite for removal of lead and copper ions from aqueous solutions

Abstract The clay minerals montmorillonite (MMT) was combined with ZnO to form efficient nanocomposite which was used as an adsorbent. Zinc oxide nanoparticles (ZnO-NP) were successfully incorporated into the layers of montmorillonite by green simple heat method using zinc nitrate and sodium alginate as zinc oxide precursor and stabilizer respectively. The XRD and FESEM measurements revealed the presence of ZnO nanoparticles with hexagonal wurtzite structure in the ZnO/MMT nanocomposites. The role of the ZnO in enhancing the adsorption efficiency of the ZnO/MMT nanocomposite for the removal of copper and lead ions from aqueous solutions was investigated. The effects of different parameters such as contact time, dosage, initial concentration, and pH were investigated. Kinetics of adsorption were studied using pseudo-first-order and pseudo-second order. The efficiency of the nanocomposites was studied by Langmuir and Freundlich isotherms. The material showed high efficiency in a wide pH range, for the adsorption of Pb and Cu ions. Kinetic studies showed that the adsorption followed the pseudo-second-order and equilibrium best described by Langmuir isotherm. The regeneration results show that the nanocomposites can be utilized for at least three times because of its stability and durability. Thus, it can serve as a promising adsorbent for the removal of copper and lead ions from aqueous solutions.

Experimental Study of Montmorillonite Structure and Transformation of Its Properties under Treatment with Inorganic Acid Solutions

This paper discusses the mechanism of montmorillonite structural alteration and modification of bentonites’ properties (based on samples from clay deposits Taganskoye, Kazakhstan and Mukhortala, Buriatia) under thermochemical treatment (treatment with inorganic acid solutions at different temperatures, concentrations and reaction times). Treatment conditions were chosen according to those accepted in chemical industry for obtaining acid modified clays as catalysts or sorbents. Also, more intense treatment was carried out to simulate possible influence at the liquid radioactive site repositories. A series of methods was used: XRD, FTIR, ICP-AES, TEM, nitrogen adsorption, and particle size analysis. It allowed revealing certain processes: transformation of montmorillonite structure which appears in the leaching of interlayer and octahedral cations and protonation of the interlayer and –OH groups at octahedral sheets. In turn, changes in the structure of the 2:1 layer of montmorillonite and its interlayer result in significant alterations in the properties: reduction of cation exchange capacity and an increase of specific surface area. Acid treatment also leads to a redistribution of particle sizes and changes the pore system. The results of the work showed that bentonite clays retain a significant portion of their adsorption properties even after a prolonged and intense thermochemical treatment (1 M HNO3, 60 °C, 108 h).

Study on montmorillonite/insulin/TiO2 hybrid nanocomposite as a new oral drug-delivery system

This study was conducted in two main stages. In the first stage, drug-loaded montmorillonite nanocomposites were prepared by intercalation of insulin into the montmorillonite layers in acidic deionized (DI) water. In the second stage, to increase the release of insulin from the prepared nanocomposites they were coated with TiO2, an inorganic porous coating, by using titanium (IV) butoxide, as precursor. The prepared nanocomposites were characterized by FT-IR, XRD, FE-SEM, BET, DLS and Zeta potential analysis. After investigating the release behaviour of the nanocomposites by UV–Vis absorbance technique, the results revealed that incorporation of porous TiO2 coating increased the drug entrapment noticeably, and decreased the amount of drug release, so that nanocomposites without and with TiO2 coating released the drug after 60min and 22h in pH7.4, respectively. These results could be used in converting the insulin utilization from injection to oral.

Carbon nanotube/paraffin/montmorillonite composite phase change material for thermal energy storage

A composite phase change material (PCM) comprised of organic montmorillonite (OMMT)/paraffin/grafted multi-walled nanotube (MWNT) is synthesized via ultrasonic dispersion and liquid intercalation. The microstructure of the composite PCM has been characterized to determine the phase distribution, and thermal properties (latent heat and thermal conductivity) have been measured by differential scanning calorimetry (DSC) and a thermal constant analyzer. The results show that paraffin molecules are intercalated in the montmorillonite layers and the grafted MWNTs are dispersed in the montmorillonite layers. The latent heat is 47.1J/g, and the thermal conductivity of the OMMT/paraffin/grafted MWNT composites is 34% higher than that of the OMMT/paraffin composites and 65% higher than that of paraffin.

Effects of highly exfoliated montmorillonite layers on the properties of clay reinforced terpolymer nanocomposite plugging microspheres

ABSTRACTIn this study, exfoliated montmorillonite (MMT) nanolayers were successfully encapsulated in acrylamide/acrylic acid/2‐acrylamido‐2‐methylpropanesulfonic acid (AM/AA/AMPS) terpolymer microspheres by in situ inverse suspension polymerization with the aid of the organic intercalation modification and the lateral groups of terpolymer chains. The introduction of well‐dispersed MMT nanolayers reveals a significant enhancement of the comprehensive properties of these nanocomposite microspheres, such as the viscoelasticity, thermal stability, and plugging ability. Compared with the pure terpolymer, the elastic modulus (G′) of terpolymer/2.0 wt % O‐MMT nanocomposites is 4.30 times higher and the decomposition temperature of these nanocomposites increases by 40 °C. The plugging rate reaches as high as 86.6%. Besides, surface morphology, swelling degree, and wetting behavior can be effectively tuned by varying the content of exfoliated MMT. The wetting angle increases to 82.0 ° which is suitable for modifying the formation channels. These selected nanocomposite microspheres can effectively enter and plug the high permeable microchannels. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44894.

Montmorillonite–chitosan–chlorhexidine composite films with antibiofilm activity and improved cytotoxicity for wound dressing

HypothesisChlorhexidine (CLX) is a good antimicrobial agent, but its use in treatment of wounds is limited because of its cytotoxicity towards human fibroblasts. A delivery system, able to release CLX in a localized and prolonged manner, could guarantee antimicrobial activity with reduced cytotoxic. Thus in this work the preparation and characterization of chitosan/montmorillonite composite films containing CLX, able to offer a prolonged CLX release, is described. The antimicrobial and antibiofilm activities and cytotoxicity of films were investigated. ExperimentalCLX was intercalated between the layers of montmorillonite (MONT-Na), and the intercalated product (MONT-CLX) was characterized by X-ray powder diffraction (XRPD), thermogravimetric analysis (TGA) and FT-IR spectroscopy. Then chitosan/MONT-CLX films were prepared and characterized. For comparison, films loaded with neat CLX and MONT-Na/CLX were prepared. All prepared films were tested for their antimicrobial and antibiofilm activities. Cytotoxicity towards human skin keratinocytes and human fibroblasts HuDe was evaluated as well. FindingsAll prepared films showed good antimicrobial and antibiofilm activities. As concerns cytotoxicity the film containing MONT-CLX at 1% CLX concentration resulted no cytotoxic. These results confirm the potential use of chitosan films containing MONT-CLX as a potential wound dressing material to prevent microbial colonization in wounds.

Hierarchical MoS2 intercalated clay hybrid nanosheets with enhanced catalytic activity

Emerging hierarchical MoS2/pillared-montmorillonite (MoS2/PMMT) hybrid nanosheets were successfully prepared through facile in-situ hydrothermal synthesis of MoS2 within the interlayer of cetyltrimethylammonium bromide PMMT, and their catalytic performance was evaluated by the reduction reaction of 4-nitrophenol (4-NP) using NaBH4 as a reductant. Microstructure and morphology characterization indicated that MoS2/PMMT exhibited hybrid-stacked layered structures with an interlayer spacing of 1.29 nm, and the MoS2 nanosheets were intercalated within the montmorillonite (MMT) layers, with most of the edges exposed to the outside. The catalytic activity and stability of MoS2/PMMT were both enhanced by the MMT. With the MoS2/PMMT as the catalyst, the apparent reaction rate constant of the 4-NP reduction was 0.723 min−1 and was maintained at ~0.679 min−1 after five reaction cycles. The structural evolution of MoS2/PMMT and the possible catalysis mechanism for the reduction reaction of 4-NP were investigated. The as-prepared MoS2/PMMT hybrid nanosheets are promising candidates for catalytic application in the water-treatment and biomedical fields. The strategy developed in this study can provide insights for designing hybrid nanosheets with diverse heterogeneous two-dimensional (2D) nanomaterials.

Selective self-etherification of 5-(hydroxymethyl)furfural over Sn-Mont catalyst

Sn-Mont was found to be a highly efficient catalyst for self-etherification of 5-(hydroxymethyl)furfural (HMF) to give 5,5′-oxy(bis-methylene)-2-furaldehyde (OBMF). L-B acidity of Sn(OH)4 species enwrapped into the layers of montmorillonite was responsible for the excellent activity of Sn-Mont catalyst giving almost complete conversion of HMF with 98% selectivity to OBMF. Aprotic non-polar, dichloroethane was most effective solvent due to the facile formation of oxonium ion mediating etherification reaction. The catalyst showed suitable recyclability confirming its appreciable hydrolytic stability in water, and retention of its acidity.

Properties of adsorption of vitamin B12 on nanoclay as a versatile carrier.

In this study properties of adsorption of vitamin B12 onto nanoclay were investigated. Results of kinetics of adsorption were used to investigate the structural formation and nature of interaction of vitamin B12 onto montmorillonite as a carrier. The results showed that at the early stages of adsorption with migration of interlayer cations of montmorillonite (Ca2+and Na+) to the edges a cationic bridge was formed and the vitamin biomolecules were adsorbed at the edges of montmorillonite. By increasing the adsorption duration, vitamin B12 molecules gradually diffused in between montmorillonite layers. Such diffusion was facilitated when enough interaction existed between montmorillonite surface charges and vitamin biomolecules. The results of this study provided information about controlling the adsorption properties of biomolecules to the montmorillonite for preparation of nano-engineered nano/biomaterials for food and pharmaceutical applications.

Development of montmorillonite-supported nano CaO2 for enhanced dewatering of waste-activated sludge by synergistic effects of filtration aid and peroxidation

Nanosized CaO2 was first synthesized using montmorillonite clay layers as templates for combining the positive effects of filtration aid and peroxidation on the dewatering of waste-activated sludge (WAS). Exchangeable Ca2+ compensating for negative charges of montmorillonite reacted with the added H2O2, affording nano CaO2 on the surface or in the interlayer regions of montmorillonite (montmorillonite-supported nano CaO2, MMT-nano CaO2). The catalytic capacity of montmorillonite for generating OH from nano CaO2 was verified by electron paramagnetic resonance (EPR), therefore, the radical oxidation induced by MMT-nano CaO2 can destruct the floc structure of WAS with the omission of Fe(II), the conventionally used catalyst for Fenton reaction. As a result, the reduction in specific resistance of filtration (SRF) by 62.2% was achieved with the MMT-nano CaO2 dosage of 100mg/g dry solid (DS) and the weakly acidic pH of 5. OH led to the reduction of hydrophilic protein in extracellular polymeric substances (EPS), and the swelling behavior of montmorillonite contributed to the formation of a porous structure as draining medium for water withdrawing. The above factors were the dominant mechanisms for enhancing dewatering performance.

Remediation of Anthracene-Contaminated Soil by ClO2 in the Presence of Magnetic Fe3O4-CuO@Montmorillonite as Catalyst

Fe3O4-CuO@montmorillonite was prepared using coprecipitation method, and its structure was determined by XRD, IR, and transmission electron micrograph (TEM). Montmorillonite in Fe3O4-CuO@montmorillonite nanocomposite allowed the silicate layer of montmorillonite to behave as a barrier, which prevented the agglomeration and natural crystallization of Fe3O4 and CuO. Furthermore, the chlorine dioxide (ClO2) oxidative degradation of anthracene-contaminated soil was studied in detail using Fe3O4-CuO@montmorillonite as a magnetic heterogeneous catalyst. The operating parameters such as ClO2 concentration, catalyst dosage, reaction time, and pH were evaluated. Compared with the conventional ClO2 oxidation process without the catalyst, the ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (anthracene concentration 89.8 mg/kg, water soil mass ratio 3:1, initial pH 7, ClO2 concentration 1 mol/kg, catalyst dosage 1 g/kg, reaction time 30 min, and reaction temperature 25 °C), anthracene degradation efficiency achieved 96.2 %. The catalyst could be easily reused by magnetic separation and used at least 8 cycles without obvious loss of activity. The kinetic studies revealed that the ClO2 catalytic oxidation degradation of anthracene-contaminated soil with Fe3O4-CuO@montmorillonite as catalyst followed pseudo-first-order kinetics with respect to ClO2 concentration. Thus, this study showed potential application of ClO2 catalytic oxidation process in remediation of organic pollutant-contaminated soil.

Epoxy nanocomposites with carbon nanotubes and montmorillonite: Mechanical properties and electrical insulation

Multiwalled carbon nanotubes have been widely used as mechanical reinforcement fillers for polymers during the past few decades. However, high electrical conductivity of raw multiwalled carbon nanotubes hampers their application in some fields demanding not only good mechanical properties and/or high thermal conductivity but also electrical insulation. In this research, carboxyl functionalized multiwalled carbon nanotubes and organically modified montmorillonite were introduced to prepare epoxy nanocomposites with anhydride as curing agent. The obtained epoxy nanocomposites possessed improved impact toughness, and the electrical insulation was maintained. Compared to the volume resistivity of the raw multiwalled carbon nanotubes (0.6 wt%)/epoxy nanocomposites, the volume resistivity of the organically modified montmorillonite/carboxyl functionalized multiwalled carbon nanotubes (0.6 wt%)/epoxy nanocomposites increased more than four order of magnitude. These excellent properties were attributed to the synergistic effect of carboxyl functionalized multiwalled carbon nanotubes and organically modified montmorillonite on toughening epoxy, as well as the suppression of electron transport by multiwalled carbon nanotubes surface modification and the organically modified montmorillonite layer in the multiwalled carbon nanotubes conductive network. The effects of adding nanofillers on the dielectric constant and dielectric loss values of epoxy nanocomposites were also studied. This work has demonstrated the feasibility of using multiwalled carbon nanotubes as mechanical reinforcement fillers, while simultaneously giving electrical insulation in the polymer nanocomposites.

Facile synthesis of g-C3N4/montmorillonite composite with enhanced visible light photodegradation of rhodamine B and tetracycline

A novel g-C3N4/montmorillonite (CN/M) composite with enhanced visible light photocatalytic activity was synthesized via a facile two-step process including wet-chemical and calcination method. The microstructure, interfacial and optical properties of the obtained CN/M composites were characterized by scanning electron microscope (SEM), high-resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), surface area measurement (BET) and UV-visible diffused reflectance spectroscopy (UV-vis DRS). It is indicated that a tight interfacial combination between g-C3N4 nanosheets and montmorillonite layers was formed in the composite photocatalysts. Compared with the other reference samples, the as-received CN/M composites possess significantly enhanced photocatalytic activity towards rhodamine B and tetracycline. The optimal mass ratio of g-C3N4 with respect to montmorillonite is determined to be 31.86wt% and the corresponding reaction constant rate is almost 3.0 times that of the pure g-C3N4 under visible light. The enhanced photocatalytic activity of the g-C3N4/montmorillonite composite could be attributed not only to its relatively higher surface area and enhanced light-adsorption ability under visible light but also the synergistic effect arising from the tight combination between g-C3N4 and montmorillonite due to the electrostatic interaction, which leads to efficient separation of the photo-generated charge carriers.

Mesoscale simulation of clay aggregate formation and mechanical properties

This paper proposes a novel methodology for understanding the meso-scale aggregation of clay platelets in water. We use Molecular Dynamics simulations using the CLAYFF force fields to represent the interactions between two layers of Wyoming montmorillonite (Na-smectite) in bulk water. The analyses are used to establish the potential of mean force at different spacings between the layers for edge-to-edge and face-to-face interactions. This is accomplished by finding the change in free energy as a function of the separation distance between the platelets using thermodynamic perturbation theory with a simple overlap sampling method. These nanoscale results are then used to calibrate the Gay–Berne (GB) potential that represents each platelet as a single-site ellipsoidal body. A coarse-graining upscaling approach then uses the GB potentials and molecular dynamics to represent the meso-scale aggregation of clay platelets (at submicron length scale). Results from meso-scale simulations obtain the equilibrium/jamming configurations for mono-disperse clay platelets. The results show aggregation for a range of clay platelets dimensions and pressures with mean stack size ranging from 3 to 8 platelets. The particle assemblies become more ordered and exhibit more pronounced elastic anisotropy at higher confining pressures. The results are in good agreement with previously measured nano-indentation moduli over a wide range of clay packing densities.

A Highly Permeable Aligned Montmorillonite Mixed‐Matrix Membrane for CO2 Separation

AbstractHighly permeable montmorillonite layers bonded and aligned with the chain stretching orientation of polyvinylamineacid are immobilized onto a porous polysulfone substrate to fabricate aligned montmorillonite/polysulfone mixed‐matrix membranes for CO2 separation. High‐speed gas‐transport channels are formed by the aligned interlayer gaps of the modified montmorillonite, through which CO2 transport primarily occurs. High CO2 permeance of about 800 GPU is achieved combined with a high mixed‐gas selectivity for CO2 that is stable over a period of 600 h and independent of the water content in the feed.