Structure Of MMT Research Articles

Highly Active and Selective Fe‐MOF/2D‐Montmorillonite Photocatalyst via in‐situ Preparation for Hydroxylation of Benzene to Phenol

AbstractThe photocatalytic hydroxylation of benzene to phenol is an important reaction for the synthesis of fine chemicals and pharmaceuticals. However, the development of efficient and selective photocatalysts for this reaction remains a challenge. Here, a highly active and selective Fe‐MOF/2D‐montmorillonite (Fe‐MOF/MMT) photocatalyst was prepared via an in‐situ method for the hydroxylation of benzene to phenol under the visible light irradiation. The Fe‐MOF/MMT composite exhibited excellent photocatalytic performance, with phenol yield of 30.3 % and benzene selectivity of 96.5 % within 4 hours. The high activity and selectivity of the Fe‐MOF/MMT photocatalyst were attributed to the synergistic effect between the Fe‐MOF and MMT, as well as the unique 2D structure of MMT, which facilitated charge separation and transfer. The Fe‐MOF/MMT composite also showed good stability and re‐used without significant decrease of activity. This study demonstrated that the potential of Fe‐MOF/MMT as a highly efficient and selective photocatalyst for the hydroxylation of benzene to phenol and provided an insight into the design of advanced photocatalysts for sustainable chemical synthesis.

Effect of montmorillonite modified with different intercalator on the protection property of sol-gel coating on AZ31B magnesium alloy

Composite coating was prepared on magnesium alloy AZ31B through different hyamine intercalated montmorillonite (MMT) doping in glycidoxypropyltrimethoxysilane (GPTMS) and tetraethoxysilane (TEOS) hydrolyzed hybrid sol-gel system. Corrosion behaviors of different coated samples were investigated using potentiodynamic polarization. The results indicated an improvement of protective performance when modified MMT doped in, and the CC-MMT doped sol-gel coating showed better corrosion resistance than the CTA-MMT doped one. Combining the MMT characterization and structure of the coating, it could be concluded that this difference came from the tough bonding between CC-MMT and sol-gel system, while that did not exist in CTA-MMT/sol-gel coating. Due to this tough bonding, CC-MMT could guide the assembly of hydrolyzed silane molecules and silica sol particles, thus a denser structure and better protection performance.

Use of montmorillonite to improve flame retardancy, thermal stability and reducing smoke toxicity of chicken feather protein‐based rigid polyurethane foam

AbstractThe aim of this article is to solve the problem of improving the flame retardancy of rigid polyurethane foam (RPUF) while improving the environmental pollution caused by flame retardancy. Using the special layered structure of montmorillonite (MMT) and the stable chemical bond formed by the reaction with chicken feather (CF) protein, RPUF co‐modified with MMT and CF was successfully prepared by using the “one‐step method” of all‐water foaming. It was found by experiments and theoretical calculations that the addition of MMT improved the flame retardancy of the samples. When 3 wt% of MMT was added, RPUF‐CF1/MMT3 had the highest initial decomposition temperature and the largest activation energy, and its thermal stability was the best. In addition, RPUF‐CF1/MMT3 had the smallest peak heat release rate (28.77, 32.04, and 42.18 kW/m2) and total heat release (1.87, 2.15, and 2.38 MJ/m2) at different radiation fluxes. Meanwhile, RPUF‐CF1/MMT3 had the smallest smoke density (32.17 and 28.32), the largest light transmission (57.05% and 60.91%), the lowest toxic gas emission and the lowest fire risk.Highlights Flame retardant modified bioprotein‐based RPUF by MMT is proposed. The flame retardant mechanism depends on the “sandwich biscuit” structure of MMT and its POSi bond with chicken hair protein. MMT‐modified RPUF can improve its thermal stability, flame retardancy and smoke toxicity.

“Moist, Living”: The Hydro-Logics of Red Tory

ABSTRACT In this essay, I offer a hydro-logical account of Red Tory (2019) and its critique of individualism’s contemporary capitalist forms. Drawing on the queer posthumanism of Astrida Neimanis, and the idea that we are all “bodies of water,” I examine the novel as a world comprising sexual, chemical, and political flows and the channels that organize them: pipes, reservoirs, Grindr, gay sex, metaphors, and, finally, MMT, the mysterious new drug referred to as the novel’s radical, communist “infrastructure.” MMT structures the psycho-sexual-political conversion of the novel’s protagonist, Tom, requiring him to conceive of embodiment not as a solitary, extractive activity but as sensuously inter-dependent, thus reconceiving the body as a dependence on infrastructure, in Judith Butler’s formulation. This sense of collectivity disavows the individualist metaphysics of neoliberal capitalism. However, this disavowal is not a smooth process. I argue that Tom’s political awakening involves a more specific concern about the heterogeneity of flows, and that his learning to embrace the failure of flows to dissolve into one another is central to the novel’s politics. Immiscibility makes far too visible our inter-dependence – and, in organizing the antagonistic interaction of flows, serves as Red Tory’s most insurgent infrastructure.

Constructing ZIF-8-decorated montmorillonite composite with charge neutralization effect and pore structure optimization for enhanced Pb2+ capture from water

A zeolitic imidazole framework-8/montmorillonite (ZIF-8/MMT) composite was synthesized by a simple method through in-situ growth of ZIF-8 on MMT for efficient Pb2+ capture from water. The adsorption process of Pb2+ by ZIF-8/MMT composite followed the Langmuir model and the maximum adsorption could reach up to 336.89 mg/g, which was much better than that of the monocomponent of ZIF-8 (117.78 mg/g) or MMT (85.20 mg/g). Kinetics result suggested that Pb2+ adsorption by ZIF-8/MMT was a pseudo-second-order dynamic process, indicating a chemisorption process dominates. Ion exchange, electrostatic attraction and hydroxyl complexation were main pathways for Pb2+ removal by ZIF-8/MMT composite. The enhanced performance of ZIF-8/MMT composite should be attributed to following points. Firstly, the lamellar structure of MMT was in favor of ZIF-8 nanoparticles grow and disperse uniformly on the surface, thus avoiding the aggregation. Secondly, the positive charge on ZIF-8 was neutralized by the negative charge on the surface of MMT, and thus the adsorption capacity of ZIF-8 for Pb2+ is effectively released. Thirdly, the combination of MMT and ZIF-8 optimized the pore structure, which was favorable for Pb2+ adsorption and diffusion. Therefore, the synthesized ZIF-8/MMT composites is a prospective candidate for Pb2+ removal from wastewater.

Development of natural sodium montmorillonite as a cathode material

Montmorillonite (MMT) is naturally occurring clay mineral in Sri Lanka. It is an aluminosilicate crystalline compound with layered structure. In this structure an octahedral sheet of aluminum-oxygen (Al-O) is sandwiched between two tetrahedral sheets of silicon-oxygen (Si-O). The MMT structure can accommodate various monovalent and divalent cations such as H⁺, Li⁺, Na⁺, Mg²⁺ within the interlayer spacing. Natural Li-MMT and Na-MMT are found in various parts of the world. The MMT structure has an ability to exchange interlayer cations with various other divalent cations. MMT with interlayer alkali cations show appreciable ionic conductivity. Natural Na-MMT found in Sri Lanka was used for the present study. To improve the ionic conductivity of natural Na-MMT, the structure was further saturated with Na⁺ ions. The Na⁺ ion concentration of saturated Na-MMT was measured by Inductive Couple Plasma Mass Spectroscopy. The structural and electrical properties of Na saturated MMT were characterized by SEM and Complex Impedance Spectroscopy. As a result of Na⁺ ion saturation the bulk conductivity of Na-MMT was increased to 3.41×10^–4 S cm^–1 at 30⁰C . Saturated Na-MMT has negligible electronic conductivity which is less than 0.001%. For using Na-MMT as intercalation cathode materials in rechargeable batteries, an appreciable electronic conductivity must also be present. To enhance the electronic conductivity of saturated Na-MMT, carbon black was mixed. The electronic transference number of saturated Na-MMT pellets was measured by the DC polarization technique. The electronic transference number of saturated Na-MMT with 25% and 30% carbon black were 0.81 and 0.87 respectively.

Eco‐friendly bio‐based composites of cassava starch and natural rubber compatibilized with nanoclays

AbstractBiocomposite films from cassava starch (CS) blended with natural rubber (NR) compatibilized with nanoclay were prepared. Three types of nanoclays, that is, montmorillonite (MMT), kaolinite (KAO) and intercalated kaolinite (DKAO) were used with various content of 2, 4, 6 and 8 wt%, respectively. The mechanical property, water vapor transmission and water solubility of CS/NR composite films were investigated and the interaction of constituents in the CS/NR composites was also characterized by using x‐ray diffraction, Fourier‐transform infrared spectroscopy, scanning electron microscope and dynamic mechanical analysis. The results revealed that the addition of clays considerably improved both the tensile property and water resistance over the pristine starch and CS/NR film. Biocomposite film with 4 wt% of MMT exhibited minimum water vapor transmission and solubility in water content. The tensile strength of CS/NR composites significantly increased while the elongation at break of composites tended to decrease with the increasing nanoclay content. Both mechanical and physical properties were attributed to strong interaction by forming the intercalated structure of MMT and exfoliated structure of DKAO within biocomposites while less interaction was obtained in the case of KAO. The compatibilizing effect of nanoclay in CS/NR composites was also indicated that the glass transition temperature (Tg) of NR or CS‐glycerol phase shifted to higher Tg than that of CS/NR film.

Absorption behavior of polycarboxylate superplasticizer with different molecular structures on montmorillonite

Polycarboxylate (PCE) is a high performance superplasticizer for modern concrete. With the high quality sand becoming precious, more and more low quality sands are used in concrete. However, low quality sands generally contain a relatively high content of montmorillonite (MMT), which could seriously reduce the efficiency of PCE. In order to develop PCE suitable for concrete with low quality sands, the absorption behavior on MMT of PCE with different side chains and acid/ether ratio was investigated. In order to explore the effect of MMT on PCE, two macromonomers were selected, isoprene glycol ether 400(TPEG400) and isoprene glycol ether 2400 (TPEG2400), to synthesize six long and short side chain comb-type PCEs with acid-ether ratios of 1.5:1, 2.5:1 and 3.5:1, respectively. The MMT tolerance mechanism of comb-type PCE in MMT-containing cement slurry was examined by FT-IR, DLS, TOC and other analysis. The PCE with long side chain is much easier to be inserted into the layered structure of MMT, resulting in intercalation absorption. The absorption amount of two kinds of side chain PCE on the MMT particles decreased as the acid ether ratio increases. PCE with long side chains showed shear-thickening properties in MMT-containing cement slurry, on the contrary, short side chains showed shear-thinning properties.

Molecular insights into supercritical methane sorption and self-diffusion in monospecific and composite nanopores of deep shale

• Montmorillonite, kerogen and MMT-kerogen composite slit nanopores with desirable pore sizes are constructed; • GCMC and EMD simulations are conducted to study the sorption and self-diffusion behaviors of methane in various nanopores; • Pore surface roughness can impede the diffusion of gases, especially in smaller pores. Up to now, a large number of studies have utilized various representative materials to approximate the replacement of shale and investigate the gas adsorption and diffusion behavior in various shapes of nanopores by means of molecular simulations. However, the study of methane sorption and self-diffusion behavior under high temperature and pressure reservoir conditions in deep shale is not clear. In this study, we first established montmorillonite (MMT), kerogen and MMT-kerogen composite slit nanopores using representative shale components of MMT and kerogen. On this basis, we investigated the methane sorption and self-diffusion characteristics employing the grand canonical Monte Carlo (GCMC) and equilibrium molecular dynamics (EMD) simulations. The results show that the differences in the molecular composition and structure of MMT and kerogen surfaces lead to stronger adsorption performance of MMT surface than kerogen in a single nanopore for the same conditions, which results in the inhomogeneity of spatial distribution of methane molecules in the pores. While the sorption capacity of the kerogen matrix is more potent than MMT due to its larger specific surface area (SSA). The smaller pores have stronger adsorption capacity compared to the larger pores. At the same time, the methane density profiles indicate that the adsorption of the MMT and kerogen in smaller pores is less differentiated. The methane sorption energy distribution and isosteric heat of sorption also mutually corroborate the more stable methane sorption at a higher pressure and smaller pores. The self-diffusion coefficient of methane in nanopores gradually decreases with increasing pressure, with a more pronounced variation at lower pressure. Pore surface roughness will hinder the diffusion of gas, and the closer the distance is, the more noticeable the effect will be. This study sheds light on the sorption and self-diffusion phenomena and difference of gas in monospecific and composite nanopores, which provides insights into the reserve evaluation and development of the deep shale gas reservoirs, and is further expected to furnish ideas for exploring the occurrence and transport characteristics of supercritical fluids on other composite nanomaterials.

Dimer acid polyamide/montmorillonite bio-based film for the challenge of air cushions

The increasing use of air cushions in transport packaging brings increased environmental damage due to discarded packaging. A possible solution is to replace petroleum-based polymers with dimer acid polyamide. This work studied the qualities of dimer acid polyamide films with montmorillonite (MMT) addition. The layer structure of MMT and the heterogeneous nucleation effect augment the crystal content of the γ-crystal phase. The oxygen permeability and thermal stability of the film improve as the MMT content is increased, while optical properties decline. The mechanical properties of the film are also affected. Finite-element analysis was used to assess how long air cushions made from dimer acid polyamide/MMT film can last. The results show that dimer acid polyamide/MMT film can fully meet the requirements of air cushions for short-term transportation.

Constructing two dimensional composite nanosheets with montmorillonite and graphene-like carbon: Towards high-rate-performance PVA based gel polymer electrolytes for quasi-solid-state supercapacitors

A novel functional montmorillonite@graphene-like carbon nanosheets (P-MMT@C) has been synthesized via mutual template method. The P-MMT@C has a special structure, which is composed of porous MMT and graphene-like carbon doped with heteroatoms (N-, S- and O-). The P-MMT@C/PVA gel polymer electrolytes prepared by P-MMT@C as inorganic filler exhibit superior mechanical properties (tensile strength of 0.38 MPa, break elongation of 509.56%) and impressive ionic conductivity (0.133 S cm−1). Both the directional channels that formed by the layered structure of MMT and the H-bonding networks that formed by doped heteroatoms of graphene-like carbon layers are able to provide the new ion transportation pathways. Additionally, the assembled supercapacitor with P-MMT@C/PVA gel polymer electrolytes has outstanding rate performance (60.42%, 1–10 A g−1) and cycle performance at a high current density. The strategy of constructing two dimensional composite fillers with multiple ion transportation pathways in this work has great potential in improving the performance of gel polymer electrolytes for quasi-solid-state energy storage devices.

Progress in Montmorillonite Functionalized Artificial Bone Scaffolds: Intercalation and Interlocking, Nanoenhancement, and Controlled Drug Release

Montmorillonite (MMT) has attracted widespread attention in the field of bone tissue engineering in recent years because of its interlayer domain structure. The progress of MMT application was reviewed in this article. Concretely, the application of MMT was mainly explained from the structural characteristics, mechanical strengthening mechanism, organic functionalization, and drug loading and release. Firstly, the polar polymer molecular chains are easily induced into the interlayer domain of MMT to form an interlock and achieve the mechanical strengthening of scaffold. Secondly, the “sandwich” sheet structure of MMT can be exfoliated into graphene‐like MMT nanosheets, providing a nanostrengthening effect for polymer matrix. In addition, MMT’s interlayer domain provides a favorable environment for the loading and slow release of drugs, and it is an ideal platform for the functionalization of bone scaffolds. More importantly, MMT can be easily modified by cation exchange and chemical reaction to further improve the compatibility of composites: such as strengthening mechanical interlocking and nanostrengthening effects and achieving controllable loading and release of drugs. It is expected to provide a reference for improving the application of bone tissue engineering scaffolds.

Study on UV aging resistance of nano-TiO2/montmorillonite/styrene-butadiene rubber composite modified asphalt based on rheological and microscopic properties

In order to improve the high-temperature performance and anti-ultraviolet aging performance of butadiene styrene rubber (SBR) modified asphalt, nano-TiO2 and Montmorillonite (MMT) were used for composite modification, and the test scheme was determined by Box Behnken Design (BBD). The high-speed shearing method is used to prepare nano-TiO2/MMT/SBR composite modified asphalt. Meanwhile, the dynamic shear rheometer (DSR) test and the bending beam rheometer (BBR) test were used to evaluate the rheological properties of the composite modified asphalt before and after aging to evaluate its anti-ultraviolet aging performance. Finally, the interaction and modification mechanism of the modifiers were revealed by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR). The results show that the optimal dosage of nano-TiO2, nano-MMT and SBR latex (solid content 60%) are 1.5%, 4%, and 6%, respectively. The synergistic effect of nano-TiO2 and nano-MMT can significantly delay the conversion process of light components to asphaltenes during asphalt aging, and makes CMI value of SBR modified asphalt significantly reduced and almost stabilized at about 2, and the average stiffness modulus change rate decreases from 0.27 to 0.13, and the carbonyl index dropped from 5.16 to 0.28. SEM test results show that nano-TiO2 particles can be used as physical cross-linking points to promote the combination of nano-MMT/SBR modifiers and asphalt, making the microstructure of nano-TiO2/MMT/SBR modified asphalt more stable and uniform. The modification of Nano-TiO2/MMT/SBR to asphalt is a physical modification process, more Si-O-Si functional groups were generated during the aging process of MMT, which further promote the formation of MMT and asphalt network structure. In conclusion, the study of nano-TiO2/MMT/SBR composite modified asphalt in this paper provided a reference for the selection of modified asphalt in cold and ultraviolet regions.

Ultrasonic-modified montmorillonite uniting ethylene glycol diglycidyl ether to reinforce protein-based composite films

Abstract A novel biodegradable protein-based material (UMSPIE) that consists of natural polymer soy protein isolate (SPI), ultrasonic-modified montmorillonite (UMMT), and ethylene glycol diglycidyl ether (EGDE) was produced by solution casting. Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), and scanning electron microscopy (SEM) were used to characterize the chemical structure and micro-morphologies of as-synthesized protein-based composite films. The results showed that the interlayer structure of MMT was destroyed by ultrasonic treatment, and the hydrogen bonding between SPI chains and the ultrasound-treated MMT plates was enhanced. The synergistic effect of UMMT and EGDE on SPI molecules made the network structure of the UMSPIE film denser. In addition, the mechanical and barrier properties of the as-synthesized films were explored. Compared with pure soy protein film, the tensile strength of the UMSPIE film has an increase of 266.82% (increasing from 4.4 to 16.14 MPa). From the above, the modified strategy of layered silicates filling combining crosslinking agents is considered as an effective method to improve the functional properties of bio-based polymer composites.

Study on crystalline phases and degree of crystallinity of the melt compounded PVA/MMT and PVA/PVP/MMT nanocomposites

Polymer nanocomposite (PNC) films comprised poly(vinyl alcohol) (PVA) and also its blend with poly(vinylpyrrolidone) (PVP) (i.e., PVA/PVP = 75/25 wt/wt%) as host matrices loaded with different amounts of montmorillonite (MMT) nanoclay up to 10 wt% were prepared by melt compounded method. X-ray diffraction (XRD) patterns of these PNC films were recorded in the appropriate angular range of 2θ values 3.8°–26° for their crystalline phase structural characterization. In comparison to the broader-type single diffraction peak for the aqueous solution cast prepared pure PVA film and that of the PVA/PVP blend film which is attributed to the hydrogen bonded isotactic and syndiotactic PVA crystals, five sharp diffraction peaks of different intensities corresponding to the evolution of various crystallites in the melt compounded PVA and PVA/PVP blend films were observed. Further, these peaks intensities were found significantly affected by the amounts of loaded MMT in these polymer matrices-based nanocomposites. It was observed that the prominent crystalline phase of the pure PVA converted into alternative tactic phases in the PVA/MMT films with the variation of MMT concentration. The prime crystalline phase of the PVA/PVP/MMT nanocomposites underwent alternative crystal structures formation abruptly on the initial loading of the 1 wt% amount of MMT in the PVA/PVP blend matrix reflecting a substantial alteration in the direction and nature of hydrogen bonding within the PVA crystal structures, and less changes were found with the further increase of MMT concentration up to 10 wt%. The effect of MMT loading on the crystallite sizes, degree of crystallinity, and the exfoliated and intercalated MMT structures in these PNC materials were analyzed in detail.

Ultrathin clay-containing layer-by-layer separator coating enhances performance of lithium-sulfur batteries

Dissolution of polysulfides upon cycling of the sulfur cathode and their diffusion through the separator membrane ‒ the shuttle effect ‒ is a major factor which deteriorates performance and safety of lithium-sulfur (Li-S) batteries. Here, ultrathin, light-weight polyelectrolyte-clay layer-by-layer assemblies have been developed as versatile nanocoatings on the polypropylene (PP) separator to suppress the shuttle effect. The use of weak polyelectrolytes (polyethyleneimine, PEI, and polyacrylic acid, PAA) and montmorillonite (MMT) or halloysite (Hal) clay nanoparticles enabled full control over mass and charge balance of polyelectrolyte/clay film components, which was critical for achieving ion selectivity and reduction of the polysulfide diffusion. The differences in the geometry and structure of MMT and Hal (nanoplatelets vs. nanotubes), as well as in the pH-controlled charge density of PEI and PAA greatly affected the thickness, morphology, and the ultimate performance of the nanocoatings. In particular, deposition of 450 nm MMT-based coatings at pH 3 and 6 lead to an increase in electrolyte uptake, delayed the lithium dendrite growth and enhanced the discharge capacity of the cell from 300 mAh g−1 for bare to 690 mAh g−1 for coated PP separator over 200 charge-discharge cycles 0.5 C. At the same time, 250 nm-thick Hal-based coatings deposited at pH 3 resulted in an increase in the Coulombic efficiency from 50% for the bare PP separator to ~99% for the coated one, showing an outstanding performance. Additionally, the polyelectrolyte-clay nanocoatings significantly improve thermal and dimensional stability of the PP separator. The results demonstrate that ultrathin LbL clay-containing coatings on the PP separator membrane can drastically improve the cyclability of the Li-S cells.

Novel synthesis route of porous clay heterostructures via mixed surfactant template and their dielectric behavior

Porous clay heterostructures (PCHs) have been developed for a decade now especially for adsorbent and catalytic support applications because of their high specific surface area with uniform small pore size. PCHs have been prepared through the surfactant-directed assembly of organosilicate in the galleries of montmorillonite (MMT), generally, single surfactant was applied. Challenge of using mixed surfactant template derived PCH is proposed to obtain higher surface area aiming for dielectric application. In this study, BC-PCH synthesized from mixed CTAB and CTAC surfactant systems was named and compared with B-PCH and C-PCH that synthesized from CTAB and CTAC surfactant system, respectively. The results revealed that the structure of MMT changed after modification and calcination process, as confirmed by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. Textural properties characterization showed that the BC-PCH samples exhibited higher specific surface area (SBET) 644–738 m2/g than that of B-PCH and C-PCH sample and slightly smaller pore size because the size of micelles in solution system from mixed surfactant decreases, which was confirmed by Dynamic Light Scattering analysis (DLS). Field Emission Scanning Electron Microscopy analysis (FE-SEM) illustrated the rough surface structure of mesoporous BC-PCH samples. The dielectric properties were measured by using the Inductance–Capacitance–Resistance meter (LCR). The dielectric constant (at 103 Hz) increased from 9 and 10 of single CTAB and CTAC surfactant template B-PCH and C-PCH to 15–17 of mixed surfactant series BC-PCHs, almost two-fold was obtained. The improvements of dielectric constant in BC-PCH samples are achieved by the increasing of interfacial polarization. Considering these results, BC-PCH materials can be further applied as candidates for an attractive filler to enhance the dielectric properties of polymer nanocomposite.

Oil-based mud waste reclamation and utilisation in low-density polyethylene composites.

Oil-based mud (OBM) waste from the oil and gas exploration industry can be valorised to tailor-made reclaimed clay-reinforced low-density polyethylene (LDPE) nanocomposites. This study aims to fill the information gap in the literature and to provide opportunities to explore the effective recovery and recycling techniques of the resources present in the OBM waste stream. Elemental analysis using inductively coupled plasma–optical emission spectrometry (ICP-OES) and X-ray fluorescence analysis, chemical structural analysis by Fourier transform infrared (FTIR) spectroscopy, and morphological analysis of LDPE/organo-modified montmorillonite (LDPE/MMT) and LDPE/OBM slurry nanocomposites by scanning electron microscopy (SEM) have been conducted. Further analysis including calorimetry, thermogravimetry, spectroscopy, microscopy, energy dispersive X-ray analysis and X-ray diffraction (XRD) was carried out to evaluate the thermo-chemical characteristics of OBM waste and OBM clay-reinforced LDPE nanocomposites, confirming the presence of different clay minerals including inorganic salts in OBM slurry powder. The microscopic analysis revealed that the distance between polymer matrix and OBM slurry filler is less than that of MMT, which suggests better interfacial adhesion of OBM slurry compared with the adhesion between MMT and LDPE matrix. This was also confirmed by XRD analysis, which showed the superior delamination structure OBM slurry compared with the structure of MMT. There is a trend noticeable for both of these fillers that the nanocomposites with higher percentage filler contents (7.5 and 10.0 wt% in this case) were indicated to act as a thermal conductive material. The heat capacity values of nanocomposites decreased about 33% in LDPE with 7.5 wt% MMT and about 17% in LDPE with 10.0 wt% OBM slurry. It was also noted, for both nanocomposites, that the residue remaining after 1000°C increases with the incremental wt% of fillers in the nanocomposites. There is a big difference in residue amount (in %) left after thermogravimetric analysis in the two nanocomposites, indicating that OBM slurry may have significant influence in decomposing LDPE matrix; this might be an interesting area to explore in the future. The results provide insight and opportunity to manufacture waste-derived renewable nanocomposites with enhanced structural and thermal properties.

Effect of montmorillonite on PEBAX® 1074-based mixed matrix membranes to be used in humidifiers in proton exchange membrane fuel cells

Abstract To meet the increasing requirements of membrane humidification in proton exchange membrane fuel cells (PEMFCs), a series of montmorillonite (MMT)/PEBAX® 1074 mixed matrix membranes (MMMs) were fabricated using the solvent casting method. Pristine MMT and poly(oxyalkylene)amine (APOP)-modified MMT were added as the filler. Using the XRD, FT-IR, SEM, and TEM, the morphology and chemical structure of MMT during modification were investigated. Using the tests of water vapor permeability, air permeability, water contact angle, and crystallinity, the effects of montmorillonite on membrane properties were investigated. The results showed that surface hydrophilicity and crystallinity of MMMs increased as the MMT content increases, which leads to higher vapor permeability and selectivity than the pure PEBAX® 1074 membrane. After modification, APOP-MMT/PEBAX® 1074 MMMs showed better performance in vapor permeability and vapor/air selectivity. The best selectivity was 1.7 × 105, which is three times higher than that of pure PEBAX® 1074 membrane.

Applicability of Montmorillonite Immobilized in Hydrogel for the Determination of Labile Cd, Pb, Mn, and Zn in Water Using Diffusive Gradient in Thin Films (DGT)

Diffusive gradient in thin films (DGT) is one of useful techniques regarding in situ metal speciation in water environment. It has attracted significant research interest aimed at finding new binding phases in order to diversify DGT application. In this study, montmorillonite (MMT), the natural clay mineral with high ion-exchange capacity and trace metal adsorbability, was immobilized in hydrogel and investigated for its applicability as a binding phase in the DGT technique. The structure of the new binding material before and after the acid treatment was characterized using X-ray Powder Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Brunauer Emmet Teller (BET) specific surface area testing, and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The montmorillonite embedded in DGT (DGT-MMT) was tested for the determination of labile Cd, Pb, Mn, and Zn in standard solutions. Various parameters affecting the working performance of DGT-MMT including deployment period, pH, ionic strength, and complexing agent (EDTA) were examined. The results showed that after the acid treatment, most of trace metals such as Cd, Pb, Mn, and Zn in MMT were removed to levels of under the detection limits of the analytical instrument, while the major structure of MMT remained stable. The MMT K10 exhibited high adsorbability to all tested trace metals and Langmuir adsorption isotherm was considered the best fit. In each standard solution containing 20 μg L−1 of tested trace metal, it took only 6 h to recover 85.7–93.5% of labile Cd, Pb, Mn, and Zn by the DGT-MMT. Better working performance of the DGT-MMT was observed at pH, ionic strength, and complexing agent conditions similar to those found in natural water environments. Moreover, we found no significant difference in working efficiency between the new DGT-MMT and traditional DGT-Chelex100 techniques.