Presence Of Montmorillonite Clay Research Articles

Green bio-synthesis of Ni/montmorillonite nanocomposite using extract of Allium jesdianum as the nano-catalyst for electrocatalytic oxidation of methanol

In this work, synthesis of Ni nanoparticles was carried out successfully by water extract of Allium jesdianum as a biochemical reducing agent in the presence of montmorillonite clay (MMT) as a natural solid support for the first time. Then the electrochemical activity of the synthesized nanocomposite was investigated in methanol electrocatalytic oxidation. MMT with high cation exchange capacity and nano layer structure was exposed to ion exchange conditions in nickel solution. Then Ni 2+ ion exchanged form was used in this process as a source of ions and also capping agent. Water extract of Allium jesdianum used as a reducing agent due to abundant availability of phenolic and flavonoid contents. The synthesized Ni/MMT nanocomposite was characterized using UV–Vis spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDX). The surface of prepared modified electrode has been characterized using SEM to evaluate the morphology, showing uniform dispersion of Ni nanoparticles with mean diameter of 12 to 20 nm. The modified carbon paste electrode was then used in methanol electrocatalytic oxidation reaction. Methanol oxidation on the proposed modified electrode surface occurs at 0.6 V and 0.3 V in alkaline and acidic medium respectively. Also, the results showed the better performance of modified electrode toward methanol electrocatalytic oxidation in comparison with carbon paste electrode that is modified by ion exchanged MMT. Charge transfer coefficients and apparent charge transfer rate constant for the modified electrode in the absence of methanol in alkaline medium were respectively found as: α a = 0.53, α c = 0.37 and k s = 1.6 × 10 −1 s −1 . Also, the average value of catalytic rate constant for the electrocatalytic oxidation of methanol by the prepared nano-catalyst was estimated to be about 0.9 L·mol -1 ·s -1 by chronoamperometry technique. The prepared electrode was also effective for electrocatalytic oxidation of ethanol and formaldehyde in alkaline medium. Ni/MMT nanocomposite which was synthesized by green method has the suitable electrocatalytic activity to methanol electrocatalytic oxidation. • Ni/MMT nanocomposite was synthesized by green method using Allium jesdianum water extract. • Ni/MMT nanocomposite was characterized by UV–Vis, XRD, SEM, TEM and EDX techniques. • The particles size of Ni/MMT was in the range of 12–20 nm. • Ni/MMT nanocomposite has electrochemical activity for oxidation of methanol in alkaline and acidic medium.

Synthesis and analgesic activity of aliphatic ketones-derived chiral hexahydro-2H-chromenes

New hexahydro-2H-chromenes were synthesized by reactions of monoterpenoid (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol with aliphatic ketones in the presence of montmorillonite clay H+-K10. The compounds formed and isolated as a pair of diastereoisomers were evaluated for their analgesic activity in vivo. It was found that the analgesic activity of (4aR,8R,8aR)-4,7-dimethyl-3,4,4a,5,8,8a-hexahydrospiro[chromene-2,1ʹ-cyclohexane]-4,8-diol 8b significantly exceeds (two orders of magnitude higher) the activity of diclofenac sodium in the acetic acid-induced writhing test. It has low acute toxicity and is very promising for further development.

Nonenzymatic RNA Oligomerization at the Mineral–Water Interface: An Insight into the Adsorption–Polymerization Relationship

Nonenzymatic RNA polymerization, a major challenge in understanding the origins of life on early Earth, was previously achieved in the presence of montmorillonite clay and high magnesium concentrat...

Investigating the Kinetics of Montmorillonite Clay-Catalyzed Conversion of Anthracene to 9,10-Anthraquinone in the Context of Prebiotic Chemistry.

Carbonaceous meteorites contributed polycyclic aromatic hydrocarbons (PAHs) to the organic inventory of the primordial Earth where they may have reacted on catalytic clay mineral surfaces to produce quinones capable of functioning as redox species in emergent biomolecular systems. To address the feasibility of this hypothesis, we assessed the kinetics of anthracene (1) conversion to 9,10-anthraquinone (2) in the presence of montmorillonite clay (MONT) over the temperature range 25 to 250°C. Apparent rates of conversion were concentration independent and displayed a sigmoidal relationship with temperature, and conversion efficiencies ranged from 0.027 to 0.066%. Conversion was not detectable in the absence of MONT or a sufficiently high oxidation potential (in this case, molecular oxygen (O2)). These results suggest a scenario in which meteoritic 1 and MONT interactions could yield biologically important quinones in prebiotic planetary environments.

Investigation of the clay sensitivity and cement hydration process of modified HPEG‐type polycarboxylate superplasticizers

ABSTRACTIn this work, three kinds of HPEG‐type polycarboxylate superplasticizers (PCs) were synthesized with three kinds of typical functional monomers: [diallyl dimethyl ammonium chloride (DMDAAC), 2‐hydroxyethyl methacrylate (HEMA), and 2‐(dimethylamino) ethyl methacrylate (DMAM), respectively. The effects of montmorillonite clay on the fluidity of cement/PC pastes were investigated. It was found that the fluidity was negatively affected by the clays in the order: DMAM‐PC < HEMA‐PC < conventional PC (CPC) < DMDAAC‐PC. The DMAM‐PC was found to disperse cement well even in presence of montmorillonite clay. The dispersion performance of DMDAAC‐PC was much more effectively affected by clay due to the reaction between ammonium and montmorillonite. More study including mortar fluidity, adsorption behavior and morphology of the cement samples were investigated in details. Thermogravimetric analysis and X‐ray diffraction experiments allowed us to observe the influence of PCs on the hydrated products. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46572.

Superabsorbent nanocomposite from sugarcane bagasse, chitin and clay: Synthesis, characterization and swelling behaviour

A nanocomposite comprising crosslinked hybrid polymer network was prepared using chitin and sugarcane bagasse in presence of montmorillonite clay. Chitin and sugarcane bagasse were micro-fibrillated by ultrasonication of their suspension in an ionic liquid 2-hydroxy ethylammonium formate. Optimum reaction conditions were established by variation of amounts of initiator, monomer and crosslinker, and microwave irradiation to obtain nanocomposite with swelling degree above 1000% in 24 h. Slow and steady swelling was observed and the sample swelled to about 15,000% to form a hydrogel in 15 days. The nanocomposite was characterized by swelling degree, infrared spectroscopy, X-ray diffraction and scanning electron microscopy. Swelling and reswelling in water was studied for four cycles, erosion was highest after first cycle but became negligible for consecutive cycles. The swelling degree increased up to three cycles then became constant. Nanocomposite shows sufficient antimicrobial activity against S. aureus and E. coli. It is biodegradable in moist garden soil in three months.

New efficient chelating polymers based on plastic waste for removal of toxic heavy metal pollutants

New efficient chelating polymers (CPs) based on waste polystyrene functionalized by itaconic acid moieties in absence and presence of montmorillonite clay have been prepared using high shearing effect homogenizer. The obtained CPs have been characterized using spectrophotometric and thermal analyses. The prepared CPs have been used as potential adsorbents for removal of different toxic metal ions from their aqueous solutions. The adsorption performance of the obtained CPs was found to match well with Langmuir adsorption isotherms. The highest sorption affinity of the obtained CPs toward different metal ions was for copper and lead.

New polyelectrolyte complex from pectin/chitosan and montmorillonite clay

A new nanocomposite hydrogel was prepared by forming a crosslinked hybrid polymer network based on chitosan and pectin in the presence of montmorillonite clay. The influence of clay concentration (0.5 and 2% wt) as well as polymer ratios (1:1, 1:2 and 2:1) was investigated carefully. The samples were characterized by different techniques: transmission and scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, swelling degree and compression test. Most samples presented swelling degree above 1000%, which permits characterizing them as superabsorbent material. Images obtained by transmission electron microscopy showed the presence of clay nanoparticles into hydrogel. The hydrogels’ morphological properties were evaluated by scanning electron microscope in high and low-vacuum. The micrographs showed that the samples presented porous. The incorporation of clay produced hydrogels with differentiated morphology. Thermogravimetric analysis results revealed that the incorporation of clay in the samples provided greater thermal stability to the hydrogels. The compression resistance also increased with addition of clay.

Process Optimization for Biodiesel Production from Waste Frying Oil over Montmorillonite Clay K-30

Biodiesel that mostly comes from pure renewable resources provide an alternative fuel option for future because of limited fossil fuel resources as well as environmental concerns. The transesterification of non-edible oils for biodiesel production is one of the promising process for biodiesel production to overcome this future crises of energy. The utilization of waste frying oil into biodiesel have great worth for economization of biodiesel cost as well as the conversion of waste into value added product with environmental protection. The purpose of the present work is to optimize the process of biodiesel production over a heterogeneous clay based catalyst. Particularly, the transesterification of waste frying palm oil with methanol was studied in the presence of montmorillonite clay K-30 as solid base catalyst that have both of acid and basic nature. The observed date was then optimized with the help of Design of Experiments software. The Response Surface Methodology (RSM) based on four-variable central composite design (CCD) with α (alpha) = 2 was used for this purpose. The transesterification process variables were reaction temperature, x1 (40-140oC), reaction period, x2 (60-300min), methanol/oil ratio, x3 (6:1- 18:1 mol/ mol) and amount of catalyst, x4 (1-5% wt). The results showed that waste frying oil is a good feedstock for biodiesel production and high yield of 78.4% was obtained during optimization of this biodiesel process that was noted after 180min at temperature 90°C, with a 12:1molar ratio of methanol to waste frying oil and using 3%wt of montmorillonite clay K-30 catalyst.

Study on adsorption of Cu(II) on magnetic starch‐g‐polyamidoxime/montmorillonite/Fe3O4 nanocomposites as novel chelating ligands

In this study, novel magnetic chelating ligands focused on Cu2+ removal from aqueous solutions were synthesized. The magnetic adsorbents were obtained by amidoximation of nitrile groups on starch‐g‐polyacrylonitrile/montmorillonite/Fe3O4. The magnetic Fe3O4 nanoparticles were obtained in situ in the presence of montmorillonite clay. The structure of nanocomposites was characterized by FT‐IR, SEM, TEM, XRD, TGA, and VSM techniques. Batch adsorption experiments were done on the subject of nanocomposite composition, pH, adsorption time, initial Cu2+ ions concentration, and temperature. Moreover, the thermodynamic and kinetic of adsorption process as well as the equilibrium of adsorption process were studied. The efficiency of Cu2+ removal by nanocomposites was dependent on the content of magnetic montmorillonite, and the magnetic adsorbents showed high adsorption capacity for Cu2+. Adsorption capacity of adsorbents was found to increase with increasing the pH of Cu2+ solution up to 5.5. According to the thermodynamic parameters, the adsorption of Cu2+ on magnetic adsorbents occurred spontaneously. The equilibrium adsorption data were analyzed with Langmuir and Freundlich models and it was found that the equilibrium process followed the Langmuir model well.

The short way to chiral compounds with hexahydrofluoreno[9,1-bc]furan framework: Synthesis and cytotoxic activity

A simple and efficient method for synthesizing chiral heterocyclic compounds with the hexahydrofluoreno[9,1-bc]furan framework via interaction between trans-4-hydroxymethyl-2-carene and aromatic aldehydes containing methoxy and hydroxyl moieties in the presence of montmorillonite clay was found. One of the synthesized compounds exhibited a high cytotoxic activity against lymphoblastoid cell line MT-4 (CTD50 0.9μM), which was higher than that of the comparative drug Doxorubicin. Death of cancer cells in this case substantially occurs via induction of apoptosis.

Highly potent analgesic activity of monoterpene-derived (2S,4aR,8R,8aR)-2-aryl-4,7-dimethyl-3,4,4a,5,8,8a-hexahydro-2H-chromene-4,8-diols

New chiral heterocyclic compounds with a hexahydro-2H-chromene framework were synthesized by reactions of (1R,2R,6S)-3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1,2-diol with aromatic aldehydes in the presence of montmorillonite clay. The analgesic activity of the compounds was studied in vivo. The majority of these compounds showed significant analgesic activity in the acetic acid-induced writhing test; the compounds containing one hydroxy and one methoxy substituents also showed analgesic activity in the hot-plate test. (2S,4aR,8R,8aR)-2-(3-Hydroxy-4-methoxyphenyl)-4,7-dimethyl-3,4,4a,5,8,8a-hexahydro-2H-chromene-4,8-diol was as effective as the diclofenac sodium reference taken in the same dose in both tests. It has low acute toxicity and is very promising for further development.

Synthesis and analgesic activity of monoterpenoid-derived 2-aryl-4,4,7-trimethyl-4a,5,8,8a-tetrahydro-4H-benzo[d][1,3]dioxin-8-ols

A new series of chiral heterocyclic compounds with frameworks of different types were synthesized by reactions of verbenol epoxide with aromatic aldehydes in the presence of montmorillonite clay. The analgesic activity of compounds with frameworks of 2-aryl-4,4,7-trimethyl-4a,5,8,8a-tetrahydro-4H-benzo[d][1,3]dioxin-8-ol type was studied in vivo. The majority of these compounds showed a significant analgesic activity in the acetic acid-induced writhing test; two compounds also showed analgesic activity in the hot-plate test. ED50 in acetic acid-induced writhing test for compound where aryl is 4-chlorophenyl substituent was determined to be 4.5 mg/kg. Compound with 4-nitrophenyl substituent demonstrated high analgesic activity in both tests.

Conducting chelating polymer composites based on grafted waste polystyrene for removal of toxic copper ions

A new type of synthesis route for the preparation of conducting chelating polymer composites (CCPCs) based on waste polystyrene grafted with acrylic (AA) and maleic (MA) acids in the presence of montmorillonite clay was investigated. The prepared composites were characterized using various techniques including Fourier-transform infrared spectroscopy, thermogravimetric analysis, light microscopy and x-ray diffraction analysis. The prepared composites of different AA and MA weight percentage (wt%) have been used as adsorbents for removal of toxic copper ions from their aqueous solutions. The copper uptake by the CCPC grafted with AA was found to be much higher than that of the CCPCs grafted with MA. The key parameters that can affect copper ion uptake such as time and pH were also investigated, and it was found that the increase in pH highly enhanced the copper uptake. The study was further extended to measure the alternating current (AC) conductivities of the prepared composites and their copper complexes which proved that the AC conductivities of the copper-free composites are higher than the AC conductivities of the composites complexed with copper ions.

Nano-magnetite catalyzed heterogeneous Fenton-like degradation of emerging contaminants carbamazepine and ibuprofen in aqueous suspensions and montmorillonite clay slurries at neutral pH

The widespread occurrence of pharmaceutically active compounds (PhACs) in the environment has prompted great concern due to their potential impacts on wildlife and humans. The degradation of two of the most commonly detected PhACs, carbamazepine (CBZ) and ibuprofen (IBP), was investigated by a nano-magnetite (Fe3O4) heterogeneous Fenton-like reaction in aqueous suspensions of nano-Fe3O4 in the absence and presence of montmorillonite clay. Experimental design and response surface methodology (RSM) were applied to evaluate the effects of important factors. The results showed that hydroxyl radical (OH) formation by the heterogeneous decomposition of H2O2 on the Fe3O4 nanoparticle surface (OHss) plays the dominant role in CBZ and IBP degradation at neutral pH. The degradation of CBZ and IBP followed pseudo-first-order kinetics, and the degradation rate constants (k) in aqueous suspensions were 0.182 and 0.121h−1, respectively. In addition, significant adsorption of CBZ to the montmorillonite clay occurs at neutral pH, while IBP is not adsorbed, due to electrostatic repulsion. As a result, an inhibition effect of adsorption on the degradation of CBZ (kCBZ=0.127h−1) in clay slurry was observed, but not for IBP degradation (kIBP=0.202h−1). The major intermediates, identified by solid phase extraction (SPE) followed LC–MS analysis, included hydroxy-CBZs, dihydroxy-CBZs, CBZ-10,11-diol, and hydroxy-CBZ-10,11-diols in CBZ degradation; and hydroxy-IBPs, dihydroxy-IBPs, trihydroxy-IBPs, tetrahydroxy-IBPs, 4-isobutylacetophenone and 1-(4-isobutylphenyl)ethanol in IBP degradation. The possible pathways of CBZ and IBP degradation were proposed based on the identified intermediates.

A concept for a polycarboxylate superplasticizer possessing enhanced clay tolerance

Conventional PCEs are known to easily incorporate into the layer structure of clay by means of their pendant PEO side chains, hence their dispersing ability in concrete is much impeded by clay impurities. Here, modified PCEs possessing hydroxy alkyl lateral chains were synthesized from methacrylic acid and hydroxy alkyl methacrylate esters (alkyl=ethyl, propyl and butyl), characterized and tested for their dispersion performance in cement in absence and presence of montmorillonite clay. The novel PCE type was found to disperse cement well, even when clay was present. Similar to polycondensate superplasticizers it is much less affected by clay than conventional PCEs. A mechanistic study including adsorption and XRD experiments revealed that the novel PCE only adsorbs on the surface of clay and does not incorporate into the layer structure of alumosilicates. This behavior explains its high tolerance against clay contamination.

New Biopolymer Nanocomposite of Starch-Graft Polystyrene/Montmorillonite Clay Prepared Through Emulsion Polymerization Method

Starch-g-polystyrene (Starch-g-PS)/Montmorillonite nanocomposites were prepared via free-radical graft copolymerization of styrene and starch in the presence of montmorillonite clay, by emulsion polymerization method using potassium persulfate (KPS) as an initiator/catalyst and sodium dodecylbenzensulfonate (SDBS) as an emulsifier. The nanocomposites with different clay content 0, 2.5, 5.0, 7.5 and 10 weight percent of starch were prepared and the changes in layer-stacked structures of the clay particles in the resulted nanocomposite compounds were examined by using of X-ray diffraction and FT-IR spectroscopy. Finally the thermal degradation behavior and morphology of nanocomposites were studied using thermal gravimetric analysis (TGA) and SEM, respectively.

Reactions of Verbenol Epoxide with Aromatic Aldehydes Containing Hydroxy or Methoxy Groups in the Presence of Montmorillonite Clay

AbstractThe reactions of (−)‐cis‐verbenol epoxide with a number of aromatic aldehydes containing OH and/or MeO groups in the presence of montmorillonite K10 clay have been studied. Several new O‐containing heterocyclic compounds with different frameworks, including compounds with a previously unknown octahydro‐2H‐4,6‐(epoxymethano)chromene framework, have been synthesized. Introduction of one donor substituent in the benzaldehyde molecule led to a decrease in the total yield of intermolecular by formed products, while the introduction of two and more substituents led to an increase in the yield of these products.

Reactions between organic acids and montmorillonite clay under Earth-forming conditions

The stability and evolution of organic materials found in carbonaceous and ordinary chondrites in the evolution of terrestrial planet interiors are unknown. It has been determined that massive amounts of carbonaceous material fell on the early Earth during the Late Hadean, but the processes by which this material became the Earth's hydrosphere, atmosphere and biosphere are also unknown. We here demonstrate that reactions between these primordial organic molecules and the silicate mineral montmorillonite clay occur at the pressures associated with the upper mantle and planetary assembly. These reactions have consequences for the origin of complex organic chemistry on Earth. Using synchrotron-source Fourier transform infrared (FTIR) spectroscopy with high spatial resolution and the diamond anvil cell (DAC) to reach pressures up to 9.1 GPa, we were able to observe the formation of new peaks (i.e., new bonds) at 952, 969, and 1026 cm − 1 in situ. These peaks, which appear in formic acid (HCOOH) in the presence of montmorillonite clay, may represent either the formation of organo-silicate molecules, or the formation of more complex organic molecules via templating of the crystalline structure of the minerals.

Unusual Reactions of (+)‐Car‐2‐ene and (+)‐Car‐3‐ene with Aldehydes on K10 Clay

AbstractThe reactions of (+)‐car‐2‐ene (1) and (+)‐car‐3‐ene (2) with aldehydes in the presence of montmorillonite clay were studied for the first time (Schemes 3 and 5). The major products of these reactions are optically active, substituted hexahydroisobenzofurans, probably formed as a result of an attack of the protonated aldehyde at the cyclopropane ring. Quite unexpectedly, the products are cis‐configured at the ring‐fusion site; the fact was established by means of quantum‐chemical calculations and NMR data. It appeared that the behavior of the 2 : 3 mixture 1/2 in reactions with aldehydes in the presence of K10 clay differed substantially from the reactivities of the corresponding individual monoterpenes.