01793nas a2200217 4500008004100000022001400041245006800055210006700123260007300190300001200263490000700275520104100282653002001323653001701343653002701360653001501387100002501402700002301427700002301450856010201473 2008 eng d a0169-131700aSynthesis and characterization of novel organo-montmorillonites0 aSynthesis and characterization of novel organomontmorillonites aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcFEB a203-2080 v383 a

Sodium Montmorillonite (NaMMT) has been modified via cation exchange reaction using three different organic cations. Basal spacings, interlamellar structure and thermal stability of these organo-montmorillonites (OMMT) clays have been characterized using wide angle X-ray diffraction (WARD) and thermogravimetric analysis (TGA) techniques. Increase in the basal spacing due to organic modification is in good agreement with simple theoretical calculations based on van der Waals volume of the cationic ammonium ions. TGA characterization and analysis show that the amount of organic modifier in the OMMT's is in good agreement with theoretically calculated stoichiometric content expected for almost complete exchange of Na+ ions by organic cations. The OMMT's shows stepwise decomposition corresponding to initial weight loss from residual water desorption, followed by decomposition of the organic surfactant and the dehydroxylation of structural water of the montmorillonite layers. (C) 2007 Elsevier B.V. All rights reserved.

10aMontmorillonite10aorgano-clays10aorgano-montmorillonite10asurfactant1 aTiwari, Rajkiran, R.1 aKhilar, Kartic, C.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/synthesis-and-characterization-novel-organo-montmorillonites-002396nas a2200301 4500008004100000022001400041245009500055210006900150260007300219300001000292490000800302520135400310653002301664653001701687653004501704653001801749653001901767653002001786653004101806100002301847700002101870700001701891700001801908700001801926700001501944700001701959856011801976 2009 eng d a0926-860X00aCharacterization of clay intercalated cobalt-salen catalysts for the oxidation of p-cresol0 aCharacterization of clay intercalated cobaltsalen catalysts for  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcNOV a16-230 v3703 a

The intercalation of cobalt-salen complexes into the interlamelar spaces of montmorillonite clay was investigated by various characterization studies. The ``neat'' cobalt-salen complex showed a weight loss at 368 degrees C while the weight loss for the corresponding intercalated complex was observed at much higher temperature of 492 degrees C due to decomposition of the complex. The thermal stabilization observed was due to the host-guest interaction of clay and metal complex and thus confirmed the intercalation. The XANES spectrum of Co(salen)-mont sample revealed the change of symmetry from the tetrahedral in plane to the octahedral structure having an axial bonding of oxygen to the cobalt, indicating that cobalt atoms in Co(salen)-mont were coordinated axially with the lattice oxygen of montmorillonite. Both XANES and EXAFS results indicated that cobalt atoms in Co(salen)-mont form two additional Co-O bonds with a bond length of 0.199 nm by the intercalation while retaining the Co-salen structure. Co-salen intercalated into the montmorillonite clay showed the highest activity for the air oxidation of p-cresol, giving 88% selectivity to the oxidation products. Effects of NaOH concentration and various solvents on the conversion and selectivity patterns also have been studied. (C) 2009 Elsevier B.V. All rights reserved.

10aCobalt-oxygen bond10aCobalt-salen10aExtended X-ray absorption fine structure10aIntercalation10aLattice oxygen10aMontmorillonite10aX-ray absorption near edge structure1 aKshirsagar, V., S.1 aGarade, Ajit, C.1 aMane, R., B.1 aPatil, K., R.1 aYamaguchi, A.1 aShirai, M.1 aRode, C., V. uhttps://library.ncl.res.in/content/characterization-clay-intercalated-cobalt-salen-catalysts-oxidation-p-cresol-001481nas a2200229 4500008004100000022001400041245006400055210006300119260007300182300001200255490000700267520072400274653001600998653002701014653002201041653002001063653001601083100002101099700002001120700001701140856009401157 2009 eng d a0169-131700aMontmorillonite for selective hydroxyalkylation of p-cresol0 aMontmorillonite for selective hydroxyalkylation of pcresol aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJAN a113-1170 v433 a

Performances of montmorillonite titanium silicate (TS-1) and dodecatungstophosphoric acid (DTP) were compared for the hydroxyalkylation of p-cresol into dihydroxydiarylmethane (DAM). Ammonia TPD studies of various catalysts showed that an appropriate combination of both strong and weak acid sites of montmorillonite was mainly responsible rather than only the stronger acidity of bulk DTP for its highest catalytic activity for selective hydroxyalkylation of p-cresol to DAM. The selectivity to DAM could be enhanced by adjusting reaction conditions like mole ratio of p-cresol to formaldehyde, reaction temperature, catalyst concentration, solvent and reaction time. (C) 2008 Elsevier B.V. All rights reserved.

10aAmmonia TPD10aDihydroxydiarylmethane10aHydroxyalkylation10aMontmorillonite10aSolid acids1 aGarade, Ajit, C.1 aMate, Vivek, R.1 aRode, C., V. uhttps://library.ncl.res.in/content/montmorillonite-selective-hydroxyalkylation-p-cresol-002344nas a2200265 4500008004100000022001400041245014100055210006900196260007300265300001200338490000800350520135100358653002301709653002801732653002001760653001901780653001401799100002201813700002201835700002301857700002401880700002501904700002901929856012001958 2011 eng d a0926-337300aEfficiency and recycling capability of montmorillonite supported Fe-Ni bimetallic nanocomposites towards hexavalent chromium remediation0 aEfficiency and recycling capability of montmorillonite supported aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAY a407-4140 v1043 a

The remediation of Cr(VI) from simulated water streams is investigated using Fe-Ni bimetallic nanoparticles (Fe-Ni NPs) and their nanocomposites prepared with montmorillonite (MMT) clay. These nanocomposites are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) surface area analyses. XRD analysis revealed proper dispersion as well as intercalation of Fe-Ni NPs in the clay matrix. TEM of nanocomposites showed the presence of spherical particles having a size of 20-40 nm. Batch experiments with a 25 mg L(-1) Cr(VI) solution and 2 g L-1 Fe-Ni NPs exhibited complete reduction of Cr(VI) within 10 min that follows first order reaction kinetics. Amongst 25%, 50%, 75% in situ and loaded nanocomposites, 75% compositions possess better activity with enhanced reduction capacity below pH 4 due to generation of reactive H center dot species. XPS analysis of nanocomposites after Cr(VI) treatment suggested that reduction process occurs through Cr(111) formation followed by its subsequent reduction to Cr(0). Their potentiality towards reusage is established from the recycling experiments that revealed the order of efficiency as 75% in situ > Fe-Ni NPs > 75% loaded nanocomposites. (C) 2011 Elsevier B.V. All rights reserved.

10aCr(VI) remediation10aIron-nickel bimetallics10aMontmorillonite10aNanocomposites10aRecycling1 aKadu, Brijesh, S.1 aSathe, Yogesh, D.1 aIngle, Abhijit, B.1 aChikate, Rajeev, C.1 aPatil, Kashinath, R.1 aRode, Chandrashekhar, V. uhttps://library.ncl.res.in/content/efficiency-and-recycling-capability-montmorillonite-supported-fe-ni-bimetallic-001946nas a2200229 4500008004100000022001400041245009200055210006900147260007300216300001200289490000700301520114400308653002701452653002001479653001201499653001601511100001401527700002101541700001501562700001701577856012201594 2013 eng d a0169-131700aMetal cation-exchanged montmorillonite clay as catalysts for hydroxyalkylation reaction0 aMetal cationexchanged montmorillonite clay as catalysts for hydr aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a141-1460 v743 a

Several solid acid catalysts were prepared by exchanging metal cations such as Zn2+, Fe3+ and Al3+ with montmorillonite clay. Among these, Al-montmorillonite showed the highest acidity determined by the pyridine-IR as well as NH3-TPD methods. A systematic comparison of the performance of these catalysts along with parent montmorillonite was carried out for the hydroxyalkylation of p-cresol with formaldehyde to give 2, 2'-methylenebis (4-methyl phenol) (DAM). It was found that the activity of these catalysts was in accordance with the increase in acidity of parent montmorillonite after the exchange of cations in the order of Zn2+, Fe3+ and Al3+. The selectivity pattern was also influenced by the exchanged cations. Since Al-montmorillonite showed the highest conversion of 51% with 98% selectivity to DAM, the effects of various reaction parameters, namely, mole ratio, catalyst concentration, temperature, reaction time on conversion and selectivity pattern were also studied using the same catalyst This catalyst also showed an excellent stability as evidenced by its eight times reuse. (C) 2012 Published by Elsevier B.V.

10aCations-exchanged clay10aMontmorillonite10aNH3-TPD10aPyridine-IR1 aJha, Ajay1 aGarade, Ajit, C.1 aShirai, M.1 aRode, C., V. uhttps://library.ncl.res.in/content/metal-cation-exchanged-montmorillonite-clay-catalysts-hydroxyalkylation-reaction-002147nas a2200229 4500008004100000022001400041245013000055210006900185260000800254300001400262490000700276520134400283653001101627653002601638653002001664653001901684653001501703653003001718100002501748700002301773856012101796 2020 eng d a0032-388800aCritical organic modifier aliphatic tail length for the formation of poly(methyl methacrylate)-montmorillonite nanocomposites0 aCritical organic modifier aliphatic tail length for the formatio cJUL a1604-16170 v603 a

In this article, we report the influence of organic modifier structure (alkyl chain length C8-C20, single vs ditallow) and thereby, the effect of hydrophobicity on the structure, thermal and mechanical properties of poly(methyl methacrylate) (PMMA)-clay hybrids. Melt processed PMMA-clay hybrids were characterized using wide-angle X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry. The organoclays having an alkyl chain length of more than 12 CH2 groups resulted in the formation of nanocomposites. The glass transition temperature (T-g) of PMMA increased in the presence of clay. The mean-field lattice model was used to predict the free energy for nanocomposite formation, which showed a reasonable match with the experimental results and provided a general guideline for the proper selection of polymer and organoclay (ie, organic modifier) to obtain nanocomposite. Tensile modulus showed maximum improvement of 58% for the nanocomposites compared to 9% improvement for the composites. Tensile modulus increased with increases in the alkyl chain length of the organic modifier and clay loading. The level of improvement for the tensile properties of nanocomposites prepared from primary and secondary ammonium-modified clay is the same as that obtained with the commercial organoclays.

10ahybrid10amechanical properties10aMontmorillonite10aNanocomposites10aorganoclay10apoly(methyl methacrylate)1 aTiwari, Rajkiran, R.1 aNatarajan, Upendra uhttps://library.ncl.res.in/content/critical-organic-modifier-aliphatic-tail-length-formation-polymethyl-methacrylate