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Sample records for hydroxide acetylacetonate lanthanideiii

  1. Photochemical transformation of vanadium(5) acetylacetonate complexes

    Energy Technology Data Exchange (ETDEWEB)

    Kuchmij, S.Ya.; Turchaninov, A.M.; Kryukov, A.I. (AN Ukrainskoj SSR, Kiev. Inst. Fizicheskoj Khimii)

    1980-08-01

    Photochemical transformations of mixed vanadium (5) complex formed as a result of interaction between ethylorthovanadate and acetylacetone which includes in the first coordination sphere vanadyl oxygen, two enolate-ions and enthoxygroup are studied spectrophotometrically and using ESR method. During irradiation of ethanol solutions of the complex a successive reduction of central atom with formation of acetyl-acetonate complexes of vanadium (4) and (3) takes place. At that the solvent is oxidated. In CCl/sub 4/ solution under the effect of UV irradiation ethoxygroup is replaced by chlorine ion with the formation of new mixed vanadium (5) complex, sensible to visible and UV radiation.

  2. Enantiomeric self-recognition in homo- and heterodinuclear macrocyclic lanthanide(III) complexes.

    Science.gov (United States)

    Lisowski, Jerzy

    2011-06-20

    The controlled formation of lanthanide(III) dinuclear μ-hydroxo-bridged [Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes (where X = H(2)O, NO(3)(-), or Cl(-)) of the enantiopure chiral macrocycle L is reported. The (1)H and (13)C NMR resonances of these complexes have been assigned on the basis of COSY, NOESY, TOCSY, and HMQC spectra. The observed NOE connectivities confirm that the dimeric solid-state structure is retained in solution. The enantiomeric nature of the obtained chiral complexes and binding of hydroxide anions are reflected in their CD spectra. The formation of the dimeric complexes is accompanied by a complete enantiomeric self-recognition of the chiral macrocyclic units. The reaction of NaOH with a mixture of two different mononuclear lanthanide(III) complexes, [Ln(1)L](3+) and [Ln(2)L](3+), results in formation of the heterodinuclear [Ln(1)Ln(2)L(2)(μ-OH)(2)X(2)](n+) complexes as well as the corresponding homodinuclear complexes. The formation of the heterodinuclear complex is directly confirmed by the NOESY spectra of [EuLuL(2)(μ-OH)(2)(H(2)O)(2)](4+), which reveal close contacts between the macrocyclic unit containing the Eu(III) ion and the macrocyclic unit containing the Lu(III) ion. While the relative amounts of homo- and heterodinuclear complexes are statistical for the two lanthanide(III) ions of similar radii, a clear preference for the formation of heterodinuclear species is observed when the two mononuclear complexes contain lanthanide(III) ions of markedly different sizes, e.g., La(III) and Yb(III). The formation of heterodinuclear complexes is accompanied by the self-sorting of the chiral macrocyclic units based on their chirality. The reactions of NaOH with a pair of homochiral or racemic mononuclear complexes, [Ln(1)L(RRRR)](3+)/[Ln(2)L(RRRR)](3+), [Ln(1)L(SSSS)](3+)/[Ln(2)L(SSSS)](3+), or [Ln(1)L(rac)](3+)/[Ln(2)L(rac)](3+), results in mixtures of homochiral, homodinuclear and homochiral, heterodinuclear complexes. On the contrary, no

  3. Synthesis and spectroscopic characterization of some lanthanide(III nitrate complexes of ethyl 2-[2-(1-acetyl-2-oxopropylazo]-4,5-dimethyl-3-thiophenecarboxyate

    Directory of Open Access Journals (Sweden)

    CHEMPAKAM JANARDHANAN ATHIRA

    2011-02-01

    Full Text Available Ethyl 2-[2-(1-acetyl-2-oxopropylazo]-4,5-dimethyl-3-thiophenecarboxyate was synthesized by coupling diazotized ethyl 2-amino-4,5-dimethylthiophene-3-carboxylate with acetylacetone. Based on various spectral studies and elemental analysis, an intramolecularly hydrogen-bonded azo-enol structural form was assigned for the ligand. This ligand is versatile in forming a series of lanthanide(III complexes, viz., lanthanum(III, cerium(III, praseodymium(III, neodymium(III, samarium(III and gadolinium(III, which were characterized through various spectral studies, elemental analysis, magnetic susceptibility measurements, molar conductance and thermal analysis. The spectral data revealed that the ligand acted as a neutral tridentate, coordinating to the metal ion through one of the azo nitrogen atoms, the ester carbonyl and the enolic oxygen of the acetylacetone moiety, without deprotonation. Molar conductance values adequately supported their non-electrolytic nature. The ligand and lanthanum(III complex were subjected to X-ray diffraction studies. In addition, the lanthanum(III complex underwent a facile transesterification reaction on refluxing with methanol for a long period. The thermal behaviour of the lanthanum(III complex was also examined

  4. Magnesium Hydroxide

    Science.gov (United States)

    Magnesium hydroxide is used on a short-term basis to treat constipation.This medication is sometimes prescribed ... Magnesium hydroxide come as a tablet and liquid to take by mouth. It usually is taken as ...

  5. Acetone and the precursor ligand acetylacetone : distinctly different electron beam induced decomposition?

    NARCIS (Netherlands)

    Warneke, Jonas; Van Dorp, Willem F.; Rudolf, Petra; Stano, Michal; Papp, Peter; Matejcik, Stefan; Borrmann, Tobias; Swiderek, Petra

    2015-01-01

    In focused electron beam induced deposition (FEBID) acetylacetone plays a role as a ligand in metal acetylacetonate complexes. As part of a larger effort to understand the chemical processes in FEBID, the electron-induced reactions of acetylacetone were studied both in condensed layers and in the ga

  6. The Electrochemical Synthesis of Transition-Metal Acetylacetonates

    Science.gov (United States)

    Long, S. R.; Browning, S. R.; Lagowski, J. J.

    2008-01-01

    The electrochemical synthesis of transition-metal acetylacetonates described here can form the basis of assisting in the transformation of an entry-level laboratory course into a research-like environment where all members of a class are working on the same problem, but where each member has a personal responsibility for the synthesis and…

  7. Infrared and Near-Infrared Spectroscopy of Acetylacetone and Hexafluoroacetylacetone.

    Science.gov (United States)

    Howard, Daryl L; Kjaergaard, Henrik G; Huang, Jing; Meuwly, Markus

    2015-07-23

    The infrared and near-infrared spectra of acetylacetone, acetylacetone-d8, and hexafluoroacetylacetone are characterized from experiment and computations at different levels. In the fundamental region, the intramolecular hydrogen bonded OH-stretching transition is clearly observed as a very broad band with substantial structure and located at significantly lower frequency compared to common OH-stretching frequencies. There is no clear evidence for OH-stretching overtone transitions in the near-infrared region, which is dominated by the CH-stretching overtones of the methine and methyl CH bonds. From molecular dynamics (MD) simulations, with a potential energy surface previously validated for tunneling splittings, the infrared spectra are determined and used in assigning the experimentally measured ones. It is found that the simulated spectrum in the region associated with the proton transfer mode is exquisitely sensitive to the height of the barrier for proton transfer. Comparison of the experimental and the MD simulated spectra establishes that the barrier height is around 2.5 kcal/mol, which favorably compares with 3.2 kcal/mol obtained from high-level electronic structure calculations.

  8. Incorporation of trinuclear lanthanide(III) hydroxo bridged clusters in macrocyclic frameworks.

    Science.gov (United States)

    Kobyłka, Michał J; Ślepokura, Katarzyna; Acebrón Rodicio, Maria; Paluch, Marta; Lisowski, Jerzy

    2013-11-18

    A cluster of lanthanide(III) or yttrium(III) ions, Ln3(μ3-OH)2, (Ln(III) = Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Yb(III), or Y(III)) can be bound in the center of a chiral macrocyclic amines H3L1(R), H3L1(S), and H3L2(S) obtained in a reduction of a 3 + 3 condensation product of (1R,2R)- or (1S,2S)-1,2-diaminocyclohexane and 2,6-diformyl-4-methylphenol or 2,6-diformyl-4-tertbutylphenol. X-ray crystal structures of the Nd(III), Sm(III), Gd(III), Dy(III), and Y(III) complexes reveal trinuclear complexes with Ln(III) ions bridged by the phenolate oxygen atoms of the macrocycle as well as by μ3-hydroxo bridges. In the case of the Nd(III) ion, another complex form can be obtained, whose X-ray crystal structure reveals two trinuclear macrocyclic units additionally bridged by hydroxide anions, corresponding to a [Ln3(μ3-OH)]2(μ2-OH)2 cluster encapsulated by two macrocycles. The formation of trinuclear complexes is confirmed additionally by (1)H NMR, electrospray ionization mass spectrometry (ESI MS), and elemental analyses. Titrations of free macrocycles with Sm(III) or Y(III) salts and KOH also indicate that a trinuclear complex is formed in solution. On the other hand, analogous titrations with La(III) salt indicate that this kind of complex is not formed even with the excess of La(III) salt. The magnetic data for the trinuclear Gd(III) indicate weak antiferromagnetic coupling (J = -0.17 cm(-1)) between the Gd(III) ions. For the trinuclear Dy(III) and Tb(III) complexes the χ(M)T vs T plots indicate a more complicated dependence, resulting from the combination of thermal depopulation of mJ sublevels, magnetic anisotropy, and possibly weak antiferromagnetic and ferromagnetic interactions.

  9. Solvents and supporting electrolytes for vanadium acetylacetonate flow batteries

    Science.gov (United States)

    Shinkle, Aaron A.; Pomaville, Timothy J.; Sleightholme, Alice E. S.; Thompson, Levi T.; Monroe, Charles W.

    2014-02-01

    Properties of supporting electrolytes and solvents were examined for use with vanadium acetylacetonate - a member of the class of metal(β-diketonate) active species - in non-aqueous redox flow batteries. Twenty supporting-electrolyte/solvent combinations were screened for ionic conductivity and supporting-electrolyte solubility. Hexane, tetrahydrofuran, and dimethylcarbonate solvents did not meet minimal conductivity and solubility criteria for any of the electrolytes used, which included tetraethylammonium tetrafluoroborate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, and (1-butyl, 3-methyl)imidazolium bis(trifluoromethanesulfonyl)imide. Ionic conductivities and solubilities for solutions of these electrolytes passed screening criteria in acetonitrile and dimethylformamide solvents, in which maximum supporting-electrolyte and active-species solubilities were determined. Active-species electrochemistry was found to be reversible in several solvent/support systems; for some systems the voltammetric signatures of unwanted side reactions were suppressed. Correlations between supporting-solution properties and performance metrics suggest that an optimal solvent for a vanadium acetylacetonate RFB should have a low solvent molar volume for active-species solubility, and a high Hansen polarity for conductivity.

  10. Photo-induced DNA cleavage activity and remarkable photocytotoxicity of lanthanide(III) complexes of a polypyridyl ligand.

    Science.gov (United States)

    Hussain, Akhtar; Gadadhar, Sudarshan; Goswami, Tridib K; Karande, Anjali A; Chakravarty, Akhil R

    2012-01-21

    Lanthanide(III) complexes [Ln(pyphen)(acac)(2)(NO(3))] (1, 2), [Ln(pydppz)(acac)(2)(NO(3))] (3, 4) and [La(pydppz)(anacac)(2)(NO(3))] (5), where Ln is La(III) (in 1, 3, 5) and Gd(III) (in 2, 4), pyphen is 6-(2-pyridyl)-1,10-phenanthroline, pydppz is 6-(2-pyridyl)-dipyrido[3,2-a:2',3'-c]phenazine, anacac is anthracenylacetylacetonate and acac is acetylacetonate, were prepared, characterized and their DNA photocleavage activity and photocytotoxicity studied. The crystal structure of complex 2 displays a GdO(6)N(3) coordination. The pydppz complexes 3-5 show an electronic spectral band at ~390 nm in DMF. The La(III) complexes are diamagnetic, while the Gd(III) complexes are paramagnetic with seven unpaired electrons. The molar conductivity data suggest 1 : 1 electrolytic nature of the complexes in aqueous DMF. They are avid binders to calf thymus DNA giving K(b) in the range of 5.4 × 10(4)-1.2 × 10(6) M(-1). Complexes 3-5 efficiently cleave supercoiled DNA to its nicked circular form in UV-A light of 365 nm via formation of singlet oxygen ((1)O(2)) and hydroxyl radical (HO˙) species. Complexes 3-5 also exhibit significant photocytotoxic effect in HeLa cancer cells giving respective IC(50) value of 0.16(±0.01), 0.15(±0.01) and 0.26±(0.02) μM in UV-A light of 365 nm, while they are less toxic in dark with an IC(50) value of >3 μM. The presence of an additional pyridyl group makes the pydppz complexes more photocytotoxic than their dppz analogues. FACS analysis of the HeLa cells treated with complex 4 shows apoptosis as the major pathway of cell death. Nuclear localization of complex 5 having an anthracenyl moiety as a fluorophore is evidenced from the confocal microscopic studies.

  11. An application of the coincidence Doppler spectroscopy for substances of chemical interest: phthalocyanine and acetylacetonate complexes

    CERN Document Server

    Ito, Y

    2000-01-01

    Coincidence Doppler spectroscopy, which is particularly powerful when one is concerned with high momentum components of positron annihilation gamma-rays, has been applied to two different kinds of organo-metallic ligands: metal phthalocyanines and metal acetylacetonates. The energy (momentum) profiles of the annihilation gamma-rays were the same for metal phthalocyanines indicating that positron and/or positronium are not interacting with the metal ions. However, the profiles for the metal acetylacetonates evidently showed a dependence on the kind of metal ions. Discussion is made on the features of positron interaction which are different for phthalocyanines and acetylacetonates.

  12. UV Spectral Analysis of the Chemical Modification and Photolysis of Acetylacetone Modified Alumina Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Chengbin JING; Xiujian ZHAO; Haizheng TAO; Xina WANG; Aiyun LIU

    2004-01-01

    Acetylacetone was firstly introduced into the aqueous media with the presence of aluminum sec-butoxide and peptizator. It was confirmed that the UV (ultraviolet) absorption band of acetylacetone underwent 14 nm of red-shift due to the formation of the six-membered ring of the complex between alumina and acetylacetone in the aqueous solution. It was also found that the chemical modification can be dissociated by the UV irradiation with a wavelength shorter than 286 nm as a result of the excitation of π-π* transition in the complex.

  13. CAN Catalyzed Preparation of β-Enamino Ketones from Amines and Acetylacetone

    Institute of Scientific and Technical Information of China (English)

    Zheng DUAN; Ting LI; Xue Jie XUAN; Yang Jie WU

    2006-01-01

    A variety of β-enamino ketones were synthesized in high to excellent yields by reacting acetylacetone with amines in the presence of a catalytic amount of cerium(Ⅳ) ammonium nitrate(CAN) under ultrasonic irradiation.

  14. Lanthanide(III) complexation with an amide derived pyridinophane.

    Science.gov (United States)

    Castro, Goretti; Bastida, Rufina; Macías, Alejandro; Pérez-Lourido, Paulo; Platas-Iglesias, Carlos; Valencia, Laura

    2015-02-16

    Herein we report a detailed investigation of the solid state and solution structures of lanthanide(III) complexes with the 18-membered pyridinophane ligand containing acetamide pendant arms TPPTAM (TPPTAM = 2,2',2″-(3,7,11-triaza-1,5,9(2,6)-tripyridinacyclododecaphane-3,7,11-triyl)triacetamide). The ligand crystallizes in the form of a clathrated hydrate, where the clathrated water molecule establishes hydrogen-bonding interactions with the amide NH groups and two N atoms of the macrocycle. The X-ray structures of 13 different Ln(3+) complexes obtained as the nitrate salts (Ln(3+) = La(3+)-Yb(3+), except Pm(3+)) have been determined. Additionally, the X-ray structure of the La(3+) complex obtained as the triflate salt was also obtained. In all cases the ligand provides 9-fold coordination to the Ln(3+) ion, ten coordination being completed by an oxygen atom of a coordinated water molecule or a nitrate or triflate anion. The bond distances of the metal coordination environment show a quadratic change along the lanthanide series, as expected for isostructural series of Ln(3+) complexes. Luminescence lifetime measurements obtained from solutions of the Eu(3+) and Tb(3+) complexes in H2O and D2O point to the presence of a water molecule coordinated to the metal ion in aqueous solutions. The analysis of the Ln(3+)-induced paramagnetic shifts indicates that the complexes are ten-coordinated throughout the lanthanide series from Ce(3+) to Yb(3+), and that the solution structure is very similar to the structures observed in the solid state. The complexes of the light Ln(3+) ions are fluxional due to a fast Δ(λλλλλλ) ↔ Λ(δδδδδδ) interconversion that involves the inversion of the macrocyclic ligand and the rotation of the acetamide pendant arms. The complexes of the small Ln(3+) ions are considerably more rigid, the activation free energy determined from VT (1)H NMR for the Lu(3+) complex being ΔG(⧧)298 = 72.4 ± 5.1 kJ mol(-1).

  15. Studies of Some Lanthanide(III Nitrate Complexes of Schiff Base Ligands

    Directory of Open Access Journals (Sweden)

    Kishor Arora Mukesh Sharma

    2009-01-01

    Full Text Available The studies of 16 new lanthanide(III nitrate complexes of Schiff base ligands are discussed. Schiff bases were obtained by the condensation of 2–methyl–4–N,N–bis–2' –cyanoethyl aminobenzaldehyde with aniline and 3 different substituted anilines. Lanthanide(III nitrates, viz. gadolinium(III nitrate, lanthanum(III nitrate, samarium(III nitrate and cerium(III nitrate were chosen to synthesize new complexes. The complexes were characterized on the basis of physicochemical studies viz. elemental analysis, spectral, viz. IR and electronic spectral and magnetic studies. TGA studies of some of the representative complexes were also done. Some of the representative complexes were also screened for the anti microbial studies.

  16. The crystal morphology effect of Iridium tris-acetylacetonate on MOCVD iridium coatings

    Science.gov (United States)

    Shi, Jing; Hao, Yupeng; Yu, Xiaodong; Tan, Chengwen

    2017-07-01

    Iridium tris-acetylacetonate is the most commonly used precursor for the metal organic chemical vapour deposition (MOCVD) of iridium coating. In this paper, the crystal morphology effect of iridium tris-acetylacetonate on iridium coatings prepared by MOCVD was studied. Two kinds of Ir(acac)3 crystalline powder were prepared. A precursor sublimation experiment in a fixed bed reactor and an iridium deposition experiment in a cold-wall atmospheric CVD reactor were designed. It is found that the volatility of the hexagonal columnar crystals is better than that of the tetragonal flake crystals under the experimental conditions. It’s due to the hexagonal columnar crystals exposed more crystal faces than the tetragonal flake crystals, increasing its contact area with the transport gas. An adequate supply of iridium tris-acetylacetonate during the pre-deposition period contributed to obtain an iridium coating with a smooth and uniform continuity surface.

  17. Zinc acetylacetonate hydrate adducted with nitrogen donor ligands: Synthesis, spectroscopic characterization, and thermal analysis

    Science.gov (United States)

    Brahma, Sanjaya; Shivashankar, S. A.

    2015-12-01

    We report synthesis, spectroscopic characterization, and thermal analysis of zinc acetylacetonate complex adducted by nitrogen donor ligands, such as pyridine, bipyridine, and phenanthroline. The pyridine adducted complex crystallizes to monoclinic crystal structure, whereas other two adducted complexes have orthorhombic structure. Addition of nitrogen donor ligands enhances the thermal property of these complexes as that with parent metal-organic complex. Zinc acetylacetonate adducted with pyridine shows much higher volatility (106 °C), decomposition temperature (202 °C) as that with zinc acetylacetonate (136 °C, 220 °C), and other adducted complexes. All the adducted complexes are thermally stable, highly volatile and are considered to be suitable precursors for metal organic chemical vapor deposition. The formation of these complexes is confirmed by powder X-ray diffraction, Fourier transform infrared spectroscopy, mass spectroscopy, and elemental analysis. The complexes are widely used as starting precursor materials for the synthesis of ZnO nanostructures by microwave irradiation assisted coating process.

  18. Lanthanide Complexes with Acetylacetonate and 5,10,15,20-Tetra[para-(4-chlorobenzoyloxy)phenyl]porphyrin

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    @@ The lanthanide complexes of acetylacetonate and 5,10,15,20-tetra[para-(chlorobenzoyloxy)phenyl]porphyrin having a general formula Ln[(cbop)4p]acac(where Ln=Tb,Ho,Er,Tm;cbop=(4-chlorobenzoyloxy)phenyl;Hacac=acetylacetone;p=porphyrin) were prepared and characterized.The structure of the complexs was proposed.

  19. Prototypes of Lanthanide(III) Agents Responsive to Enzymatic Activities in Three Complementary Imaging Modalities: Visible/Near-Infrared Luminescence, PARACEST-, and T1-MRI.

    Science.gov (United States)

    He, Jiefang; Bonnet, Célia S; Eliseeva, Svetlana V; Lacerda, Sara; Chauvin, Thomas; Retailleau, Pascal; Szeremeta, Frederic; Badet, Bernard; Petoud, Stéphane; Tóth, Éva; Durand, Philippe

    2016-03-09

    We report first prototypes of responsive lanthanide(III) complexes that can be monitored independently in three complementary imaging modalities. Through the appropriate choice of lanthanide(III) cations, the same reactive ligand can be used to form complexes providing detection by (i) visible (Tb(3+)) and near-infrared (Yb(3+)) luminescence, (ii) PARACEST- (Tb(3+), Yb(3+)), or (iii) T1-weighted (Gd(3+)) MRI. The use of lanthanide(III) ions of different natures for these imaging modalities induces only a minor change in the structure of complexes that are therefore expected to have a single biodistribution and cytotoxicity.

  20. Radioactive Holmium Acetylacetonate Microspheres for Interstitial Microbrachytherapy: An In Vitro and In Vivo Stability Study

    NARCIS (Netherlands)

    Bult, W.; De Leeuw, H.; Steinebach, O.M.; Van der Bom, M.J.; Wolterbeek, H.T.; Heeren, R.M.A.; Bakker, C.J.G.; Van het Schip, A.D.; Hennink, W.E.; Nijsen, F.W.

    2011-01-01

    Purpose The clinical application of holmium acetylacetonate microspheres (HoAcAcMS) for the intratumoral radionuclide treatment of solid malignancies requires a thorough understanding of their stability. Therefore, an in vitro and an in vivo stability study with HoAcAcMS was conducted. Methods

  1. Radioactive holmium acetylacetonate microspheres for interstitial microbrachytherapy : an in vitro and in vivo stability study

    NARCIS (Netherlands)

    Bult, Wouter; de Leeuw, Hendrik; Steinebach, Olav M; van der Bom, Martijn J; Wolterbeek, Hubert Th; Heeren, Ron M A; Bakker, Chris J G; van Het Schip, Alfred D; Hennink, Wim E; Nijsen, J Frank W

    2012-01-01

    PURPOSE: The clinical application of holmium acetylacetonate microspheres (HoAcAcMS) for the intratumoral radionuclide treatment of solid malignancies requires a thorough understanding of their stability. Therefore, an in vitro and an in vivo stability study with HoAcAcMS was conducted. METHODS: HoA

  2. Exploring the ability of the nalidixate to sensitize visible and near-infrared emitting lanthanide(III) cations

    Science.gov (United States)

    Eliseeva, Svetlana V.; Liasotkyi, Valerii S.; Golovach, Iurii P.; Doga, Pavel G.; Antonovich, Valery P.; Petoud, Stéphane; Meshkova, Svetlana B.

    2017-03-01

    Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sensitization of lanthanide(III) cations with an appropriate chromophore. This condition is especially challenging to address for the lanthanide(III) cations emitting in the NIR. The quest for new chromophores well adapted to the NIR-emitting lanthanide(III) ions is an important direction of research in order to broaden the rationalization of the parameters that control the sensitization process. In this work, we have investigated the ability of a readily available chromophoric ligand, the nalidixic acid, to sensitize lanthanide(III) cations with a specific interest for those emitting in the NIR. We have therefore performed an extensive study of the luminescence properties of lanthanide(III) complexes emitting in the visible and in the NIR ranges formed in situ upon mixing the corresponding Ln(III) nitrates (Ln(III)  =  Pr, Nd, Sm, Eu, Tb, Dy, Ho, Tm, Yb) with nalidixic acid (HNA) in a 1:3 molar ratio in the presence of a base. Luminescence spectra, quantum yields and luminescence lifetimes have been measured and discussed. The red emission of Eu with a quantum yield value of 5.90(3)%, red and NIR of Pr (7(1) · 10-4 and 5.6(1) · 10-4%) and Ho (9.3(2) · 10-4 and 2.8(1) · 10-4%), green of Tb (5.21(5)%), yellow and NIR of Dy (0.51(2) and 0.065(4)%), orange and NIR of Sm (0.147(5) and 0.037(2)%), as well as NIR of Nd (0.0321(2)%) and Yb (0.021(1)%) were observed. These results and analysis show that the nalidixate is a versatile chromophoric ligand that is suitable for the sensitization of nine different lanthanide(III) cations, five of them emitting in the NIR.

  3. HIGH PERFORMANCE LIQUID CHROMATOGRAPHY OF COBALT(III) MIXED LIGAND COMPLEXES WITH ACETYLACETONATE AND OXINATE AND MONOMETHYLOXINATE IONS

    National Research Council Canada - National Science Library

    Kidani, Yoshinori; Naga, Shinobu; Koike, Hisashi

    1976-01-01

    In the presence of Co(III) mixed ligand complexes with acetylacetonate, and oxinate and monomethyloxinate ions, the authors attempted to employ high performance liquid chromatography, HPLC, for the separation and purification...

  4. Operando study of iridium acetylacetonate decomposition on amorphous silica-alumina for bifunctional catalyst preparation.

    Science.gov (United States)

    Nassreddine, Salim; Bergeret, Gérard; Jouguet, Bernadette; Geantet, Christophe; Piccolo, Laurent

    2010-07-28

    The decomposition of iridium acetylacetonate Ir(acac)(3) impregnated on amorphous silica-alumina (ASA) has been investigated by combined thermogravimetry-differential thermal analysis-mass spectrometry (TG-DTA-MS) and by in situ X-ray diffraction (XRD). The resulting Ir/ASA hydrotreating catalysts have also been characterized by transmission electron microscopy (TEM). The effects of heating treatments under oxidative, reductive or inert gas flows are compared with each other and with similar experiments on ASA-supported acetylacetone (acacH). It is shown that Ir(acac)(3) undergoes exothermic combustion during calcination in air, leading to agglomerated IrO(2) particles. Conversely, direct reduction involves hydrogenolysis of the acac followed by hydrogenation of the ligand residues to alkanes and water. These two processes are catalyzed by Ir clusters, the gradual growth of which is followed in situ by XRD. The resulting nanoparticles are highly and homogeneously dispersed.

  5. STUDIES ON THE INITIATION MECHANISM OF CERIC ION AND ACETYLACETONE REDOX SYSTEM IN VINYL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    QIU Kunyuan; GUO Xinqiu; ZHANG Dong; FENG Xinde

    1991-01-01

    The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy ofAAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.

  6. Metal Acetylacetonates as General Precursors for the Synthesis of Early Transition Metal Oxide Nanomaterials

    Directory of Open Access Journals (Sweden)

    Amanda L. Willis

    2007-01-01

    Full Text Available A versatile, convenient, and nontoxic solvothermal method for the synthesis of nanocrystalline iron, chromium, and manganese oxides is described. This method employs the reactions of metal acetylacetonate precursors and oxygen-containing solvents in a reaction to prepare metal oxide nanoparticles. Characterization of these nanocrystalline materials was carried out employing transmission electron microscopy (TEM, high-resolution TEM (HRTEM, X-ray diffraction (XRD, and elemental analysis.

  7. Metal Acetylacetonates as General Precursors for the Synthesis of Early Transition Metal Oxide Nanomaterials

    OpenAIRE

    Willis, Amanda L.; Zhuoying Chen; Jiaqing He; Yimei Zhu; Turro, Nicholas J.; Stephen O'Brien

    2007-01-01

    A versatile, convenient, and nontoxic solvothermal method for the synthesis of nanocrystalline iron, chromium, and manganese oxides is described. This method employs the reactions of metal acetylacetonate precursors and oxygen-containing solvents in a reaction to prepare metal oxide nanoparticles. Characterization of these nanocrystalline materials was carried out employing transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), and elemental analysis.

  8. Performance and Characterization for Blend Membrane of PES with Manganese(III Acetylacetonate as Metalorganic Nanoparticles

    Directory of Open Access Journals (Sweden)

    H. Abdallah

    2015-01-01

    Full Text Available This study describes the preparation, characterization, and evaluation of performance of blend Polyethersulfone (PES with manganese(III acetylacetonate Mn(acac3 to produce reverse osmosis blend membrane. The manganese(III acetylacetonate nanoparticles were prepared by a simple and environmentally benign route based on hydrolysis of KMnO4 followed by reaction with acetylacetone in rapid stirring rate. The prepared nanoparticle powder was dissolved in polymer solution mixture to produce RO PES/Mn(acac3 blend membrane, without any treatment of Polyethersulfone membrane surface. The membrane morphology, mechanical properties, and performance were presented. The scanning electron microscopy (SEM images have displayed a typical asymmetric membrane structure with a dense top layer due to the migration of Mn(acac3 nanoparticles to membrane surface during the phase inversion process. Contact angle measurements have indicated that the hydrophilicity of the membrane was improved by adding Mn(acac3. AFM images have proved excellent pores size distribution of blend membrane and lower surface roughness compared with bare PES. The desalination test was applied to blend membrane, where the blend membrane provided good performance; particularly, permeate flux was 24.2 Kg/m2·h and salt rejection was 99.5%.

  9. Double deuterated acetylacetone in neon matrices: infrared spectroscopy, photoreactivity and the tunneling process.

    Science.gov (United States)

    Gutiérrez-Quintanilla, Alejandro; Chevalier, Michèle; Crépin, Claudine

    2016-07-27

    The effect of deuteration of acetylacetone (C5O2H8) is explored by means of IR spectroscopy of its single and double deuterated isotopologues trapped in neon matrices. The whole vibrational spectra of chelated enols are very sensitive to the H-D exchange of the hydrogen atom involved in the internal hydrogen bond. UV excitation of double deuterated acetylacetone isolated in neon matrices induces the formation of four open enol isomers which can be divided into two groups of two conformers, depending on their formation kinetics. Within each group, one conformer is more stable than the other: slow conformer interconversion due to a tunneling process is observed in the dark at low temperature. Moreover, IR laser irradiation at the OD stretching overtone frequency is used to induce interconversion either from the most stable to the less stable conformer or the opposite, depending on the excitation wavelength. The interconversion process is of great help to assign conformers which are definitively identified by comparison between experimental and calculated IR spectra. Kinetic constants of the tunneling process at play are theoretically estimated and agree perfectly with experiments, including previous experiments with the totally hydrogenated acetylacetone [Lozada García et al., Phys. Chem. Chem. Phys., 2012, 14, 3450].

  10. Coordinatively Unsaturated Lanthanide(III) Helicates: Luminescence Sensors for Adenosine Monophosphate in Aqueous Media.

    Science.gov (United States)

    Sahoo, Jashobanta; Arunachalam, Rajendran; Subramanian, Palani S; Suresh, Eringathodi; Valkonen, Arto; Rissanen, Kari; Albrecht, Markus

    2016-08-08

    Coordinatively unsaturated double-stranded helicates [(H2 L)2 Eu2 (NO3 )2 (H2 O)4 ](NO3 )4 , [(H2 L)2 Tb2 (H2 O)6 ](NO3 )6 , and [(H2 L)2 Tb2 (H2 O)6 ]Cl6 (H2 L=butanedioicacid-1,4-bis[2-(2-pyridinylmethylene)hydrazide]) are easily obtained by self-assembly from the ligand and the corresponding lanthanide(III) salts. The complexes are characterized by X-ray crystallography showing the helical arrangement of the ligands. Co-ligands at the metal ions can be easily substituted by appropriate anions. A specific luminescence response of AMP in presence of ADP, ATP, and other anions is observed. Specificity is assigned to the perfect size match of AMP to bridge the two metal centers and to replace quenching co-ligands in the coordination sphere.

  11. Evidence of Different Stoichiometries for the Limiting Carbonate Complexes across the Lanthanide(III) Series

    Energy Technology Data Exchange (ETDEWEB)

    Philippini, V.; Vercouter, T.; Vitorge, P. [CEA Saclay, DEN DPC SECR Lab Speciat Radionucleides and Mol, F-91191 Gif Sur Yvette (France); Vitorge, P. [Univ Evry Val Essonne, CNRS, Lab Anal and Modelisat Biol and Environm, UMR 8587, F-91025 Evry (France)

    2010-07-01

    The stoichiometries of limiting carbonate complexes of lanthanide(III) ions were investigated by solubility measurements of hydrated NaLn(CO{sub 3}){sub 2} solid compounds (Ln = La, Nd, Eu and Dy) at room temperature in aqueous solutions of high ionic strength (3. 5 mol. kg{sup -1}) NaClO{sub 4}) and high CO{sub 3}{sup 2-} concentrations (0. 1 to 1. 5 mol. kg{sup -1}). The results were interpreted by considering the stability of carbonate complexes, with limiting species found to be La(CO{sub 3}){sub 4}{sup 5-}, Nd(CO{sub 3}){sub 4}{sup 5-}, Eu(CO{sub 3}){sub 3}{sup 3-} and Dy(CO{sub 3}){sub 3}{sup 3-}. TRLFS measurements on the Eu and Dy solutions confirmed the predominance of a single aqueous complex in all the samples. Equilibrium constants were determined for the reaction Ln(CO{sub 3}){sub 3}{sup 3-} + CO{sub 3}{sup 2-} reversible arrow Ln(CO{sub 3}){sub 4}{sup 5-}: log(10) K{sub 4,} {sub L}a{sup 3}. 5{sup m} {sup N}a{sup C}l{sup O}{sub 4} = 0. 7 {+-} 0. 3, log(10) K{sub 4,} {sub N}d{sup 3}. 5{sup m} {sup N}a{sup C}l{sup O}{sub 4} = 1. 3 {+-} 0. 3, and for Ln = Eu and Dy, log(10) K{sub 4,} {sub L}n{sup 3}. 5{sup m} {sup N}a{sup C}l{sup O}{sub 4}) {<=} -0. 4. These results suggest that tetra-carbonato complexes are stable only for the light lanthanide ions in up to 1. 5 molal CO{sub 3}{sup 2-} aqueous solutions, in agreement with our recent capillary electrophoresis study. Comparison with literature results indicates that analogies between actinide(III) and lanthanide(III) ions of similar ionic radii do not hold in concentrated carbonate solutions. Am(CO{sub 3}){sub 3}{sup 3-} was previously evidenced by solubility measurements, whereas we have observed that Nd(CO{sub 3}){sub 4}{sup 5-} predominates in similar conditions. We may speculate that small chemical differences between Ln(III) and An(III) could result in macroscopic differences when their coordination sphere is complete. (authors)

  12. Electrodeposition of uranium in dimethyl sulfoxide and its inhibition by acetylacetone as studied by EQCM

    Energy Technology Data Exchange (ETDEWEB)

    Shirasaki, K. [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan)]. E-mail: kshira@imr.tohoku.ac.jp; Yamamura, T. [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Herai, T. [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan); Shiokawa, Y. [Institute for Materials Research, Tohoku University, Sendai, Miyagi 980-8577 (Japan)

    2006-07-20

    In the study of the all-uranium redox-flow battery with a high efficiency, electrochemical investigations of the negative electrode reaction, i.e. U(IV)/U(III) of uranium {beta}-diketone complexes, is necessary in aprotic solvents. In our recent studies, the uranium(IV) acelylacetonate, known to show the simplest voltammograms due to a quasi-reversible U(IV)/U(III) reaction at -2.6 V versus Fc/Fc{sup +} in the solvent with the small donor number, shows more complicated voltammograms in the solvents with the larger donor numbers such as dimethyl sulfoxide (DMSO). For U{sup 4+} ion without acetylacetone in such solvents, several researchers reported an electrodeposition at around -1.6 to -2 V versus Fc/Fc{sup +}, whereas its details have not known at all. Therefore in this study, the electrode reactions of the U(IV)/U(III) and the U(III)/U(0) reaction of U(dmso){sub 8}(ClO{sub 4}){sub 4} were investigated by direct monitoring of weight changes of a Au electrode during potential sweeps by using the EQCM, as well as the HMDE. Also, an inhibition of the uranium electrodeposition by an addition of the acetylacetone was investigated.

  13. Metal Organic Chemical Vapour Deposited Thin Films of Cobalt Oxide Prepared via Cobalt Acetylacetonate

    Institute of Scientific and Technical Information of China (English)

    C.U. Mordi; M.A. Eleruja; B.A. Taleatu; G.O. Egharevba; A.V. Adedeji; 0.0. Akinwunmi; B. Olofinjana; C. Jeynes; E.O.B. Ajayi

    2009-01-01

    The single solid source precursor, cobalt (Ⅱ) acetylacetonate was prepared and characterized by infrared spec-troscopy. Thin films of cobalt oxide were deposited on soda lime glass substrates through the pyrolysis (metal organic chemical vapour deposition (MOCVD)) of single solid source precursor, cobalt acetylaceto-nate, Co[C5H7O2]2 at a temperature of 420℃. The compositional characterization carried out by rutherford backscattering spectroscopy and X-ray diffraction (XRD), showed that the films have a stoichiometry of Co2O3 and an average thickness of 227±0.2 nm. A direct energy gap of 2.15±0.01 eV was calculated by the data obtained by optical absorption spectroscopy. The morphology of the films obtained by scanning electron mi-croscopy, showed that the grains were continuous and uniformly distributed at various magnifications, while the average grain size was less than 1 micron for the deposited thin films of cobalt oxide.

  14. A New Homogeneous Catalyst for the Dehydrogenation of Dimethylamine Borane Starting with Ruthenium(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Ebru Ünel Barın

    2015-06-01

    Full Text Available The catalytic activity of ruthenium(III acetylacetonate was investigated for the first time in the dehydrogenation of dimethylamine borane. During catalytic reaction, a new ruthenium(II species is formed in situ from the reduction of ruthenium(III and characterized using UV-Visible, Fourier transform infrared (FTIR, 1H NMR, and mass spectroscopy. The most likely structure suggested for the ruthenium(II species is mer-[Ru(N2Me43(acacH]. Mercury poisoning experiment indicates that the catalytic dehydrogenation of dimethylamine-borane is homogeneous catalysis. The kinetics of the catalytic dehydrogenation of dimethylamine borane starting with Ru(acac3 were studied depending on the catalyst concentration, substrate concentration and temperature. The hydrogen generation was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Evaluation of the kinetic data provides the activation parameters for the dehydrogenation reaction: the activation energy Ea = 85 ± 2 kJ·mol−1, the enthalpy of activation ∆H# = 82 ± 2 kJ·mol−1 and the entropy of activation; ∆S# = −85 ± 5 J·mol−1·K−1. The ruthenium(II catalyst formed from the reduction of ruthenium(III acetylacetonate provides 1700 turnovers over 100 hours in hydrogen generation from the dehydrogenation of dimethylamine borane before deactivation at 60 °C.

  15. Novel synthesis of layered double hydroxides (LDHs) from zinc hydroxide

    Science.gov (United States)

    Meng, Zilin; Zhang, Yihe; Zhang, Qian; Chen, Xue; Liu, Leipeng; Komarneni, Sridhar; Lv, Fengzhu

    2017-02-01

    The most common synthesis methods for layered double hydroxides (LDHs) are co-precipitation and reconstruction, which can have some limitations for application. Here, we report a novel synthesis method for LDHs. We use zinc hydroxide as the precursor to synthesize LDHs phase through a simple transformation process of zinc hydroxide phase. For this transformation process, aluminum can enter into zinc hydroxide and replace zinc quickly to transform it into LDH by creating positive charges in the zinc hydroxide solid phase. The mechanism of LDH formation was through Al3+ reaction first with zinc hydroxide followed by recrystallization of the original structure of zinc hydroxide. Thus, the new process of LDH formation involves a reaction of Al to substitute for Zn and recrystallization leading to LDH and the final pH influences the crystallization of LDHs by this process. In addition, Cr3+ was employed as a trivalent cation for LDH formation to react with zinc hydroxide, which also led to LDH structure.

  16. Synthesis, spectral characterization, thermal and biological studies of lanthanide(III) complexes of oxyphenbutazone

    Institute of Scientific and Technical Information of China (English)

    PS Binil; MR Anoop; KR Jisha; S Suma; MR Sudarsanakumar

    2014-01-01

    Lanthanide(III) complexes of 4-butyl-1-(4-hydroxyphenyl)-2-phenyl-3,5-pyrazolidinedione (OPB) were prepared by ho-mogeneous precipitation. The solid complexes were characterized by elemental analysis, magnetic susceptibility data, molar conduc-tivity measurements and IR, UV-Vis, mass, 1H NMR and 13C NMR spectral methods. The thermal decomposition of the complexes under static air atmosphere was investigated by simultaneous TG/DTG at a heating rate of 10 °C/min. The final decomposition prod-ucts were found to be metal oxides. The spectroscopic data suggested that OPB acted as a bidentate, mono-ionic ligand coordinating through two carbonyl oxygens of the pyrazolidinedione ring. The kinetic and thermodynamic parameters such as activation energy, pre-exponential factor and entropy of activation for each step of the decomposition reactions were evaluated using Coats-Redfern and MacCallum-Tanner equations. The negative entropy values of the complexes indicated that the activated complexes had a more or-dered structure than the reactant and that the reactions were slower than normal. Investigations of antimicrobial activity of the com-pounds were carried out by the disk diffusion technique.

  17. Synthesis, X-ray crystal structure, DNA binding and Nuclease activity of lanthanide(III) complexes of 2-benzoylpyridine acetylhydrazone

    Indian Academy of Sciences (India)

    KARREDDULA RAJA; AKKILI SUSEELAMMA; KATREDDI HUSSAIN REDDY

    2016-08-01

    Lanthanide(III) complexes of general formula [La(BPAH)₂(NO₃)₃] and [Ce(BPAH)₂(NO₃)(H₂O)₂] 2NO₃.H₂O (where, BPAH = 2-benzoylpyridine acetyl hydrazone), were synthesized and characterized by elemental analysis, molar conductance, IR spectroscopy and single crystal X-ray diffraction and Hirschfeld studies. The central metal ion is 12-coordinate in lanthanum complex and 10-coordinated in the cerium complex. The coordination polyhedra around the lanthanum and cerium were found to have distorted icosahedron and distorted bicapped square antiprism respectively. DNA binding and nuclease activity of these complexes were also investigated in the present work.

  18. AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS XIX: THE POLYMERIZATION OF SUBSTITUTED BENZONITRILES CATALYZED BY COBALTIC ACETYLACETONATE

    Institute of Scientific and Technical Information of China (English)

    QIN Wei; HUANG Zhitang

    1996-01-01

    The polymerization kinetics of 4,4'-biphenyldicarbonitrile and other substituted benzonitriles catalyzed by cobaltic acetylacetonate was studied. The structure of polymer of different substituted benzonitrile was also determined. It is found that the rate of polymerization and the structure of polymer is greatly affected by the substituent of benzonitriles.

  19. AROMATIC AND HETEROCYCLIC NITRILES AND THEIR POLYMERS ⅩⅤⅢ. THE POLYMERIZATION KINETICS OF BENZONITRILE CATALYZED BY METAL ACETYLACETONATE

    Institute of Scientific and Technical Information of China (English)

    QIN Wei; HUANG Zhitang

    1993-01-01

    The bulk polymerization of benzonitrile catalyzed by Co (Ⅱ), Co (Ⅲ) and Fe(Ⅲ)acetylacetonate was studied. The results of kinetics study show that the rate of polymerization was proportional to first power of the concentration of catalyst and second power of the concentration of monomer.

  20. Carbonaceous alumina films deposited by MOCVD from aluminium acetylacetonate: a spectroscopic ellipsometry study

    Indian Academy of Sciences (India)

    M P Singh; G Raghavan; A K Tyagi; S A Shivashankar

    2002-04-01

    Spectroscopic ellipsometry was used to characterize carbonaceous, crystalline aluminium oxide films grown on Si(100) by low-pressure metal organic chemical vapour deposition, using aluminium acetylacetonate as the precursor. The presence of carbon in the films, attribured to the use of a metalorganic precursor for the deposition of films, was identified and analysed by secondary ion mass spectroscopy and X-ray photoelectron sectroscopy, for the elemental distribution and the chemical nature of the carbon in the films, respectively. Ellipsometry measurments over the photon energy range 1.5-5 eV were used to derive the pseudo-dielectric function of the aluminium oxide-containing films. Multi-layer modelling using linear regression techniques and the effective medium approximation were carried out to extract the structural details of the specimens. The excellent fit between the simulated and experimental optical data validates the empirical model for alumina-containing coatings grown by MOCVD.

  1. Binary Diffusion Coefficients of Platinum(II) Acetylacetonate in Supercritical Carbon Dioxide.

    Science.gov (United States)

    Kong, Chang Yi; Siratori, Tomoya; Wang, Guosheng; Sako, Takeshi; Funazukuri, Toshitaka

    2013-11-14

    Binary diffusion coefficients (D12) and retention factors (k) of platinum(II) acetylacetonate at infinitesimal concentration in supercritical (sc) carbon dioxide (CO2) were measured by the chromatographic impulse response method with a poly(ethylene glycol) coated capillary column at temperatures from (308.15 to 343.15) K and pressures from (8.5 to 40.0) MPa, and D12 in liquid ethanol at temperatures from (298.15 to 333.15) K and atmospheric pressure by the Taylor dispersion method. As has been seen for our previously reported data on other metal complexes measured in sc CO2 and organic solvents, the D12 data in sc CO2 and liquid ethanol were represented by a function of temperature and solvent viscosity. The D12 values for metal complexes were not related to the solute molecular weights. The k values in sc CO2 were expressed by a function of temperature and CO2 density.

  2. Microwave assisted synthesis, spectroscopic, electrochemical and DNA cleavage studies of lanthanide(III) complexes with coumarin based imines.

    Science.gov (United States)

    Kapoor, Puja; Fahmi, Nighat; Singh, R V

    2011-12-01

    The present work stems from our interest in the synthesis, characterization and biological evaluation of lanthanide(III) complexes of a class of coumarin based imines which have been prepared by the interaction of hydrated lanthanide(III) chloride with the sodium salts of 3-acetylcoumarin thiosemicarbazone (ACTSZH) and 3-acetylcoumarin semicarbazone (ACSZH) in 1:3 molar ratio using thermal as well as microwave method. Characterization of the ligands as well as the metal complexes have been carried out by elemental analysis, melting point determinations, molecular weight determinations, magnetic moment, molar conductance, IR, (1)H NMR, (13)C NMR, electronic, EPR, X-ray powder diffraction and mass spectral studies. Spectral studies confirm ligands to be monofunctional bidentate and octahedral environment around metal ions. The redox behavior of one of the synthesized metal complex was investigated by cyclic voltammetry. Further, free ligands and their metal complexes have been screened for their antimicrobial as well as DNA cleavage activity. The results of these findings have been presented and discussed.

  3. Surface defect modification of ZnO quantum dots based on rare earth acetylacetonate and their impacts on optical performance

    Science.gov (United States)

    Wang, Lixi; Yang, Xiaojuan; Yang, Weimin; Zhang, Jing; Zhang, Qitu; Song, Bo; Wong, Chingping

    2017-03-01

    The surface defect modification has an important effect on the application of ZnO quantum dots, and it has gained much progress in recently years, propelled by the development of additives. Our research efforts are directed toward developing a new surface modification additive RE(AcAc)3 (RE = Ce, Dy, Tb) to achieve fine ZnO QDs and adjust their surface properties. RE(AcAc)3/ZnO QDs nanostructured materials have been designed and prepared, and particular emphasis has been given to the relation between the surface modification and optical properties. The effects of RE(III) acetylacetonate modification on the FT-IR, TEM images and photoluminescence (PL) spectra were investigated, and the surface defect modification principle and effect were discussed in details. The band gap (Eg) was also calculated to prove the surface modification effect. For the RE(AcAc)3/ZnO QDs complex materials, stable linkage occurs because of the affinity of sbnd COOH from acetylacetonate anionic ligand to zinc oxide surfaces, with attachment to the zinc oxide by hydrogen bonding between the protons of the hydroxyl groups on the surface of ZnO QDs and the π-system of acetylacetone.

  4. 21 CFR 184.1428 - Magnesium hydroxide.

    Science.gov (United States)

    2010-04-01

    ... hydration of reactive grades of magnesium oxide. (b) The ingredient meets the specifications of the Food... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium hydroxide. 184.1428 Section 184.1428 Food... Specific Substances Affirmed as GRAS § 184.1428 Magnesium hydroxide. (a) Magnesium hydroxide (Mg(OH)2,...

  5. Contribution to the knowledge of nickel hydroxide electrodes. 5. Analysis and electrochemical behavior of cadmium nickel hydroxides

    Science.gov (United States)

    Bode, H.; Dennstedt, W.

    1981-01-01

    Electrochemical experiments performed at sintered and bulk electrodes show that beta nickel hydroxide contains an electrochemically inactive proportion of cadmium hydroxide of up to 10%. The electrochemically ineffective cadmium hydroxide is homogeneously dissolved in beta nickel hydroxide.

  6. Analysis of barium hydroxide and calcium hydroxide slurry carbonation reactors

    Energy Technology Data Exchange (ETDEWEB)

    Patch, K.D.; Hart, R.P.; Schumacher, W.A.

    1980-05-01

    The removal of CO/sub 2/ from air was investigated by using a continuous-agitated-slurry carbonation reactor containing either barium hydroxide (Ba(OH)/sub 2/) or calcium hydroxide (Ca(OH)/sub 2/). Such a process would be applied to scrub /sup 14/CO/sub 2/ from stack gases at nuclear-fuel reprocessing plants. Decontamination factors were characterized for reactor conditions which could alter hydrodynamic behavior. An attempt was made to characterize reactor performance with models assuming both plug flow and various degrees of backmixing in the gas phase. The Ba(OH)/sub 2/ slurry enabled increased conversion, but apparently the process was controlled under some conditions by phenomena differing from those observed for carbonation by Ca(OH)/sub 2/. Overall reaction mechanisms are postulated.

  7. Deposition of nanocrystalline nonstoichiometric chromium oxide coatings on the surface of multiwalled carbon nanotubes by chromium acetylacetonate vapor pyrolysis

    Science.gov (United States)

    Kremlev, K. V.; Ob'edkov, A. M.; Ketkov, S. Yu.; Kaverin, B. S.; Semenov, N. M.; Gusev, S. A.; Andreev, P. V.

    2017-04-01

    Nanocrystalline coatings of nonstoichiometric chromium oxide have been obtained for the first time on the surface of multiwalled carbon nanotubes (MWCNTs) by the method of metalorganic chemical-vapor deposition using chromium acetylacetonate as a precursor. The new hybrid nanomaterial (Cr2O2.4/MWCNT) has been characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. It is established that oxidation of the hybrid nanomaterial in air under soft conditions (at 380°C) leads to the formation of nanocrystalline chromium oxide (Cr2O3) on the surface of MWCNTs.

  8. Synergistic Inhibition Effect of Zinc Acetylacetonate and Benzothiazole in Epoxy Coating on the Corrosion of Mild Steel

    Science.gov (United States)

    Amoozadeh, S. M.; Mahdavian, M.

    2015-06-01

    The corrosion inhibition effect of zinc acetylacetonate (ZAA) and benzothiazole (BTH) mixture was evaluated for mild steel in 3.5% NaCl solution. To this end, ZAA:BTH mixtures ranged from 6:1 to 1:6 mol ratios were examined by weight loss and open circuit potential to obtain optimal mole ratio. The optimal mixture of ZAA:BTH at 1:5 mol ratio showed a significant corrosion inhibition efficiency proved by electrochemical impedance spectroscopy and polarization studies. The addition of the optimal mixture of ZAA:BTH to epoxy coating showed a considerable increase of corrosion protection evaluated by salt spray exposure.

  9. Supermolecular layered dou- ble hydroxides

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Research progresses in the layered double hydroxides ·mH2O intercalated with metal coordinate ions or oxometalates in the last ten years are reviewed. These layered double hydroxides are mainly intercalated with polyoxometalate (POM) ions, a LiAl-LDH photochemical assembly containing TiO2 and CH3(CH2)12COO- anions, together with Zn(TPPC) (porphy-rin derivate) and macrocyclic ligand-containing porphyrin derivate anions. Emphasis is put on the synthesis methods for intercalation of the anions into the interlayer regions, the characterization techniques and structures for the layered compounds and the newest research progress in the fields such as catalysis. The review also forecasts the prospects of the field.

  10. Silica functionalized Cu(II) acetylacetonate Schiff base complex: An efficient catalyst for the oxidative condensation reaction of benzyl alcohol with amines

    Science.gov (United States)

    Anbarasu, G.; Malathy, M.; Karthikeyan, P.; Rajavel, R.

    2017-09-01

    Silica functionalized Cu(II) acetylacetonate Schiff base complex via the one pot reaction of silica functionalized 3-aminopropyltriethoxysilane with acetyl acetone and copper acetate has been reported. The synthesized material was well characterized by analytical techniques such as FT-IR, UV-DRS, XRD, SEM-EDX, HR-TEM, EPR, ICP-AES and BET analysis. The characterization results confirmed the grafting of Cu(II) Schiff base complex on the silica surface. The catalytic activity of synthesized silica functionalized Cu(II) acetylacetonate Schiff base complex was evaluated through the oxidative condensation reaction of benzyl alcohol to imine.

  11. Configuration-averaged open shell ab initio method for crystal field levels and magnetic properties of lanthanide(III) complexes

    CERN Document Server

    Heuvel, Willem Van den; Soncini, Alessandro

    2015-01-01

    We present an ab initio methodology dedicated to the determination of the electronic structure and magnetic properties of ground and low-lying excited states, i.e., the crystal field levels, in lanthanide(III) complexes. Currently, the most popular and successful ab initio approach is the CASSCF/RASSI-SO method, consisting of the optimization of multiple complete active space self-consistent field (CASSCF) spin eigenfunctions, followed by full diagonalization of the spin--orbit coupling (SOC) Hamiltonian in the basis of the CASSCF spin states featuring spin-dependent orbitals. Based on two simple observations valid for Ln(III) complexes, namely: (i) CASSCF 4f atomic orbitals are expected to change very little when optimized for different multiconfigurational states belonging to the 4f-electronic configuration, (ii) due to strong SOC the total spin is not a good quantum number, we propose here an efficient ab initio strategy which completely avoids any multiconfigurational calculation, by optimizing a unique s...

  12. Effect of magnesium acetylacetonate on the signal of organic forms of vanadium in graphite furnace atomic absorption spectrometry.

    Science.gov (United States)

    Kowalewska, Zofia; Welz, Bernhard; Castilho, Ivan N B; Carasek, Eduardo

    2013-01-15

    The aim of this work was to investigate the influence of magnesium acetylacetonate (MgA) on the signal of organic forms of vanadium in xylene solution by graphite furnace atomic absorption spectrometry. MgA alone or mixed with palladium acetylacetonate (PdA) was considered as a chemical modifier. It has been found that MgA does not improve, but decreases significantly the integrated absorbance of V in the form of alkyl-aryl sulfonates, acetylacetonates, porphyrins and in lubricating oils, while its effect is negligible in the case of "dark products" from petroleum distillation, i.e., heavy oil fractions and residues. The decrease is also observed in the presence of Pd. The MgA (or MgA+PdA) effect on the integrated absorbance of V has been studied using the following variants: different ways of modifier application, various pyrolysis temperature, additional application of air ashing, preliminary pretreatment with iodine and methyltrioctylammonium chloride, application of various graphite furnace heating systems (longitudinal or transverse) and various optical and background correction systems (medium-resolution line source spectrometer with deuterium background correction or high-resolution continuum source spectrometer). The experiments indicate formation of more refractory compounds as a possible reason for the decrease of the integrated absorbance for some forms of V in the presence of MgA. The application of MgA as a chemical modifier in V determination is not recommended. Results of this work have general importance as, apart from the intentional use of MgA as a modifier, organic Mg compounds, present in petroleum products for other reason (e.g. as an additive), can influence the signal of V compounds and hence the accuracy in V determination. Generally, petroleum products with known amount of V are recommended as standards; however, lubricating oils can be inadequate for "dark products" from petroleum distillation. In the case of unknown samples it is

  13. Pharmacokinetic Profile of Oral Magnesium Hydroxide

    DEFF Research Database (Denmark)

    Dolberg, Mette Konow Bøgebjerg; Nielsen, Lars Peter; Dahl, Ronald

    2016-01-01

    Despite the presumption of a beneficial effect of magnesium (Mg) supplementation on various diseases, little is known concerning the pharmacokinetics of Mg hydroxide. This study was designed to provide a pharmacokinetic profile of Mg hydroxide after a single oral dose. Ten healthy male adults...

  14. Effect of chelating agent acetylacetone on corrosion protection properties of silane-zirconium sol-gel coatings

    Science.gov (United States)

    Yu, Mei; Liang, Min; Liu, Jianhua; Li, Songmei; Xue, Bing; Zhao, Hao

    2016-02-01

    The hybrid sol-gel coatings on AA2024-T3 were prepared with a silane coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS) and a metal alkoxide tetra-n-propoxyzirconium (TPOZ) as precursors. The effect of acetylacetone (AcAc) as a chelating agent on the corrosion protection properties of sol-gel coatings were evaluated and the optimal AcAc/TPOZ molar ratio was obtained. The sol-gel coatings were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The corrosion protection properties of the coatings were evaluated by means of potentiodynamic polarization study (PDS) and electrochemical impedance spectroscopy (EIS). It is demonstrated that AcAc avoids fast hydrolysis of TPOZ and benefits to form stable sols. The coating with AcAc/TPOZ molar ratio of 3 shows the best corrosion protection performance in 0.05 M NaCl solution.

  15. Economically attractive route for the preparation of high quality magnetic nanoparticles by the thermal decomposition of iron(III) acetylacetonate

    Science.gov (United States)

    Effenberger, Fernando B.; Couto, Ricardo A.; Kiyohara, Pedro K.; Machado, Giovanna; Masunaga, Sueli H.; Jardim, Renato F.; Rossi, Liane M.

    2017-03-01

    The thermal decomposition (TD) methods are among the most successful in obtaining magnetic nanoparticles with a high degree of control of size and narrow particle size distribution. Here we investigated the TD of iron(III) acetylacetonate in the presence of oleic acid, oleylamine, and a series of alcohols in order to disclose their role and also investigate economically attractive alternatives for the synthesis of iron oxide nanoparticles without compromising their size and shape control. We have found that some affordable and reasonably less priced alcohols, such as 1,2-octanediol and cyclohexanol, may replace the commonly used and expensive 1,2-hexadecanediol, providing an economically attractive route for the synthesis of high quality magnetic nanoparticles. The relative cost for the preparation of Fe3O4 NPs is reduced to only 21% and 9% of the original cost when using 1,2-octanediol and cyclohexanol, respectively.

  16. Reactions of 15-crown-5 and bis-15-crown-5 ethers with metal acetylacetonate ions in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Timofeev, O.S.; Bogatskii, A.V.; Gren, A.I.; Lobach, A.V.; Nekarsov, Y.S.; Zagorevskii, D.V.

    1985-05-20

    A study was carried out on the ion-molecule reactions of ions arising in the dissociation of ferric, cobaltic, chromic, manganous, neodymium(II), gallium(III), and indium(III) acetylacetonates upon electron impact with 15-crown-5 and bis-15-crown-5. The ratio of the yields of (acac)x-1 /SUP M+L/ ions is determined by the case of reduction of M /SUP x+1+/ to M /SUP x+/ and for (acac)/sub 3/M complexes, this ratio decreases in the series Nd, In, GA > Cr > Fe, Co. The rate constant for the formation of acacCoL/sup +/ ions is greater than for acacFeL/sup +/ ions. The possibility of fixing transition metals in unstable oxidation states by crown ethers is demonstrated in the case of nickel.

  17. Predicting the Potentials, Solubilities and Stabilities of Metal-Acetylacetonates for Non-Aqueous Redox Flow Batteries Using Density Functional Theory Calculations.

    Energy Technology Data Exchange (ETDEWEB)

    Kucharyson, J. F.; Cheng, L.; Tung, S. O.; Curtiss, L. A.; Thompson, L. T.

    2017-07-14

    New active materials are needed to improve the performance and reduce the cost of non-aqueous redox flow batteries (RFBs) for grid-scale energy storage applications. Efforts to develop better performing materials, which have largely been empirical, would benefit from a better understanding of relationships between structural, electronic and RFB-relevant functional properties. This paper focuses on metal-acetylacetonates, a class of metal coordination complexes that has shown promise for use in RFBs, and describes correlations between their experimentally measured standard potentials, solubilities, and stabilities (cycle lifes), and selected chemical, structural and electronic properties determined from Density Functional Theory (DFT) calculations. The training set consisted of 16 complexes including 5 different metals and 11 different substituents on the acetylacetonate ligand. Standard potentials for those compounds were calculated and are in good agreement with experimentally measured results. A predictive equation based on the solvation energies and dipole moments, two easily computed properties, reasonably modeled the experimentally determined solubilities. Importantly, we were able to identify a descriptor for the stability of acetylacetonates. The experimentally determined stability, quantified as the cycle life to a given degree of degradation, correlated with the percentage of the highest occupied (HOMO) or lowest unoccupied molecular orbital (LUMO) on the metal of the complex. This percentage is influenced by the degree of ligand innocence (irreducibility), and complexes with the most innocent ligands yielded the most stable redox reactions. To this end, VO(acetylacetonate)(2) and Fe(acetylacetonate)(3), with nearly 80% of the HOMO and LUMO on the metal, possessed the most stable oxidation and reduction half-reactions, respectively. The structure-function relationships and correlations presented in this paper could be used to predict new, highly soluble

  18. Neutral and anionic superhalogen hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Swierszcz, Iwona [Department of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland); Anusiewicz, Iwona, E-mail: iwonaa@chem.univ.gda.pl [Department of Chemistry, University of Gdansk, Sobieskiego 18, 80-952 Gdansk (Poland)

    2011-05-26

    Graphical abstract: The energy profile for the Na(OH){sub 2}{sup -} anionic hydroxide formation according to the NaOH+OH{sup -}{yields}Na(OH){sub 2}{sup -} reaction. Display Omitted Highlights: {yields} The superhalogen hydroxides and their anions were studied at the CCSD(T)/6-311++G(3df,3pd) level. {yields} All anionic superhalogen hydroxides were found to be thermodynamically stable. {yields} The VDE values calculated for the M(OH){sub k+1}{sup -} anions exceed 4 eV in all cases. {yields} The largest VDEs were found for the Al(OH){sub 4}{sup -} (6.07 eV) and Ga(OH){sub 4}{sup -} (6.21 eV). - Abstract: The properties of superhalogen M(OH){sub k+1}{sup -} anions and their M(OH){sub k+1} neutral parents (where M = Li, Na, K, Be, Mg, Ca, B, Al, Ga) were investigated at the ab initio CCSD(T)/6-311++G(3df,3pd)//MP2/6-311++G(d,p) level of theory. All the M(OH){sub k+1}{sup -} anions and some of their M(OH){sub k+1} neutral parents (k is the maximal formal valence of M) were found to be thermodynamically stable against the fragmentations (OH, OH{sup -}, O{sub 2} or H{sub 2}O loss). The vertical electron detachment energies (VDE) of the M(OH){sub k+1}{sup -} anions were calculated with the OVGF method and using the 6-311++G(3df,3pd) basis sets. The VDE values calculated for the anions studied exceed 4 eV in all cases, whereas the largest values of the electron binding energies were found for the Al(OH){sub 4}{sup -} (6.07 eV) and Ga(OH){sub 4}{sup -} anions (6.21 eV). Finally, formation of most of the species considered was predicted to be spontaneous due to the lack of kinetic barriers for these processes and their thermodynamic favorability.

  19. Transport of Indium, Gallium and Thallium Metal Ions Through Chromatographic Fiber Supported Solid Membrane in Acetylacetone Containing Mixed Solvents

    Institute of Scientific and Technical Information of China (English)

    Abaji Gaikwad

    2011-01-01

    The transport of metal ions of indium, gallium and thallium from source solution to receiving phase through the chromatographic fiber supported solid membrane in the acetylacetone (HAA) containing mixed solvent system has been explored. The fibers supported solid membranes were prepared with chemical synthesis from cellulose fibers and citric acid with the carboxylic acid ion exchange groups introduced. The experimental variables, such as concentration of metal ions (10^-2 to 10^-4 mol.L^-1) in the source solution, mixed solvent composition [for exampl, e, acetylacetone, (2,4-pentanedione), (HAA) 20% (by volume), 1,4-dioxane 10% to 60% and HC1 0.25 to 2 mol.L^-1] in the receiving phase and stirring speed (50-130 r.min ) of the bulk source and receiving phase, were explored. The efficiency of mixed solvents for the transport of metal ions from the source to receiving phase through the fiber supported solid membrane was evaluated. The combined ion exchange solvent extraction (CIESE) was observed effective for the selective transport of thallium, indium and gallium metal ions through fiber supported solid membrane in mixed solvents. The oxonium salt formation in the receiving phase enhances thallium, indium and gallium metal ion transport through solid membrane phase. The selective transport of thallium metal ions from source phase was observed from indium and gallium metal ions in the presence of hydrochloric acid in organic solvents in receiving phase. The separation of thallium metal ions from the binary mixtures of Be(II), Ti(IV), AI(III) Ca(II), Mg(II), K (I), La(III) and Y(III) was carried out in the mixed solvent system using cellulose fiber supported solid membrane.

  20. Increasing the luminescence of lanthanide(III) macrocyclic complexes by the use of polymers and lanthanide enhanced luminescence

    Science.gov (United States)

    Leif, Robert C.; Becker, Margie C.; Bromm, Alfred J., Jr.; Vallarino, Lidia M.; Williams, Steven A.; Yang, Sean

    2001-05-01

    A Eu (III)-macrocycle-isothiocyanate, Quantum DyeTM, has been reacted with lysine homo- and hetero-peptides to give polymers with multiple luminescent side chains. Contrary to the concentration quenching that occurs with conventional organic fluorophores, the attachment of multiple Quantum Dyes to a polymer results in a concomitant increase in luminescence. The emission intensity of the peptide-bound Quantum Dye units is approximately linearly related to their number. The attachment of peptides containing multiple lanthanide (III) macrocycles to analyte-binding species is facilitated by employing solid-phase technology. Bead-bound peptides are first labeled with multiple Quantum Dye units, then conjugated to an antibody, and finally released from the bead by specific cleavage with Proteinase K unedr physiological conditions. Since the luminescence of lanthanide(III) macrocycles is enhanced by the presence of GD(III) or Y(III) ions in a micellar system, a significant increase in signal can be achieved by attaching a polymer labeled with multiple Quantum Dye units to an analyte- binding species, such as a monoclonal antibody, or by taking advantage of the luminescence enhancing effects of Gd(III) or Y(III), or by both approaches concomitantly. A comparison between the integrated intensity and lifetime measurements of the Eu(III)-macrocycle under a variety of conditions show that the signal increase caused by Gd(III) can not be explained solely by the increase in lifetime, and must result in significant part from an energy transfer process invloving donors not directly bound to the Eu(III).

  1. Thermodynamics of Volatile Silicon Hydroxides Studied

    Science.gov (United States)

    Copland, Evan H.; Opila, Elizabeth J.; Jacobson, Nathan S.

    2001-01-01

    Silicon-based ceramics are promising candidate structural materials for heat engines. The long-term stability of these materials to environmental degradation is dependent on the formation and retention of a protective SiO2 layer. It is well known that SiO2 forms stable volatile hydroxides in the presence of water vapor at elevated temperatures. Combustion conditions, which characteristically are at high velocities, contain significant water vapor pressures, and high temperatures tend to promote continuous formation of these hydroxides with resulting material degradation. For the degradation of silicon-based ceramics to be predicted, accurate thermodynamic data on the formation of silicon hydroxides are needed.

  2. Properties of oxide-hydroxide sintered ceramics

    Science.gov (United States)

    Levkov, R. V.; Kulkov, S. N.

    2017-02-01

    In this paper the study of porous ceramics obtained from aluminum hydroxide with gibbsite modification is presented. It was shown that aluminum hydroxide may be used for pore formation and pore volume in the sintered ceramics can be controlled by varying the aluminum hydroxide concentration and sintering temperature. It was shown that compressive strength of alumina ceramics increases by 40 times with decreasing the pore volume from 65 to 15%. Based on these results one can conclude that the obtained structure is very close to inorganic bone matrix and can be used as promising material for bone implants production.

  3. Nickel hydroxide precipitation from aqueous sulfate media

    Science.gov (United States)

    Sist, Cinziana; Demopoulos, George P.

    2003-08-01

    Hydrometallurgical processing of laterite ores constitutes a major industrial and R&D activity in extractive metallurgy. In some of the process flowsheets, nickel hydroxide precipitation is incorporated. For these operations, the optimization of nickel hydroxide precipitation is important to assure efficiency and product quality. The main objective of this investigation was to study and improve the precipitation characteristics of Ni(OH)2 in a sulfate system using supersaturation controlled precipitation.

  4. A novel mass spectrometric method for formaldehyde in children's personal-care products and water via derivatization with acetylacetone.

    Science.gov (United States)

    Backe, Will J

    2017-06-30

    New legislation in the state of Minnesota prohibits the sale of children's personal-care products (PCPs) that contain more than 500 ng/mg formaldehyde. Previous attempts to quantify formaldehyde in PCPs use nonspecific derivatization procedures that employ harsh reagents and/or nonspecific detection. Derivatization of formaldehyde by acetylacetone occurs under mild conditions and is specific for formaldehyde but it has not been investigated using high-performance liquid chromatography/tandem mass-spectrometry (HPLC/MS/MS). To determine formaldehyde, PCPs were dissolved and then interferences were minimized by graphitized-carbon solid-phase extraction. Formaldehyde was derivatized to 3,5-diacetyl-1,4-dihydrolutidine (DDL) using an acetylacetone solution. Post-derivatization, samples were diluted and analyzed by HPLC/MS/MS. Quantification was performed by isotopic dilution. Product-ion spectra were acquired for DDL and D12 -DDL. The mass shifts between the two product-ion spectra were used to assign fragment structures. To confirm molecular formulas, high-resolution accurate-mass analysis of the DDL product ions was performed by quadrupole time-of-flight MS. Structures were proposed for all product ions of DDL above 10% relative intensity. Method accuracy ranged between 96-104% for all matrices at all concentrations tested. Method precision was less than 4% relative standard deviation. The reporting limit was 10 ng/mg in PCPs and 100 μg/L in water. Twenty children's PCPs were tested to demonstrate the method and formaldehyde was reported in five from 23-1500 ng/mg. Of those five, two samples contained formaldehyde above the Minnesota regulatory limit. The developed method allows for the accurate quantification of formaldehyde in PCPs at levels below those required by a new regulation on children's products in Minnesota. The method includes a derivatization procedure that is newly adapted to HPLC/MS/MS; therefore, structures were proposed for the product ions of

  5. Studies of magnetite nanoparticles synthesized by thermal decomposition of iron (III) acetylacetonate in tri(ethylene glycol)

    Science.gov (United States)

    Maity, Dipak; Kale, S. N.; Kaul-Ghanekar, Ruchika; Xue, Jun-Min; Ding, Jun

    2009-10-01

    In this paper, water-soluble magnetite nanoparticles have been directly synthesized by thermal decomposition of iron (III) acetylacetonate, Fe(acac) 3 in tri(ethyleneglycol). Size and morphology of the nanoparticles are determined by transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements while the crystal structure is identified using X-ray diffraction (XRD). Surface charge and surface coating of the nanoparticles are recognized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectra (XPS) and zeta potential measurements. Magnetic properties are determined using vibrating sample magnetometer (VSM) and superconducting quantum interference device (SQUID) measurements. The results show that as-prepared magnetite nanoparticles are relatively monodisperse, single crystalline and superparamagnetic in nature with the blocking temperature at around 100 K. The magnetite nanoparticles are found to be highly soluble in water due to steric and electrostatic interactions between the particles arising by the surface adsorbed tri(ethyleneglycol) molecules and associated positive charges, respectively. Cytotoxicity studies on human cervical (SiHa), mouse melanoma (B16F10) and mouse primary fibroblast cells demonstrate that up to a dose of 80 μg/ml, the magnetic nanoparticles are nontoxic to the cells. Specific absorption rate (SAR) value has been calculated to be 885 and 539 W/gm for samples with the iron concentration of 1 and 0.5 mg/ml, respectively. The high SAR value upon exposure to 20 MHz radiofrequency signifies the applicability of as-prepared magnetite nanoparticles for a feasible magnetic hyperthermia treatment.

  6. Efficient alkene epoxidation catalyzed by molybdenyl acetylacetonate supported on aminated UiO-66 metal−organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Kardanpour, Reihaneh [Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Tangestaninejad, Shahram, E-mail: stanges@sci.ui.ac.ir [Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Mirkhani, Valiollah, E-mail: mirkhani@sci.ui.ac.ir [Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Moghadam, Majid, E-mail: moghadamm@sci.ui.ac.ir [Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of); Mohammadpoor-Baltork, Iraj; Zadehahmadi, Farnaz [Department of Chemistry, Catalysis Division, University of Isfahan, Isfahan 81746-73441 (Iran, Islamic Republic of)

    2015-03-15

    Metal–organic frameworks (MOFs) containing Mo Schiff base complexes were prepared by post-synthesis method and applied as efficient catalysts in the epoxidation of alkenes with tert-BuOOH. In this manner, UiO-66-NH{sub 2} (UiO=University of Oslo) MOF was reacted with salicylaldehyde and thiophene-2-carbaldehyde to produce bidentate Schiff bases. Then, the Schiff base ligands were used for immobilization of molybdenyl acetylacetonate. These new catalysts were characterized by FT-IR, UV–vis spectroscopic techniques, X-ray diffraction (XRD), BET, inductively coupled plasma atomic emission spectroscopy (ICP-AES) and field emission scanning electron microscopy (FE-SEM). These catalytic systems showed excellent activity in the epoxidation of alkenes such as cyclic and linear ones with tert-butyl hydroperoxide (TBHP) in 1,2-dichloroethane, and reused several times without any appreciable loss of their activity. - Graphical abstract: Efficient alkene epoxidation with TBHP catalyzed by heterogeneous and reusable molybdenum base catalysts is reported. - Highlights: • UiO-66-NH{sub 2} was modified with salicylaldehyde and thiophene-2-carbaldehyde. • The Schiff base groups were used for immobilization of MoO{sub 2}(acac){sub 2}. • The heterogeneous catalysts were prepared. • The prepared catalysts were used for epoxidation of alkenes. • Compared to other catalyst, our catalysts were more efficient and forceful.

  7. Effect of chelating agent acetylacetone on corrosion protection properties of silane-zirconium sol–gel coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Mei, E-mail: yumei@buaa.edu.cn; Liang, Min; Liu, Jianhua; Li, Songmei; Xue, Bing; Zhao, Hao

    2016-02-15

    Graphical abstract: - Highlights: • AcAc was employed as a chelating agent in order to form stable sols. • The sol particle size depends on the concentration of AcAc. • AFM results indicate that AcAc content affects the morphology of the coatings. • Coating AcAc3 shows the optimal corrosion protection. - Abstract: The hybrid sol–gel coatings on AA2024-T3 were prepared with a silane coupling agent 3-glycidoxypropyltrimethoxysilane (GPTMS) and a metal alkoxide tetra-n-propoxyzirconium (TPOZ) as precursors. The effect of acetylacetone (AcAc) as a chelating agent on the corrosion protection properties of sol–gel coatings were evaluated and the optimal AcAc/TPOZ molar ratio was obtained. The sol–gel coatings were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The corrosion protection properties of the coatings were evaluated by means of potentiodynamic polarization study (PDS) and electrochemical impedance spectroscopy (EIS). It is demonstrated that AcAc avoids fast hydrolysis of TPOZ and benefits to form stable sols. The coating with AcAc/TPOZ molar ratio of 3 shows the best corrosion protection performance in 0.05 M NaCl solution.

  8. Thermal aging effect of vanadyl acetylacetonate precursor for deposition of VO{sub 2} thin films with thermochromic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Jung-Hoon [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Nam, Sang-Hun [Institute of Basic Science, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Kim, Donguk; Kim, Minha [School of Electronic and Electrical Engineering, Sungkyunkwan University (Korea, Republic of); Seo, Hyeon Jin; Ro, Yu Hyeon [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Joo, Yong Tae [YOUNG DO Glass Industry Co., Ltd., Jeongeup (Korea, Republic of); Lee, Jaehyeong [School of Electronic and Electrical Engineering, Sungkyunkwan University (Korea, Republic of); Boo, Jin-Hyo, E-mail: jhboo@skku.edu [Department of Chemistry, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of); Institute of Basic Science, Sungkyunkwan University, 440-746 Suwon (Korea, Republic of)

    2016-10-15

    Highlights: • 7 day aged VO(acac){sub 2} sol shows enhanced adhesivity on the SiO{sub 2} compared with non-aged sol. • The aging process has significantly affected the morphologies of VO{sub 2} films. • From the FT-IR spectra, thermal aging process provides the deformation of precursor. • The metal insulator transition (MIT) efficiency (ΔT{sub at2000} {sub nm}) reached a maximum value of 51% at 7 day aging. • Thermal aging process could shorten the aging time of sol solution. - Abstract: Thermochromic properties of vanadium dioxide (VO{sub 2}) have been studied extensively due to their IR reflection applications in energy smart windows. In this paper, we studied the optical switching property of VO{sub 2} thin film, depending on the thermal aging time of the vanadyl acetylacetonate (VO(acac){sub 2}) precursor. We found the alteration of the IR spectra of the precursor by tuning the aging time as well as heat treatments of the precursor. An aging effect of vanadium precursor directly affects the morphologies, optical switching property and crystallinity of VO{sub 2} films. The optimum condition was achieved at the 7 day aging time with metal insulator transition (MIT) efficiency of 50%.

  9. Synthesis, Structure and Photoluminescence of Cu[(PPh3)2](acac) (PPh3=Triphenylphosphine, acac = Acetylacetone)

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A novel complex Cu(PPh3)2(acac) 1 (PPh3 = triphenylphosphine, acac = acetylacetone) was obtained by a solution reaction and structurally characterized by X-ray diffraction. The crystal belongs to monoclinic, space group P21/n with a = 13.7361(8), b = 12.8204(7), c =19.7638(13)(A), β = 95.946(2)°, C41H37CuO2P2, Mr= 687.19, V= 3461.7(4)(A)3, Z = 4, Dc = 1.319g/cm3, S = 1.067, μ(MoKα) = 0.758 mm-1, F(000) = 1432, R = 0.0403 and wR = 0.0990. Complex 1is characterized by an isolated structure. X-ray structure analysis of 1 shows that acac behaves as a chelating ligand and PPh3 coordinates as a monodentate ligand to the Cu(Ⅰ) atoms. Photoluminescent investigation reveals that the title complex displays a strong green-light emission.

  10. Phosphorescence quantum yield determination with time-gated fluorimeter and Tb(III)-acetylacetonate as luminescence reference

    Energy Technology Data Exchange (ETDEWEB)

    Penzkofer, A., E-mail: alfons.penzkofer@physik.uni-regensburg.de [Fakultät für Physik, Universität Regensburg, Universitätsstrasse 31, D-93053 Regensburg (Germany)

    2013-03-29

    Highlights: ► Procedure for absolute phosphorescence quantum yield measurement is described. ► Experimental setup for absolute luminescence quantum yield standard calibration. ► Tb(acac){sub 3} proposed as phosphorescence quantum yield reference standard. ► Luminescence quantum yield of Tb(acac){sub 3} in cyclohexane measured. ► Luminescence lifetime of Tb(acac){sub 3} in cyclohexane measured. - Abstract: Phosphorescence quantum yield measurements of fluorescent and phosphorescent samples require the use of time-gated fluorimeters in order to discriminate against the fluorescence contribution. As reference standard a non-fluorescent luminescent compound is needed for absolute phosphorescence quantum yield determination. For this purpose the luminescence behavior of the rare earth chelate terbium(III)-acetylacetonate (Tb(acac){sub 3}) was studied (determination of luminescence quantum yield and luminescence lifetime). The luminescence quantum yield of Tb(acac){sub 3} was determined by using an external light source and operating the fluorimeter in chemo/bioluminescence mode with a fluorescent dye (rhodamine 6G in methanol) as reference standard. A procedure is developed for absolute luminescence (phosphorescence) quantum yield determination of samples under investigation with a time-gated fluorimeter using a non-fluorescent luminescent compound of known luminescence quantum yield and luminescence lifetime.

  11. Synthesis, structure, theoretical studies and luminescent properties of a ternary erbium(III) complex with acetylacetone and bathophenanthroline ligands

    Energy Technology Data Exchange (ETDEWEB)

    Martín-Ramos, Pablo [CEMDRX, Department of Physics, Universidade de Coimbra, Rua Larga, P-3004-516 Coimbra (Portugal); Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain); Silva, Pedro S. Pereira, E-mail: psidonio@pollux.fis.uc.pt [CEMDRX, Department of Physics, Universidade de Coimbra, Rua Larga, P-3004-516 Coimbra (Portugal); Chamorro-Posada, Pedro [Higher Technical School of Telecommunications Engineering, Universidad de Valladolid, Campus Miguel Delibes, Paseo Belén 15, 47011 Valladolid (Spain); Silva, Manuela Ramos [CEMDRX, Department of Physics, Universidade de Coimbra, Rua Larga, P-3004-516 Coimbra (Portugal); Milne, Bruce F. [Centre for Computational Physics, Department of Physics, Universidade de Coimbra, P-3004-516 Coimbra (Portugal); Donostia International Physics Centre, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián (Spain); Nogueira, Fernando [Centre for Computational Physics, Department of Physics, Universidade de Coimbra, P-3004-516 Coimbra (Portugal); Martín-Gil, Jesús [Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, 34004 Palencia (Spain)

    2015-06-15

    A novel erbium(III) complex with acetylacetone (Hacac) and bathophenanthroline (4,7-diphenyl-1,10-phenanthroline, bath) ligands, formulated as [Er(acac){sub 3}(bath)], has been characterized by elemental analysis, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, absorption and emission spectroscopies. In the theoretical part of this study, semi-empirical quantum chemistry methods using AM1, PM3, PM6 and PM7 models have been employed to predict the structure of the complex, calculate the geometric and crystallographic parameters, and make comparisons with spectroscopic data using INDO/S-CI calculations. Real-time time-dependent density-functional theory (TDDFT) has also been used to calculate the optical absorption spectrum of the complex in the gas phase. - Highlights: • Synthesis and structure of a new erbium(III) β-diketonate complex. • TDDFT used for the first time to calculate the optical absorption spectrum. • Complex show strong near-infrared luminescence at 1.53 µm due to antenna effect.

  12. Acetylacetonate anchors for robust functionalization of TiO2 nanoparticles with Mn(II)-terpyridine complexes.

    Science.gov (United States)

    McNamara, William R; Snoeberger, Robert C; Li, Gonghu; Schleicher, James M; Cady, Clyde W; Poyatos, Macarena; Schmuttenmaer, Charles A; Crabtree, Robert H; Brudvig, Gary W; Batista, Victor S

    2008-10-29

    A novel class of derivatized acetylacetonate (acac) linkers for robust functionalization of TiO2 nanoparticles (NPs) under aqueous and oxidative conditions is reported. The resulting surface adsorbate anchors are particularly relevant to engineering photocatalytic and photovoltaic devices since they can be applied to attach a broad range of photosensitizers and photocatalytic complexes and are not affected by humidity. Acac is easily modified by CuI-mediated coupling reactions to provide a variety of scaffolds, including substituted terpy complexes (terpy = 2,2':6,2''-terpyridine), assembled with ligands coordinated to transition-metal ions. Since Mn-terpy complexes are known to be effective catalysts for oxidation chemistry, functionalization with Mn(II) is examined. This permits visible-light sensitization of TiO2 nanoparticles due to interfacial electron transfer, as evidenced by UV-vis spectroscopy of colloidal thin films and aqueous suspensions. The underlying ultrafast interfacial electron injection is complete on a subpicosecond time scale, as monitored by optical pump-terahertz probe transient measurements and computer simulations. Time-resolved measurements of the Mn(II) EPR signal at 6 K show that interfacial electron injection induces Mn(II) --> Mn(III) photooxidation, with a half-time for regeneration of the Mn(II) complex of ca. 23 s.

  13. Lanthanide(III and Yttrium(III Complexes of Benzimidazole-2-Acetic Acid: Synthesis, Characterisation and Effect of La(III Complex on Germination of Wheat

    Directory of Open Access Journals (Sweden)

    2006-01-01

    Full Text Available The synthesis and characterisation of lanthanide(III and yttrium(III nitrate complexes of benzimidazole-2-acetic acid (HBIA are reported. The complexes have been characterised by elemental analysis, molar conductance, magnetic studies, IR, 1 H NMR, UV-visible, EPR, and TG/DTA studies. They have the stoichiometry [ Ln 3 ( BIA 2 ( NO 3 7 ( H 2 O 4 ]⋅3 H 2 O where Ln=La(III, Pr(III, Nd(II, Sm(III, Eu(III, Gd(III, Tb(III, Dy(III, and Y(III. The effect of La(III complex on germination, coleoptile, and root length of two local varieties of wheat DWR-195 and GW-349 for different treatment periods has been investigated. The complex was found to exhibit enhanced activity, compared to HBIA or metal salt alone at lower treatment periods.

  14. Synthesis and Characterization of Lanthanide(III Nitrate Complexes with Terdentate ONO Donor Hydrazone Derived from 2-Benzimidazolyl Mercaptoaceto Hydrazide and o-Hydroxy Aromatic Aldehyde

    Directory of Open Access Journals (Sweden)

    Vinayak M. Naik

    2011-01-01

    Full Text Available A few eight coordinated complexes of lanthanide(III nitrate with 2-benzimidazolyl mercaptoaceto hydrazone ligand (LH2 with the general formula [Ln(LH2NO2]H2O (where Ln = La, Pr, Nd, Sm and Gd have been synthesized and characterized by elemental analysis, magnetic susceptibility, molar conductance, UV-Visible, IR and 1H NMR spectral studies. The experimental data sustain stoichiometry of 1:2 (metal/ligand for the complexes. The spectral data shows that the ligand reacts in keto form and behaves as monobasic terdentate in nature. The nitrate appears to coordinate in the bidentate fashion to the metal ion. The thermal stabilities of the complexes have been studied by TGA and their kinetic parameters were calculated using Coats-Redfern and MKN methods. The antimicrobial activity studies have been under taken and results are discussed.

  15. Synthesis of layered double hydroxides from eggshells

    Energy Technology Data Exchange (ETDEWEB)

    Li Songnan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Fangyong [College of Engineering and Technology, Northeast Forestry University, 150001 (China); Jing Xiaoyan [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Wang Jun, E-mail: zhqw1888@sohu.com [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China); Saba, Jamil; Liu Qi; Ge Lan; Song Dalei; Zhang Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, 150001 (China)

    2012-01-16

    Graphical abstract: This is the XRD pattern and TEM image of 4Ca-Al layered double hydroxide, which is obtained from eggshells. It can be seen that the sample is of layered double hydroxide and shows the plate-like agglomerations with an average size of 20-100 nm. Highlights: Black-Right-Pointing-Pointer We synthesize layered double hydroxides from eggshells. Black-Right-Pointing-Pointer Eggshells are the mainly material in this method. Black-Right-Pointing-Pointer The additional alkaline solution is not required. - Abstract: Ca-Al and Ca-Fe layered double hydroxides (LDHs) were successfully synthesized from chicken eggshells by an ultrasonic wave assistant method. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR) techniques. XRD and TEM analyses showed that the 4Ca-Al LDHs were of high purity but other samples were not. The present study provides a simple, efficient and environmental friendly method to obtain LDHs from biowaste eggshells, in which additional alkaline solution is not required for synthesis. Moreover, eggshells provide all the requisite bivalent metal ions, which are needed to form layered double hydroxides.

  16. Surface Acidity of Amorphous Aluminum Hydroxide

    Institute of Scientific and Technical Information of China (English)

    K. FUKUSHI; K. TSUKIMURA; H. YAMADA

    2006-01-01

    The surface acidity of synthetic amorphous Al hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous Al hydroxide rapidly transformed to crystalline bayerite at the alkaline condition (pH>10). The solution analyses after and during the titration experiments showed that the solubility of amorphous aluminum hydroxide, Ksp =aAl3+/a3H+,was 1010.3,The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved Al species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.

  17. Aluminium hydroxide-induced granulomas in pigs

    DEFF Research Database (Denmark)

    Valtulini, S; Macchi, C; Ballanti, P

    2005-01-01

    The effect of intramuscular injection of 40 mg/2 ml aluminium hydroxide in the neck of pigs was examined in a number of ways. The investigation followed repeated slaughterhouse reports, according to which 64.8% of pigs from one particular farm were found at slaughter to have one or more nodules...... in the muscles of the neck (group slaughtered). The pigs had been injected with a vaccine containing 40 mg/2 ml dose of aluminium hydroxide as adjuvant. Research consisted of two phases: first, an epidemiological study was carried out, aimed at determining the risk factors for the granulomas. The results...... and adjuvant) to pigs inoculated twice with apyrogenic bi-distilled water (group water) and to pigs inoculated once with the adjuvant and once with apyrogenic bi-distilled water (group adjuvant/water). Both studies agreed in their conclusions, which indicate that the high amount of aluminium hydroxide...

  18. Layered double hydroxide stability. 1. Relative stabilities of layered double hydroxides and their simple counterparts

    Science.gov (United States)

    Boclair, J. W.; Braterman, P. S.

    1999-01-01

    Solutions containing di- and trivalent metal chlorides [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+; M(III) = Al3+, Fe3+] were titrated with NaOH to yield hydrotalcite-like layered double hydroxides (LDH), [[M(II)]1-x[M(III)]x(OH)2][Cl]x yH2O, by way of M(III) hydroxide/hydrous oxide intermediates. Analysis of the resultant titration curves yields nominal solubility constants for the LDH. The corresponding LDH stabilities are in the order Mg hydroxides/hydrous oxides is discussed.

  19. Iron-Mediated Homogeneous ICAR ATRP of Methyl Methacrylate under ppm Level Organometallic Catalyst Iron(III Acetylacetonate

    Directory of Open Access Journals (Sweden)

    Jian Wu

    2016-01-01

    Full Text Available Atom Transfer Radical Polymerization (ATRP is an important polymerization process in polymer synthesis. However, a typical ATRP system has some drawbacks. For example, it needs a large amount of transition metal catalyst, and it is difficult or expensive to remove the metal catalyst residue in products. In order to reduce the amount of catalyst and considering good biocompatibility and low toxicity of the iron catalyst, in this work, we developed a homogeneous polymerization system of initiators for continuous activator regeneration ATRP (ICAR ATRP with just a ppm level of iron catalyst. Herein, we used oil-soluble iron (III acetylacetonate (Fe(acac3 as the organometallic catalyst, 1,1′-azobis (cyclohexanecarbonitrile (ACHN with longer half-life period as the thermal initiator, ethyl 2-bromophenylacetate (EBPA as the initiator, triphenylphosphine (PPh3 as the ligand, toluene as the solvent and methyl methacrylate (MMA as the model monomer. The factors related with the polymerization system, such as concentration of Fe(acac3 and ACHN and polymerization kinetics, were investigated in detail at 90 °C. It was found that a polymer with an acceptable molecular weight distribution (Mw/Mn = 1.43 at 45.9% of monomer conversion could be obtained even with 1 ppm of Fe(acac3, making it needless to remove the residual metal in the resultant polymers, which makes such an ICAR ATRP process much more industrially attractive. The “living” features of this polymerization system were further confirmed by chain-extension experiment.

  20. XPS study of thermal and electron-induced decomposition of Ni and Co acetylacetonate thin films for metal deposition

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Theodor; Warneke, Jonas; Zielasek, Volkmar, E-mail: zielasek@uni-bremen.de; Swiderek, Petra; Bäumer, Marcus [Institut für Angewandte und Physikalische Chemie, Universität Bremen, Postfach 330440, D-28334 Bremen (Germany)

    2016-07-15

    Optimizing thin metal film deposition techniques from metal-organic precursors such as atomic layer deposition, chemical vapor deposition (CVD), or electron beam-induced deposition (EBID) with the help of surface science analysis tools in ultrahigh vacuum requires a contamination-free precursor delivery technique, especially in the case of the less volatile precursors. For this purpose, the preparation of layers of undecomposed Ni(acac){sub 2} and Co(acac){sub 2} was tried via pulsed spray evaporation of a liquid solution of the precursors in ethanol into a flow of nitrogen on a CVD reactor. Solvent-free layers of intact precursor molecules were obtained when the substrate was held at a temperature of 115 °C. A qualitative comparison of thermally initiated and electron-induced precursor decomposition and metal center reduction was carried out. All deposited films were analyzed with respect to chemical composition quasi in situ by x-ray photoelectron spectroscopy. Thermally initiated decomposition yielded higher metal-to-metal oxide ratios in the deposit than the electron-induced process for which ratios of 60:40 and 20:80 were achieved for Ni and Co, resp. Compared to continuous EBID processes, all deposits showed low levels of carbon impurities of ∼10 at. %. Therefore, postdeposition irradiation of metal acetylacetonate layers by a focused electron beam and subsequent removal of intact precursor by dissolution in ethanol or by heating is proposed as electron beam lithography technique on the laboratory scale for the production of the metal nanostructures.

  1. Acid mine water neutralisation with ammonium hydroxide and ...

    African Journals Online (AJOL)

    2013-05-30

    May 30, 2013 ... Keywords: acid mine water, ammonium hydroxide, barium hydroxide, sulphate removal ... oxygen becomes oxidised to soluble iron and sulphuric acid, .... The effects of the following parameters on the Fe (II) oxidation.

  2. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, R.W.; Muller, R.H.

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 {endash} 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  3. Structural transformation of nickel hydroxide films during anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Crocker, Robert W. [Univ. of California, Berkeley, CA (United States); Muller, Rolf H. [Univ. of California, Berkeley, CA (United States)

    1992-05-01

    The transformation of anodically formed nickel hydroxide/oxy-hydroxide electrodes has been investigated. A mechanism is proposed for the anodic oxidation reaction, in which the reaction interface between the reduced and oxidized phases of the electrode evolves in a nodular topography that leads to inefficient utilization of the active electrode material. In the proposed nodular transformation model for the anodic oxidation reaction, nickel hydroxide is oxidized to nickel oxy-hydroxide in the region near the metal substrate. Since the nickel oxy-hydroxide is considerably more conductive than the surrounding nickel hydroxide, as further oxidation occurs, nodular features grow rapidly to the film/electrolyte interface. Upon emerging at the electrolyte interface, the reaction boundary between the nickel hydroxide and oxy-hydroxide phases spreads laterally across the film/electrolyte interface, creating an overlayer of nickel oxy-hydroxide and trapping uncharged regions of nickel hydroxide within the film. The nickel oxy-hydroxide overlayer surface facilitates the oxygen evolution side reaction. Scanning tunneling microscopy of the electrode in its charged state revealed evidence of 80 - 100 Angstrom nickel oxy-hydroxide nodules in the nickel hydroxide film. In situ spectroscopic ellipsometer measurements of films held at various constant potentials agree quantitatively with optical models appropriate to the nodular growth and subsequent overgrowth of the nickel oxy-hydroxide phase. A two-dimensional, numerical finite difference model was developed to simulate the current distribution along the phase boundary between the charged and uncharged material. The model was used to explore the effects of the physical parameters that govern the electrode behavior. The ratio of the conductivities of the nickel hydroxide and oxy-hydroxide phases was found to be the dominant parameter in the system.

  4. Hydroxide catalysis bonding of silicon carbide

    NARCIS (Netherlands)

    Veggel, A.A. van; Ende, D.A. van den; Bogenstahl, J.; Rowan, S.; Cunningham, W.; Gubbels, G.H.M.; Nijmeijer, H.

    2008-01-01

    For bonding silicon carbide optics, which require extreme stability, hydroxide catalysis bonding is considered [Rowan, S., Hough, J. and Elliffe, E., Silicon carbide bonding. UK Patent 040 7953.9, 2004. Please contact Mr. D. Whiteford for further information: D.Whiteford@admin.gla.ac.uk]. This techn

  5. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    The synthesis of layered double hydroxides (LDHs) provides a relatively easy and traditional way to build versatile chemical compounds with a rough control of the bulk structure. The delamination of LDHs to form their single host layers (2D nanosheets) and the capability to reassemble them offer ...

  6. Polysulfide intercalated layered double hydroxides for metal capture applications

    Science.gov (United States)

    Kanatzidis, Mercouri G.; Ma, Shulan

    2017-04-04

    Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

  7. Polysulfide intercalated layered double hydroxides for metal capture applications

    Energy Technology Data Exchange (ETDEWEB)

    Kanatzidis, Mercouri G.; Ma, Shulan

    2017-04-04

    Polysulfide intercalated layered double hydroxides and methods for their use in vapor and liquid-phase metal capture applications are provided. The layered double hydroxides comprise a plurality of positively charged host layers of mixed metal hydroxides separated by interlayer spaces. Polysulfide anions are intercalated in the interlayer spaces.

  8. Reducing hysteresis and enhancing performance of perovskite solar cells using acetylacetonate modified TiO2 nanoparticles as electron transport layers

    Science.gov (United States)

    He, Xin; Wu, Jihuai; Tu, Yongguang; Jia, Jinbiao; Dong, Jia; Xu, Rui; Guo, Qiyao; Wu, Tongyue; Lan, Zhang; Lin, Jianming; Xie, Yimin

    2017-10-01

    Electron transport layer (ETL) plays an important role in improving charge transportation, suppressing current-voltage hysteresis and enhancing photovoltaic performance of perovskite solar cells (PSCs). Here we successfully synthesize anatase titania nanoparticles (TiO2 NPs) with an average diameter about 3.6 nm by a facile and low-cost solvothermal method. Using the as-synthesized TiO2 NPs as ETL, the planar perovskite solar cells exhibit good photovoltaic performance. Encouragingly, when the TiO2 NPs are modified with titanium acetylacetonate [TiO(acac)2], a pinhole-free, dense, low charge transfer resistance and high charge extraction TiO2 ETL is formed and the power conversion efficiency of the planar perovskite solar cell is enhanced from 17.25% to 19.21%, accompanied by a significant decrease of J-V hysteresis. The facile process and significant performance improvement suggest that acetylacetonate modified TiO2 nanoparticles could be good ETL candidates for high-performance planar perovskite solar cells with low hysteresis.

  9. Applicability of light sources and the inner filter effect in UV/acetylacetone and UV/H{sub 2}O{sub 2} processes

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Bingdang; Yang, Minghui [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China); Yin, Ran [Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhang, Shujuan, E-mail: sjzhang@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China)

    2017-08-05

    Highlights: • Acetylacetone (AA) could directly use solar irradiation to decolorize dyes. • AA had a wider applicability than H{sub 2}O{sub 2} to a variety of light sources. • The photonic efficiency in the UV/AA process was target-dependent. • An accurate calculation approach for the inner filter effect was developed. - Abstract: Light source is a crucial factor in the application of a photochemical process, which determines the energy efficiency. The performances of acetylacetone (AA) in conversion of aqueous contaminants under irradiation with a low-pressure mercury lamp, a medium-pressure mercury lamp, a xenon lamp, and natural sunlight were investigated and compared with those of H{sub 2}O{sub 2} as reference. In all cases, AA was superior to H{sub 2}O{sub 2} in the degradation of Acid Orange 7. Using combinations of the different light sources with various cut-off and band-pass filters, the spectra responses of the absorbed photons in the UV/AA and UV/H{sub 2}O{sub 2} processes were determined for two colored and two colorless compounds. The photonic efficiency (φ) of the two photochemical processes was found to be target-dependent. A calculation approach for the inner filter effect was developed by taking the obtained φ into account, which provides a more accurate indication of the reaction mechanisms.

  10. Synthesis, Structure and Electrochemistry of Tetranuclear Oxygen-Centered Copper(II) Clusters with Acetylacetone and Benz-pyrazole Hydrolyzed Derivatives as Ligand.

    Science.gov (United States)

    Vafazadeh, Rasoul; Willis, Anthony C

    2016-01-01

    Two copper(II) clusters Cu(4)OCl(6)(pyrazole)4, 1, and Cu(4)OBr(6)(Br-pyrazole)4, 2, have been synthesized by reacting acetylacetone and benzohydrazide (1:1 ratio) with CuX(2) (X = Cl for 1 and X= Br for 2) in methanol solutions. The structures of both clusters have been established by X-ray crystallography. The clusters contain four Cu, one O, six μ(2)-X atoms, and four pyrazole ligands. The pyrazoles was prepared in situ by the reaction of acetylacetone with benzohydrazide in methanol under reflux. In 2, the methine hydrogens of the pyrazole ligands have been replaced by bromine atoms. The four copper atoms encapsulate the central O atom in a tetrahedral arrangement. All copper atoms are five-coordinate and have similar coordination environments with slightly distorted trigonal bipyramidal geometry. The cyclic voltammogram of the clusters 1 and 2 show a one-electron quasi-reversible reduction wave in the region 0.485 to 0.731 V, and a one-electron quasi-reversible oxidation wave in the region 0.767 to 0.898 V. In 1, one irreversible oxidative response is observed on the positive of side of the voltammogram at 1.512 V and this can be assigned to Cu(II) to Cu(III) oxidation.

  11. Thermal behaviour of hydroxides, hydroxysalts and hydrotalcites

    Indian Academy of Sciences (India)

    Parthasarathi Bera; Michael Rajamathi; M S Hegde; P Vishnu Kamath

    2000-04-01

    Mass spectrometric analysis of gases evolved during thermal decomposition of divalent metal hydroxides, hydroxysalts and hydrotalcites show that all these compounds undergo dehydration in the temperature range 30 < T < 220°C followed by decomposition at temperatures above 250°C. The latter step involves simultaneous deanation and dehydroxylation of the layers. Our observations conclusively prove that alternative mechanisms which envisage CO2 evolution due to deanation at lower temperatures proposed by Kanezaki to be wrong.

  12. Layered Double Hydroxide as Cordycepin Delivery Nanocarrier

    Institute of Scientific and Technical Information of China (English)

    Qin Zheng YANG; Jing YANG; Chang Kai ZHANG

    2006-01-01

    Layered double hydroxide was investigated as cordycepin delivery nanocarrier for the first time in this study. Negatively charged biomolecule-cordycepin was intercalated in the gallery spaces of [Mg-Al-NO3], which was confirmed by the results of X-ray diffraction and electrophoretic mobility. Cell experiment suggested that the new bio-LDH nanohybrid could prevent cordycepin decomposition by adenosine deaminase. This new formulation could possibly be used as a novel form cordycepin intravenous injection.

  13. Single sheet metal oxides and hydroxides

    DEFF Research Database (Denmark)

    Huang, Lizhi

    the possibility to gain precise control of the structure, composition, morphology, and property of desired nanostructures. In the present Ph.D. project, examples to produce 2D nanosheets with novel functionalities are presented. This comprises: (1) Synthesis of LDHs with a new structure and composition. (2......) Delamination of the LDHs structure (oxGRC12) with the formation of single sheet iron (hydr)oxide (SSI). (3) Assembly of the new 2D nanosheets layer by layer to achieve desired functionalities....

  14. Nickel hydroxide modified electrodes for urea determination

    Directory of Open Access Journals (Sweden)

    Luiz Henrique Dall´Antonia

    2007-03-01

    Full Text Available Nickel hydroxide films were prepared by electrodeposition from a solution Ni(NO32 0,05 mol L ?¹ on ITO electrodes (Tin oxide doped with Indium on PET-like plastic film, applying a current of - 0,1 A cm ?² during different time intervals between 1800 and 7200 s. The electrochemical behavior of the nickel hydroxide electrode was investigated through a cyclic voltammogram, in NaOH 1,0 mol L ?¹, where it was observed two peaks in the profile in 0,410 and 0,280 V, corresponding to redox couple Ni(II/Ni(III. A sensor for urea presenting a satisfactory answer can be obtained when, after the deposit of the film of Ni(OH2 on the electrode of nickel, it is immersed in a solution of NaOH 1,0 mol L ?¹ and applying a potential of + 0,435 V, where the maximum of the anodic current occurs in the cyclic voltammogram. Analyzing the results it can be observed that, for a range of analite concentration between 5 to 50 m mol L ?¹, the behavior is linear and the sensibility found was of 20,3 mA cm?² (mol L?¹?¹, presenting reproducibility confirming the nickel hydroxide electrodes utilization for the determination of urea.

  15. Calcium hydroxide silylation reaction with trimethylchlorosilane

    Directory of Open Access Journals (Sweden)

    Novoselnov Anatoliy A.

    2016-01-01

    Full Text Available The silylation reaction of a calcium hydroxide with a trimethylchlorosilane is studied as a silylation model by the gas-liquid chromatography. The silylation process is divided into three stages. A material balance of these stages is calculated. The schemes of the reactions at each stage of the process are proposed. The modified calcium hydroxide obtained at three repetitive stages of the silylation reaction has been investigated by the x-ray phase analysis, IR spectroscopy, thermal analysis, electron microscopy in a combination with the elemental analysis. It has been determined that at the first stage of the interaction the processes of the trimethylchlorosilane hydrolysis and of the hydrolysis products condensation dominate, and at the same time an adsorption process of the trimethylchlorosilane and its derivatives starts. Further, the hydrolysis of the trimethylchlorosilane by the «new» portions of a water formed in the reaction of a calcium hydroxide with a hydrogen chloride takes place, simultaneously the secondary reactions of the Si-O-Ca – ties’ formation and cleavage occur including as a silylation-desilylation dynamic equilibrium process.

  16. Effect of three different calcium hydroxide mixtures (calcium hydroxide with glycerine, normal saline and distilled water on root dentin microhardness

    Directory of Open Access Journals (Sweden)

    Hasheminia SM

    2007-06-01

    Full Text Available Background and Aim: During root canal therapy, it is necessary to remove as many bacteria as possible from the root canal. The use of medicaments is recommended to reduce the microbial population prior to root filling. Calcium hydroxide pastes have been used because of their antibacterial effects and the ability of tissue dissolving. The aim of this study was to evaluate the effect of calcium hydroxide/glycerine mixture, calcium hydroxide/normal saline mixture and calcium hydroxide/distilled water mixture on root dentin microhardness in storage times of 7 and 14 days.Materials and Methods: In this in vitro study, fifteen extracted maxillary canines and central incisors were selected. The crowns of the teeth were removed and the canals were prepared. Teeth were sectioned transversally to produce a total of 30 dentin discs from the middle third of the roots. Specimens were divided into three groups of 10 discs each. Dentin samples were subjected to calcium hydroxide/glycerine, calcium hydroxide/normal saline and calcium hydroxide/distilled water mixtures for 7 and 14 days. Dentin microhardness was measured by a Vickers indenter with a load of 200 g for 15 seconds. Data were analyzed using ANOVA, Paired t-test and LSD with p<0.05 as the level of significance.Results: Statistical analysis showed that all three mixtures decreased dentin microhardness. After 7 days, reduction in dentin microhardness by calcium hydroxide/glycerine combination was significantly higher than calcium hydroxide/normal saline and calcium hydroxide/distilled water combinations. After 14 days, reduction in dentin microhardness by calcium hydroxide/distilled water combination was significantly higher than the other two groups.Conclusion: Based on the results of this study, the use of calcium hydroxide combinations for intracanal dressing reduces dentin microhardness. After 7 days calcium hydroxide/glycerine combination and after 14 days calcium hydroxide/distilled water

  17. Polytypic transformations of aluminum hydroxide: A mechanistic investigation

    Institute of Scientific and Technical Information of China (English)

    Thimmasandra Narayan Ramesh

    2012-01-01

    The diffusion of ammonia vapors into a solution of aluminum nitrate or ferric nitrate results in the precipitation of their respective hydroxides and oxyhydroxides.Polymorphic phase formation of aluminum hydroxide is controlled by the rate of crystallization.The PXRD patterns of products obtained via vapor phase diffusion revealed that poorly ordered aluminum hydroxide is formed during the initial stages of crystallization.After 8 days,the formation of the bayerite phase of aluminum hydroxide was observed.Upon prolonged exposure to ammonia vapors,bayerite was transformed into gibbsite.The infrared spectrum of the product confirmed the presence of different polytypic phases of aluminum hydroxide.The results demonstrated that the crystal structure of metal hydroxides is controlled by the rate of crystallization,nature of the metal ion,site selectivity and specificity and preparative conditions.

  18. Pulp response to a novel adhesive calcium hydroxide based cement.

    Science.gov (United States)

    Watts, A; Paterson, R C; Cohen, B D; Combe, E C

    1994-09-01

    This study compares pulp responses to 3 formulations of calcium hydroxide, namely: a) An experimental adhesive calcium hydroxide cement containing polyacrylic acid, b) Dycal (L.D> Caulk Co, Milford, Delaware) Batch Nos 176970/176990, c) "Analar" calcium hydroxide mixed with sterile distilled water. After 28 days dentine bridges were present in 77% of teeth capped with the test material, 64% of teeth treated with Dycal and in 62% of teeth capped with calcium hydroxide and water. Inflammatory infiltrates were observed in a number of teeth remote from the bridges. Bacteria were detected in these specimens. Exposed rat molar pulp responses to an experimental adhesive calcium hydroxide cement were similar to to those observed with 2 other calcium hydroxide formulations.

  19. Antimicrobial Activity of Calcium Hydroxide in Endodontics: A Review

    Science.gov (United States)

    Shalavi, S; Yazdizadeh, M

    2012-01-01

    The purpose of endodontic therapy is to preserve the patient's natural teeth without compromising the patient's local or systemic health. Calcium hydroxide has been included in several materials and antimicrobial formulations that are used in several treatment modalities in endodontics, such as inter-appointment intracanal medicaments. The purpose of this article was to review the antimicrobial properties of calcium hydroxide in endodontics. Calcium hydroxide has a high pH (approximately 12.5-12.8) and is classified chemically as a strong base. The lethal effects of calcium hydroxide on bacterial cells are probably due to protein denaturation and damage to DNA and cytoplasmic membranes. Calcium hydroxide has a wide range of antimicrobial activity against common endodontic pathogens but is less effective against Enterococcus faecalis and Candida albicans. Calcium hydroxide is also a valuable anti-endotoxin agent. However, its effect on microbial biofilms is controversial. PMID:23323217

  20. Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Kamakura, Nao, E-mail: minnie04_tb@yahoo.co.jp; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

    2014-03-01

    A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac){sub 3}) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac){sub 3} and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac){sub 3} was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L{sup −1} nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L{sup −1} nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac){sub 3} using infrared spectroscopy. The eluate of Cr(acac){sub 3} was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac){sub 3} aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac){sub 3} exhibited desirable results (96.0%–107%) when 5 μg of each species (50 μg L{sup −1}) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac){sub 3} was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively). - Highlights: • A determination method of Cr(III), Cr(VI), and Cr(III) acetylacetonate in water was developed. • The combination of ion-exchange resin disks with metal furnace AAS was used. • No effect of humic acid on the recovery of Cr(III) acetylacetonate was

  1. Effect of the substituents on the photophysical, electrochemical and electroluminescence properties of OLED dopant Iridium bis(2-phenylbenzothiozolato- N,C2')(acetylacetonate)

    Science.gov (United States)

    Ivanov, P.; Tomova, R.; Petrova, P.

    2014-12-01

    The effect of two substituents: clorine and 1,3-diphenylpropane-1,3-dionate, placed on different position in the molecule of Iridium (III) bis(2-phenylbenzothiozolato-N,C2')- (acetylacetonate) (bt)2Ir(acac), on its electrochemical behaviour, photophysical and electroluminescence properties were investigated. Three complexes (bt)2Ir(acac), Iridium (III) bis[2-(4-chlorophenyl)benzothiazolato-N,C2']-acetylacetonate (Clbt)2Ir(acac), in which the Cl atom was introduced on the 4-position in the benzothiazole ring, and the new Iridium (Ill) bis[2 -phenylbenzothiazolato -N,C2'] -(1,3 -diphenylpropane-1,3 -dionate) (bt)2Ir(dbm), where ancillary acetylacetonate ligand was replaced by 1,3-diphenylpropane-1,3-dionate, were synthesized and characterised by 1H-NMR and elemental analysis. The HOMO/LUMO energy levels of the complexes were determined by cyclic voltammetry (CV) and their properties were established by UV-Visible and fluorescence spectroscopy. The application of (Clbt)2Ir(acac), (bt)2Ir(bsm) and (bt)2Ir(acac) as dopants in hole transporting layer (HTL) of Organic light- emitting diodes(OLEDs). It was found that with respect to the reference (bt)2Ir(acac): both LUMO and HOMO of the substituted complexes were shifted to more positive values accordingly with 0.23 and 0.19 eV for (Clbt)2Ir(acac) and 0.14 and 0.12 eV for (bt)2Ir(dbm). OLEDs doped with 1 w% of the complexes irradiated the warm white light with Commission internationale de l'eclairage (CIE) coordinates: 0.24;0.38 for (Clbt)2Ir(acac), 0.30;0.44 for (bt)2Ir(acac) and 0.28;0.46 for (bt)2Ir(dbm). Devices doped with 10 w% of all complexes irradiated in the yellow orange region of the spectrum.

  2. Plasma assisted metal-organic chemical vapor deposition of hard chromium nitride thin film coatings using chromium(III) acetylacetonate as the precursor

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Arup; Kuppusami, P.; Lawrence, Falix; Raghunathan, V.S.; Antony Premkumar, P.; Nagaraja, K.S

    2004-06-15

    A new technique has been developed for depositing hard nanocrystalline chromium nitride (CrN) thin films on metallic and ceramic substrates using plasma assisted metal-organic chemical vapor deposition (PAMOCVD) technique. In this low temperature and environment-friendly process, a volatile mixture of chromium(III) acetylacetonate and either ammonium iodide or ammonium bifluoride were used as precursors. Nitrogen and hydrogen have been used as the gas precursors. By optimizing the processing conditions, a maximum deposition rate of {approx}0.9 {mu}m/h was obtained. A comprehensive characterization of the CrN films was carried out using X-ray diffraction (XRD), microhardness, and microscopy. The microstructure of the CrN films deposited on well-polished stainless steel (SS) showed globular particles, while a relatively smooth surface morphology was observed for coatings deposited on polished yittria-stabilized zirconia (YSZ)

  3. A general method for preparing lanthanide oxide nanoparticles via thermal decomposition of lanthanide(III) complexes with 1-hydroxy-2-naphthoic acid and hydrazine ligands

    Science.gov (United States)

    Parimalagandhi, Karuppannan; Premkumar, Thathan; Vairam, Sundararajan

    2016-09-01

    Six new lanthanide(III) complexes (i.e., [Ln(L)2(NA)1.5]·3H2O, where Ln=La(III), Pr(III), Nd(III), Sm(III), Gd(III), and Ce(III) and L and NA indicate N2H4 and C10H6(1-O)(2-COO), respectively) with 1-hydroxy-2-naphthoic acid [C10H6(1-O)(2-COOH)] and hydrazine (N2H4) as co-ligands were characterized by elemental, FTIR, UV-visible, and XRD techniques. In the FT-IR spectra, the N-N stretching frequency in the range of 981-949 cm-1 demonstrates evidence of the presence of coordinated N2H4, indicating the bidentate bridging nature of hydrazine in the complexes. These complexes show symmetric and asymmetric COO- stretching from 1444 to 1441 cm-1 and 1582 to 1557 cm-1, respectively, indicating bidentate coordination. TG-DTA studies revealed that the compounds underwent endothermic dehydration from 98 to 110 °C. This was followed by the exothermic decomposition of oxalate intermediates to yield the respective metal oxides as the end products. From SEM images, the average size of the metal oxide particles prepared by thermal decomposition of the complexes was determined to be 39-42 nm. The powder X-ray and SEM coupled with energy dispersive X-ray (EDX) studies revealed the presence of the respective nano-sized metal oxides. The kinetic parameters of the decomposition of the complexes were calculated using the Coats-Redfern equation.

  4. Hydrolytic synthesis of novel lanthanide(III) complexes with pyridine-2,6-dicarboxylic acid: Characterization of the structure and the physical properties

    Science.gov (United States)

    Hojnik, Nuša; Kristl, Matjaž; Golobič, Amalija; Jagličić, Zvonko; Drofenik, Miha

    2015-01-01

    The coordination compounds of pyridine-2,6-dicarboxylic acid and two lanthanide(III) ions, Ho3+ and Dy3+, were hydrolytically synthesized in aqueous solutions at a slightly basic pH, and then characterized by thermogravimetric analysis, IR spectroscopy, magnetic measurements as well as X-ray powder and single-crystal diffraction analysis. The elemental analyses were performed to check the purity of the compounds. The formula for these compounds is identified as Na3[Ln(Pydc)3]ṡ14H2O (Ln = Ho, 1; Ln = Dy, 2) in agreement with the X-ray structural analysis and all the other experimental data. The absence of the 1709 cm-1 band corresponding to ν(C dbnd O) in the IR spectra of the compounds evidences the deprotonating of the carboxyl group. The very strong inductive effect of the metal ion that is readily coordinated by the carboxylate group of the zwitterionic ligand is responsible for the formation of the product. The single-crystal X-ray structural analysis revealed that compounds 1 and 2 are isostructural. Their structure can be described as interchanging layers of complex anions [Ln(Pydc)3]3 (Ln = Ho and Dy for 1 and 2, respectively) and layers of hydrated sodium cations. In complex anions the holmium and dysprosium atoms are coordinated by three crystallographically independent pyridinedicarboxylate ligands in tridentate-chelate mode, via one O atom of both carboxylate groups and the ring N atom. The coordination number is nine and the coordination polyhedron is a tricapped trigonal prism with O atoms at the corners.

  5. Synthesis and luminescent properties of novel lanthanide(III) beta-diketone complexes with nitrogen p,p'-disubstituted aromatic ligands.

    Science.gov (United States)

    Bellusci, Anna; Barberio, Giovanna; Crispini, Alessandra; Ghedini, Mauro; La Deda, Massimo; Pucci, Daniela

    2005-03-21

    Tris-beta-diketonate lanthanide(III) complexes (Ln = Eu, Er, Yb, Tb), of general formula [Ln(acac)3 L(m)], with chelating ligands such as 4,7-disubstituted-1,10-phenanthrolines and 4,4'-disubstituted-2,2'-bipyridines, have been synthesized and fully characterized. The inductive effects of the para-substituents on the aromatic N-donor ligands have been investigated both in the solid and in the solution states. Single-crystal X-ray structures have been determined for the diethyl 1,10-phenanthroline-4,7-dicarboxylate europium and 4,4'-dimethoxy-2,2'-bipyridine erbium derivatives, revealing a distorted square antiprismatic geometry around the lanthanide atom in both cases. The influence exerted by the p,p'-substituents with respect to the nitrogen coordinating atoms on the Ln-N bond distances is discussed comparing the geometrical parameters with those found for the crystal structures containing the fragments [Ln(III)(phen)] and [Ln(III)(bipy)] obtained from the Cambridge Structural Database. The influence exerted by the electron-attracting groups on the coordination ability of the ligands, that in some cases becomes lack of coordination of the lanthanide ions, has been also detected in solution where the loss of the ligand has been followed by UV-vis spectroscopy. Moreover, the use of relatively long alkoxy chains as substituents on the 1,10-phenanthroline ligand led to the formation of a promesogenic lanthanide complex, whose thermal behavior is encouraging for the synthesis of new lanthanide liquid-crystalline species.

  6. 21 CFR 872.3250 - Calcium hydroxide cavity liner.

    Science.gov (United States)

    2010-04-01

    ... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3250 Calcium hydroxide cavity liner. (a) Identification. A calcium hydroxide cavity liner is a device material intended to be applied to the interior of a prepared cavity before insertion of restorative material, such as amalgam, to protect the pulp of a...

  7. FIBRED MAGNESIUM HYDROXIDE AND FLAME-RESISTANT POLYENE MATERIAL

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The fibred mangesiun hydroxide from the bracite was treated with a surface active agent. The modified fibred magesium hydroxide as f lame-retardant,boric acid, barium stearate, polydimethyl siloxane fluid,vinyltr iethoxysilane as synergists of the flame-retardant were added to polyene resin. The flame-resistance polyene material prepared meets the requirements of EWCZ -6287-1.

  8. Role of Calcium Hydroxide in Endodontics: A Review

    OpenAIRE

    Arun A; Sangameshwar Sajjanshetty; Deepak Jain; Saujanya KP; Mohammed Mustafa; Laxmi Uppin; Mahnoor Kadri

    2012-01-01

    Calcium hydroxide is a multipurpose agent, and there have been an increasing number of indications for its use in endodontics. Some of its indications include inter-appointment intracanal medicaments, endodontic sealers, pulp capping agents, apexification, pulpotomy and weeping canals. The purpose of this article is to review the properties, advantages, disadvantages and various indications for the use of calcium hydroxide in endodontics.

  9. Hydroxide depletion in dilute supernates stored in waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T.

    1985-10-10

    Free hydroxide ion in dilute supernates are depleted by reaction with atmospheric carbon dioxide to form bicarbonate and carbonate species and by reaction with acidic compounds formed by the radiolytic decomposition of tetraphenylborate salts. A model of the kinetics and thermodynamics of absorption of carbon dioxide in the waste tanks has been developed. Forecasts of the rate of hydroxide depletion and the requirements for sodium hydroxide to maintain technical standards have been made for the washed sludge and washed precipitate storage tanks. Hydroxide depletion is predicted to have a minimal impact on sludge processing operations. However, in-tank precipitation and downstream DWPF operations are predicted to be significantly affected by hydroxide depletion in Tank 49H. The installation of a carbon dioxide scrubber on Tank 49H may be justified in view of the decrease in alkali content and variation in the melter feed.

  10. Nickel hydroxide/cobalt-ferrite magnetic nanocatalyst for alcohol oxidation.

    Science.gov (United States)

    Bhat, Pooja B; Inam, Fawad; Bhat, Badekai Ramachandra

    2014-08-11

    A magnetically separable, active nickel hydroxide (Brønsted base) coated nanocobalt ferrite catalyst has been developed for oxidation of alcohols. High surface area was achieved by tuning the particle size with surfactant. The surface area of 120.94 m2 g(-1) has been achieved for the coated nanocobalt ferrite. Improved catalytic activity and selectivity were obtained by synergistic effect of transition metal hydroxide (basic hydroxide) on nanocobalt ferrite. The nanocatalyst oxidizes primary and secondary alcohols efficiently (87%) to corresponding carbonyls in good yields.

  11. Electrochemical Properties of Nanocomposite Nanoporous Carbon / Nickel Hydroxide

    Directory of Open Access Journals (Sweden)

    O.M. Hemiy

    2016-12-01

    Full Text Available The electrochemical properties of composite nanoporous carbon / nickel hydroxide as electrode material for hybrid supercapacitors were investigated. Fast reversible faradaic reactions flow was determined in connection with chemical makeup of the -Ni(OH2/С composite. It is shown that increase of nickel hydroxide concentration can intensify reactions. It is found that clean -Ni(OH2 has 238 F/g of specific capacity, but -Ni(OH2/С nanocomposite with 90 % nickel hydroxide has 292 F/g. Such capacity value can be considered as a maximum for these composites.

  12. HYDROGEN PEROXIDE BLEACHING OF CMP PULP USING MAGNESIUM HYDROXIDE

    Directory of Open Access Journals (Sweden)

    Farhad Zeinaly

    2009-11-01

    Full Text Available Conventional bleaching of hardwood CMP pulp with magnesium hydroxide (Mg(OH2 show significant benefits over bleaching with sodium hydroxide (NaOH under various conditions. Magnesium hydroxide bleaching generate higher optical properties, higher pulp yield and lower effluent COD at the same chemical charge, but the physical properties were found to be similar for both processes. The initial freeness of the bleached pulps and refining value to reach a target freeness (about 350 ml. CSF were more for the Mg(OH2-based process. The residual peroxide of filtrate from the Mg(OH2-based process was very high as compared to conventional bleaching.

  13. The electronic structure of the adducts of nickel(II) and cobalt(II) acetylacetonate with 2,2ʹ-dipyridyl by the method of quantum chemical modeling

    Science.gov (United States)

    Komissarov, A. A.; Korochentsev, V. V.; Vovna, V. I.

    2016-02-01

    The electronic structure of the nickel(II) and cobalt(II) bis-acetylacetonate with the additional 2,2ʹ-dipyridyl ligand is investigated using density functional theory calculations and X-ray photoelectron spectroscopy. Additional ligand effect on geometry, charges, electronic structure and X-ray photoelectron spectrum is studied. Our calculations show that the electron-donating ability of the 2,2ʹ-dipyridyl ligand is low. The computed data is compared with experimental data.

  14. Homogeneous Precipitation of Nickel Hydroxide Powders

    Energy Technology Data Exchange (ETDEWEB)

    Bora Mavis

    2003-12-12

    Precipitation and characterization of nickel hydroxide powders were investigated. A comprehensive precipitation model incorporating the metal ion hydrolysis, complexation and precipitation reactions was developed for the production of the powders with urea precipitation method. Model predictions on Ni{sup 2+} precipitation rate were confirmed with precipitation experiments carried out at 90 C. Experimental data and model predictions were in remarkable agreement. Uncertainty in the solubility product data of nickel hydroxides was found to be the large contributor to the error. There were demonstrable compositional variations across the particle cross-sections and the growth mechanism was determined to be the aggregation of primary crystallites. This implied that there is a change in the intercalate chemistry of the primary crystallites with digestion time. Predicted changes in the concentrations of simple and complex ions in the solution support the proposed mechanism. The comprehensive set of hydrolysis reactions used in the model described above allows the investigation of other systems provided that accurate reaction constants are available. the fact that transition metal ions like Ni{sup 2+} form strong complexes with ammonia presents a challenge in the full recovery of the Ni{sup 2+}. On the other hand, presence of Al{sup 3+} facilitates the complete precipitation of Ni{sup 2+} in about 3 hours of digestion. A challenge in their predictive modeling studies had been the fact that simultaneous incorporation of more than one metal ion necessitates a different approach than just using the equilibrium constants of hydrolysis, complexation and precipitation reactions. Another limitation of using equilibrium constants is that the nucleation stage of digestion, which is controlled mainly by kinetics, is not fully justified. A new program released by IBM Almaden Research Center (Chemical Kinetics Simulator{trademark}, Version 1.01) lets the user change the order of

  15. Thermal co-decomposition of silver acetylacetonate and tin(II) hexafluoroacetylacetonate: Formation of carbonaceous Ag/Ag{sub x}Sn(x = 4 and 6.7)/SnO{sub 2} composites

    Energy Technology Data Exchange (ETDEWEB)

    Křenek, T.; Duchek, P. [Research Centre of New Technologies, University of West Bohemia, 30614 Plzeň (Czech Republic); Urbanová, M.; Pokorná, D. [Laboratory of Laser Chemistry, Institute of Chemical Process Fundamentals, ASCR v.v.i., 16502 Prague (Czech Republic); Bezdička, P.; Jakubec, I. [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic); Pola, M.; Čerstvý, R.; Kovářík, T. [Research Centre of New Technologies, University of West Bohemia, 30614 Plzeň (Czech Republic); Galiková, A. [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic); Pola, J., E-mail: pola@icpf.cas.cz [Institute of Inorganic Chemistry, ASCR v.v.i., 25068 Husinec-Řež (Czech Republic)

    2013-08-20

    Highlights: • Ag acetylacetonate increases thermal stability by mixing with Sn hexafluoroacetylacetonate. • Heated mixture of chelates yields a residue containing Ag, Sn, O and C elements. • Residues obtained at higher temperature contain Ag–Sn intermetallic compounds. - Abstract: Thermal co-decomposition of silver(I) acetylacetonate and tin(II) hexafluoroacetylacetonate has been examined by using thermal gravimetry, differential scanning calorimetry and complementary analyses of gaseous products and solid residues by Fourier transform infrared and Raman spectroscopy, X-ray diffraction and scanning electron microscopy. It is revealed that poorly stable silver(I) acetylacetonate mixed with tin(II) hexafluoroacetylacetonate does not undergo thermal decomposition at around 120 °C, but takes part in a room-temperature solid-state interaction with the Sn counterpart, which is ensued by an exothermal process at 109 °C and subsequent co-decomposition involving a pronounced stage at around 275 °C. All steps lead to carbonaceous Ag/SnO{sub 2} composites containing crystalline Ag at 200 °C, Ag and SnO{sub 2} at 400 °C, and Ag, SnO{sub 2}, Ag{sub 4}Sn and Ag{sub 6.7}Sn at 600 °C. The intermetallic Ag{sub 6.7}Sn compound is judged to arise from nanostructured environment of alloying Ag and Sn.

  16. Hydroxide-Assisted Bonding of Ultra-Low-Expansion Glass

    Science.gov (United States)

    Abramovici, Alexander; White, Victor

    2008-01-01

    A process for hydroxide-assisted bonding has been developed as a means of joining optical components made of ultra-low-expansion (ULE) glass, while maintaining sufficiently precise alignment between. The process is intended mainly for use in applications in which (1) bonding of glass optical components by use of epoxy does not enable attainment of the required accuracy and dimensional stability and (2) conventional optical contacting (which affords the required accuracy and stability) does not afford adequate bond strength. The basic concept of hydroxide-assisted bonding is not new. The development of the present process was prompted by two considerations: (1) The expertise in hydroxide-assisted bonding has resided in very few places and the experts have not been willing to reveal the details of their processes and (2) data on the reliability and strength attainable by hydroxide-assisted bonding have been scarce.

  17. Tertiary dentinogenesis with calcium hydroxide: a review of proposed mechanisms.

    Science.gov (United States)

    Sangwan, P; Sangwan, A; Duhan, J; Rohilla, A

    2013-01-01

    Calcium hydroxide has been used extensively in dentistry for a century. Despite its widespread use as a pulp-capping agent, its mechanisms of action still remain ambiguous. Understanding its modes of action will lead to a broader understanding of the mechanisms associated with induced dentinogenesis and help in optimizing the currently available agents to target specific regenerative processes to obtain the best possible clinical outcomes. A literature search relating to mechanisms of dentinogenesis of calcium hydroxide up to December 2011 was carried out using pubmed and MEDLINE database searches as well as manual searching of cross-references from identified studies. Resulting suggestions regarding dentinogenic mechanisms of calcium hydroxide range from direct irritating action of the material to induction of release of biologically active molecules. The purpose of this article is to discuss various mechanisms through which calcium hydroxide may induce tertiary dentinogenesis in the light of observations made in included studies.

  18. USING COLLOIDAL LAYERED DOUBLE HYDROXIDES AS CATIONICMICROPARTICULATE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    SonglinWang; WenxiaLiu

    2004-01-01

    Layered double hydroxides consisting of layers withcationic charges may be potential candidates ofcationic microparticles forming synergetic retentioneffect with anionic polyacrylamide. In this work, thelayered double hydroxides with various molar ratiosof Mg/AI were synthesized by co-precipitation ofmagnesium chloride and aluminum chloride and pep-tized by intense washing with water. The chemicalformula, particle size, Zeta potential of the layereddouble hydroxide were analyzed. It was found thatpositively charged magnesium aluminum hydroxidewith particle diameter in nanoparticle size could beprepared. The Zeta potential and particle size varywith the feed molar ratio of Mg/A1 and the peptizingprocess, respectively. The Zeta potential is also pHdependent. The retention experiments carried out onDDJ show that when used together with anionic poly-acrylamide, the positively charged colloidal doublehydroxide greatly improves the retention of reedpulps. The chemical formula, particle size and Zetapotential of the colloidal double hydroxide all affectits retention behavior.

  19. Synthesis of beta alumina from aluminum hydroxide and oxyhydroxide precursors

    CSIR Research Space (South Africa)

    Van Zyl, A

    1993-02-01

    Full Text Available Two aluminium oxyhydroxides, boehmite and pseudoboehmite, and two aluminium hydroxides, bayerite and gibbsite, have been investigated as precursors for the synthesis of the solid electrolyte, beta alumina. Reaction pathways and products have been...

  20. Hydrothermal synthesis of lanthanide (hydr)oxide micro/nanorods in presence of tetrabutylammonium hydroxide

    Institute of Scientific and Technical Information of China (English)

    李银艳; 徐时清

    2016-01-01

    Uniform and well-defined lanthanide hydroxide and oxide micro/nanorods Ln(OH)3(Ln=La, Pr, Sm, Eu, Gd, Er) and Gd(OH)3:Eu3+, Gd2O3:Eu3+ were successfully synthesized through a green and facile hydrothermal method. Tetrabutylammonium hydroxide (TBAH) and lanthanide nitrides were used as the hydrothermal precursors without the addition of any templates/surfactants. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) spectra. The result demonstrated that lanthanide hydroxide micro/nanorods with 20–80 nm in diameter and 50–450 in length were obtained. The size of the Ln(OH)3 (Ln=La, Pr, Sm, Eu, Gd, Er) rods increased with the increase of the atomic number. The size of the Gd(OH)3:Eu3+ rods decreased with the increase of pH value by modulating the amount of the TBAH solution. The as-formed product via the hydrothermal process, Gd(OH)3:Eu3+, could be transformed to Gd2O3:Eu3+ with the same morphology and a slight shrinking in size after a post annealing process. It is a facial method to synthesize photoluminescent nanomaterial of Gd2O3:Eu3+. The Gd2O3:Eu3+ microrods exhibited strong red emission corresponding to5D0→7F2 transition (610 nm) of Eu3+ under UV light excitation (257 nm).

  1. Structure and properties of porous ceramics obtained from aluminum hydroxide

    OpenAIRE

    Levkov, R.; Kulkov, Sergey Nikolaevich

    2016-01-01

    In this paper the study of porous ceramics obtained from aluminum hydroxide with gibbsite modification is presented. The dependence of porosity and mechanical characteristics of the material sintered at different temperatures was studied. It was shown that compressive strength of alumina ceramics increases by 40 times with decreasing the pore volume from 65 to 15%. It was shown that aluminum hydroxide may be used for pore formation and pore volume in the sintered ceramics can be controlled by...

  2. Role of Calcium Hydroxide in Endodontics: A Review

    Directory of Open Access Journals (Sweden)

    Arun A

    2012-01-01

    Full Text Available Calcium hydroxide is a multipurpose agent, and there have been an increasing number of indications for its use in endodontics. Some of its indications include inter-appointment intracanal medicaments, endodontic sealers, pulp capping agents, apexification, pulpotomy and weeping canals. The purpose of this article is to review the properties, advantages, disadvantages and various indications for the use of calcium hydroxide in endodontics.

  3. Optimization of the Energy Level Alignment between the Photoactive Layer and the Cathode Contact Utilizing Solution-Processed Hafnium Acetylacetonate as Buffer Layer for Efficient Polymer Solar Cells.

    Science.gov (United States)

    Yu, Lu; Li, Qiuxiang; Shi, Zhenzhen; Liu, Hao; Wang, Yaping; Wang, Fuzhi; Zhang, Bing; Dai, Songyuan; Lin, Jun; Tan, Zhan'ao

    2016-01-13

    The insertion of an appropriate interfacial buffer layer between the photoactive layer and the contact electrodes makes a great impact on the performance of polymer solar cells (PSCs). Ideal interfacial buffer layers could minimize the interfacial traps and the interfacial barriers caused by the incompatibility between the photoactive layer and the electrodes. In this work, we utilized solution-processed hafnium(IV) acetylacetonate (Hf(acac)4) as an effective cathode buffer layer (CBL) in PSCs to optimize the energy level alignment between the photoactive layer and the cathode contact, with the short-circuit current density (Jsc), open-circuit voltage (Voc), and fill factor (FF) all simultaneously improved with Hf(acac)4 CBL, leading to enhanced power conversion efficiencies (PCEs). Ultraviolet photoemission spectroscopy (UPS) and scanning Kelvin probe microscopy (SKPM) were performed to confirm that the interfacial dipoles were formed with the same orientation direction as the built-in potential between the photoactive layer and Hf(acac)4 CBL, benefiting the exciton separation and electron transport/extraction. In addition, the optical characteristics and surface morphology of the Hf(acac)4 CBL were also investigated.

  4. Evaluation of a synergetic effect between Rh as permanent chemical modifier and acetylacetone as complexing agent in Sc determination in sediment slurry samples by ETAAS

    Energy Technology Data Exchange (ETDEWEB)

    Flores, Araceli Veronica [Departamento de Quimica Analitica, Instituto de Quimica, Universidade Estadual de Campinas, P.O. Box 6154, 13084 971 Campinas, Sao Paulo (Brazil); Perez, Carlos Alberto [Laboratorio Nacional de Luz Sincrotron, P.O. Box 6192, 13084 971 Campinas, Sao Paulo (Brazil); Arruda, Marco Aurelio Zezzi [Departamento de Quimica Analitica, Instituto de Quimica, Universidade Estadual de Campinas, P.O. Box 6154, 13084 971 Campinas, Sao Paulo (Brazil)]. E-mail: zezzi@iqm.unicamp.br

    2005-02-14

    In the present work, scandium was determined in sediment slurry samples (from three different rivers) by electrothermal atomic absorption spectrometry (ETAAS). Slurries were prepared by weighting 100 mg of dry sediment samples ({<=}53 {mu}m particle sizes) and adding 6 ml of HCl:HNO{sub 3}:HF (3:1:2, v/v). Accurate results were only possible due to the synergetic effect between Rh as permanent chemical modifier and acetylacetone (Acac) as complexing agent. The same platform was used for 400 heating cycles. The performance of the chemical modification was evaluated by using scanning electron microscopy (SEM), synchrotron radiation X-ray fluorescence (SRXRF) and some figures of merit (precision and detectability). The best analytical conditions were attained using 1500 and 2550 deg. C as pyrolysis and atomization temperatures. The scandium content in the liquid phase of the slurries ranged from 61 to 73%, thus indicating, in this study, that both liquid and solid phases play an important role in slurry analyses. An amount of 5.0-20.0 {mu}g l{sup -1} Sc linear range as well as LOD and LOQ of 0.19 and 0.62 {mu}g l{sup -1}, respectively, were obtained under these conditions. The accuracy was checked by using microwave-assisted decomposition, and the results compared to those obtained with the proposed methodology (slurry analysis). By checking both sets of the results, there is no statistical difference at the 95% confidence levels.

  5. In-situ Fourier transform infrared spectroscopy gas phase studies of vanadium (IV) oxide coating by atmospheric pressure chemical vapour deposition using vanadyl (IV) acetylacetonate

    Energy Technology Data Exchange (ETDEWEB)

    Vernardou, D. [Institute for Materials Research, University of Salford, Cockroft Building, Salford, Manchester, M5 4WT (United Kingdom); Pemble, M.E. [Tyndall National institute, Lee Maltings, Prospect Row, Cork (Ireland)], E-mail: martyn.pemble@tyndall.ie; Sheel, D.W. [Institute for Materials Research, University of Salford, Cockroft Building, Salford, Manchester, M5 4WT (United Kingdom)

    2008-05-30

    This paper describes the use of in-situ Fourier transform infrared spectroscopy to monitor the gas phase reactions of the formation of VO{sub 2} thin films from VO(acac){sub 2} under atmospheric pressure chemical vapour deposition conditions. In the absence of O{sub 2}, it is found that anhydride species may form, while there is also some evidence of ester species. In the presence of O{sub 2}, the spectra obtained are almost identical to those in the absence of O{sub 2}. However in this case, there is also some indication for the enhanced production of CO and the suppression of the formation of C-H species. A possible mechanism for the formation of VO{sub 2} is proposed, which involves the release of two C{sub 3}H{sub 4} molecules and the decomposition of vanadyl (IV) acetylacetonate into VO(CH{sub 3}COO){sub 2}, which then further decomposes to yield (CH{sub 3}CO){sub 2}O and VO{sub 2}. However, while spectroscopic evidence for the formation of these species is presented, the mechanism proposed cannot be confirmed on the basis of these data alone.

  6. Spectral characterization, optical band gap calculations and DNA binding of some binuclear Schiff-base metal complexes derived from 2-amino-ethanoic acid and acetylacetone

    Science.gov (United States)

    Hussien, Mostafa A.; Nawar, Nagwa; Radwan, Fatima M.; Hosny, Nasser Mohammed

    2015-01-01

    Bi-nuclear metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-ethanoic acid (glycine) and acetylacetone have been synthesized and characterized by elemental analyses, Raman spectra, FT-IR, ES-MS, UV-Vis., 1H NMR, ESR, thermal analyses (TG, DTG and DTA) and magnetic measurements. The results showed that, the Schiff base ligand can bind two metal ions in the same time. It coordinates to the first metal ion as mono-negative bi-dentate through azomethine nitrogen and enolic carbonyl after deprotonation. At the same time, it binds to the second metal ion via carboxylate oxygen after deprotonation. The thermodynamic parameters E∗, ΔH∗, ΔG∗ and ΔS∗ have been calculated by Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The optical band gaps of the isolated complexes have been calculated from absorption spectra and the results indicated semi-conducting nature of the investigated complexes. The interactions between the copper (II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA.

  7. Surface chemistry of copper metal and copper oxide atomic layer deposition from copper(ii) acetylacetonate: a combined first-principles and reactive molecular dynamics study.

    Science.gov (United States)

    Hu, Xiao; Schuster, Jörg; Schulz, Stefan E; Gessner, Thomas

    2015-10-28

    Atomistic mechanisms for the atomic layer deposition using the Cu(acac)2 (acac = acetylacetonate) precursor are studied using first-principles calculations and reactive molecular dynamics simulations. The results show that Cu(acac)2 chemisorbs on the hollow site of the Cu(110) surface and decomposes easily into a Cu atom and the acac-ligands. A sequential dissociation and reduction of the Cu precursor [Cu(acac)2 → Cu(acac) → Cu] are observed. Further decomposition of the acac-ligand is unfavorable on the Cu surface. Thus additional adsorption of the precursors may be blocked by adsorbed ligands. Molecular hydrogen is found to be nonreactive towards Cu(acac)2 on Cu(110), whereas individual H atoms easily lead to bond breaking in the Cu precursor upon impact, and thus release the surface ligands into the gas-phase. On the other hand, water reacts with Cu(acac)2 on a Cu2O substrate through a ligand-exchange reaction, which produces gaseous H(acac) and surface OH species. Combustion reactions with the main by-products CO2 and H2O are observed during the reaction between Cu(acac)2 and ozone on the CuO surface. The reactivity of different co-reactants toward Cu(acac)2 follows the order H > O3 > H2O.

  8. New Ru(II)/Os(II)-polypyridyl complexes for coupling to TiO2 surfaces through acetylacetone functionality and studies on interfacial electron-transfer dynamics.

    Science.gov (United States)

    Banerjee, Tanmay; Biswas, Abul Kalam; Sahu, Tuhin Subhra; Ganguly, Bishwajit; Das, Amitava; Ghosh, Hirendra Nath

    2014-09-28

    New Ru(ii)- and Os(ii)-polypyridyl complexes have been synthesized with pendant acetylacetone (acac) functionality for anchoring on nanoparticulate TiO2 surfaces with a goal of developing an alternate sensitizer that could be utilized for designing an efficient dye-sensitized solar cell (DSSC). Time-resolved transient absorption spectroscopic studies in the femtosecond time domain have been carried out. The charge recombination rates are observed to be very slow, compared with those for strongly coupled dye molecules having catechol as the anchoring functionality. The results of such studies reveal that electron-injection rates from the metal complex-based LUMO to the conduction band of TiO2 are faster than one would expect for an analogous complex in which the chromophoric core and the anchoring moiety are separated with multiple saturated C-C linkages. Such an observation is rationalized based on computational studies, and a relatively smaller spatial distance between the dye LUMO and the TiO2 surface accounted for this. Results of this study are compared with those for analogous complexes having a gem-dicarboxy group as the anchoring functionality for covalent binding to the TiO2 surface to compare the role of binding functionalities on electron-transfer dynamics.

  9. Synthesis, spectral characterization and DNA binding of Schiff-base metal complexes derived from 2-amino-3-hydroxyprobanoic acid and acetylacetone.

    Science.gov (United States)

    Hosny, Nasser Mohammed; Hussien, Mostafa A; Radwan, Fatima M; Nawar, Nagwa

    2014-11-11

    Four new metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H3L) resulted from the condensation of the amino acid 2-amino-3-hydroxyprobanoic acid (serine) and acetylacetone have been synthesized and characterized by, elemental analyses, ES-MS, IR, UV-Vis., 1H NMR, 13C NMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that the Schiff-base ligand acts as bi-negative tridentate through the azomethine nitrogen, the deprotonated carboxylate oxygen and the enolic carbonyl oxygen. The optical band gaps measurements indicated the semi-conducting nature of these complexes. Molecular docking was used to predict the binding between the Schiff base ligand with the receptor of prostate cancer mutant H874Y. The interactions between the Cu(II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA in an intercalative mode.

  10. Synthesis, spectral, thermal and optical properties of Schiff-base complexes derived from 2(E)-2-((z)-4-hydroxypent-3-en-2-ylideneamino)-5-guanidinopentanoic acid and acetylacetone

    Science.gov (United States)

    Hosny, Nasser Mohammed; Hussien, Mostafa A.; Radwan, Fatima M.; Nawar, Nagwa

    2017-09-01

    New metal complexes derived from the in situ reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-5-guanidinopentanoic acid (arginine) and acetylacetone have been synthesized. The resulting complexes have been characterized by, elemental analyses, ES-MS, IR, Raman spectra, UV-Vis., 1HNMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that, The Schiff-base ligand acts as bi-negative tridentate coordinating via azomethine nitrogen, enolic carbonyl oxygen and carboxylate oxygen after displacement of hydrogen. The thermodynamic parameters E∗, ΔH, ΔG and ΔS of the isolated complexes have been calculated. The optical band gap (Eg) values of Cu, Co, Ni and Zn were found to be 3.3, 3.4, 3.7 and 4.3 eV, respectively, arising from direct transitions. Optical band gap measurements indicate the semi-conductivity nature of these complexes.

  11. Contribution to the study of the chemical consequences of the (n, {gamma}) reaction in solid Co(3) tris-acetylacetone; Contribution a l'etude des consequences chimiques de la reaction (n, {gamma}) dans le tris-acetylacetonate de cobalt (3)

    Energy Technology Data Exchange (ETDEWEB)

    Magnane Machado, R. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    The fragmentation and annealing of thermal neutron irradiated Co(III) tris-acetylacetone was investigated using the thin layer chromatographic technique (silica-gel 1 mm thickness). Low temperature irradiations (0 C - -72 C and -180 C) lead to {sup 60}Co retentions as low as (1,1 {+-} 0,2) per cent. Annealing by linear temperature programming at different heating rates has shown the existence of eight reactions. The influences of pile dose and of gases (air and helium) as well as of thermal decomposition on the annealing processes were confirmed. A temperature and dose dependent effect was found out for the retentions of the {sup 60m}Co - {sup 60}Co isomers. (author) [French] On a etudie par chromatographie en couches minces (silicagel 1 mm), les phenomenes de fragmentation et de recuit sur l'acetylacetonate de Co(III) irradie aux neutrons thermiques. La valeur minimale de la retention observee pour des irradiations a basse temperature (0 C, -72 C, -180 C) se situe a (1,1 {+-} 0,2) pour cent. Le recuit thermique, par montee lineaire de la temperature a differentes vitesses de chauffage, montre l'existence de huit reactions. On confirme, de plus, l'influence sur les processus de recuit de la dose recue en pile, de l'atmosphere dans laquelle l'echantillon se trouve (air et helium) ainsi que de la decomposition thermique. Cette dependance de la temperature et de la dose est prouvee par les valeurs des retentions mesurees sur les isomeres {sup 60m}Co - {sup 60}Co. (auteur)

  12. USING COLLOIDAL LAYERED DOUBLE HYDROXIDES AS CATIONIC MICROPARTICULATE COMPONENT

    Institute of Scientific and Technical Information of China (English)

    Songlin Wang; Wenxia Liu

    2004-01-01

    Layered double hydroxides consisting of layers with cationic charges may be potential candidates of cationic microparticles forming synergetic retention effect with anionic polyacrylamide. In this work, the layered double hydroxides with various molar ratios of Mg/Al were synthesized by co-precipitation of magnesium chloride and aluminum chloride and peptized by intense washing with water. The chemical formula, particle size, Zeta potential of the layered double hydroxide were analyzed. It was found that positively charged magnesium aluminum hydroxide with particle diameter in nanoparticle size could be prepared. The Zeta potential and particle size vary with the feed molar ratio of Mg/Al and the peptizing process, respectively. The Zeta potential is also pH dependent. The retention experiments carried out on DDJ show that when used together with anionic polyacrylamide, the positively charged colloidal double hydroxide greatly improves the retention of reed pulps. The chemical formula, particle size and Zeta potential of the colloidal double hydroxide all affect its retention behavior.

  13. [Preparation and characterization of zirconium hydroxide powder for fluoride adsorption].

    Science.gov (United States)

    Yang, Shuo; Dou, Xiao-min; Liang, Wen-yan; Wang, Yi-li; Lin, Wei

    2010-07-01

    The method co-precipitation was applied to preparation the zirconium hydroxide as a type drinking-water defluoridation adsorbent. The effect of the preparation conditions on the adsorptive capacity was studied. The optimization of preparation condition for zirconium hydroxide concludes that co-precipitation time is 10 h, pH value is 7.0, drying time is 72 h, calcination temperature is below 100 degrees C. Also, the adsorbent samples were characterized. SEM measurements reveal that zirconium hydroxide powder are constructed by several small particles, with a diameter about 20-30 microm. XRD and TG/DTA measurements show that the zirconium hydroxide samples have amorphous phase and converse to tetragonal phase when calcined at 600 degrees C. Nitrogen adsorption/desorption measurements show that samples have large surface areas of 138.4 m2/g and a 2 nm average pore size distribution in the mesopore region. The performance of zirconium hydroxide regeneration process was investigated. The results show that the regeneration techniques are very suitable to restore the fluorine-removal ability for zirconium hydroxide.

  14. Ageing behaviour of unary hydroxides in trivalent metal salt solutions: Formation of layered double hydroxide (LDH)-like phases

    Indian Academy of Sciences (India)

    Michael Rajamathi; P Vishnu Kamath

    2000-10-01

    The hydroxides of Mg, Ni, Cu and Zn transform into layered double hydroxide (LDH)-like phases on ageing in solutions of Al or Cr salts. This reaction is similar to acid leaching and proceeds by a dissolution–reprecipitation mechanism offering a simple method of LDH synthesis, with implications for the accepted theories of formation of LDH minerals in the earth’s crust.

  15. The Effects of Aluminium Hydroxide and Magnesium Hydroxide on the Mechanical Properties of Thermoplastic Polyurethane Materials

    Directory of Open Access Journals (Sweden)

    Erkin Akdoğan

    2015-12-01

    Full Text Available Thermoplastic polyurethane materials are widely used in automotive, clothing, electrical and electronics, medical, construction, machine industry due to excellent physical and chemical properties. Thermoplastic polyurethane materials combustion and resistance to high temperature characteristics are poor. Additives and fillers are added into the polyurethane matrix to improve those properties. Particularly adding these agents as a flame retardant are affect mechanical properties of polyurethane materials. Therefore, it is important to determinate the mechanical properties of these materials. In this study, 5% by weight of the thermoplastic polyurethane material, aluminium tri hydroxide (ATH, (Al2O3 3H2O and magnesium hydroxide (MgOH, (Mg(OH2 were added. Ammonium polyphosphate (APP as an intumescent flame retardant with inorganic flame retardants were added to increase the flame resistance of produced composite structure. Tensile test, tear test, hardness and Izod impact tests were made and compared of those produced composites. As a result of experiments the addition of ATH has lowered the tensile strength and tear strength contrast to this the addition of MgOH has improved those properties. Hardness and Izod impact test results were showed that both of the additives have no negative effect.

  16. Chemical modification of zinc hydroxide nitrate and Zn-Al-layered double hydroxide with dicarboxylic acids.

    Science.gov (United States)

    Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; da Costa Gardolinski, José Eduardo Ferreira; Wypych, Fernando

    2008-04-01

    A zinc hydroxide nitrate (ZHN), Zn5(OH)8(NO3)2.2H2O, and a layered double hydroxide (LDH), Zn/Al-NO3 were doped with 0.2 mol% of Cu2+ during alkaline chemical precipitation. Both compounds were intercalated with adipate ((-)OOC(CH2)4COO(-)), azelate ((-)OOC(CH2)7COO(-)), and benzoate (C6H5COO(-)) ions through ion exchange reactions. Solid state 13C nuclear magnetic resonance spectroscopy showed only one signal of carboxylic carbon for adipate and azelate intercalated into LDH, indicating that the carboxylic ends of both acids were equivalent, whereas the signal split when the intercalation was into the ZHN matrix. The electron paramagnetic resonance (EPR) spectrum of copper in octahedral cation sites of LDH layers showed a Hamiltonian parameter ratio g ||/A ||=170 cm and, after intercalation of adipate, the change was not significant: g ||/A ||=174 cm. This result indicates that the carboxylate ions did not coordinate with copper centers. Nonetheless, the intercalation of azelate increased the ratio to g ||/A ||=194 cm, similar to the spectra of ZHN modified with adipate, g ||/A ||=199 cm, and azelate, g ||/A ||=183 and 190 cm, which are associated with the coordination of copper by weak carboxylate anion ligands. Copper occupies octahedral or tetrahedral sites in ZHN layers, and the EPR spectra indicate that the dicarboxylate anions reacted preferentially with octahedral sites, whereas benzoate reacted with both sites.

  17. Tri- and tetra-substituted cyclen based lanthanide(III) ion complexes as ribonuclease mimics: a study into the effect of log Ka, hydration and hydrophobicity on phosphodiester hydrolysis of the RNA-model 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP).

    Science.gov (United States)

    Fanning, Ann-Marie; Plush, Sally E; Gunnlaugsson, Thorfinnur

    2015-05-28

    A series of tetra-substituted 'pseudo' dipeptide ligands of cyclen (1,4,7,10,-tetraazacyclododecane) and a tri-substituted 3'-pyridine ligand of cyclen, and the corresponding lanthanide(III) complexes were synthesised and characterised as metallo-ribonuclease mimics. All complexes were shown to promote hydrolysis of the phosphodiester bond of 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP, τ1/2 = 5.87 × 10(3) h), a well known RNA mimic. The La(III) and Eu(III) tri-substituted 3'-pyridine lanthanide(III) complexes being the most efficient in promoting such hydrolysis at pH 7.4 and at 37 °C; with τ1/2 = 1.67 h for La(III) and 1.74 h for Eu(III). The series was developed to provide the opportunity to investigate the consequences of altering the lanthanide(III) ion, coordination ability and hydrophobicity of a metallo-cavity on the rate of hydrolysis using the model phosphodiester, HPNP, at 37 °C. To further provide information on the role that the log Ka of the metal bound water plays in phosphodiester hydrolysis the protonation constants and the metal ion stability constants of both a tri and tetra-substituted 3'pyridine complex were determined. Our results highlighted several key features for the design of lanthanide(III) ribonucelase mimics; the presence of two metal bound water molecules are vital for pH dependent rate constants for Eu(III) complexes, optimal pH activity approximating physiological pH (∼7.4) may be achieved if the log Ka values for both MLOH and ML(OH)2 species occur in this region, small changes to hydrophobicity within the metallo cavity influence the rate of hydrolysis greatly and an amide adjacent to the metal ion capable of forming hydrogen bonds with the substrate is required for achieving fast hydrolysis.

  18. EFFICACY OF DIFFERENT ENDODONTIC IRRIGATION PROTOCOLS IN CALCIUM HYDROXIDE REMOVAL

    Directory of Open Access Journals (Sweden)

    Elka N. Radeva

    2016-10-01

    Full Text Available Introduction: Calcium hydroxide is widely used in the field of endodontics as a temporary root canal filling. This medicament significantly increases pH and optimizes the treatment outcome. Its total removal before final obturation is very important. Otherwise it could affect the hermetic filling and respectively the endodontic success. Aim: To evaluate the most effective irrigation protocol of calcium hydroxide removal from root canals. Materials and methods: In this study 36 single root canal teeth were observed. They were randomly divided into three groups (n=10 each group according to the technique applied for calcium hydroxide removal - manual irrigation, irrigation and Revo-S rotary instrumentation; and passive ultrasonic irrigation, and a control group (n=6 – irrigation with distilled water only. After calcium hydroxide removals following the procedures above, teeth were separated longitudinally in a buccal-lingual direction and remnants of medicaments were observed in the apical, middle and coronal part of each tooth. Then all of the specimens were observed using scanning electron microscopy and evaluated by a specified scale. The results have undergone statistical analysis. Results: In the case of calcium hydroxide in the apex and in the middle with highest average is Revo-S, followed by Ultrasonic and irrigation. In the coronal part the highest average belongs to Revo-S, irrigation and Ultrasonic. In all groups the highest average is represented by control group. Conclusion: There is not a universal technique for removal of intracanal medicaments and applying more than one protocol is required.

  19. The citotoxicity of calcium hydroxide intracanal dressing by MTT assay

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2007-12-01

    Full Text Available Calcium hydroxide had been used as the intracanal dressing in endodontic treatment due to its high alkaline and high antimicrobial capacity. It also be able to dissolve the necrotic tissue, prevent the root resorbtion and regenerate a new hard tissue. The aim of this study is to identify the concentration of calcium hydroxide that has the lowest citotoxicity. There are 5 groups, each group had 8 samples with different concentration of calcium hydroxide. Group I: 50%, Group II: 55%, Group III: 60%, Group IV: 65% and Group V: 70%. The citotoxicity test by using enzymatic assay of MTT [3-(4.5- dimethylthiazol-2yl ]-2.5 diphenyl tetrazolium bromide, against fibroblast cell (BHK-21. The result of susceptibility test was showed by the citotoxicity detection of the survive cell of fibroblast that was measured spectrophotometrically using 595 nm beam. The data was analyzed using One-Way ANOVA test with significant difference α = 0.05 and subsequently LSD test. The result showed that in concentration 50%, 55%, 60%, 65%, and 70% calcium hydroxide had low toxicity, but calcium hydroxide 60%, had the lowest toxicity.

  20. Synthesis, interactions, molecular structure, biological properties and molecular docking studies on Mn, Co, Zn complexes containing acetylacetone and pyridine ligands with DNA duplex.

    Science.gov (United States)

    Thamilarasan, V; Sengottuvelan, N; Stalin, N; Srinivasan, P; Chakkaravarthi, G

    2016-07-01

    Three metal complexes (1-3) of the type [Mn(acac)2(py)·H2O] (1), [Co(acac)2(py)·H2O] (2) and [Zn(acac)2(py)·H2O] (3), [Where acac=acetylacetone, py=pyridine] were synthesized and characterized by spectral (UV-vis, FT-IR, ESI-mass) analysis. The structure of complex 2 has been determined by single crystal X-ray diffraction studies and the configuration of ligand-coordinated to metal(II) ion was well described as distorted octahedral coordination geometry. The interaction of the complexes with CT-DNA has been explored by absorption, fluorescence, circular dichromism spectroscopy, viscosity measurements and molecular docking studies. The intrinsic binding constant Kb of complexes 1-3 with CT-DNA obtained from UV-vis absorption spectral studies were 2.1×10(4), 2.1×10(5) and 1.98×10(4)M(-1), respectively, which revealed that the complexes could interact with CT-DNA through groove binding. The results indicated that the complexes (1-3) were able to bind to DNA with different binding affinity, in the order: 2>1>3. The interaction of the compounds with bovine serum albumins were also investigated using fluorescence methods and the gel electrophoresis assay demonstrates weak cleavage ability of the pBR322 plasmid DNA in the presence of the metal complexes (1-3) with various activators. Further, the in vitro cytotoxic effect of the complexes were examined on cancerous cell line, with human breast cancer cells MCF-7.

  1. Photo-oxidation of EPDM/layered double hydroxides composites: Influence of layered hydroxides and stabilizers

    Directory of Open Access Journals (Sweden)

    2007-11-01

    Full Text Available The photo-oxidation of ethylene propylene diene monomer (EPDM/ layered double hydroxide (LDH composites as well as EPDM/LDH with stabilizers is studied under accelerated UV irradiation (λ≥290 nm at 60°C for different time intervals. The development of functional groups during oxidation was monitored by FT-IR spectroscopy. The photodegradation of the pristine polymer and composites take place and the increase in hydroxyl and carbonyl groups with irradiation times, was estimated. EPDM filled LDH showed higher degradation rate than pristine EPDM, while in acidic medium EPDM/LDH showed almost equal degradation as in isolated conditions. These results show the advantages of LDHs as a filler as well as an acid killer. The effect of stabilizers is very less because of their concentration in comparison of LDH.

  2. Carbonate inhibits the crystallization of aluminum hydroxide in bauxite

    Energy Technology Data Exchange (ETDEWEB)

    Bardossy, G.; White, J.L.

    1979-01-01

    Although the role of anions such as nitrate, chloride, and sulfate in inhibiting the crystallization of aluminum hydroxide in soils and geological deposits is generally accepted, the dramatic effect of the carbonate ion in maintaining aluminum hydroxide gel in the amorphous form has been overlooked by most earth scientists. Examination of bauxite occurrences suggests that the inhibiting effect of carbonate is quite apparent in the smaller grain size of gibbsite in karstic bauxite deposits as compared to that in lateritic bauxite. Scarbroeite, a crystalline aluminum hydroxy carbonate, has been observed in rare instances. It is suggested that the highly reactive carbonate-containing aluminum hydroxide gells used as pharmaceutical antacids are amorphous or poorly crystalline forms of scarbroeite. The effect of the sulfate anion is also apparent in certain bauxite deposits where dissolution of gibbsite by sulfuric acid has resulted from the oxidation of pyrite, with subsequent reprecipitation of gibbsite.

  3. Structure and properties of porous ceramics obtained from aluminum hydroxide

    Science.gov (United States)

    Levkov, R.; Kulkov, S.

    2016-08-01

    In this paper the study of porous ceramics obtained from aluminum hydroxide with gibbsite modification is presented. The dependence of porosity and mechanical characteristics of the material sintered at different temperatures was studied. It was shown that compressive strength of alumina ceramics increases by 40 times with decreasing the pore volume from 65 to 15%. It was shown that aluminum hydroxide may be used for pore formation and pore volume in the sintered ceramics can be controlled by varying the aluminum hydroxide concentration and sintering temperature. Based on these results one can conclude that the obtained structure is very close to inorganic bone matrix and can be used as promising material for bone implants production.

  4. ANTIBACTERIAL EFFECT OF CALCIUM HYDROXIDE IN DIFFER ENT VEHICLES

    Directory of Open Access Journals (Sweden)

    Hari

    2012-11-01

    Full Text Available ABSTRACT: AIM: This study evaluated the antibacterial effect of ca lcium hydroxide in different vehicles in an in vitro model. MATERIAL AND METHODS: Calcium hydroxide paste prepared with two conventionally used vehicles namely, campho rated monochlophenol, distilled water and also propylene glycol. The antibacterial activity of these paste were tested against five micro- organisms that can commonly occur in the inf ected root canals. RESULTS AND CONCLUSIONS: The results of the study indicate that a paste of ca lcium hydroxide made with propylene glycol exerts significant antibacterial act ion. Hence, it can be recommended for use as an intracanal medicament in preference to a paste prepa red with a tissue toxic phenolic compound like camphorated mono chlorophenol

  5. Oxidative leaching of chromium from layered double hydroxides: Mechanistic studies

    Indian Academy of Sciences (India)

    A V Radha; P Vishnu Kamath

    2004-08-01

    The layered double hydroxide (LDH) of Zn with Cr on treatment with a hypochlorite solution releases chromate ions as a result of oxidative leaching by a dissolution–reprecipitation mechanism. The residue is found to be -Zn(OH)2. The LDH of Mg with Cr on the other hand is resistant to oxidative leaching. In contrast, a X-ray amorphous gel of the coprecipitated hydroxides of Mg and Cr yields chromate ions. These results suggest that the oxidation potential of Cr(III) in LDHs is determined by the nature of the divalent ion and the crystallinity of the phase while being unaffected by the nature of the intercalated anions.

  6. The effect of sodium hydroxide treatment on biomass binder preparation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.; Xu, D.; Xu, Z.; Chen, Q. [China University of Mining and Technology, Beijing (China). Beijing Campus

    2001-02-01

    The possibility of rice straw which has been treated with sodium hydroxide for use as coal briquette binder was studied. The main factor which influenced the binder preparation was the concentration of sodium hydroxide. It was found that the binding ability of the solid component was higher than the liquid part. The prepared rice straw binder was mixed with inorganic material, bentonite, or high molecular synthetic organic materials to manufacture a compound coal briquette binder. This compound binder is waterproofing and can further enhance the strength of the briquette. 5 refs., 5 figs., 2 tabs.

  7. Microwave Assisted Synthesis of N,N' - Bis (acetylacetone) - 1,2 -propenediimine and Its Co ( Ⅱ ) Complex%乙酰丙酮缩邻苯二胺及其Co(Ⅱ)配合物的微波合成

    Institute of Scientific and Technical Information of China (English)

    牛永盛; 李红春

    2011-01-01

    N,N' -Bis(acetylacetone) - 1,2- propenediimine and their cobalt complex were synthesized by microwave radicalization. The structures of as - prepared products were characterized by the infra - red, element analysis, magnetic spectrometer and meting point meter.%采用微波辐射方法合成了乙酰丙酮缩邻苯二胺Schiff碱及其Co(Ⅱ)金属配合物;通过红外光谱、元素分析、质谱、熔点仪对Schiff碱及其配合物进行了表征.

  8. From Zn-Al layered double hydroxide to ZnO nanostructure:Gradually etching by sodium hydroxide

    Institute of Scientific and Technical Information of China (English)

    Gang Qiang Wan; Dong Xiang Li; Chun Fang Li; Jie Xu; Wan Guo Hou

    2012-01-01

    Zn-Al layered double hydroxide (LDH) was used as precursor to produce ZnO nanostructures through dissolution of aluminum hydroxide in caustic soda.The Zn-Al LDH could transform into different nanostructures of ZnO on LDH nanosheets and even pure ZnO nanorods under various NaOH concentration.The formed ZnO nanorods vertically aligned on both LDH sides.UV-vis diverse reflectance spectra show that the obtained ZnO nanorods have a band gap of approximately 3.05 eV.Such ZnO/LDH nanostructures might be used as photocatalyst in the organic pollutant decomposition.

  9. Determination of Chromium(III), Chromium(VI), and Chromium(III) acetylacetonate in water by ion-exchange disk extraction/metal furnace atomic absorption spectrometry

    Science.gov (United States)

    Kamakura, Nao; Inui, Tetsuo; Kitano, Masaru; Nakamura, Toshihiro

    A new method for the separate determination of Chromium(III) (Cr(III)), Chromium(VI) (Cr(VI)), and Cr(III) acetylacetonate (Cr(acac)3) in water was developed using a cation-exchange extraction disk (CED) and an anion-exchange extraction disk (AED) combined with metal furnace atomic absorption spectrometry (MFAAS). A 100-mL water sample was adjusted to pH 5.6 and passed through the CED placed on the AED. Cr(acac)3 and Cr(III) were adsorbed on the CED, and Cr(VI) was adsorbed on the AED. The adsorbed Cr(acac)3 was eluted with 50 mL of carbon tetrachloride, followed by the elution of Cr(III) with 50 mL of 3 mol L- 1 nitric acid. Cr(VI) was eluted with 50 mL of 3 mol L- 1 nitric acid. The chemical species of Cr eluted from the CED with carbon tetrachloride was identified as Cr(acac)3 using infrared spectroscopy. The eluate of Cr(acac)3 was diluted to 100 mL with carbon tetrachloride, and those of Cr(III) and Cr(VI) were diluted to 100 mL with deionized water. All of the solutions were subsequently analyzed by MFAAS. The calibration curve for the Cr(acac)3 aqueous solutions exhibited good linearity in the range of 0.1 to 1 ng. The detection limit of Cr, which corresponded to three times the standard deviation (n = 10) of the blank values, was 20 pg. The recovery test for Cr(III), Cr(VI), and Cr(acac)3 exhibited desirable results (96.0%-107%) when 5 μg of each species (50 μg L- 1) was added to 100 mL water samples (i.e., tap water, rainwater, and bottled drinking water). In a humic acid solution, Cr(acac)3 was quantitatively recovered (103%), but Cr(III) and Cr(VI) exhibited poor recoveries (i.e., 84.8% and 78.4%, respectively).

  10. Synthesis and characterization of Fe(II) β-diketonato complexes with relevance to acetylacetone dioxygenase: insights into the electronic properties of the 3-histidine facial triad.

    Science.gov (United States)

    Park, Heaweon; Baus, Jacob S; Lindeman, Sergey V; Fiedler, Adam T

    2011-12-05

    A series of high-spin iron(II) β-diketonato complexes have been prepared and characterized with the intent of modeling the substrate-bound form of the enzyme acetylacetone dioxygenase (Dke1). The Dke1 active site features an Fe(II) center coordinated by three histidine residues in a facial geometry--a departure from the standard 2-histidine-1-carboxylate (2H1C) facial triad dominant among nonheme monoiron enzymes. The deprotonated β-diketone substrate binds to the Fe center in a bidentate fashion. To better understand the implications of subtle changes in coordination environment for the electronic structures of nonheme Fe active sites, synthetic models were prepared with three different supporting ligands (L(N3)): the anionic (Me2)Tp and (Ph2)Tp ligands ((R2)Tp = hydrotris(pyrazol-1-yl)borate substituted with R-groups at the 3- and 5-pyrazole positions) and the neutral (Ph)TIP ligand ((Ph)TIP = tris(2-phenylimidazol-4-yl)phosphine). The resulting [(L(N3))Fe(acac(X))](0/+) complexes (acac(X) = substituted β-diketonates) were analyzed with a combination of experimental and computational methods, namely, X-ray crystallography, cyclic voltammetry, spectroscopic techniques (UV-vis absorption and (1)H NMR), and density functional theory (DFT). X-ray diffraction results for complexes with the (Me2)Tp ligand revealed six-coordinate Fe(II) centers with a bound MeCN molecule, while structures of the (Ph2)Tp and (Ph)TIP complexes generally exhibited five-coordinate geometries. Each [(L(N3))Fe(acac(X))](0/+) complex displays two broad absorption features in the visible region that arise from Fe(II)→acac(X) charge transfer and acac(X)-based transitions, consistent with UV-vis data reported for Dke1. These absorption bands, along with the Fe redox potentials, are highly sensitive to the identity of L(N3) and substitution of the β-diketonates. By interpreting the experimental results in conjunction with DFT calculations, detailed electronic-structure descriptions of the

  11. 21 CFR 73.1010 - Alumina (dried aluminum hydroxide).

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Alumina (dried aluminum hydroxide). 73.1010 Section 73.1010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1010 Alumina (dried...

  12. Dewatering of alumino-humic sludge: impacts of hydroxide.

    Science.gov (United States)

    Bache, D H; Papavasilopoulos, E N

    2003-08-01

    The paper draws together information on factors which influence the conditioning and dewatering behaviour of an alum sludge gained from the coagulation of a low-turbidity coloured water. A principal focus is the potential impact of aluminium hydroxide on the sludge character. Background information is provided on the composition of the source floc for the domain pH 6.0-6.5 and Al>2.0mg/l. From this, there were many pointers to the presence of Al(OH)(3)(s) within the floc. A series of comparisons were made between an alum sludge and a hydroxide suspension at a concentration equivalent to the coagulant fraction within the sludge. The parameters studied included floc size, floc density, polymer adsorption and dewatering behaviour at different time-scales. In all cases, there were strong similarities in the behaviour of the two suspensions-indicating the potential impact of the hydroxide. There was also evidence of common features being displayed by both the organic fractions and the hydroxide. It was suggested that some of the behavioural features might emanate from a common fractal structure within the source floc, the fractal dimension (approximately 1) being insensitive to composition.

  13. Recent progress in polymer/layered double hydroxide nanocomposites

    Institute of Scientific and Technical Information of China (English)

    DING Peng; CHEN Wei; QU Baojun

    2006-01-01

    New developments in the studies of nanocomposites based on polymer matrixes and layered double hydroxides (LDHs)in recent years are reviewed combining our relative research work, among which the synthesis techniques, the physicochemical characterizations, and the improved material properties are especially discussed. The possible application of polymer/LDH nanocomposites is also proposed.

  14. Intratubular disinfection with tri-antibiotic and calcium hydroxide pastes.

    Science.gov (United States)

    Pereira, Thais Cristina; Vasconcelos, Layla Reginna Silva Munhoz De; Graeff, Marcia Sirlene Zardin; Duarte, Marco Antonio Hungaro; Bramante, Clóvis Monteiro; Andrade, Flaviana Bombarda De

    2017-03-01

    The aim of this study was to compare the in vitro intradentinal antimicrobial ability of the calcium hydroxide and tri-antibiotic pastes. Standard bovine dentin tubes were sterilized and then infected with Enterococcus faecalis by a new contamination protocol of great depths of dentin. The specimens were filled with the medications, divided into two test-groups: calcium hydroxide (Group 1) and tri-antibiotic (Group 2) pastes. After 15 days, the teeth were evaluated by microbiological culture and confocal laser scanning microscopy (CLSM) with viability dye assay LIVE/DEAD inside dentinal tubules. In experiment of culture, the bacterial collection of the dentin fragments was done for counting the colony-forming units. The tri-antibiotic paste had a slightly greater antimicrobial effect; however, there was no statistical difference between the groups. It was concluded that the tri-antibiotic paste and the calcium hydroxide paste exercise the same effect on intra-tubular decontamination against E. faecalis. So, due the multiples advantages, the calcium hydroxide paste can be the choice for dentinal decontamination in regenerative procedures.

  15. DOUBLE SHELL TANK (DST) HYDROXIDE DEPLETION MODEL FOR CARBON DIOXIDE ABSORPTION

    Energy Technology Data Exchange (ETDEWEB)

    OGDEN DM; KIRCH NW

    2007-10-31

    This document generates a supernatant hydroxide ion depletion model based on mechanistic principles. The carbon dioxide absorption mechanistic model is developed in this report. The report also benchmarks the model against historical tank supernatant hydroxide data and vapor space carbon dioxide data. A comparison of the newly generated mechanistic model with previously applied empirical hydroxide depletion equations is also performed.

  16. Clinical and radiographic outcomes of calcium hydroxide and formocresol pulpotomies performed by dental students.

    Science.gov (United States)

    Alaçam, Alev; Odabaş, Mesut E; Tüzüner, Tamer; Sillelioğlu, Hilal; Baygin, Ozgül

    2009-11-01

    The aim of this study was to compare the clinical and radiographic success rates of 3 pulpotomy techniques: formocresol, calcium hydroxide, and calcium hydroxide/iodoform. The pulpotomies were performed by fifth-year undergraduate dental students. Members of senior staff at the clinics supervised all of the procedures. Informed consent was obtained from each child's parents. The teeth were randomly assigned to the experimental (calcium hydroxide and calcium hydroxide/iodoform) or control (formocresol) groups. After coronal pulp removal and hemostasis, remaining pulp tissue was covered with calcium hydroxide or calcium hydroxide/iodoform paste in the experimental groups. In the control group, formocresol was placed with a cotton pellet over the pulp tissue for 5 minutes and removed; the pulp tissue was then covered with zinc oxide-eugenol. All teeth were restored with stainless-steel crowns. Clinical and radiographic successes and failures were recorded at 1-, 3-, 6-, and 12-month follow-ups by the authors. Data were statistically analyzed using chi-squared tests. The follow-up evaluations revealed that the clinical success rates were 89.7% for formocresol, 33.3% for calcium hydroxide, and 17.2% for calcium hydroxide/iodoform. The radiographic success rates were 89.7% for formocresol, 33.3% for calcium hydroxide, and 13.8% for calcium hydroxide/iodoform. Formocresol was superior to calcium hydroxide and calcium hydroxide/iodoform pastes for primary molar pulpotomies. Internal resorption was the most common radiographic failure in all 3 pulpotomy techniques.

  17. Assignment of solid-state 13C and 1H NMR spectra of paramagnetic Ni(II) acetylacetonate complexes aided by first-principles computations

    DEFF Research Database (Denmark)

    Rouf, Syed Awais; Jakobsen, Vibe Boel; Mareš, Jiří

    2017-01-01

    Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)2L2] with L = H2O, D2O, NH3, ND3, and PMe2Ph have provided detailed insight into the origin of the par......Recent advances in computational methodology allowed for first-principles calculations of the nuclear shielding tensor for a series of paramagnetic nickel(II) acetylacetonate complexes, [Ni(acac)2L2] with L = H2O, D2O, NH3, ND3, and PMe2Ph have provided detailed insight into the origin...... of the paramagnetic contributions to the total shift tensor. This was employed for the assignment of the solid-state 1,2H and 13C MAS NMR spectra of these compounds. The two major contributions to the isotropic shifts are by orbital (diamagnetic-like) and contact mechanism. The orbital shielding, contact, as well...... as dipolar terms all contribute to the anisotropic component. The calculations suggest reassignment of the 13C methyl and carbonyl resonances in the acac ligand [Inorg. Chem. 53, 2014, 399] leading to isotropic paramagnetic shifts of δ(13C) ≈ 800–1100 ppm and ≈180–300 ppm for 13C for the methyl and carbonyl...

  18. 乙酰丙酮比色法在流感病毒裂解疫苗游离甲醛含量测定中的应用%The application of acetylacetone colorimetric method for determination of free formaldehyde content in influenza vaccine (split virion)

    Institute of Scientific and Technical Information of China (English)

    方曼莉; 马雷钧; 郁佳俊; 封向明; 沈坚; 程鹏飞

    2014-01-01

    目的 验证乙酰丙酮比色法测定流感病毒裂解疫苗游离甲醛含量的可行性,并确认该法测定游离甲醛含量优于品红亚硫酸法. 方法 对乙酰丙酮比色法进行准确度、精密度、专属性、线性、耐用性验证,并将该法与品红亚硫酸法进行比较.结果 乙酰丙酮比色法的标准曲线具有可靠性,甲醛回收率为100.3%~100.9%,相对标准偏差(relative standard deviation,RSD)为0.49%.该法的精密度和专属性良好,实验间和实验内RSD均<5.0%,甲醛加样回收率均>99.0%.与品红亚硫酸法相比,该法的线性更好,偏差更小.结论 乙酰丙酮比色法可用于流感病毒裂解疫苗游离甲醛含量测定.%Objective To validate feasibility of using acetylacetone colorimetric method for determination of free formaldehyde content in influenza vaccine (split virion),and to confirm the acetylacetone colorimetric method was better than the magenta sulphurous acid colorimetric method.Methods The accuracy,precision,specificity,linearity and durability of the acetylacetone colorimetric method were validated.The acetylacetone colorimetric method was compared with the magenta sulphurous acid colorimetric method.Results The standard curve of the acetylacetone colorimetric method was reliable,recoveries of formaldehyde were 100.3%-100.9% and relative standard deviation (RSD) was 0.49%.The precision and specificity of the acetylacetone colorimetric method were good,RSDs of intra-assay and inter-assay were both <5.0% and recoveries of formaldehyde were >99.0%.The acetylacetone method had better linearity and lower deviation as compared with the magenta sulphurous acid colorimetric method.Conclusion The acetylacetone colorimetric method for the determination of free formaldehyde content in influenza vaccine (split virion) is feasible.

  19. Thermal stability and oil absorption of aluminum hydroxide treated by dry modification with phosphoric acid

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The dry modification of aluminum hydroxide powders with phosphoric acid and the effects of modification of technological conditions on thermal stability, morphology and oil absorption of aluminum hydroxide powders were investigated. The results show that the increase of mass ratio of phosphoric acid to aluminum hydroxide, the decrease of mass concentration of phosphoric acid and prolongation of mixing time are favorable to the improvement of thermal stability of aluminum hydroxide; when the mass ratio of phosphoric acid to aluminum hydroxide is 5:100, the mass concentration of phosphoric acid is 200 g/L and the mixing time is 10 min, the initial temperature of loss of crystal water in aluminum hydroxide rises from about 192.10 to 208.66 ℃2,but the dry modification results in the appearance of agglomeration and macro-aggregate in the modified powders, and the oil absorption of modified powders becomes higher than that of original aluminum hydroxide.

  20. Immobilization of laccase on hybrid layered double hydroxide

    Directory of Open Access Journals (Sweden)

    David Isidoro Camacho Córdova

    2009-01-01

    Full Text Available Crystals of Mg/Al layered double hydroxide were synthesized by alkaline precipitation and treated in an aqueous solution of glutamic acid. The glutamate ions were not intercalated into the interlayer space, but were detected in the material by Fourier transform infrared spectroscopy, suggesting that only the external surfaces of crystals were modified with glutamate ions. The resulting hybrid material was tested as a support for immobilization of the enzyme laccase (Myceliophthora thermophila. The immobilized enzyme preparation was characterized by electronic paramagnetic resonance spectroscopy and by assays of catalytic activity. The activity of the immobilized laccase was 97% of the activity in the free enzyme. Layered double hydroxide is a suitable support for use in remediation of soil studies.

  1. Synthesis and characterization of α-cobalt hydroxide nanobelts

    Science.gov (United States)

    Tian, L.; Zhu, J. L.; Chen, L.; An, B.; Liu, Q. Q.; Huang, K. L.

    2011-08-01

    α-Cobalt hydroxide was synthesized by a facile hydrothermal process from Co(Ac)2 and NH3·H2O in the presence of 1,3-propanediol. The large-scale-prepared cobalt hydroxide has a uniform nanobelt morphology with a considerably high aspect-ratio more than 20 which may be advantageous for exploration of their physicochemical properties. This synthetic method is convenient, economical, and controllable. The samples were characterized by powder X-ray diffraction, energy dispersive spectrum, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, CHN element analysis, thermogravimetric and differential-thermogravimetric analysis, which revealed the compound is lamellar structural cobalt organic-inorganic hybrid with the chemical formula of Co(OH)1.49(NH3)0.01(CO3 2-)0.22(Ac-)0.07(H2O)0.11 and single-crystalline.

  2. Leaching kinetics of gibbsitic bauxite with sodium hydroxide

    Directory of Open Access Journals (Sweden)

    Abdel-Aal El-Sayed A.

    2016-01-01

    Full Text Available In this paper the results of a leaching kinetics study of bauxite ore with sodium hydroxide are presented. The effect of ore particle size, sodium hydroxide concentration and reaction temperature on the Al2O3 extraction rate was determined. The results obtained showed that 99% of Al2O3 was leached out using −200+270 mesh ore particle size at a reaction temperature of 105 °C for 60 min reaction time with 250 g/L NaOH. The solid-to-liquid ratio was maintained constant at 1:20. The results indicated that leaching of bauxite is the rate controlling process. The activation energy was determined to be 46.04 kJ/mole, which was characteristic for a chemically controlled process.

  3. CALCIUM HYDROXIDE IN ENDODONTIC TREATMENT OF PERIAPICALLY INFECTED TEETH

    Directory of Open Access Journals (Sweden)

    Rahmi Alma Farah Adang

    2006-04-01

    Full Text Available An inadequate endodontic treatment may affect the root canal system and spread beyond its apical foramina that elicit periodontal tissue developing into abscess, granuloma and radicular cyst. Periodical lesions can be treated with non surgical endodontic treatment using calcium hydroxide dressing. This case study is reporting teeth 11 with periodical lesions and infection. Evidence of a clinical healing and radiographic assessments were followed by a non surgical endodontic therapy. Successful treatment outcome is related to the elimination of infection agents from the root canal. This can activate a stimulation zone to promote regeneration. Calcium hydroxide used as a root canal dressing may promote alkalinity at the adjacent tissue , create favourable environmental condition in which hard tissue formation can occur, interfere the bactericidal activity, increase mineralization, and induce healing.

  4. Surface tension of calcium hydroxide associated with different substances

    OpenAIRE

    Carlos Estrela; Cyntia Rodrigues de Araújo Estrela; Luiz Fernando Guimarães; Reginaldo Santana Silva; Jesus Djalma Pécora

    2005-01-01

    The purpose of this study was to evaluate the surface tension of calcium hydroxide (CH) associated with different substances (deionized distilled water, camphorated paramonochlorophenol, 2% chlorhexidine digluconate, Otosporin, 3% sodium lauryl ether sulphate; Furacin, PMC Furacin) using tensiometer. The action of the substances studied on the dentinal structure enhances the property of surface tension. This method consists in the application of force to separate a platinum ring immersed in t...

  5. Hydrothermal Synthesis of Ni/Al Layered Double Hydroxide Nanorods

    OpenAIRE

    Yun Zhao; Fenfei Xiao; Qingze Jiao

    2011-01-01

    Ni/Al layered double hydroxide (LDH) nanorods were successfully synthesized by the hydrothermal reaction. The crystal structure of the products was characterized by X-ray diffraction (XRD). The morphology of the products was observed using transmission electron microscopy (TEM) and field emission scanning electron microscopy (SEM). The influences of reaction time and pH value on the morphology of the Ni/Al LDHs were investigated. The result showed that the well-crystallized nanorods of Ni/Al ...

  6. A comparison between sodium hydroxide treated and untreated bird ...

    African Journals Online (AJOL)

    determine the effect of sodium hydroxide (NaOH)treatment of bird-proof sorghum (BPS) ... (11070)and with an 8070poorer feed-utilization ratio than pigs fed NS and ... batches of grain were soaked for 2 hours in a NaOH solution made up of 500 g ... amount of 1 500 g of air-dry meal was fed to each pig in two equal portions ...

  7. [Aluminum hydroxide hydrogel to remove arsenic from water].

    Science.gov (United States)

    Luján, J C

    2001-05-01

    To describe the making of and the preliminary results from an aluminum hydroxide hydrogel that, when added directly to water, can totally eliminate arsenic, regardless of the nature of the water and the oxidation state of the metalloid. The raw materials used to make the aluminum hydroxide hydrogel were: hydrated aluminum sulfate (which is used to make water safe for drinking), calcium hypochlorite in powder form, ammonium hydroxide, and distilled water (when done at the laboratory scale), and water from inverse osmosis of the same or better quality than the distilled water (when done at a pilot scale). Quality control for the finished product consisted of determining its ability to adsorb arsenic and performing bacteriological tests to demonstrate its sterility. The product was used with water samples to which arsenic had been added in the laboratory and with water samples from the province of Tucumán, Argentina, with naturally occurring arsenic. To analyze the arsenic in the water the colorimetric silver diethyldithiocarbamate method was used. Using the hydrogel greatly reduced the amount of arsenic. Treating both the natural and laboratory-produced arsenical waters yielded arsenic concentrations under the limit (0.01 parts per million) that was detectable with the analytical method used. The bacteriological tests of the finished product indicated there were no viable bacteria. Using the aluminum hydroxide hydrogel produced the desired reduction in the arsenic concentration in the water. This method for removing arsenic is inexpensive and easy to use in scattered rural populations in areas having high arsenic levels and lacking drinkable water, as well as an adequate sanitary and electric-power infrastructure.

  8. Adsorption behavior of condensed phosphate on aluminum hydroxide

    Institute of Scientific and Technical Information of China (English)

    GUAN Xiao-hong; CHEN Guang-hao; SHANG Chii

    2007-01-01

    Sodium pyrophosphate(pyro-P,Na4P207),sodium tripolyphosphate(tripoly-P,NasP3010),and sodium hexametaphosphate(metaP,(NaP03)6)were selected as the model compounds of condensed phosphate to investigate the adsorption behavior of condensed phosphate on aluminum hydroxide.The adsorption was found to be endothermic and divisible into two stages:(1)fast adsorption within 1 h:and(2)slow adsorption between 1 and 24 h.The modified Freundlich model simulated the fast adsorption stage well;the slow adsorption stage was described well by the first-order kinetics.The activation energies of pyro-P,tripoly-P,and meta-P adsorption on aluminum hydroxide were determined to be 20.2,22.8 and 10.9 kJ/mol P adsorbed,respectively,in the fast adsorption stage and to be 66.3.53.5 and 72.5 kJ/tool P adsorbed,respectively,in the slow adsorption stage.The adsorption increased the negative charge of the aluminum hydroxide surface.Transmission electron microscopy and energy dispersive X-ray analysis analyses provided evidence that the adsorption was not uniform on the surface and that the small crystals contfibuted more to the fast adsorption than the normal sites did.The results from X-ray fluorescence spectrometry and X-ray photoelectron spectroscopy tests also revealed the uneven adsorption of condensed phosphate as a function of the penetration depth.More condensed phosphates were adsorbed on the outer surface of aluminum hydroxide than in its inner parts.

  9. Lanthanide(III) complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H6do2a2p) in solution and in the solid state: structural studies along the series.

    Science.gov (United States)

    Campello, M Paula C; Lacerda, Sara; Santos, Isabel C; Pereira, Giovannia A; Geraldes, Carlos F G C; Kotek, Jan; Hermann, Petr; Vanek, Jakub; Lubal, Premysl; Kubícek, Vojtech; Tóth, Eva; Santos, Isabel

    2010-07-26

    Complexes of 4,10-bis(phosphonomethyl)-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid (trans-H(6)do2a2p, H(6)L) with transition metal and lanthanide(III) ions were investigated. The stability constant values of the divalent and trivalent metal-ion complexes are between the corresponding values of H(4)dota and H(8)dotp complexes, as a consequence of the ligand basicity. The solid-state structures of the ligand and of nine lanthanide(III) complexes were determined by X-ray diffraction. All the complexes are present as twisted-square-antiprismatic isomers and their structures can be divided into two series. The first one involves nona-coordinated complexes of the large lanthanide(III) ions (Ce, Nd, Sm) with a coordinated water molecule. In the series of Sm, Eu, Tb, Dy, Er, Yb, the complexes are octa-coordinated only by the ligand donor atoms and their coordination cages are more irregular. The formation kinetics and the acid-assisted dissociation of several Ln(III)-H(6)L complexes were investigated at different temperatures and compared with analogous data for complexes of other dota-like ligands. The [Ce(L)(H(2)O)](3-) complex is the most kinetically inert among complexes of the investigated lanthanide(III) ions (Ce, Eu, Gd, Yb). Among mixed phosphonate-acetate dota analogues, kinetic inertness of the cerium(III) complexes is increased with a higher number of phosphonate arms in the ligand, whereas the opposite is true for europium(III) complexes. According to the (1)H NMR spectroscopic pseudo-contact shifts for the Ce-Eu and Tb-Yb series, the solution structures of the complexes reflect the structures of the [Ce(HL)(H(2)O)](2-) and [Yb(HL)](2-) anions, respectively, found in the solid state. However, these solution NMR spectroscopic studies showed that there is no unambiguous relation between (31)P/(1)H lanthanide-induced shift (LIS) values and coordination of water in the complexes; the values rather express a relative position of the central ions between the N(4

  10. Why does hydronium diffuse faster than hydroxide in liquid water?

    Science.gov (United States)

    Zheng, Lixin; Santra, Biswajit; Distasio, Robert; Klein, Michael; Car, Roberto; Wu, Xifan

    Experiments show that the hydronium ion (H3O+) diffuses much faster than the hydroxide ion (OH-) in liquid water. ab initio molecular dynamics (AIMD) simulations correctly associated the diffusion mechanism to proton transfer (PT) but have been unable so far to clearly identify the reason for the faster diffusion of hydronium compared to hydroxide, as the diffusion rate was found to depend sensitively on the adopted functional approximation. We carried out AIMD simulations of the solvated water ions using a van der Waals (vdW) inclusive PBE0 hybrid density functional. It is found that not only hydronium diffuses faster than hydroxide but also the absolute rates agree with experiment. The fast diffusion of H3O+ occurs via concerted PT that enables the ion to jump across several H-bonded molecules in successful transfer events; in contrast, such concerted motion is significantly hindered in OH- where the ion is easily trapped in a hyper-coordination configuration (a local solvation structure that forbids PT). As a result multiple PT events are rare and the diffusion of OH- is significantly slowed down. Such a clear difference between the two ions results from the combined effect of vdW interactions and self-interaction correction. Doe SciDac: DE-SC0008626 and DE-SC0008726.

  11. Oxidation of Dodecanoate Intercalated Iron(II)–Iron(III) Layered Double Hydroxide to Form 2D Iron(III) (Hydr)oxide Layers

    DEFF Research Database (Denmark)

    Huang, Li‐Zhi; Ayala‐Luis, Karina B.; Fang, Liping;

    2013-01-01

    A planar trioctahedral iron(II)–iron(III) hydroxide (green rust, GR) intercalated with dodecanoate (GRC12) has been oxidized by dioxygen to produce the corresponding planar iron(III) (hydr)oxide. The formulae of GRC12 and the final iron(III) product (oxGRC12) were determined to be FeII2.00FeIII1...

  12. Mechanistic study of inhibition of levofloxacin absorption by aluminum hydroxide.

    Science.gov (United States)

    Tanaka, M; Kurata, T; Fujisawa, C; Ohshima, Y; Aoki, H; Okazaki, O; Hakusui, H

    1993-10-01

    The mechanisms of reduction in absorption of levofloxacin (LVFX) by coadministration of aluminum hydroxide were studied. The partition coefficient of LVFX (0.1 mM) between chloroform and phosphate buffer (pH 5.0) was reduced by 60 to 70% with the addition of metal ions such as Cu2+, Al3+, and Fe2+ (0.8 mM), which indicated the formation of LVFX-metal ion chelates. However, there was no significant difference in absorption from rat intestine between the synthetic LVFX-Al3+ (1:1) chelate (6.75 mM) and LVFX (6.75 mM) in an in situ recirculation experiment. On the other hand, Al(NO3)3 (1.5 mM) significantly inhibited the absorption of LVFX (1.5 mM) by 20% of the control in the in situ ligated loop experiment, in which partial precipitation of aluminum hydroxide was observed in the dosing solution. Data for adsorption of LVFX and ofloxacin (OFLX) from aqueous solution by aluminum hydroxide were shown to fit Langmuir plots, and the adsorptive capacities (rmax) and the K values were 7.0 mg/g and 1.77 x 10(4) M-1 for LVFX and 7.4 mg/g and 1.42 x 10(4) M-1 for OFLX, respectively. The rate of adsorption of several quinolones (50 microM) onto aluminum hydroxide (2.5 mg/ml) followed the order norfloxacin (NFLX) (72.0%) > enoxacin (ENX) (61.0%) > OFLX (47.2%) approximately LVFX (48.1%). The elution rate of adsorbed quinolones with water followed the rank order LVFX (17.9%) approximately OFLX (20.9%) approximately ENX (18.3%) > NFLX (11.9%). These results strongly suggest that adsorption of quinolones by aluminum hydroxide reprecipitated in the small intestine would play an important role in the reduced bioavailability of quinolones after coadministration with aluminum-containing antacids.

  13. Application of recovered magnesium hydroxide from a flue gas desulfurization system for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, P.L.; Wu, Q.; Keener, T.; Zhuang, L.A.; Gurusamy, R.; Pehkonen, S.

    1999-07-01

    Magnesium hydroxide, reclaimed from the flue gas desulfurization system (FGD) at the Zimmer Power Plant, Cincinnati, Ohio, is a weak base, in the form of either a slurry or powder. It has many potential applications for wastewater treatment. The objectives of this research are (1) to characterize the reclaimed magnesium hydroxide, e.g., purity, particle size distribution, dissolution kinetics; (2) to evaluate neutralization capacity and buffering intensity of the reclaimed magnesium hydroxide; (3) to study the efficacy of the reclaimed magnesium hydroxide for nutrient removal in wastewater treatment processes; (4) to investigate whether and how the magnesium hydroxide influences the characteristics of the activated sludge floc; (5) to determine whether magnesium hydroxide improves the anaerobic sludge digestion process and associated mechanisms; and (6) to conduct a cost-benefit analysis for the application of the reclaimed magnesium hydroxide in wastewater treatment and the possibility of marketing this product. Research results to date show that the purity of the reclaimed magnesium hydroxide depends largely on the recovery hydroxide slurry. This product proved to be very effective for wastewater neutralization, compared with other commonly used chemicals, both for its neutralization capacity and its buffering intensity. Due to its relatively low solubility in water and its particle size distribution characteristics, magnesium hydroxide behaves like a weak base, which will be very beneficial for process control. The authors also found that nitrogen and phosphorus could be removed from the wastewater using magnesium hydroxide due to their complexation and precipitation as magnesium ammonium phosphate (struvite). Magnesium hydroxide also greatly enhanced the settleability of the activated sludge. Intensive research on the mechanisms associated with these phenomena reveals that sweep flocculation and magnesium ion bridging between exopolymeric substances (EPS) of

  14. Synthesis, characterisation and electrochemical behaviour of Cu(II), Co(II), Ni(II) and Zn(II) complexes derived from acetylacetone and p-anisidine and their antimicrobial activity

    Indian Academy of Sciences (India)

    N Raman; V Muthuraj; S Ravichandran; A Kulandaisamy

    2003-06-01

    Neutral tetradentate N2O2 type complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesised using the Schiff base formed by the condensation of acetylacetone and p-anisidine. Microanalysis, molar conductance, magnetic susceptibility, IR, UV-Vis, 1H NMR, CV and EPR studies have been carried out to determine the structure of the complexes. From the data, it is found that all the complexes possess square-planar geometry. The EPR spectrum of the copper complex in DMSO at 300 K and 77 K was recorded and its salient features are reported. All the title complexes were screened for antimicrobial activity by the well diffusion technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values were calculated at 37°C for a period of 24 h. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand.

  15. Hydroxide ion concentration at an interface between concrete and a self-levelling flooring compound

    OpenAIRE

    Anderberg, Anders; Wadsö, Lars

    2007-01-01

    This article presents results from measurements of hydroxide ion transport between a concrete and a floor screed of a lower alkalinity than the concrete. As many floor coverings and floor adhesives are sensitive to high alkaline conditions it is important to know how hydroxide ions are transported to be able to evaluate the long-term function of floor constructions. It was found that only minor transport of hydroxide ions occurs in the hygroscopic moisture range. One conclusion is therefore t...

  16. Direct ethanol fuel cell using hydrotalcite clay as a hydroxide ion conductive electrolyte.

    Science.gov (United States)

    Tadanaga, Kiyoharu; Furukawa, Yoshihiro; Hayashi, Akitoshi; Tatsumisago, Masahiro

    2010-10-15

    An alkaline-type direct ethanol fuel cell (DEFC) using a natural clay electrolyte with non-platinum catalysts is proposed. So-called hydrotalcite clay, Mg–Al layered double hydroxide intercalated with CO₃²⁻, is shown to be a hydroxide ion conductor. An alkaline-type DEFC using this natural clay as the electrolyte and aqueous solution of ethanol and potassium hydroxide as a source of fuel exhibits excellent electrochemical performance from room temperature to 80 °C.

  17. Cu2+ ions as a paramagnetic probe to study the surface chemical modification process of layered double hydroxides and hydroxide salts with nitrate and carboxylate anions.

    Science.gov (United States)

    Arizaga, Gregorio Guadalupe Carbajal; Mangrich, Antonio Salvio; Wypych, Fernando

    2008-04-01

    A layered zinc hydroxide nitrate (Zn5(OH)8(NO3)2.2H2O) and a layered double hydroxide (Zn/Al-NO3) were synthesized by coprecipitation and doped with different amounts of Cu2+ (0.2, 1, and 10 mol%), as paramagnetic probe. Although the literature reports that the nitrate ion is free (with D3h symmetry) between the layers of these two structures, the FTIR spectra of two zinc hydroxide nitrate samples show the C2v symmetry for the nitrate ion, whereas the g ||/A || value in the EPR spectra of Cu2+ is high. This fact suggests bonding of some nitrate ions to the layers of the zinc hydroxide nitrate. The zinc hydroxide nitrate was used as matrix in the intercalation reaction with benzoate, o-chlorobenzoate, and o-iodobenzoate ions. FTIR spectra confirm the ionic exchange reaction and the EPR spectroscopy reveals bonding of the organic ions to the inorganic layers of the zinc hydroxide nitrate, while the layered double hydroxides show only exchange reactions.

  18. Effective Production of Sorbitol and Mannitol from Sugars Catalyzed by Ni Nanoparticles Supported on Aluminium Hydroxide

    OpenAIRE

    Rodiansono Rodiansono; Shimazu Shogo

    2013-01-01

    Effective production of hexitols (sorbitol and mannitol) was achieved from sugars by means of nickel nanoparticles supported on aluminium hydroxide (NiNPs/AlOH) catalyst. NiNPs/AlOH catalyst was prepared by a simple and benign environmentally procedure using less amount of sodium hydroxide. ICP-AES and XRD analyses confirmed that the NiNPs/AlOH catalysts comprised a large amount of remained aluminium hydroxide (i.e. bayerite and gibbsite). The presence of aluminium hydroxide caused a high dis...

  19. Effects of salinity and humic acid on the sorption of Hg on Fe and Mn hydroxides.

    Science.gov (United States)

    Liang, Peng; Li, Yi-Chun; Zhang, Chan; Wu, Sheng-Chun; Cui, Hao-Jie; Yu, Shen; Wong, Ming H

    2013-01-15

    The objective of this study was to investigate the influence of humic acid (HA) and salinity on adsorption of Hg on the amorphous and crystalline of iron and manganese hydroxides. The results show that the adsorption of Hg(2+) on Fe and Mn hydroxides was inhibited in marine system due to the formation of stable, nonsorbing aqueous HgCl(2) complexes in solution. Moreover, Cl(-) inhibited the Hg(2+) adsorption more severely on amorphous than crystalline hydroxides. The addition of HA inhibited Hg(2+) adsorption on Fe and Mn hydroxides in freshwater system might be attributed to the competition between Hg(2+) and HA on adsorption to Fe and Mn hydroxides. In contrast, the addition of HA promoted Hg(2+) adsorption on Fe and Mn hydroxides in the marine system, which might be due to the addition of humic acid resulted in the reaction between Cl(-) and HA, and therefore the reducing of Cl(-) promoted more Hg(2+) on Fe and Mn hydroxides. In addition, the influence of HA on Hg(2+) adsorption on Fe and Mn hydroxides are more visible for crystalline than amorphous hydroxides.

  20. Antimicrobial activity of calcium hydroxide and chlorhexidine on intratubular Candida albicans

    Institute of Scientific and Technical Information of China (English)

    Ronan Jacques Rezende Delgado; Thaís Helena Gasparoto; Carla Renata Sipert; Claudia Ramos Pinheiro; Ivaldo Gomes de Moraes; Roberto Brandāo Garcia; Marco Antonio Hungaro Duarte; Clóvis Monteiro Bramante; Sérgio Aparecido Torres; Gustavo Pompermaier Garlet; Ana Paula Campanelli; Norberti Bernardineli

    2013-01-01

    This study investigated the efficacy of calcium hydroxide and chlorhexidine gel for the elimination of intratubular Candida albicans (C. albicans). Human single-rooted teeth contaminated with C. albicans were treated with calcium hydroxide, 2% chlorhexidine gel, calcium hydroxide plus 2% chlorhexidine gel, or saline (0.9% sodium chloride) as a positive control. The samples obtained at depths of 0-100 and 100-200 μm from the root canal system were analyzed for C. albicans load by counting the number of colony forming units and for the percentage of viable C. albicans using fluorescence microscopy. First, the antimicrobial activity of calcium hydroxide and the 2% chlorhexidine gel was evaluated by counting the number of colony forming units. After 14 days of intracanal medication, there was a significant decrease in the number of C. albicanscolony forming units at a depth of 0-100 lzm with chlorhexidine treatment either with or without calcium hydroxide compared with the calcium hydroxide only treatment. However, there were no differences in the number of colony forming units at the 100-200 μm depth for any of the medications investigated. C. albicans viability was also evaluated by vital staining techniques and fluorescence microscopy analysis. Antifungal activity against C. albicans significantly increased at both depths in the chlorhexidine groups with and without calcium hydroxide compared with the groups treated with calcium hydroxide only. Treatments with only chlorhexidine or chlorhexidine in combination with calcium hydroxide were effective for elimination of C. albicans.

  1. Cellular Uptake Behavior of Fluorescein: Intercalated Layered Double Hydroxide

    Science.gov (United States)

    Tanaka, Miyuki; Aisawa, Sumio; Hirahara, Hidetoshi; Narita, Eiichi; Yin, Shu; Sato, Tsugio

    2012-06-01

    In order to define the ability of layered double hydroxide (LDH) as materials for drug delivery, fluorescein (Fluo) anion intercalated LDH (Fluo/LDH) was synthesized by hydrothermal treatment and observed the cellular uptake of the Fluo/LDH for mammalian cell (L929). The synthesized Fluo/LDH showed a LDH structure, high fluorescence and low cytotoxicity. According to the fluorescence, confocal and TEM images of cells, the Fluo/LDH seemed to be internalized into the L929 cell by cellular endocytosis and dissolved inside the cell to exhibit the fluorescence of cellular cytoplasm.

  2. Kinetics of sorption of oil products by hydroxide precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Petrova, N.A.; Dubrovskaya, G.E.; Berezyuk, V.G.; Pushkarev, V.V.

    1976-01-01

    Study of the kinetics of sorption of oils (palm and coriander oils, Genrex-26, Emulsol E-2(B)) under static conditions by aluminum and iron hydroxide precipitates (with FeSO/sub 4/, FeCl/sub 3/, and AlCl/sub 3/ as coagulants) showed that an increase of temperature to 40 to 50/sup 0/C raises the sorption rate substantially. The kinetic relations can be represented by equations for first-order reactions. The calculated rate constants and the values of the empirical activation energies are evidence of physical sorption with diffusion as the controlling step.

  3. Kinetics of gibbsite leaching in sodium hydroxide aqueous solution

    Directory of Open Access Journals (Sweden)

    Pavlović Ljubica J.

    2002-01-01

    Full Text Available In order to study the kinetics and mechanism of the reaction, laboratory leaching was carried out with industrially produced gibbsite γ-Al(OH3 in aqueous solutions containing an excess of sodium hydroxide. The results obtained reaction temperature, duration and base concentration varied. The basic kinetic parameters were determined from: the reaction rate constant k=8.72·107 exp (-74990/RT and the process activation energy in the range Ea=72.5-96.81 kJ/mol.

  4. The photoluminescence of Co-Al-layered double hydroxide

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    We report a new optical behaviour of pure Co-Al-layered double hydroxide (LDH). It was found that the Co-Al-LDH sample could emit fluorescence without any fluorescent substances intercalated. Its excitation spectrum shows a maximum peak near the wavelength 370 nm, the maximum emission peak appears at 430 nm and the photoluminescence colour of the Co-Al-LDH sample is blue. This new optical property will be expected to extend the potential applications of LDHs in optical materials field.

  5. LAYERED DOUBLE HYDROXIDES: NANOMATERIALS FOR APPLICATIONS IN AGRICULTURE

    Directory of Open Access Journals (Sweden)

    Luíz Paulo Figueredo Benício

    2015-02-01

    Full Text Available The current research aims to introduce Layered Double Hydroxides (LDH as nanomaterials to be used in agriculture, with particular reference to its use as storage and slow release matrix of nutrients and agrochemicals for plant growing. Structural characteristics, main properties, synthesis methods and characterization of LDH were covered in this study. Moreover, some literature data have been reported to demonstrate their potential for storage and slow release of nitrate, phosphate, agrochemicals, besides as being used as adsorbent for the wastewater treatment. This research aims to expand, in near future, the investigation field on these materials, with application in agriculture, increasing the interface between chemistry and agronomy.

  6. Ions in water: the microscopic structure of concentrated hydroxide solutions.

    Science.gov (United States)

    Imberti, S; Botti, A; Bruni, F; Cappa, G; Ricci, M A; Soper, A K

    2005-05-15

    Neutron-diffraction data on aqueous solutions of hydroxides, at solute concentrations ranging from 1 solute per 12 water molecules to 1 solute per 3 water molecules, are analyzed by means of a Monte Carlo simulation (empirical potential structure refinement), in order to determine the hydration shell of the OH- in the presence of the smaller alkali metal ions. It is demonstrated that the symmetry argument between H+ and OH- cannot be used, at least in the liquid phase at such high concentrations, for determining the hydroxide hydration shell. Water molecules in the hydration shell of K+ orient their dipole moment at about 45 degrees from the K+-water oxygen director, instead of radially as in the case of the Li+ and Na+ hydration shells. The K+-water oxygen radial distribution function shows a shallower first minimum compared to the other cation-water oxygen functions. The influence of the solutes on the water-water radial distribution functions is shown to have an effect on the water structure equivalent to an increase in the pressure of the water, depending on both ion concentration and ionic radius. The changes of the water structure in the presence of charged solutes and the differences among the hydration shells of the different cations are used to present a qualitative explanation of the observed cation mobility.

  7. Cation ordering and superstructures in natural layered double hydroxides.

    Science.gov (United States)

    Krivovichev, Sergey V; Yakovenchuk, Victor N; Zolotarev, Andrey A; Ivanyuk, Gregory N; Pakhomovsky, Yakov A

    2010-01-01

    Layered double hydroxides (LDHs) constitute an important group of materials with many applications ranging from catalysis and absorption to carriers for drug delivery, DNA intercalation and carbon dioxide sequestration. The structures of LDHs are based upon double brucite-like hydroxide layers [M(2+)(n)M(3+)(m)(OH)(2(m+n)](m+), where M(2+) = Mg(2+), Fe(2+), Mn(2+), Zn(2+), etc.; M(3+) = Al(3+), Fe(3+), Cr(3+), Mn(3+), etc. Structural features of LDHs such as cation ordering, charge distribution and polytypism have an immediate influence upon their properties. However, all the structural studies on synthetic LDHs deal with powder samples that prevent elucidation of such fine details of structure architecture as formation of superstructures due to cation ordering. In contrast to synthetic materials, natural LDHs are known to form single crystals accessible to single-crystal X-ray diffraction analysis, which provides a unique possibility to investigate 3D cation ordering in LDHs that results in formation of complex superstructures, where 2D cation order is combined with a specific order of layer stacking (polytypism). Therefore LDH minerals provide an indispensable source of structural information for modeling of structures and processes happening in LDHs at the molecular and nanoscale levels.

  8. Experimental and Theoretical Studies of Volatile Metal Hydroxides

    Science.gov (United States)

    Myers, Dwight L.; Jacobson, Nathan S.

    2015-01-01

    Modern superalloys used in the construction of turbomachinery contain a wide range of metals in trace quantities. In addition, metal oxides and silicon dioxide are used to form Thermal Barrier Coatings (TBC) to protect the underlying metal in turbine blades. Formation of volatile hydroxides at elevated temperatures is an important mechanism for corrosion of metal alloys or oxides in combustion environments (N. Jacobson, D. Myers, E. Opila, and E. Copland, J. Phys. Chem. Solids 66, 471-478, 2005). Thermodynamic data is essential to proper design of components of modern gas turbines. It is necessary to first establish the identity of volatile hydroxides formed from the reaction of a given system with high temperature water vapor, and then to determine the equilibrium pressures of the species under operating conditions. Theoretical calculations of reaction energies are an important check of experimental results. This presentation reports results for several important systems: Si-O-H, Cr-O-H, Al-O-H, Ti-O-H, and ongoing studies of Ta-O-H.

  9. Electrochemical Recovery of Sodium Hydroxide from Alkaline Salt Solution

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Westinghouse Savannah River Company, AIKEN, SC (United States); Edwards, T.B.

    1996-10-01

    A statistically designed set of tests determined the effects of current density, temperature, and the concentrations of nitrate/nitrite, hydroxide and aluminate on the recovery of sodium as sodium hydroxide (caustic) from solutions simulating those produced from the Savannah River Site (SRS) In-Tank Precipitation process. These tests included low nitrate and nitrite concentrations which would be produced by electrolytic nitrate/nitrite destruction. The tests used a two compartment electrochemical cell with a Nafion Type 324 ion-exchange membrane. Caustic was successfully recovered from the waste solutions. Evaluation of the testing results indicated that the transport of sodium across the membrane was not significantly affected by any of the varied parameters. The observed variance in the sodium flux is attributed to experimental errors and variations in the performance characteristics of individual pieces of the organic-based Nafion membrane.Additional testing is recommended to determine the maximum current density, to evaluate the chemical durability of the organic membrane as a function of current density and to compare the durability and performance characteristics of the organic-based Nafion membrane with that of other commercially available organic membranes and the inorganic class of membranes under development by Ceramatec and PNNL.

  10. Selectivity of Crystal Growth Direction in Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    赵芸; 梁吉; 李峰; 段雪

    2004-01-01

    Investigation of selectivity of crystal growth direction in layered double hydroxides is helpful to control their particle sizes in different directions. Mg-Al layered double hydroxides (LDHs) were synthesized using a coprecipitation method. The influences of aging temperature, aging time, and Mg/Al molar ratio on the crystal structure, the LDHs particle size, and the selectivity of crystal growth in different directions were investigated. The results show that the size of the crystallites in the a direction is larger than that in the c direction for all experimental conditions, indicating faster crystal growth in the a direction than in the c direction. The crystallite sizes in the a and c directions both increase with decreasing Mg/Al molar ratio but with less difference between the sizes in the two directions. Therefore, the crystal growth rate in the c direction increases more than that in the a direction as the Mg/Al molar ratio decreases. The influence of the aging time, aging temperature, and Mg/Al molar ratio on the selectivity of the crystal growth direction can be used to prepare LDHs with selected sizes in the a and c directions.

  11. Biodiesel synthesis using calcined layered double hydroxide catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Schumaker, J. Link [University of Kentucky; Crofcheck, Czarena [University of Kentucky; TAckett, S. Adam [University of Kentucky; Santillan-Jimenez, Eduardo [University of Kentucky; Morgan, Tonya [University of Kentucky; Ji, Yaying [University of Kentucky; Crocker, Mark [University of Kentucky; Toops, Todd J [ORNL

    2008-01-01

    The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

  12. Rapid collection of iron hydroxide for determination of Th isotopes in seawater.

    Science.gov (United States)

    Okubo, Ayako; Obata, Hajime; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi

    2013-12-04

    This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin directly, resulting in a pH increase of the effluent by release of hydroxide ion from the iron hydroxide. The co-precipitated thorium isotopes were quantitatively collected within the column, which indicated that thorium was retained on the iron hydroxide remaining on the chelating column. The chelating column quantitatively collected (232)Th with iron hydroxide in seawater at flow rates of 20-25 mL min(-1). Based on this flow rate, a 5 L sample was processed within 3-4 h. The >20 h aging of iron hydroxide tends to reduce the recovery of (232)Th. The rapid collection method was successfully applied to the determination of (230)Th and (232)Th in open-ocean seawater samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Physisorption of hydroxide ions from aqueous solution to a hydrophobic surface

    NARCIS (Netherlands)

    Zangi, R; Engberts, JBFN

    2005-01-01

    We present results from detailed molecular dynamics simulations revealing a counterintuitive spontaneous physical adsorption of hydroxide ions at a water/hydrophobic interface. The driving force for the migration of the hydroxide ions from the aqueous phase is the preferential orientation of the

  14. Structural perturbation of diphtheria toxoid upon adsorption to aluminium hydroxide adjuvant

    NARCIS (Netherlands)

    Regnier, Marie; Metz, Bernard; Tilstra, Wichard; Hendriksen, Coenraad; Jiskoot, Wim; Norde, Willem; Kersten, Gideon

    2012-01-01

    Aluminium-containing adjuvants are often used to enhance the potency of vaccines. In the present work we studied whether adsorption of diphtheria toxoid to colloidal aluminium hydroxide induces conformational changes of the antigen. Diphtheria toxoid has a high affinity for the aluminium hydroxide p

  15. Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin

    Directory of Open Access Journals (Sweden)

    Janaina Corazza Montero

    2012-08-01

    Full Text Available This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

  16. Mg/Al Ordering in Layered Double Hydroxides Revealed by Multinuclear NMR Spectroscopy

    DEFF Research Database (Denmark)

    Nielsen, Ulla Gro; Grey, Clare P.; Sideris, Paul J.

    2008-01-01

    The anion- exchange ability of layered double hydroxides ( LDHs) has been exploited to create materials for use in catalysis, drug delivery, and environmental remediation. The specific cation arrangements in the hydroxide layers of hydrotalcite- like LDHs, of general formula Mg1-x2+Alx3+OH2(Anion...

  17. Layered double hydroxide stability. 2. Formation of Cr(III)-containing layered double hydroxides directly from solution

    Science.gov (United States)

    Boclair, J. W.; Braterman, P. S.; Jiang, J.; Lou, S.; Yarberry, F.

    1999-01-01

    Solutions containing divalent metal [M(II) = Mg2+, Zn2+, Co2+, Ni2+, Mn2+] chlorides and CrCl3 6H2O were titrated with NaOH to yield, for M(II) = Zn, Co, and Ni, hydrotalcite-like layered double hydroxides (LDHs), [[M(II)]1-z[Cr(III)]z(OH)2][Cl]z yH2O, in a single step, without intermediate formation of chromium hydroxide. Analysis of the resultant titration curves yields solubility constants for these compounds. These are in the order Zn < Ni approximately Co, with a clear preference for formation of the phase with z = 1/3. With Mg2+ as chloride, titration gives a mixture of Cr(OH)3 and Mg(OH)2, but the metal sulfates give Mg2Cr(OH)6 1/2(SO4) by a two-step process. Titrimetric and spectroscopic evidence suggests short-range cation order in the one-step LDH systems.

  18. Synthesis and structure refinement of layered double hydroxides of Co, Mg and Ni with Ga

    Indian Academy of Sciences (India)

    G V Manohara; P Vishnu Kamath

    2010-06-01

    Homogeneous precipitation by urea hydrolysis results in the formation of highly ordered layered double hydroxides of divalent metal ions (Co, Mg, Ni) and Ga. Structure refinement shows that these carbonate containing layered hydroxides crystallize with rhombohedral symmetry (space group -3) in the structure of the 31 polytype. An analysis of the structure shows that, coulombic attraction between the layer and interlayer remains invariant in different layered hydroxides, whereas the strength of hydrogen bonding varies. The Ni–Ga LDH has the weakest hydrogen bonding and Co–Ga, the strongest, as reflected by the layer–interlayer oxygen–oxygen distances. The poor polarity of the OH bond in the Ni–Ga hydroxide points to the greater covalency of the (2+}/′3+)-oxygen bond in this compound as opposed to the Co–Ga hydroxide. These observations are supported by IR spectra.

  19. The Deactivation of Nickel Hydroxide to Hypophosphite Electrooxidation on a Nickel Electrode

    Institute of Scientific and Technical Information of China (English)

    Yue ZENG; Min MO; Jian Long YI; Xin Jun TANG; Hui Xian WANG

    2004-01-01

    The deactivation of nickel hydroxide to the electrooxidation of hypophosphite on a nickel electrode was studied by means of in situ UV-Vis subtractive reflectance spectroscopy. The experimental results show that when the potential is lower than -1.0 V (SCE), the surface on nickel electrode is free of nickel hydroxide, on which hypophosphite is active. When the potential moves positively to about-0.75V, two absorbency bands around 300 nm and 550 nm, which were ascribed to the formation of α-nickel hydroxide, were observed, nickel is oxidized to α-nickel hydroxide.Severe deactivation of the surface occurs when the nickel surface is covered with nickel hydroxide,which separates the hypophosphite ion from nickel substrate.

  20. Electronic spectra of anions intercalated in layered double hydroxides

    Indian Academy of Sciences (India)

    S Radha; P Vishnu Kamath

    2013-10-01

    Transition metal complexes intercalated in layered double hydroxides have a different electronic structure as compared to their free state owing to their confinement within the interlayer gallery. UV–Vis absorptions of the intercalated complex anions show a significant shift as compared to their free state. The ligand to metal charge transfer transitions of the ferricyanide anion show a red shift on intercalation. The ferrocyanide ion shows a significant blue shift of – bands due to the increased separation between 2g and g levels on intercalation. MnO$^{-}_{4}$ ion shows a blue shift in its ligand to metal charge transfer transition since the non-bonding 1 level of oxygen from which the transition arises is stabilized.

  1. Biological evaluation of layered double hydroxides as efficient drug vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan; Liu Dan; Chang Qing; Liu Dandan; Xia Ying; Liu Shuwen; Peng Nanfang; Yang Xu [Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Science, Huazhong Normal University, Wuhan 430079 (China); Ai Hanhua [College of Physical Science and Technology, Huazhong Normal University, Wuhan 430079 (China); Xi Zhuge, E-mail: yangxu@mail.ccnu.edu.cn [Tianjin Institutes of Health and Environmental Medicine, Tianjin 300050 (China)

    2010-03-12

    Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

  2. Synthesis of tetramethyl ammonium hydroxide by cell diaphragm electrolytic method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Under the conditions of tetramethyl ammonia chloride (TMAC) used as starting material, Ti-based Dimensionally Stable Anode (DSA), stainless steel used as cathode and Nafion 900 cation membrane as cell diaphragm, this paper studies the synthesis of tetramethyl ammonium hydroxide (TMAH) by cell diaphragm electrolytic method, examining not only the effects of current density, concentration of starting material and cell temperature, on the product purity and current efficiency, but also the effects of electrolyte circulation rate on the service life of Ti-based DSA.The experiment puts forward an optimum processing condition, and experimental findings show that preparing TMAH by using this technique can obtain a current efficiency 74.7 % and get product with a purity greater than 99.9%.

  3. Application of Hydrosoluble Polymers to Preparation of Nanoscale Calcium Hydroxide

    Institute of Scientific and Technical Information of China (English)

    XU Jing; CHEN Qing-hua; QIAN Qing-rong

    2004-01-01

    Calcium hydroxide with uniform diameters about 50-100 nm was firstly prepared under moderate condition by adding different kinds of hydrosoluble polymers. From the results of TEM and IR, the polymers were proved not only to improve the agglomeration of the nanoparticles but also to be used as a template to control the formation of the special structure and the needed size of Ca (OH)2 by changing the concentration of the polymers. The experimental results of TG-DTA indicate that the Ca(OH)2 can absorb most of the acid gases released during the decomposition of polymers. So this kind of nano-Ca(OH)2 can be used as a useful additive of environmental friendly plastics.

  4. Polymerization reaction in restricted space of layered double hydroxides (LDHs)

    Institute of Scientific and Technical Information of China (English)

    SI Lichun; WANG Ge; CAI Fuli; WANG Zhiqiang; DUAN Xue

    2004-01-01

    This paper reported the preparation of styrene sulfonate intercalated layered double hydroxides (LDHs) material, SS-LDHs by coprecipitation method, followed by in-situ polymerization of the monomers in the interlayer space of LDHs. The polymerization reaction was monitored by UV and NMR. It is confirmed that when the reaction occurred at 100℃ for 24 h, part of monomers did not react .When the reaction was carried out at 150℃, the polymeriza tion of the intercalated monomers is complete to afford the polymer intercalated product PSS-LDHs. During the polymerization process, the layered structure remains well. At thesame time the gallery height increases with the lengthening of reaction time. This is preliminarily because that the PSS becomes more swelling with the amount of water it absorbs due to its hygroscopicity property.

  5. Hydrothermal Synthesis of Ni/Al Layered Double Hydroxide Nanorods

    Directory of Open Access Journals (Sweden)

    Yun Zhao

    2011-01-01

    Full Text Available Ni/Al layered double hydroxide (LDH nanorods were successfully synthesized by the hydrothermal reaction. The crystal structure of the products was characterized by X-ray diffraction (XRD. The morphology of the products was observed using transmission electron microscopy (TEM and field emission scanning electron microscopy (SEM. The influences of reaction time and pH value on the morphology of the Ni/Al LDHs were investigated. The result showed that the well-crystallized nanorods of Ni/Al LDHs could be obtained when the pH value was about 10.0 with a long reaction time (12–18 h at 180°C.

  6. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    Science.gov (United States)

    Bi, Xue; Zhang, Hui; Dou, Liguang

    2014-01-01

    Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS). In this article, we review developments in the use of layered double hydroxides (LDHs) for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i) DDS with cardiovascular drugs as guests; (ii) DDS with anti-inflammatory drugs as guests; and (iii) DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed. PMID:24940733

  7. Layered Double Hydroxide-Based Nanocarriers for Drug Delivery

    Directory of Open Access Journals (Sweden)

    Xue Bi

    2014-06-01

    Full Text Available Biocompatible clay materials have attracted particular attention as the efficient drug delivery systems (DDS. In this article, we review developments in the use of layered double hydroxides (LDHs for controlled drug release and delivery. We show how advances in the ability to synthesize intercalated structures have a significant influence on the development of new applications of these materials. We also show how modification and/or functionalization can lead to new biotechnological and biomedical applications. This review highlights the most recent progresses in research on LDH-based controlled drug delivery systems, focusing mainly on: (i DDS with cardiovascular drugs as guests; (ii DDS with anti-inflammatory drugs as guests; and (iii DDS with anti-cancer drugs as guests. Finally, future prospects for LDH-based drug carriers are also discussed.

  8. Hydroxide as general base in the saponification of ethyl acetate.

    Science.gov (United States)

    Mata-Segreda, Julio F

    2002-03-13

    The second-order rate constant for the saponification of ethyl acetate at 30.0 degrees C in H(2)O/D(2)O mixtures of deuterium atom fraction n (a proton inventory experiment) obeys the relation k(2)(n) = 0.122 s(-1) M(-1) (1 - n + 1.2n) (1 - n + 0.48n)/(1 - n + 1.4n) (1 - n + 0.68n)(3). This result is interpreted as a process where formation of the tetrahedral intermediate is the rate-determining step and the transition-state complex is formed via nucleophilic interaction of a water molecule with general-base assistance from hydroxide ion, opposite to the direct nucleophilic collision commonly accepted. This mechanistic picture agrees with previous heavy-atom kinetic isotope effect data of Marlier on the alkaline hydrolysis of methyl formate.

  9. The kinetic parameters of carbonaceous materials activated with potassium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Z.; Han, B.X.

    2000-07-01

    On the basis of microspore formation in carbonaceous materials, the activation energy for the potassium hydroxide activation of Chinese petroleum coke and coal has been deduced theoretically as dB(O)/dt = A exp(-E(a)) is an element of/RT), where is an element of is the formation energy for the metastable solid formed at the activation temperature. The kinetic parameters (frequency factor, A, and apparent activation energy, E(a) were calculated from this equation as being 5.319 mg/(g min), 36.51 kJ/mol and 6.64 mg/(g min), 49.46 kJ/mol, respectively, for the two carbonaceous materials studied.

  10. An Aluminum Magnesium Hydroxide Stearate-based Skin Barrier Protection Cream Used for the Management of Eczematous Dermatitis

    Science.gov (United States)

    Bhambri, Sanjay; Michaels, Brent

    2008-01-01

    Eczematous dermatoses can often be very difficult to treat. An aluminum magnesium hydroxide stearate-based cream has recently become available for clinical use. Aluminum magnesium hydroxide stearate-based cream provides an alternative option in treating these dermatoses while providing barrier protection against external allergens and irritants. This article reviews various studies evaluating aluminum magnesium hydroxide stearate-based cream. PMID:21212843

  11. Structural characterisation of a layered double hydroxide nanosheet

    Science.gov (United States)

    Funnell, Nicholas P.; Wang, Qiang; Connor, Leigh; Tucker, Matthew G.; O'Hare, Dermot; Goodwin, Andrew L.

    2014-06-01

    We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves.We report the atomic-scale structure of a Zn2Al-borate layered double hydroxide (LDH) nanosheet, as determined by reverse Monte Carlo (RMC) modelling of X-ray total scattering data. This study involves the extension of the RMC method to enable structural refinement of two-dimensional nanomaterials. The refined LDH models show the intra-layer geometry in this highly-exfoliated phase to be consistent with that observed in crystalline analogues, with the reciprocal-space scattering data suggesting a disordered arrangement of the Zn2+ and Al3+ cations within the nanosheet. The approach we develop is generalisable and so offers a method of characterising the structures of arbitrary nanosheet phases, including systems that support complex forms of disorder within the nanosheets themselves. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01265h

  12. Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with μ3-η2:η2:η2 bonding.

    Science.gov (United States)

    Bag, Pradip; Dutta, Supriya; Biswas, Papu; Maji, Swarup Kumar; Flörke, Ulrich; Nag, Kamalaksha

    2012-03-28

    A series of mononuclear lanthanide(III) complexes [Ln(LH(2))(H(2)O)(3)Cl](ClO(4))(2) (Ln = La, Nd, Sm, Eu, Gd, Tb, Lu) of the tetraiminodiphenolate macrocyclic ligand (LH(2)) in 95 : 5 (v/v) methanol-water solution fix atmospheric carbon dioxide to produce the carbonato-bridged trinuclear complexes [{Ln(LH(2))(H(2)O)Cl}(3)(μ(3)-CO(3))](ClO(4))(4)·nH(2)O. Under similar conditions, the mononuclear Y(III) complex forms the dimeric compound [{Y(LH(2))(H(2)O)Cl}(μ(2)-CO(3)){Y(LH(2))(H(2)O)(2)}](ClO(4))(3)·4H(2)O. These complexes have been characterized by their IR and NMR ((1)H, (13)C) spectra. The X-ray crystal structures have been determined for the trinuclear carbonato-bridged compounds of Nd(III), Gd(III) and Tb(III) and the dinuclear compound of Y(III). In all cases, each of the metal centers are 8-coordinate involving two imine nitrogens and two phenolate oxygens of the macrocyclic ligand (LH(2)) whose two other imines are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The oxygen atoms of the carbonate anion in the trinuclear complexes are bonded to the metal ions in tris-bidentate μ(3)-η(2):η(2):η(2) fashion, while they are in bis-bidentate μ(2)-η(2):η(2) mode in the Y(III) complex. The magnetic properties of the Gd(III) complex have been studied over the temperature range 2 to 300 K and the magnetic susceptibility data indicate a very weak antiferromagnetic exchange interaction (J = -0.042 cm(-1)) between the Gd(III) centers (S = 7/2) in the metal triangle through the carbonate bridge. The luminescence spectral behaviors of the complexes of Sm(III), Eu(III), and Tb(III) have been studied. The ligand LH(2) acts as a sensitizer for the metal ions in an acetonitrile-toluene glassy matrix (at 77 K) and luminescence intensities of the complexes decrease in the order Eu(3+) > Sm(3+) > Tb(3+).

  13. Preparation of amorphous aluminum oxide-hydroxide nanoparticles in amphiphilic silicone-based copolymer microemulsions.

    Science.gov (United States)

    Berkovich, Yana; Aserin, Abraham; Wachtel, Ellen; Garti, Nissim

    2002-01-01

    Organo-inorgano nanocomposites with colloidal dimensions have interesting optical, catalytic, and mechanical properties, particularly when such hybrids are reinforced with transition metal oxide nanoparticles. Nanoparticles with a mean size of 1.0-2.4 nm are obtained through hydrolysis of aluminum isopropoxide in the L(2) phase of amphiphilic (PDMS-POE) polydimethylsiloxane-polyoxyethylene Silwet L-7607-octanol/acetylacetone-water mixtures. The particle sizes are related weakly to the microemulsion composition: 0.8-1.2 nm for 20 wt% Silwet L-7607 and 2.0-2.4 nm for 50 wt% Silwet L-7607. Protection of the particles against aggregation is ensured through their confinement in the intraaggregate colloidal domains. Factors affecting the hydrolysis-condensation process of acetylacetone-complexed aluminum isopropoxide in copolymer-poor and copolymer-rich regions of PDMS-POE W/O microemulsions are studied by Fourier transform infrared spectroscopy, small angle X-ray scattering, and transmission electron microscopy. Prepared nanoparticulate dispersions possess long-term stability and form clear mixtures in different organic polar and nonpolar solvents.

  14. Evaluation of antibacterial effects of different calcium hydroxide compositions on planktonic Enterococcus faecalis

    Directory of Open Access Journals (Sweden)

    Mahdi Tabrizizadeh

    2012-01-01

    Full Text Available Background and Aims: Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in infected root canals and endodontic infections. It is one of the most frequently used intracanal medications in endodontic therapy. The objective of this study was to determine the antimicrobial efficacy of six calcium hydroxide formulations (mixed with saline, lidocaine 2%, chlorhexidine 2%, chlorhexidine 0.2%, Iodine Potassium iodide (IKI 2%, and glycerin on Enterococcus faecalis using agar diffusion test.Materials and Methods: Twelve culture plates were incubated with Enterococcus faecalis. Five cavities were made in each plate with 5 mm diameter and 4 mm depth. Two plates were randomly considered for each calcium hydroxide formulation and filled completely with creamy mixture of tested materials. The plates were incubated at 37ºC for 48 hours. The diameter of inhibition zone around each well was recorded in millimetres and data were submitted to ANOVA and Tukey tests.Results: The results of this study showed that all tested calcium hydroxide pastes had good antimicrobial activity. The antimicrobial activity of calcium hydroxide mixed with lidocaine, chlorhexidine 2% and IKI 2% were significantly greater than that of calcium hydroxide mixed with saline (P0.01.Conclusion: Considering the results of this study, lidocaine 2%, chlorhexidine 2% and IKI 2% are suggested to be used for preparation of calcium hydroxide paste. Further studies with different methods are needed for confirming these results.

  15. Radiation induced synthesis of In{sub 2}O{sub 3} nanoparticles - Part II: Synthesis of In{sub 2}O{sub 3} nanoparticles by thermal decomposition of un-irradiated and γ-irradiated indium acetylacetonate

    Energy Technology Data Exchange (ETDEWEB)

    Al-Resheedi, Ajayb Saud; Alhokbany, Norah Saad [Department of Chemistry, College of Science, King Saud University, KSU, (Saudi Arabia); Mahfouz, Refaat Mohammed, E-mail: rmhfouz@science.au.edu.eg [Chemistry Department, Faculty of Science, Assiut University, AUN, (Egypt)

    2015-09-15

    Pure cubic phase, In{sub 2}O{sub 3} nanoparticles with porous structure were synthesized by solid state thermal oxidation of un-irradiated and γ-irradiated indium acetyl acetonate in presence and absence of sodium dodecyl sulphate as surfactant. The as- synthesized In{sub 2}O{sub 3} nanoparticles were characterized by X-ray diffraction (XRD), fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transition electron microscopy (TEM) and thermogravimetry (TG). The shapes and morphologies of as- synthesized In{sub 2}O{sub 3} nanoparticles were highly affected by γ-irradiation of indium acetyl acetonate precursor and by addition of sodium dodecyl sulphate as surfactant. Calcination of un-irradiated indium acetyl acetonate precursor to 4 hours of 600 °C leads to the formation of spherical- shaped accumulative and merged In{sub 2}O{sub 3} nanoparticles with porous structure, whereas irregular porous architectures composed of pure In{sub 2}O{sub 3} nanoparticles were obtained by using γ-irradiated indium acetylacetonate precursor. The as- prepared In{sub 2}O{sub 3} nano products exhibit photoluminescence emission (PL) property and display thermal stability in a wide range of temperature (25-800 °C) which suggest possible applications in nanoscale optoelectronic devices. (author)

  16. Determination of aluminium in iron, steel and ferrous and non-ferrous alloys by atomic-absorption spectrophotometry after a mercury-cathode separation and extraction of the aluminium-acetylacetone complex.

    Science.gov (United States)

    Donaldson, E M

    1981-07-01

    A method for determining 0.0005% or more of total aluminium in high- and low-alloy steels, iron and ferrovanadium is described. Iron, chromium and other matrix elements are separated from aluminium by electrolysis with a mercury cathode and aluminium is separated from tungsten, titanium, vanadium and phosphate by chloroform extraction of its acetylacetone complex at pH 6.5 from an ammonium acetate-hydrogen peroxide medium. The extract is evaporated to dryness and organic material is destroyed with nitric and perchloric acids. Aluminium is determined by atomic-absorption spectrophotometry in a nitrous oxide-acetylene flame, at 309.3 nm, in a 5% v/v perchloric acid medium containing 1000 mug of sodium per ml. Acid-soluble and acid-insoluble aluminium can also be determined. The method is also applicable to copper- and nickel-base alloys. Results obtained by this method are compared with those obtained spectrophotometrically with Pyrocatechol Violet, after the separations described above followed by the separation of the residual co-extracted iron and copper by a combined ammonium pyrrolidinedithiocarbamate-cupferron-chloroform extraction from 10% v/v hydrochloric acid medium.

  17. Reactive transport modeling at uranium in situ recovery sites: uncertainties in uranium sorption on iron hydroxides

    Science.gov (United States)

    Johnson, Raymond H.; Tutu, Hlanganani; Brown, Adrian; Figueroa, Linda; Wolkersdorfer, Christian

    2013-01-01

    Geochemical changes that can occur down gradient from uranium in situ recovery (ISR) sites are important for various stakeholders to understand when evaluating potential effects on surrounding groundwater quality. If down gradient solid-phase material consists of sandstone with iron hydroxide coatings (no pyrite or organic carbon), sorption of uranium on iron hydroxides can control uranium mobility. Using one-dimensional reactive transport models with PHREEQC, two different geochemical databases, and various geochemical parameters, the uncertainties in uranium sorption on iron hydroxides are evaluated, because these oxidized zones create a greater risk for future uranium transport than fully reduced zones where uranium generally precipitates.

  18. Study on the modulating effect of polysaccharide upon the mineralization of iron hydroxide

    Institute of Scientific and Technical Information of China (English)

    HUANG Jiangbo; SUN Zhenya

    2008-01-01

    To investigate the modulating effect of polysaccharide upon the mineralization of iron hydroxide, a series of simulative biomineralization experiments using dextran and chitosan as organic substrates were conducted in this paper. The results showed that iron hydroxide gel nucleated and grew in polysaccharide molecules, with the self-assemble effect of dextran or chitosan, the nanometer-sized akaganeite was formed. The shape, size and crystal structural type of iron oxyhydroxide formed from iron hydroxide gel depend on the type of polysaccharide and its concentrations.

  19. Evaluation of layered zinc hydroxide nitrate and zinc/nickel double hydroxide salts in the removal of chromate ions from solutions

    Science.gov (United States)

    de Oliveira, Henrique Bortolaz; Wypych, Fernando

    2016-11-01

    Layered zinc hydroxide nitrate (ZnHN) and Zn/Ni layered double hydroxide salts were synthesized and used to remove chromate ions from solutions at pH 8.0. The materials were characterized by many instrumental techniques before and after chromate ion removal. ZnHN decomposed after contact with the chromate solution, whereas the layered structure of Zn/Ni hydroxide nitrate (Zn/NiHN) and Zn/Ni hydroxide acetate (Zn/NiHA) remained their layers intact after the topotactic anionic exchange reaction, only changing the basal distances. ZnHN, Zn/NiHN, and Zn/NiHA removed 210.1, 144.8, and 170.1 mg of CrO42-/g of material, respectively. Although the removal values obtained for Zn/NiHN and Zn/NiHA were smaller than the values predicted for the ideal formulas of the solids (194.3 and 192.4 mg of CrO42-/g of material, respectively), the measured capacities were higher than the values achieved with many materials reported in the literature. Kinetic experiments showed the removal reaction was fast. To facilitate the solid/liquid separation process after chromium removal, Zn/Ni layered double hydroxide salts with magnetic supports were also synthesized, and their ability to remove chromate was evaluated.

  20. Metal oxide and hydroxide nanoarrays: Hydrothermal synthesis and applications as supercapacitors and nanocatalysts

    National Research Council Canada - National Science Library

    Qiu Yang Zhiyi Lu Junfeng Liu Xiaodong Lei Zheng Chang Liang Luo Xiaoming Sun

    2013-01-01

    ... synthesis.This article reviews recent progress in our laboratory related to the hydrothermal synthesis of metal oxide and hydroxide nanoarrays,whose structures are designed aiming to the application on super...

  1. A Ni-Fe Layered Double Hydroxide-Carbon Nanotube Complex for Water Oxidation

    CERN Document Server

    Gong, Ming; Wang, Hailiang; Liang, Yongye; Wu, Justin Zachary; Zhou, Jigang; Wang, Jian; Regier, Tom; Wei, Fei; Dai, Hongjie

    2013-01-01

    Highly active, durable and cost-effective electrocatalysts for water oxidation to evolve oxygen gas hold a key to a range of renewable energy solutions including water splitting and rechargeable metal-air batteries. Here, we report the synthesis of ultrathin nickel iron layered double hydroxide nanoplates on mildly oxidized multi-walled carbon nanotubes. Incorporation of Fe into the nickel hydroxide induced the formation of NiFe-layered double hydroxide. The nanoplates were covalently attached to a network of nanotubes, affording excellent electrical wiring to the nanoplates. The ultra-thin Ni-Fe layered double hydroxide nanoplates/carbon nanotube complex was found to exhibit unusually high electro-catalytic activity and stability for oxygen evolution and outperformed commercial precious metal Ir catalysts.

  2. Antimicrobial effect of calcium hydroxide as endo intracanal dressing on Streptococcus viridans

    Directory of Open Access Journals (Sweden)

    Nanik Zubaidah

    2008-03-01

    Full Text Available Calcium hydroxide had been used as the intra-canal dressing in endodontic treatment due to its high alkaline and antimicrobial capacity. It can also dissolve the necrotic tissue, prevent dental root resorbtion and regenerate a new hard tissue. The aim of this study was to determine the concentration of calcium hydroxide which had the highest antimicrobial effect on Streptococcus viridans. Samples were divided into 5 groups; each group consisted of 8 samples with different concentration of calcium hydroxide. Group I: 50%, group II: 55, Group III: 60%, Group IV: 65%, Group V: 70%. The antimicrobial testing was performed using diffusion method against Streptococcus viridans. The result of susceptibility test was showed by the inhibition zone diameter which measured with caliper (in millimeter. We analyzed the data using One-Way ANOVA test with significant difference 0.05 and subsequently LSD test. The study showed that calcium hydroxide with concentration 60% has the highest antimicrobial effect.

  3. Hydroxide Ion Oxidation in Aqueous Solutions Using Boron-Doped Diamond Electrodes.

    Science.gov (United States)

    Irkham; Watanabe, Takeshi; Einaga, Yasuaki

    2017-07-05

    The electrochemical oxidation behavior of hydroxide ions at the surface of boron-doped diamond (BDD) electrodes is presented. The hydroxide ion oxidation behavior was found to be affected by the surface conditions of the BDD electrode. Over the NaOH concentration range of 0.5-10 mM, a well-defined voltammetric wave attributed to hydroxide ion oxidation was observed at ∼1.25 V versus a Ag/AgCl reference electrode when using an anodically oxidized BDD (AO-BDD) electrode, while it was observed at around ∼1.15 V when a cathodically reduced BDD (CR-BDD) electrode was used. Although the hydroxide ion oxidation profiles were slightly different for the AO-BDD and CR-BDD electrodes, the peak currents was each found to have linear relationships with the NaOH concentration over the same range.

  4. Thermochemistry of calcium oxide and calcium hydroxide in fluoride slags

    Science.gov (United States)

    Chattopadhyay, S.; Mitchell, A.

    1990-08-01

    Calcium oxide activity in binary CaF2-CaO and ternary CaF2-CaO-Al2O3 and CaF2-CaO-SiO2 slags has been determined by CO2-slag equilibrium experiments at 1400 °C. The carbonate ca-pacity of these slags has also been computed and compared with sulfide capacity data available in the literature. The similarity in trends suggests the possibility of characterizing carbonate capacity as an alternative basicity index for fluoride-base slags. Slag-D2O equilibrium experi-ments are performed at 1400°C with different fluoride-base slags to determine water solubility at two different partial pressures of D2O, employing a new slag sampling technique. A novel isotope tracer detection technique is employed to analyze water in the slags. The water solubility data found show higher values than the previous literature data by an order of magnitude but show a linear relationship with the square root of water vapor partial pressure. The activity of hydroxide computed from the data is shown to be helpful in estimating water solubility in in-dustrial electroslag remelting (ESR) slags.

  5. Defluoridation from aqueous solutions by granular ferric hydroxide (GFH).

    Science.gov (United States)

    Kumar, Eva; Bhatnagar, Amit; Ji, Minkyu; Jung, Woosik; Lee, Sang-Hun; Kim, Sun-Joon; Lee, Giehyeon; Song, Hocheol; Choi, Jae-Young; Yang, Jung-Seok; Jeon, Byong-Hun

    2009-02-01

    This research was undertaken to evaluate the feasibility of granular ferric hydroxide (GFH) for fluoride removal from aqueous solutions. Batch experiments were performed to study the influence of various experimental parameters such as contact time (1 min-24h), initial fluoride concentration (1-100 mgL(-1)), temperature (10 and 25 degrees C), pH (3-12) and the presence of competing anions on the adsorption of fluoride on GFH. Kinetic data revealed that the uptake rate of fluoride was rapid in the beginning and 95% adsorption was completed within 10 min and equilibrium was achieved within 60 min. The sorption process was well explained with pseudo-first-order and pore diffusion models. The maximum adsorption capacity of GFH for fluoride removal was 7.0 mgg(-1). The adsorption was found to be an endothermic process and data conform to Langmuir model. The optimum fluoride removal was observed between pH ranges of 4-8. The fluoride adsorption was decreased in the presence of phosphate followed by carbonate and sulphate. Results from this study demonstrated potential utility of GFH that could be developed into a viable technology for fluoride removal from drinking water.

  6. Tetramethylammonium hydroxide poisoning during a pallet cleaning demonstration.

    Science.gov (United States)

    Park, Seung-Hyun; Park, Jungsun; You, Ki-Ho; Shin, Hae-Chul; Kim, Hyun-Ock

    2013-01-01

    The purpose of this study was to examine the cause of an accidental death from acute poisoning resulting from exposure to a cleaner containing tetramethylammonium hydroxide (TMAH) and to consider measures to prevent future cases. The authors examined the details and the reason for the accidental death from acute poisoning based on the autopsy report. The victim was a 39-year-old male researcher with 7 years of work experience employed by a surfactant production company. The accident occurred when he was conducting a field test of a newly developed cleaner, containing 8.75% TMAH solution. The researcher spilled the cleaner on his work clothes in the area of both the hands/arms and legs. He was unconscious when discovered. An autopsy found no damage or injury that could have resulted in death other than burns to 12% of his body, and the cause of death was found to be acute poisoning by TMAH. TMAH is widely used in the electronics industry as a developer or cleaner. It is a dangerous material, causing neurotoxicity leading to respiratory failure by ganglion block that occurs through skin absorption, and no antidote has been developed yet. For this reason, it is best to completely prevent exposure by wearing proper personal protective equipment. Despite this fatal toxicity of TMAH, it is not classified in Korea as a "chemical requiring legal control". For this reason, it is urgent to raise awareness of the toxic properties of TMAH to prevent additional cases of TMAH poisoning

  7. Enhanced aerobic sludge granulation with layered double hydroxide

    Directory of Open Access Journals (Sweden)

    Jizhi Zhou

    2014-06-01

    Full Text Available Aerobic granular sludge technology has been developed for the biochemical treatment of wastewater in the present study. A fast cultivation of aerobic granular sludge was realized in Sequencing Batch Reactor (SBR, where Mg-Al layered double hydroxide (LDH was used as a carrier for granules growth. In comparison, the sludge particle size with LDH addition was bigger than those without LDH, with more than 50% of compact granular sludge >1.4 mm in size. This indicatestheLDH improved the growth ofthegranular sludge. The frequency of LDH addition had little effect on the granule growth. Moreover, the formation of granules led to the low sludge volume index (SVI and high mixed liquid suspended solids (MLSS in SBR reactor. With the formation of granular sludge, more than 80% of COD was removed in SBR reactor. The high COD removal efficiency of wastewater was observed regardless of various COD loading strength. The results suggest that the growth of granular sludge with LDH as a carrier enhanced the treatment efficiency. Therefore, our results have provided a promising way to prepare the granular sludge for wastewater treatment.

  8. Lithium adsorption on amorphous aluminum hydroxides and gibbsite

    Directory of Open Access Journals (Sweden)

    Konstantinos P. Prodromou

    2016-01-01

    Full Text Available Lithium (Li adsorption on both amorphous aluminum hydroxides and gibbsite was studied. For the amorphous Al(OH3 the adsorption was found to be pH dependent. Generally, 1.6 times more Li was adsorbed at initial pH value 8.0 compared with pH value 6.50. Gibbsite adsorbed 11.6 to 45.5 times less Li quantities compared with amorphous Al(OH3. Lithium adsorption was not depended on equilibrium times. It remained stable for all equilibrium times used. Lithium quantities extracted with 1N CH3COONH4 pH 7 , represent the physical adsorption, while the remaining Li that was adsorbed on Al(OH3, represents the chemical adsorption. During the desorption process 19% of Li extracted with NH4+, represents the physical adsorption, while the remaining 81% of Li, which was adsorbed represents the chemical adsorption. In gibbsite, 9.6% of Li represents the physical adsorption and 90.4% the chemical one. The experimental data conformed well to Freundlich isotherm equation.

  9. In vivo toxicity studies of europium hydroxide nanorods in mice.

    Science.gov (United States)

    Patra, Chitta Ranjan; Abdel Moneim, Soha S; Wang, Enfeng; Dutta, Shamit; Patra, Sujata; Eshed, Michal; Mukherjee, Priyabrata; Gedanken, Aharon; Shah, Vijay H; Mukhopadhyay, Debabrata

    2009-10-01

    Lanthanide nanoparticles and nanorods have been widely used for diagnostic and therapeutic applications in biomedical nanotechnology due to their fluorescence and pro-angiogenic properties to endothelial cells, respectively. Recently, we have demonstrated that europium (III) hydroxide [Eu(III)(OH)(3)] nanorods, synthesized by the microwave technique and characterized by several physico-chemical techniques, can be used as pro-angiogenic agents which introduce future therapeutic treatment strategies for severe ischemic heart/limb disease, and peripheral ischemic disease. The toxicity of these inorganic nanorods to endothelial cells was supported by several in vitro assays. To determine the in vivo toxicity, these nanorods were administered to mice through intraperitoneal injection (IP) everyday over a period of seven days in a dose dependent (1.25 to 125 mg kg(-1) day(-1)) and time dependent manner (8-60 days). Bio-distribution of europium elements in different organs was analyzed by inductively coupled plasma mass spectrometry (ICPMS). Short-term (S-T) and long-term (L-T) toxicity studies (mice euthanized on days 8 and 60 for S-T and L-T, respectively) show normal blood hematology and serum clinical chemistry with the exception of a slight elevation of liver enzymes. Histological examination of nanorod-treated vital organs (liver, kidney, spleen and lungs) showed no or only mild histological changes that indicate mild toxicity at the higher dose of nanorods.

  10. Methotrexate intercalated ZnAl-layered double hydroxide

    Science.gov (United States)

    Chakraborty, Manjusha; Dasgupta, Sudip; Soundrapandian, Chidambaram; Chakraborty, Jui; Ghosh, Swapankumar; Mitra, Manoj K.; Basu, Debabrata

    2011-09-01

    The anticancerous drug methotrexate (MTX) has been intercalated into an ZnAl-layered double hydroxide (LDH) using an anion exchange technique to produce LDH-MTX hybrids having particle sizes in the range of 100-300 nm. X-ray diffraction studies revealed increases in the basal spacings of ZnAl-LDH-MTX hybrid on MTX intercalation. This was corroborated by the transmission electron micrographs, which showed an increase in average interlayer spacing from 8.9 Å in pristine LDH to 21.3 Å in LDH-MTX hybrid. Thermogravimetric analyses showed an increase in the decomposition temperature for the MTX molecule in the LDH-MTX hybrid indicating enhanced thermal stability of the drug molecule in the LDH nanovehicle. The cumulative release profile of MTX from ZnAl-LDH-MTX hybrids in phosphate buffer saline (PBS) at pH 7.4 was successfully sustained for 48 h following Rigter-Peppas model release kinetics via diffusion.

  11. Bionanocomposites based on layered double hydroxides as drug delivery systems

    Science.gov (United States)

    Aranda, Pilar; Alcântara, Ana C. S.; Ribeiro, Ligia N. M.; Darder, Margarita; Ruiz-Hitzky, Eduardo

    2012-10-01

    The present work introduces new biohybrid materials involving layered double hydroxides (LDH) and biopolymers to produce bionanocomposites, able to act as effective drug delivery systems (DDS). Ibuprofen (IBU) and 5-aminosalicylic acid (5-ASA) have been chosen as model drugs, being intercalated in a Mg-Al LDH matrix. On the one side, the LDHIBU intercalation compound prepared by ion-exchange reaction was blended with the biopolymers zein, a highly hydrophobic protein, and alginate, a polysaccharide widely applied for encapsulating drugs. On the other side, the LDH- 5-ASA intercalation compound prepared by co-precipitation was assembled to the polysaccharides chitosan and pectin, which show mucoadhesive properties and resistance to acid pH values, respectively. Characterization of the intercalation compounds and the resulting bionanocomposites was carried out by means of different experimental techniques: X-ray diffraction, infrared spectroscopy, chemical and thermal analysis, as well as optical and scanning electron microscopies. Data on the swelling behavior and drug release under different pH conditions are also reported.

  12. Immobilization of Penicillin G Acylase on Calcined Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    REN Ling-ling; HE Jing; Evans D. G.; DUAN Xue

    2003-01-01

    A hydrotalcite-like Mg2+/Al3+ layered double hydroxide(LDH) material was prepared by means of a modified coprecipitation method involving a rapid mixing step followed by a separate aging process. LDH calcined at 500 ℃, denoted as CLDH, was characterized by XRD, IR and BET surface area measurements. CLDH has a poor crystalline MgO-like structure with a high surface area and porosity. CLDH was used as a support for the immobilization of penicillin G acylase(PGA). The effect of varying the immobilization conditions, such as pH, contact time and the ratio of enzyme to support, on the activity of the immobilized enzyme in the hydrolysis of penicillin G has been studied. It was found that the activity of the immobilized enzyme decreased slightly with decreasing pH and reached a maximum after a contact time of 24 h. The activity of the immobilized enzyme increased with increasing the ratio of enzyme to support. It was found that the adsorption of PGA inhibited the expected reaction of CLDH with an aqueous medium to regenerate a LDH phase. Its original activity(36%) after 15 cycles of reuse of the immobilized enzyme was retained, but no further loss in the activity was observed.

  13. Waste metal hydroxide sludge as adsorbent for a reactive dye.

    Science.gov (United States)

    Santos, Sílvia C R; Vílar, Vítor J P; Boaventura, Rui A R

    2008-05-30

    An industrial waste sludge mainly composed by metal hydroxides was used as a low-cost adsorbent for removing a reactive textile dye (Remazol Brilliant Blue) in solution. Characterization of this waste material included chemical composition, pH(ZPC) determination, particle size distribution, physical textural properties and metals mobility under different pH conditions. Dye adsorption equilibrium isotherms were determined at 25 and 35 degrees C and pH of 4, 7 and 10 revealing reasonably fits to Langmuir and Freundlich models. At 25 degrees C and pH 7, Langmuir fit indicates a maximum adsorption capacity of 91.0mg/g. An adsorptive ion-exchange mechanism was identified from desorption studies. Batch kinetic experiments were also conducted at different initial dye concentration, temperature, adsorbent dosage and pH. A pseudo-second-order model showed good agreement with experimental data. LDF approximation model was used to estimate homogeneous solid diffusion coefficients and the effective pore diffusivities. Additionally, a simulated real effluent containing the selected dye, salts and dyeing auxiliary chemicals, was also used in equilibrium and kinetic experiments and the adsorption performance was compared with aqueous dye solutions.

  14. Layered-double-hydroxide-modified electrodes: electroanalytical applications.

    Science.gov (United States)

    Tonelli, Domenica; Scavetta, Erika; Giorgetti, Marco

    2013-01-01

    Two-dimensional inorganic solids, such as layered double hydroxides (LDHs), also defined as anionic clays, have open structures and unique anion-exchange properties which make them very appropriate materials for the immobilization of anions and biomolecules that often bear an overall negative charge. This review aims to describe the important aspects and new developments of electrochemical sensors and biosensors based on LDHs, evidencing the research from our own laboratory and other groups. It is intended to provide an overview of the various types of chemically modified electrodes that have been developed with these 2D layered materials, along with the significant advances made over the last several years. In particular, we report the main methods used for the deposition of LDH films on different substrates, the conductive properties of these materials, the possibility to use them in the development of membranes for potentiometric anion analysis, the early analytical applications of chemically modified electrodes based on the ability of LDHs to preconcentrate redox-active anions and finally the most recent applications exploiting their electrocatalytic properties. Another promising application field of LDHs, when they are employed as host structures for enzymes, is biosensing, which is described considering glucose as an example.

  15. Mechanochemical synthesis of low-fluorine doped aluminum hydroxide fluorides

    Science.gov (United States)

    Scalise, V.; Scholz, G.; Kemnitz, E.

    2016-11-01

    Different aluminum hydroxide fluorides with varying Al/F molar ratios from 1:1.5 up to 1:0.05 were successfully synthesized by mechanochemical reactions. The characterization of the products by XRD, 27Al and 19F MAS NMR, thermal analysis, nitrogen adsorption and zeta potential techniques allows a detailed understanding of the structure and surface properties of the products. Using γ-Al(OH)3 and β-AlF3·3H2O as OH- and F-sources, respectively, strongly disordered products were obtained with an Al: F molar ratio higher than 1:0.25. The fluorination degree has affected the amount of 4- and 5-fold coordinated Al sites, not present in the reactants. An evolution of the sub-coordinated Al-species has been detected also as a consequence of annealing processes. Obviously, these species affect the phase transition to alumina, by decreasing the transition temperature of the formation of α-Al2O3. Synthesis conditions (milling time, fluorination degree) play a crucial role for the product composition.

  16. Comparison of final irrigation techniques in removal of calcium hydroxide.

    Science.gov (United States)

    Yücel, Ali Çağın; Gürel, Melek; Güler, Eda; Karabucak, Bekir

    2013-12-01

    The aim of this study was to compare new irrigation systems with a conventional irrigation technique for the removal of inter-appointment calcium hydroxide [Ca(OH)2 ]. Forty-seven extracted human single-rooted teeth were instrumented, and Ca(OH)2 paste was placed into root canals by using a lentulo spiral at the apical third. Teeth were randomly divided into three groups according to different irrigation protocols using a 30-gauge slot-tipped needle, EndoVac system and ProUltra® PiezoFlow™ ultrasonic irrigation system. Scanning electron microscopic images of the selected root canal surfaces (cervical, middle and apical third) were evaluated using a 5-grade scale. The influence of the irrigation system was evaluated using a two-way analysis of variance test and Tukey's test. The EndoVac and PiezoFlow groups demonstrated the lowest scale values (cleanest canals); however, there was no statistical difference between these two groups. The conventional irrigation group exhibited significantly higher scores (P ultrasonic irrigation systems improved the removal of the intracanal medicament resulting in cleaner root canal walls. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

  17. Reactions of cumene hydroperoxide mixed with sodium hydroxide.

    Science.gov (United States)

    Hou, Hung-Yi; Shu, Chi-Min; Tsai, Tung-Lin

    2008-04-15

    Decomposition of cumene hydroperoxide (CHP) was undertaken in a free radical chain reaction. The peroxyl group is very active and unstable, while the remainder of the molecule is inert. CHP reacted with various concentrations of dilute sodium hydroxide as a catalyst to cleave at ambient and decomposition temperature. The products were verified by GC/MS, and were quantitatively analyzed by chromatography. CHP cleaved heterolytic with NaOH at 250 degrees C, whose major product was dimethylphenyl carbinol (DMPC); however, the main products become acetophenone and alpha-methylstyrene by cleaved homolytic pathway. The catalytic concentrations of NaOH significantly affected the branch ratios of DMPC under decomposition. Based on the experimental results, a radical cleavage mechanism was proposed. To sum up, the reaction parameters, such as temperature, Lewis base, etc., could affect the incompatibilities and decomposition pathways for proper CHP cleavage process. In addition, exothermic onset temperatures (T0) and heat of decomposition (Delta Hd) of incompatible mixtures and CHP itself were studied by differential scanning calorimetry (DSC). Comparisons of T0, Delta Hd and peak power were assessed to corroborate the severity of thermal hazards. From the decay rate of CHP concentration, the reaction order was determined to be 0.5, and the Arrhenius parameters were measured as Ea=92.1 kJ/mol and frequency factor A=2.42 x 10(10)min(-1).

  18. Atomistic Simulations of Uranium Incorporation into Iron (Hydr)Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien N.; Felmy, Andrew R.; Ilton, Eugene S.

    2011-04-29

    Atomistic simulations were carried out to characterize the coordination environments of U incorporated in three Fe-(hydr)oxide minerals: goethite, magnetite, and hematite. The simulations provided information on U-O and U-Fe distances, coordination numbers, and lattice distortion for U incorporated in different sites (e.g., unoccupied versus occupied sites, octahedral versus tetrahedral) as a function of the oxidation state of U and charge compensation mechanisms (i.e., deprotonation, vacancy formation, or reduction of Fe(III) to Fe(II)). For goethite, deprotonation of first shell hydroxyls enables substitution of U for Fe(III) with a minimal amount of lattice distortion, whereas substitution in unoccupied octahedral sites induced appreciable distortion to 7-fold coordination regardless of U oxidation states and charge compensation mechanisms. Importantly, U-Fe distances of ~3.6 Å were associated with structural incorporation of U and cannot be considered diagnostic of simple adsorption to goethite surfaces. For magnetite, the octahedral site accommodates U(V) or U(VI) with little lattice distortion. U substituted for Fe(III) in hematite maintained octahedral coordination in most cases. In general, comparison of the simulations with available experimental data provides further evidence for the structural incorporation of U in iron (hydr)oxide minerals.

  19. Surface modification of magnesium hydroxide using vinyltriethoxysilane by dry process

    Science.gov (United States)

    Lan, Shengjie; Li, Lijuan; Xu, Defang; Zhu, Donghai; Liu, Zhiqi; Nie, Feng

    2016-09-01

    In order to improve the compatibility between magnesium hydroxide (MH) and polymer matrix, the surface of MH was modified using vinyltriethoxysilane (VTES) by dry process and the interfacial interaction between MH and VTES was also studied. Zeta potential measurements implied that the MH particles had better dispersion and less aggregation after modification. Sedimentation tests showed that the surface of MH was transformed from hydrophilic to hydrophobic, and the dispersibility and the compatibility of MH particles significantly improved in the organic phase. Scanning electronic microscopy (SEM), Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD) analyses showed that a thin layer had formed on the surface of the modified MH, but did not alter the material's crystalline phase. Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectra (XPS) and Thermogravimetric analysis (TGA) showed that the VTES molecules bound strongly to the surface of MH after modification. Chemical bonds (Sisbnd Osbnd Mg) formed by the reaction between Si-OC2H5 and hydroxyl group of MH, also there have physical adsorption effect in the interface simultaneously. A modification mechanism of VTES on the MH surface by dry process was proposed, which different from the modification mechanism by wet process.

  20. Surface modification of magnesium hydroxide by γ-aminopropyltriethoxysilane

    Institute of Scientific and Technical Information of China (English)

    LUO Wei; FENG Qi-ming; OU Le-ming; LIU Kun

    2008-01-01

    Magnesium hydroxide (MH), which is commonly used as a halogen-free flame retardant filler in composite materials, was modified by silanization reaction with γ-aminopropyltriethoxysilane (γ-APS) in aqueous solution at different pH values (pH range from 8.0 to 12.0). The surface properties of grafted γ-APS on MH surface as a function of solution pH value were studied using elemental analysis, Fourier transform infrared spectroscopy and zeta potential measurement. The results show that hydrolysis and condensation of γ-APS are activated in alkaline solution and lead to multilayer adsorption of γ-APS molecules on the surface of MH. The type of adsorption orientation of γ-APS on MH surface is a function of coverage density that is altered by changing solution pH value. At low coverage density (e.g.55nm-2), γ-APS molecules are preferentially adsorbed to the surface with the silicon moiety towards the surface, and increasing coverage density (e.g.90nm-2) leads to parallel orientation. At an even higher coverage density(e.g.115nm-2), γ-APS molecules bond to the surface with the amino moiety towards the surface.

  1. Layered double hydroxides as containers of inhibitors in organic coatings for corrosion protection of carbon steel

    OpenAIRE

    Hang, To Thi Xuan; Truc, Trinh Anh; Duong, Nguyen Thuy; Pébère, Nadine; Olivier, Marie-Georges

    2012-01-01

    International audience; The present work focuses on the use of layered double hydroxides (LDH) as containers for corrosion inhibitors in an epoxy coating. 2-Benzothiazolylthio-succinic acid (BTSA), used as corrosion inhibitor, was intercalated by co-precipitation in magnesium-aluminum layered double hydroxides. The obtained LDH-BTSA was characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy. BTSA release from LDH-BTSA in NaCl solutions was investigated by U...

  2. Effects of aluminum hydroxide and calcium carbonate antacids on the bioavailability of ciprofloxacin.

    OpenAIRE

    Frost, R W; Lasseter, K C; Noe, A J; Shamblen, E C; Lettieri, J T

    1992-01-01

    This study was designed to determine the effects of an aluminum hydroxide antacid and a calcium carbonate antacid on the bioavailability of ciprofloxacin (Cipro). Cipro (750 mg) was administered orally to 12 healthy volunteers in a three-way randomized crossover design. The three treatments included Cipro alone, four 850-mg calcium carbonate tablets taken 5 min before Cipro, and three 600-mg aluminum hydroxide tablets taken 5 min before Cipro. The relative bioavailability of Cipro when given ...

  3. Biodiesel production from waste cooking oil using ionic liquid choline hydroxide as a catalyst

    OpenAIRE

    Aline Mara Maia Bessa

    2015-01-01

    The production of biodiesel is generally performed by alkaline transesterification oils with low amounts of free fatty acids (FFAs). In order to decrease the costs of production of biodiesel, low quality waste cooking oils or grease have been investigated as a source alternative, but problems in the purification step due to the formation of soap are found in catalysis with sodium hydroxide. In this work, the ionic liquid choline hydroxide was produced and used as catalyst in the production o...

  4. Coordination Structure of Aluminum in Magnesium Aluminum Hydroxide Studied by 27Al NMR

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The coordination structure of aluminum in magnesium aluminum hydroxide was studiedby 27Al NMR. The result showed that tetrahedral aluminum (AlⅣ) existed in magnesiumaluminum hydroxide, and the contents of AlⅣ increased with the increase of the ratio of Al/Mg andwith the peptizing temperature. AlⅣ originated from the so-called Al13 polymer with the structureof one Al tetrahedron surrounded by twelve Al octahedrons.

  5. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    OpenAIRE

    2014-01-01

    The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution...

  6. Adsorption of hydrated hydroxide and hydronium ions on Ag(1 1 1). A quantum mechanical investigation

    Science.gov (United States)

    Patrito, E. M.; Paredes-Olivera, P.

    2003-03-01

    In this paper we have studied comparatively the adsorption of hydroxide and hydronium ions, extending our previous study on hydronium adsorption [J. Phys. Chem. B. 105 (2001) 7227] and emphasizing the adsorption of hydroxide. The calculations were performed on the 111 surface of silver using ab initio quantum mechanical methods (Hartree-Fock+Moller-Plesset second order perturbation theory). The adsorption was investigated for the bare and the hydrated ions (up to three water molecules). Binding energies, equilibrium structures and charge transfer processes were investigated. While the successive hydration of hydronium detaches the ion from the surface, the hydrated hydroxide anion remains specifically adsorbed. Charge transfer processes between the adsorbates and the surface were studied using electron density difference plots and effective charges obtained from Mulliken populations and from surface-dipole moment curves. The energetics of the surface reactions leading to the formation of the hydrated hydronium and hydroxide ions from the bare adsorbed ions and water molecules was also investigated. Both reactions are exothermic mainly due to the formation of strong hydrogen bonds. The effect of an external homogeneous electric field perpendicular to the surface on different adsorbate properties was investigated for the bare and hydrated hydroxide ion in order to model the environment of the electrical double layer. The electric field affects the orientation of the water molecules on the surface and the hydroxide surface distance.

  7. Parametric Effect of Sodium Hydroxide and Sodium Carbonate on the Potency of a Degreaser

    Directory of Open Access Journals (Sweden)

    Babatope Abimbola Olufemi

    2016-01-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE Experimental and statistical analysis was carried out on the comparative effect of sodium hydroxide and sodium carbonate on the potency of a laboratory produced degreaser in this work. The materials used include; octadecyl benzene sulphonic acid, sodium hydroxide, sodium carbonate, sodium metasilicate, carboxyl methyl cellulose (C.M.C, formadelhyde, perfume, colourant and distilled water. Different samples of degreaser were produced with varying composition of sodium hydroxide and sodium carbonate respectively. Statistical significance through methods like analysis of variance (ANOVA of some parameters on various concentrations of sodium hydroxide and sodium carbonate was investigated. The effect of the varying compositions of sodium hydroxide and sodium carbonate was also determined by using a gray scale (GS test, and also subjecting surfaces heavily stained with crude oil to determine and characterize the cleansing action of the degreaser. It was found that as the concentration of sodium hydroxide increases, the cleansing ability also increases, whereas the increase in concentration of sodium carbonate had no effect on the cleansing ability. The work would enable production of effective, useful and property controlled degreasers at moderate cost.

  8. Scientific Opinion on the safety and efficacy of sodium hydroxide for dogs, cats and ornamental fish

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP

    2012-10-01

    Full Text Available

    The additive consists, by specification, of a minimum of 98.0 % sodium hydroxide or alkali in the solid form, the content of solutions scaled accordingly, based on the stated or labelled concentration. No data have been provided that would support the specification of the solid form, only a 50.0 % w/w solution of sodium hydroxide in water, which is the final product of the production process described in the dossier. Sodium hydroxide is considered safe for the target animals, provided that the resulting total sodium concentration in feed does not compromise the overall electrolyte balance. Sodium hydroxide in solid form and in aqueous solution at concentrations > 8.0 % is corrosive. At lower concentrations it is irritant to skin and eyes (0.5 % and 0.2 %, respectively and the respiratory tract (0.5 %. Exposure via inhalation is likely to be minimal. Sodium hydroxide is not considered to be a skin sensitiser. As sodium hydroxide is used in food as an acidity regulator, and its function in feed is essentially the same as that in food, no further demonstration of efficacy is necessary.

  9. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The optimum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liquid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  10. Cadmium hydroxide and oxide nanoporous walls with high performance photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Yu-Cheng, E-mail: ychang0127@gmail.com

    2015-07-15

    Highlights: • Cd(OH){sub 2} nanowalls were directly grown on glass substrate by hydrothermal method. • The thicknesses of Cd(OH){sub 2} nanowalls can be effectively controlled by HMTA. • Cd(OH){sub 2} and CdO nanoporous walls exhibit very strong and broad emission properties. • Cd(OH){sub 2} and CdO nanoporous walls have exhibited very effective photocatalysts. • The two mixture nanoporous walls are beneficial for optoelectronic applications. - Abstract: Cadmium hydroxide nanowalls were directly grown on glass substrate by a hydrothermal method. The concentration of hexamethylenetetramine plays a crucial role for controlling the thicknesses of cadmium hydroxide nanowalls. A part of the cadmium hydroxide nanowalls can be converted to cadmium oxide nanoporous walls by annealing cadmium hydroxide in air at 350 °C for 1 h. Cadmium hydroxide and oxide nanoporous walls exhibited very strong and broad emission properties in the cathodoluminescence spectrum. Furthermore, cadmium hydroxide and oxide nanoporous walls can also provide a higher surface-to-volume ratio to result their higher photocatalytic performance in degradation of methylene blue.

  11. Synthesis and characterization of fac-[M(CO)3(P)(OO)] and cis-trans-[M(CO)2(P)2(OO)] complexes (M = Re, (99m)Tc) with acetylacetone and curcumin as OO donor bidentate ligands.

    Science.gov (United States)

    Triantis, Charalampos; Tsotakos, Theodoros; Tsoukalas, Charalampos; Sagnou, Marina; Raptopoulou, Catherine; Terzis, Aris; Psycharis, Vassilis; Pelecanou, Maria; Pirmettis, Ioannis; Papadopoulos, Minas

    2013-11-18

    The synthesis and characterization of neutral mixed ligand complexes fac-[M(CO)3(P)(OO)] and cis-trans-[M(CO)2(P)2(OO)] (M = Re, (99m)Tc), with deprotonated acetylacetone or curcumin as the OO donor bidentate ligands and a phosphine (triphenylphosphine or methyldiphenylphosphine) as the monodentate P ligand, is described. The complexes were synthesized through the corresponding fac-[M(CO)3(H2O)(OO)] (M = Re, (99m)Tc) intermediate aqua complex. In the presence of phosphine, replacement of the H2O molecule of the intermediate complex at room temperature generates the neutral tricarbonyl monophosphine fac-[Re(CO)3(P)(OO)] complex, while under reflux conditions further replacement of the trans to the phosphine carbonyl generates the new stable dicarbonyl bisphosphine complex cis-trans-[Re(CO)2(P)2(OO)]. The Re complexes were fully characterized by elemental analysis, spectroscopic methods, and X-ray crystallography showing a distorted octahedral geometry around Re. Both the monophosphine and the bisphosphine complexes of curcumin show selective binding to β-amyloid plaques of Alzheimer's disease. At the (99m)Tc tracer level, the same type of complexes, fac-[(99m)Tc(CO)3(P)(OO)] and cis-trans-[(99m)Tc(CO)2(P)2(OO)], are formed introducing new donor combinations for (99m)Tc(I). Overall, β-diketonate and phosphine constitute a versatile ligand combination for Re(I) and (99m)Tc(I), and the successful employment of the multipotent curcumin as β-diketone provides a solid example of the pharmacological potential of this system.

  12. Form and stability of aluminum hydroxide complexes in dilute solution

    Science.gov (United States)

    Hem, John David; Roberson, Charles Elmer

    1967-01-01

    Laboratory studies of solutions 4.53 x 10 -4 to 4.5 x 10 -5 molal (12.2-1.2 ppm) in aluminum, in 0.01 molal sodium perchlorate, were conducted to obtain information as to the probable behavior of aluminum in natural water. When the solutions were brought to pH 7.5-9.5 and allowed to stand for 24 hours, a precipitate was obtained which was virtually amorphous as shown by X-rays, and which had a solubility equivalent to that of boehmite. This precipitate had a hydrolysis constant (*Ks4) of 1.93 x 10 -13a. When solutions were allowed to stead at this pH range for 10 days, their precipitates gave the X-ray pattern of bayerite (*Ks4 = 1.11 > (10- 4). These hydrolysis constants were obtained at 25?C. and corrected to zero ionic strength and are in close agreement with other published values. The predominant dissolved form in this pH range is Al(OH) -4. Below neutral pH (7.0) the dissolved aluminum species consist of octahedral units in which each aluminum ion is surrounded by six water molecules or hydroxide ions. Single units such as Al(OH2)6 + 3 and AlOH(OH2)5+2 are most abundant below pH 5.0, and where the molar ratio (r) of combined hydroxide to total dissolved aluminum is low. When r is greater than 1.0, polymerization of the octahedral units occurs. When r is between 2.0 and 3.0, solutions aged for 10 days or more contained colloidal particles between 0.10 and 0.45 ? in diameter. Particles whose diameters were greater than 0.10 ? were identified by X-ray diffraction as gibbsite. Particles smaller than 0.10 ? were also present and were shown by means of the electron microscope to have a hexagonal crystal pattern. Structured material consisting of sheets of coalesced six-membered rings of aluminum ions held together by double OH bridges has a distinctive kinetic behavior. This property was used to determine amounts of polymerized material in solutions having r between 1.0 and 3.0 after aging times ranging from a few hours to more than 4 months. Aging increased the

  13. Development of polymer nanocomposites based on layered double hydroxides

    Directory of Open Access Journals (Sweden)

    Sipusic, J.

    2009-05-01

    Full Text Available Polymeric nanocomposites are commonly considered as systems composed of a polymeric matrix and - usually inorganic - filler. The types of nanofillers are indicated in Fig. 1. Beside wellknown layered silicate fillers, recent attention is attracted to layered double hydroxide fillers (LDH, mainly of synthetic origin. The structure of LDH is based on brucite, or magnesium hydroxide, Mg(OH2 and is illustrated in Fig. 2. The modification of LDHs is commonly done by organic anions, to increase the original interlayer distance and to improve the organophilicity of the filler, keeping in mind their final application as fillers for, usually hydrophobic, polymer matrices. We have used the modified rehydration procedure for preparing organically modified LDH. The stoichiometric quantities of Ca33Al2O6, CaO and benzoic (B (or undecenoic (U acid were mixed with water and some acetone. After long and vigorous shaking, the precipitated fillers were washed, dried and characterized. X-ray diffraction method (XRD has shown the increase of the original interlayer distance for unmodified LDH (OH–-saturated of 0.76 nm to the 1.6 nm in LDH-B or LDH-U fillers (Fig. 3. Infrared spectroscopy method (FTIR has confirmed the incorporation of benzoic anion within the filler layers (Fig. 4. For the preparation of LDH-B and LDH-U composites with polystyrene (PS, poly(methyl methacrylate (PMMA and copolymer (SMMA matrices, a two-step in situ bulk radical polymerization was selected (Table 1 for recipes, azobisisobutyronitrile as initiator, using conventional stirred tank reactor in the first step, and heated mold with the movable wall (Fig. 6 in the second step of polymerization. All the prepared composites with LDH-U fillers were macroscopically phase-separated, as was the PMMA/LDH-B composite.PS/LDH-B and SMMA/LDH-B samples were found to be transparent and were further examined for deduction of their structure (Fig. 5 and thermal properties. FTIR measurements showed that

  14. Arsenic adsorption by iron-aluminium hydroxide coated onto macroporous supports: Insights from X-ray absorption spectroscopy and comparison with granular ferric hydroxides.

    Science.gov (United States)

    Suresh Kumar, Prashanth; Flores, Roxana Quiroga; Sjöstedt, Carin; Önnby, Linda

    2016-01-25

    This paper evaluates the arsenic adsorption characteristics of a macroporous polymer coated with coprecipitated iron-aluminium hydroxides (MHCMP). The MHCMP adsorbent-composite fits best with a pseudo-second order model for As(III) and a pseudo-first order kinetic model for As(V). The MHCMP shows a maximum adsorption capacity of 82.3 and 49.6 mg As/g adsorbent for As(III) and As(V) ions respectively, and adsorption followed the Langmuir model. Extended X-ray absorption fine structure showed that binding of As(III) ions were confirmed to take place on the iron hydroxides coated on the MHCMP, whereas for As(V) ions the binding specificity could not be attributed to one particular metal hydroxide. As(III) formed a bidentate mononuclear complex with Fe sites, whereas As(V) indicated on a bidentate binuclear complex with Al sites or monodentate with Fe sites on the adsorbent. The column experiments were run in a well water spiked with a low concentration of As(III) (100 μg/L) and a commercially available adsorbent (GEH(®)102) based on granular iron-hydroxide was used for comparison. It was found that the MHCMP was able to treat 7 times more volume of well water as compared to GEH(®)102, maintaining the threshold concentration of less than 10 μg As/L, indicating that the MHCMP is a superior adsorbent.

  15. Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application

    Science.gov (United States)

    Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

    2017-01-01

    Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co0.54Fe0.46OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co0.54Fe0.46OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal−air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application. PMID:28272443

  16. Effective Construction of High-quality Iron Oxy-hydroxides and Co-doped Iron Oxy-hydroxides Nanostructures: Towards the Promising Oxygen Evolution Reaction Application.

    Science.gov (United States)

    Zhang, Xinyu; An, Li; Yin, Jie; Xi, Pinxian; Zheng, Zhiping; Du, Yaping

    2017-03-08

    Rational design of high efficient and low cost electrocatalysts for oxygen evolution reaction (OER) plays an important role in water splitting. Herein, a general gelatin-assisted wet chemistry method is employed to fabricate well-defined iron oxy-hydroxides and transitional metal doped iron oxy-hydroxides nanomaterials, which show good catalytic performances for OER. Specifically, the Co-doped iron oxy-hydroxides (Co0.54Fe0.46OOH) show the excellent electrocatalytic performance for OER with an onset potential of 1.52 V, tafel slope of 47 mV/dec and outstanding stability. The ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the pure iron oxy-hydroxide (FeOOH) catalysts, originate from the branch structure of Co0.54Fe0.46OOH on its surface so as to provide many active edge sites, enhanced mass/charge transport capability, easy release oxygen gas bubbles, and strong structural stability, which are advantageous for OER. Meanwhile, Co-doping in FeOOH nanostructures constitutes a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. This work may provide a new insight into constructing the promising water oxidation catalysts for practical clean energy application.

  17. A titration model for evaluating calcium hydroxide removal techniques

    Directory of Open Access Journals (Sweden)

    Mark PHILLIPS

    2015-02-01

    Full Text Available Objective Calcium hydroxide (Ca(OH2 has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH2 followed by gross Ca(OH2 removal using hand files and randomized treatment of either: 1 Syringe irrigation; 2 Syringe irrigation with use of an apical file; 3 Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI, or 4 Syringe irrigation with apical file and PUI (n=12/group. Residual Ca(OH2 was dissolved with glycerin and titrated to measure residual Ca(OH2 left in the root. Results No method completely removed all residual Ca(OH2. The addition of 30 s PUI with or without apical file use removed Ca(OH2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH2. The use of PUI (with or without apical file resulted in significantly lower Ca(OH2 residue compared to irrigation alone.

  18. Physical properties of fixed-charge layer double hydroxides

    Science.gov (United States)

    Hines, D. R.; Solin, S. A.; Costantino, Umberto; Nocchetti, Morena

    2000-05-01

    The physical properties of a series of layer double hydroxides (LDH) of the form [(CO3)0.195(1-x)Cl0.39x(H2O)y]:[Zn0.61Al0.39(OH)2], 0layer water molecules form a hydration ring which defines the height of the solvated, nested Cl anion. The water molecules can tilt around their C2v axis such that the height of the solvated Cl ion is a function of the number of molecules forming the hydration ring. The composition dependence of the basal spacing, determined from x-ray-diffraction powder patterns measured as a function of humidity and temperature for these materials, is a function of both the Cl concentration (x) and the number of guest layer water molecules (y). Distinct basal spacing curves are observed for fully hydrated, partially hydrated, and dehydrated materials. At x=1 the Cl end-member material exhibits a change in stacking sequence from a 3R polytype to a 2H polytype upon dehydration. The dehydrated form of this material also exhibits a (3×3)R30° superlattice ordering of the Cl ions. Due to the nesting of the Cl ion and the active nature of the water molecules, the basal spacing vs x curve for the dehydrated materials is the only curve that can be fit by the discrete finite layer rigidity model. The interlayer rigidity parameter for LDH materials has been determined to be p=4.84+/-0.06 indicating that these materials are stiffer than class-II layered solids but not as stiff as class-III layered solids.

  19. Preferential Intercalation of Pyridinedicarboxylates into Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    李蕾; 莫丹; 陈大舟

    2005-01-01

    Intercalation of 2,3-,2,4-,2,5-,2,6-,3,4-,or3,5-pyridincdicarboxylate into the layered double hydroxide (LDH),[Mg0.73AIo.27(OH)2](CO3)0.14*1.34H2O was carried out by the reconstruction method in the molar ratio of organic acid: calcined LDH=3:8, in 80% alcoholic aqueous solution at 70℃. Selective reaction was observed in com-petitive experiments involving an equal concentration pairs of acids. The preference order of the organic acids intercalated into the Mg-Al-LDH was found to be in the order of 2,3-pyridinedicarboxylate>2,5-pyridinedicarboxylate>2,4-pyridinedicarboxylate>3,5-pyridinedicarboxylate>3,4-pyridinedicarboxylate>2,6-pyridinedic arboxylate. The structures of the intercalates formed by the reaction of six guests with Mg-Al-LDH were characterized by X-ray diffraction, infrared and thermogravimetry techniques. And the charge density on the oxygens of each of the carboxylate groups for the six anions was investigated utilizing ab initio (HF/6-31G) method by G98w. From the X-ray diffraction data, the guest size and the charge density of the oxygens of the guest, the orientation of 2,3-,2,4-,2,5-,2,6-,3,4-, or 3,5-pyridinedicarboxylate anions between the layers was determined and the preferential intercalation mechanism was discussed. These results indicate the possibility of a molecular recognition ability of LDH and it would be exploited for the chemical separation of some anions from solution.

  20. Effect of Operating Parameters and Chemical Additives on Crystal Habit and Specific Cake Resistance of Zinc Hydroxide Precipitates

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [New Mexico State Univ., Las Cruces, NM (United States)

    1999-08-01

    The effect of process parameters and chemical additives on the specific cake resistance of zinc hydroxide precipitates was investigated. The ability of a slurry to be filtered is dependent upon the particle habit of the solid and the particle habit is influenced by certain process variables. The process variables studied include neutralization temperature, agitation type, and alkalinity source used for neutralization. Several commercially available chemical additives advertised to aid in solid/liquid separation were also examined in conjunction with hydroxide precipitation. A statistical analysis revealed that the neutralization temperature and the source of alkalinity were statistically significant in influencing the specific cake resistance of zinc hydroxide precipitates in this study. The type of agitation did not significantly effect the specific cake resistance of zinc hydroxide precipitates. The use of chemical additives in conjunction with hydroxide precipitation had a favorable effect on the filterability. The morphology of the hydroxide precipitates was analyzed using scanning electron microscopy.

  1. The Effect of Ultrafine Magnesium Hydroxide on the Tensile Properties and Flame Retardancy of Wood Plastic Composites

    Directory of Open Access Journals (Sweden)

    Zhiping Wu

    2014-01-01

    Full Text Available The effect of ultrafine magnesium hydroxide (UMH and ordinary magnesium hydroxide (OMH on the tensile properties and flame retardancy of wood plastic composites (WPC were investigated by tensile test, oxygen index tester, cone calorimeter test, and thermogravimetric analysis. The results showed that ultrafine magnesium hydroxide possesses strengthening and toughening effect of WPC. Scanning electron micrograph (SEM of fracture section of samples provided the positive evidence that the tensile properties of UMH/WPC are superior to that of WPC and OMH/WPC. The limited oxygen index (LOI and cone calorimeter test illustrated that ultrafine magnesium hydroxide has stronger flame retardancy and smoke suppression effect of WPC compared to that of ordinary magnesium hydroxide. The results of thermogravimetric analysis implied that ultrafine magnesium hydroxide can improve the char structure which plays an important role in reducing the degradation speed of the inner matrix during combustion process and increases the char residue at high temperature.

  2. ATR-FTIR investigation on the complexation of myo-inositol hexaphosphate with aluminum hydroxide.

    Science.gov (United States)

    Guan, Xiao-Hong; Shang, Chii; Zhu, Jun; Chen, Guang-Hao

    2006-01-15

    The adsorption isotherm of and the pH effect on the adsorption of myo-inositol hexaphosphate (myo-IP6) on amorphous aluminum hydroxide was investigated. It was found that the adsorption isotherm of myo-IP6 on aluminum hydroxide could be well fitted with the Freundlich isotherm. The amount of myo-IP6 adsorbed remained almost constant in the range of pH 4.0 to 7.0, but it decreased considerably as the initial pH was over 7. The adsorption of myo-IP6 resulted in an increase in the pH level due to the release of OH(-) ions, which suggested that the adsorption of myo-IP6 on aluminum hydroxide was caused by a ligand exchange reaction. ATR-FTIR analysis of myo-IP6 in solution and adsorbed on aluminum hydroxide at different pH were performed. The ATR-FTIR investigation indicated that myo-IP6 was adsorbed onto aluminum hydroxide by forming inner-sphere complexes and adsorption facilitated the deprotonation of phosphate groups. The asymmetric vibration of the PO bond in AlPO(-)(3) appearing at a lower frequency than that in the terminal HPO(-)(3) indicated that Al bound to the O atom not as strongly as the H atom did. The ATR-FTIR investigation and theoretical calculation (with the Gaussian 03 program) revealed that three of the six phosphate groups in myo-IP6 molecules were bound to aluminum hydroxide while the other three remained free when myo-IP6 was adsorbed on aluminum hydroxide.

  3. Synthesis of Zn–Fe layered double hydroxides via an oxidation process and structural analysis of products

    Energy Technology Data Exchange (ETDEWEB)

    Morimoto, Kazuya, E-mail: kazuya.morimoto@aist.go.jp [Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567 (Japan); Tamura, Kenji [Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Anraku, Sohtaro [Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 (Japan); Sato, Tsutomu [Faculty of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo 060-8628 (Japan); Suzuki, Masaya [Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8567 (Japan); Yamada, Hirohisa [Environmental Remediation Materials Unit, National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

    2015-08-15

    The synthesis of Zn–Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. The product derived from the synthesis employing Fe(II) was found to transition to a Zn–Fe(III) layered double hydroxides phase following oxidation process. In contrast, the product obtained with Fe(III) did not contain a layered double hydroxides phase, but rather consisted of simonkolleite and hydrous ferric oxide. It was determined that the valency of the Fe reagent used in the initial synthesis affected the generation of the layered double hydroxides phase. Fe(II) species have ionic radii and electronegativities similar to those of Zn, and therefore are more likely to form trioctahedral hydroxide layers with Zn species. - Graphical abstract: The synthesis of Zn–Fe(III) layered double hydroxides was attempted, employing different pathways using either Fe(II) or Fe(III) species together with Zn as the initial reagents. - Highlights: • Iron valency affected the generation of Zn–Fe layered double hydroxides. • Zn–Fe layered double hydroxides were successfully synthesized using Fe(II). • Fe(II) species were likely to form trioctahedral hydroxide layers with Zn species.

  4. Transition metal complexes with thiosemicarbazide-based ligands. Part 51. Square-planar nickel(II complex with acetylacetone bis(S-n-propylisothiosemicarbazone (L. Crystal and molecular structure of [Ni(L-H]NCS and two isomorphic complexes [Ni(L-H]I·EtOH and [Ni(L-H]I·iPrOH

    Directory of Open Access Journals (Sweden)

    VUKADIN M. LEOVAC

    2006-06-01

    Full Text Available The template reaction of a warm methanolic solution of Ni(OAc2·4H2O, S-n-propylisothiosemicarbazide hydroiodide and acetylacetone yielded the needle- like, brown, diamagnetic complex [Ni(L–H]I·MeOH, and in the presence of an excess of NH 4NCS, brown, prismatic crystals of the complex [Ni(L–H]NCS (1, both compounds involving the monoanionic form of the ligand, acetylacetone bis(S-n-propylisothiosemicarbazone, L. Slow recrystallization fromMeOH, EtOH, iPrOH and Me2CO gave the corresponding monosolvent complexes [Ni(L–H]I·solvent, of which only those involving EtOH and iPrOH were suitable for structural analysis. The crystallographic parameters of [Ni(L–H]I·EtOH (2 and [Ni(L–H]I·iPrOH (3 are very similar to each other, showing their structures are isomorphic. The crystal structures of the title compounds consist of the independent ions: NCS-, or I-, and the chemically identical cation [Ni(L–H]+, where L–H is the monoanion resulting from deprotonation of the acetylacetone moiety, a tetradentate N4 ligand forming a square-planar coordination around a Ni(II ion. It was found that the isothiosemicarbazide fragment of the ligand has an imido form. The complex cations of the compounds [Ni(L–H]NCS and [Ni(L–H]I·EtOH exhibit significant difference only in the conformation of their propyl groups.

  5. Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Aritra [Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States); Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Tokmakoff, Andrei, E-mail: tokmakoff@uchicago.edu [Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States)

    2015-11-21

    We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm{sup −1}. We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions.

  6. Zimmer slipstream magnesium hydroxide recovery demonstration. Volume II of II. Appendices

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Dravo Lime has for many years supplied magnesium containing lime in the ranges of 3-6% MgO. Several years ago Dravo Lime realized the potential operating savings its FGD customers could benefit from if magnesium could be recovered from FGD waste streams. As a result, several different proprietary processes have been developed for the recovery of magnesium hydroxide. These recovery processes include steps for magnesium hydroxide separation, purification, and crystal growth. The process implemented at The Cincinnati Gas Electric Company`s Wm. H. Zimmer Station was piloted by Dravo Lime Company at Allegheny Power System`s Mitchell Station near Monongahela, PA during the fourth quarter in 1989 and first quarter in 1990. This pilot work was the foundation for further development of the ThioClear process at Dravo`s pilot plant at CG&E Miami Fort Station. The ThioClear process is a closed loop version of the magnesium hydroxide recovery process with the same unit operations and products but also including an absorber tower for scrubbing flue gas. Testing at Miami Fort of the ThioClear process led to improvements in separation of magnesium hydroxide from gypsum that are part of the magnesium hydroxide recovery process installed at Zimmer Station. This document contains the Appendices for this report.

  7. Relationship between sealing ability of Activ GP and Gutta Flow and methods of calcium hydroxide removal

    Directory of Open Access Journals (Sweden)

    Vineeta Nikhil

    2012-01-01

    Full Text Available Aim: To evaluate the effect of method of calcium hydroxide intracanal dressing removal, on sealing ability of Gutta Flow and Activ GP. Materials and Methods: Seventy extracted mandibular premolars were sectioned at CEJ and canals were prepared with profile 4% rotary file till #40. Canals were filled with calcium hydroxide, coronally sealed with Cavit G and stored at 37°C. After 7 days, samples were divided on the basis of calcium hydroxide removal method (Master apical file, Navi Tip FX, and F File and obturating material (Activ GP and Gutta Flow. Three coats of nail polish were applied except 2 mm around apical foramen and samples were immersed in India ink dye, sectioned, and observed under stereomicroscope for microleakage. Results: The results were statistically analyzed with one way ANOVA-F with Tukey HSD test with the null hypothesis set as 5%. Conclusions: The seal of the canal system was adversely impacted by residual calcium hydroxide when Activ GP and Gutta Flow were used as obturating material and the sealing ability of Activ GP and Gutta Flow was better when MAF was used for removal of calcium hydroxide than F file or Navi tip FX.

  8. Mixing Acid Salts and Layered Double Hydroxides in Nanoscale under Solid Condition

    Directory of Open Access Journals (Sweden)

    Hirokazu Nakayama

    2014-07-01

    Full Text Available The immobilization of potassium sorbate, potassium aspartate and sorbic acid in layered double hydroxide under solid condition was examined. By simply mixing two solids, immobilization of sorbate and aspartate in the interlayer space of nitrate-type layered double hydroxide, so called intercalation reaction, was achieved, and the uptakes, that is, the amount of immobilized salts and the interlayer distances of intercalation compounds were almost the same as those obtained in aqueous solution. However, no intercalation was achieved for sorbic acid. Although intercalation of sorbate and aspartate into chloride-type layered double hydroxide was possible, the uptakes for these intercalation compounds were lower than those obtained using nitrate-type layered double hydroxide. The intercalation under solid condition could be achieved to the same extent as for ion-exchange reaction in aqueous solution, and the reactivity was similar to that observed in aqueous solution. This method will enable the encapsulation of acidic drug in layered double hydroxide as nano level simply by mixing both solids.

  9. INFLUENCE OF HEAVY METALS HYDROXIDES ON WATER DISSOCIATION IN BIPOLAR MEMBRANE

    Directory of Open Access Journals (Sweden)

    Sheldeshov N. V.

    2015-12-01

    Full Text Available The results of study of bipolar membrane – analogue of MB-2, modified with chemically introduced chromium (III, iron (III and nickel (II hydroxides by the method of frequency spectrum of electrochemical impedance, by infrared spectroscopy and scanning electron microscopy in combination with X-ray spectrum analysis are presented. It is shown, that sequential treatment of cation-exchanger, contained in cationexchange membrane, with metal salt solution and alkali solution does not result in formation of complex compounds of these metals with ionic groups of ion exchanger. It was found that in these conditions the presence of heavy metals in the phase of cationexchanger confirmed by X-ray analysis, however, crystals of hydroxides of heavy metals are not detected in the size range of 1000 nm to 20 nm. These heavy metal compounds are thermally unstable and their catalytic activity in the reaction of dissociation of water molecules decreases with increasing temperature during heat treatment. The introduction of low-soluble hydroxides of d-metals (chromium (III, iron (III, nickel(II by chemical method can significantly improve the electrochemical characteristics of a bipolar membrane. The most effective catalysts in water dissociation reaction are the hydroxides of chromium (III and iron (III and, as a consequence, membranes with these hydroxides have a lower value of overpotential compared with original membrane at the same current density

  10. The Effect of Calcium Hydroxide As an Intracanal Medication of The Apical Microleakage

    Directory of Open Access Journals (Sweden)

    Heshmat Mohajer AR

    2011-12-01

    Full Text Available Background and Aims: Nowadays, calcium hydroxide is used as a dressing for canal sterilization and repair progression of apical lesions. The aim of this study was to investigate the effect of calcium hydroxide as an intracanal medicament on the apical microleakage of root filling.Materials and Methods: In this experimental study, 46 extracted single-rooted human teeth were instrumented with step-back technique to master apical file (MAF size 35. Specimens were randomly divided into 2 groups (n = 20. In group 1, the specimens were treated with calcium hydroxide intracanal medication; and in group 2, the samples did not receive any medication. The teeth were incubated in 100% humidity at 37°C for one week. After that, calcium hydroxide was removed using irrigation with normal saline and reaming with MAF. The root canals were obturated with gutta- percha and AH26 sealer using lateral compaction technique. Specimens were incubated in 100% humility at 37°C for 72 hours and then immersed in India ink for 1 week. Finally, the teeth were cleared and the maximum linear dye penetration was measured under a stereomicroscope at 4X magnification. The data were analyzed by T-test and Chi-square.Results: There was no significant difference between the two experimental groups (P=0.068. Conclusion: The findings of this study indicated that using calcium hydroxide as an intracanal medicament did not influence the apical microleakage after final obturation of the root canal system.

  11. Efeito da concentração do catalisador acetilacetonato férrico na cura de poliuretano à base de polibutadieno líquido hidroxilado (PBLH e diisocianato de isoforona (IPDI Effect of ferric acetylacetonate catalyst concentration on the cure of polyurethane based on hydroxy terminated polybutadiene and isophorone diisocyanate

    Directory of Open Access Journals (Sweden)

    Willian César Paterlini

    2002-05-01

    Full Text Available The reaction between hydroxy-terminated polybutadiene and isophorone diisocyanate constitutes the base of the curing process of the most composite solid propellant used in the propulsion of solid rocket propellant. In this work, differential scanning calorimetry and viscosity measurements were used to evaluate the effect of the ferric acetylacetonate catalyst concentration on the reaction between HTBR and IPDI. These analyses show one exotherm, which shifts to lower temperatures as the catalyst concentration increases. The viscosity analyses show that the increase of temperature causes, at first, a reduction in the mixture viscosity, reaching a minimum range called gelification region (increasing the crosslinking density.

  12. Planar tetranuclear Dy(III) single-molecule magnet and its Sm(III), Gd(III), and Tb(III) analogues encapsulated by salen-type and β-diketonate ligands.

    Science.gov (United States)

    Yan, Peng-Fei; Lin, Po-Heng; Habib, Fatemah; Aharen, Tomoko; Murugesu, Muralee; Deng, Zhao-Peng; Li, Guang-Ming; Sun, Wen-Bin

    2011-08-01

    The syntheses, structures, and magnetic properties are reported for four new lanthanide clusters [Sm(4)(μ(3)-OH)(2)L(2)(acac)(6)]·4H(2)O (1), [Gd(4)(μ(3)-OH)(2)L(2)(acac)(6)]·4CH(3)CN (2), and [Ln(4)(μ(3)-OH)(2)L(2)(acac)(6)]·2H(2)L·2CH(3)CN (3, Ln = Tb; 4, Ln = Dy) supported by salen-type (H(2)L = N,N'-bis(salicylidene)-1,2-cyclohexanediamine) and β-diketonate (acac = acetylacetonate) ligands. The four clusters were confirmed to be essentially isomorphous by infrared spectroscopy and single-crystal X-ray diffraction. Their crystal structures reveal that the salen-type ligand provides a suitable tetradentate coordination pocket (N(2)O(2)) to encapsulate lanthanide(III) ions. Moreover, the planar Ln(4) core is bridged by two μ(3)-hydroxide, four phenoxide, and two ketonate oxygen atoms. Magnetic properties of all four compounds have been investigated using dc and ac susceptibility measurements. For 4, the static and dynamic data indicate that the Dy(4) complex exhibits slow relaxation of the magnetization below 5 K associated with single-molecule magnet behavior.

  13. Influence of sodium hydroxide in enhancing the surface plasmon resonance of silver nanoparticles

    Science.gov (United States)

    Yadav, Vijay D.; Jain, Ratnesh; Dandekar, Prajakta

    2017-08-01

    Herein, we report green synthesis of silver nanoparticles, by confluence graph described previously using acetate as the stabilizer as well as a reducing agent. The process involves use of ‘green’ chemicals and benign synthesis conditions. The synthesized nanoparticles were tuned for their surface plasmon resonance by sodium hydroxide addition and scanned between 400 to 800 nm to study the hyperchromic effect. As the concentration of sodium hydroxide increased, the surface plasmon resonance of the silver nanoparticles at 420 nm increased (hyperchromic effect). The synthesized silver nanoparticles were further characterized by TEM, for morphology analysis and laser scattering for the electromagnetic properties of nanoparticles. Our method may provide a gateway for intensive exploration of innovative approaches in synthesizing silver nanoparticles and tuning (hyperchromic effect) their localized surface plasmon resonance by using sodium hydroxide, which has tremendous utility in diverse application sectors.

  14. A role for calcium hydroxide and dolomite in water: acceleration of the reaction under ultraviolet light.

    Science.gov (United States)

    Nagase, Hiroyasu; Tsujino, Hidekazu; Kurihara, Daisuke; Saito, Hiroshi; Kawase, Masaya

    2014-04-01

    Organic environmental pollutants are now being detected with remarkably high frequency in the aquatic environment. Photodegradation by ultraviolet light is sometimes used as a method for removing organic chemicals from water; however, this method is relatively inefficient because of the low degradation rates involved, and more efficient methods are under development. Here we show that the removal of various organic pollutants can be assisted by calcined dolomite in aqueous solution under irradiation with ultraviolet light. It was possible to achieve substantial removal of bisphenol A, chlorophenols, alkylphenols, 1-naphthol and 17β-estradiol. The major component of dolomite responsible for the removal was calcium hydroxide. Our results demonstrate that the use of calcium hydroxide with ultraviolet light irradiation can be a very effective method of rapidly removing organic environmental pollutants from water. This is a new role for calcium hydroxide and dolomite in water treatment.

  15. The effect of crystal orientation on the cryogenic strength of hydroxide catalysis bonded sapphire

    Science.gov (United States)

    Haughian, K.; Douglas, R.; van Veggel, A. A.; Hough, J.; Khalaidovski, A.; Rowan, S.; Suzuki, T.; Yamamoto, K.

    2015-04-01

    Hydroxide catalysis bonding has been used in gravitational wave detectors to precisely and securely join components of quasi-monolithic silica suspensions. Plans to operate future detectors at cryogenic temperatures has created the need for a change in the test mass and suspension material. Mono-crystalline sapphire is one candidate material for use at cryogenic temperatures and is being investigated for use in the KAGRA detector. The crystalline structure of sapphire may influence the properties of the hydroxide catalysis bond formed. Here, results are presented of studies of the potential influence of the crystal orientation of sapphire on the shear strength of the hydroxide catalysis bonds formed between sapphire samples. The strength was tested at approximately 8 K; this is the first measurement of the strength of such bonds between sapphire at such reduced temperatures. Our results suggest that all orientation combinations investigated produce bonds of sufficient strength for use in typical mirror suspension designs, with average strengths >23 MPa.

  16. Nickel-vanadium monolayer double hydroxide for efficient electrochemical water oxidation

    Science.gov (United States)

    Fan, Ke; Chen, Hong; Ji, Yongfei; Huang, Hui; Claesson, Per Martin; Daniel, Quentin; Philippe, Bertrand; Rensmo, Håkan; Li, Fusheng; Luo, Yi; Sun, Licheng

    2016-06-01

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm-2 (57 mA cm-2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.

  17. The Chemical Isomerization of Lactose to Lactulose by Using Sodium Hydroxide as Batch Reaction

    Directory of Open Access Journals (Sweden)

    *Nahla T. K

    2016-06-01

    Full Text Available Lactulose is a synthetic and non-absorbable disaccharide sugar containing glucose and fructose units. It is used for the treatment of constipation and hepatic encephalopathy. The purpose of this experiment was to synthesized lactulose in the presence of sodium hydroxide as a catalyst. The evaluation of lactulose synthesis was carried out at different concentration of sodium hydroxide (1, 2 and 3M and the study was also conducted at different temperatures (30, 50, 70, and 90 °C. In addition, the kinetics of lactose isomerization with respect to the time also studied. Finally, it was concluded that the lactulose formation was determined by spectrophotometric method. The lactulose isomerization increased about more than 30.9% at 90 °C in the presence of 1M sodium hydroxide and 20 % lactose concentration.

  18. Nickel–vanadium monolayer double hydroxide for efficient electrochemical water oxidation

    Science.gov (United States)

    Fan, Ke; Chen, Hong; Ji, Yongfei; Huang, Hui; Claesson, Per Martin; Daniel, Quentin; Philippe, Bertrand; Rensmo, Håkan; Li, Fusheng; Luo, Yi; Sun, Licheng

    2016-01-01

    Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial requirements remains a challenge. Herein, we report a monolayer of nickel–vanadium-layered double hydroxide that shows a current density of 27 mA cm−2 (57 mA cm−2 after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel–iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel–vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting. PMID:27306541

  19. COMPARATIVE EVALUATION OF THE ANTIBACTERIAL EFFECT OF CALCIUM HYDROXIDE PASTES USING FOUR DIFFERENT VEHIC LES

    Directory of Open Access Journals (Sweden)

    Ganesh

    2012-10-01

    Full Text Available ABSTRACT: AIM: The present study evaluated the antibacterial effec t of calcium hydroxide pastes using four different vehicles namely propylene glycol, glycerin, distilled water and camphorated phenol. MATERIAL AND METHOD: Calcium hydroxide pastes prepared with two commonly used vehicles namely distilled water and c amphorated phenol. The antibacterial activity of these pastes were tested against five a naerobic organism that can commonly occur in the infected root canal. The pastes were also prepare d using two chemicals such as propylene glycol and glycerin. RESULTS AND CONCLUSION: The result of this study show that calcium hydroxide paste made with propylene glycol gives enhan ced antibacterial action and sustains it for longer period of time. Propylene glycol being bi ological acceptable vehicle, it can be recommended for routine use as a vehicle over glyce rin

  20. Biodiesel production using tetramethyl- and benzyltrimethyl ammonium hydroxides as strong base catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Karavalakis, Georgios; Anastopoulos, Georgios; Karonis, Dimitrios; Stournas, Stamos [Laboratory of Fuels and Lubricants Technology, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 157 80, Athens (Greece)

    2010-11-15

    In recent years, the acceptance of fatty acid methyl esters (biodiesel) as an alternative fuel has rapidly grown in EU. The most common method for biodiesel production is based on triglyceride transesterification to methyl esters with dissolved sodium hydroxide in methanol as catalyst. In this study, cottonseed oil and used frying oil were subjected to the transesterification reaction with tetramethyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide as strong base catalysts. This work investigates the optimum conditions for biodiesel production using amine-based liquid catalysts. Biodiesel ester content was strongly related with the type of feedstock and the reaction variables, such as those of the catalyst concentration, methanol to oil molar ratio, and reaction time. The overall results suggested that the transesterification of cottonseed oil achieved high conversion rates with both catalysts, while the use of waste oil resulted in lower yields of methyl esters due to the possible formation of amides. (author)

  1. An empirical model to estimate density of sodium hydroxide solution: An activator of geopolymer concretes

    Science.gov (United States)

    Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

    2016-02-01

    Geopolymer concrete is zero-Portland cement concrete containing alumino-silicate based inorganic polymer as binder. The polymer is obtained by chemical activation of alumina and silica bearing materials, blast furnace slag by highly alkaline solutions such as hydroxide and silicates of alkali metals. Sodium hydroxide solutions of different concentrations are commonly used in making GPC mixes. Often, it is seen that sodium hydroxide solution of very high concentration is diluted with water to obtain SHS of desired concentration. While doing so it was observed that the solute particles of NaOH in SHS tend to occupy lower volumes as the degree of dilution increases. This aspect is discussed in this paper. The observed phenomenon needs to be understood while formulating the GPC mixes since this influences considerably the relationship between concentration and density of SHS. This paper suggests an empirical formula to relate density of SHS directly to concentration expressed by w/w.

  2. Large-scale Hydrothermal Synthesis and Characterization of Size-controlled Lanthanum Hydroxide Nanorods

    Institute of Scientific and Technical Information of China (English)

    YI,Ran; ZHANG,Ning; SHI,Rongrong; LI,Yongbo; QIU Guanzhou; LIU Xiaohe

    2009-01-01

    Uniform lanthanum hydroxide nanorods were successfully synthesized in large quantities through a facile hydrothermal synthetic method, in which soluble lanthanum nitrate was used to supply the lanthanum source and triethylamine (TEA) was used as both alkaline agent and complexing agent. The influences of triethylamine amount, surfactant, reaction temperature and time on the size and shape of lanthanum hydroxide nanorods were investigated in detail. Trivalent rare earth ion doped lanthanum hydroxide nanorods were also obtained in this paper. The phase structures and morphologies of the as-prepared products were investigated in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and high-resolution transmis-sion electron microscopy (HRTEM). The probable formation mechanism was proposed based on the experimental results.

  3. Electroosmotic dewatering of chalk sludge, iron hydroxide sludge, wet fly ash and biomass sludge

    DEFF Research Database (Denmark)

    Hansen, H.K.; Christensen, Iben Vernegren; Ottosen, Lisbeth M.

    2003-01-01

    Electroosmotic dewatering has been tested in laboratory cells on four different porous materials: chalk sludge, iron hydroxide sludge, wet fly ash and biomass sludge from enzyme production. In all cases it was possible to remove water when passing electric DC current through the material. Casagra......Electroosmotic dewatering has been tested in laboratory cells on four different porous materials: chalk sludge, iron hydroxide sludge, wet fly ash and biomass sludge from enzyme production. In all cases it was possible to remove water when passing electric DC current through the material....... Casagrande's coefficients were determined for the four materials at different water contents. The experiments in this work showed that chalk could be dewatered from 40% to 79% DM (dry matter), fly ash from 75 to 82% DM, iron hydroxide sludge from 2.7 to 19% DM and biomass from 3 to 33% DM by electroosmosis...

  4. Removal of Indigo Carmine Dye from Aqueous Solution Using Magnesium Hydroxide as an Adsorbent

    Directory of Open Access Journals (Sweden)

    Thimmasandra Narayan Ramesh

    2015-01-01

    Full Text Available Magnesium hydroxide is used as an adsorbent for the removal of indigo carmine dye from aqueous solution. We have investigated the effectiveness of removal of indigo carmine dye from aqueous solutions at pH 6-7 and 12-13 using magnesium hydroxide thereby varying the dose of the adsorbent, concentration of the dye, duration, and temperature. Structural transformations of adsorbent during the adsorption process at different pH values are monitored using powder X-ray diffraction and infrared spectroscopy. Different types of adsorption isotherm models were evaluated and it was found that Langmuir isotherm fits well at both pH values (6-7 and 12-13. Adsorption of indigo carmine onto magnesium hydroxide at pH 6-7/pH 12-13 follows pseudo-second order rate kinetics.

  5. Determination of Ksp, , , and for the Dissolution of Calcium Hydroxide in Water: A General Chemistry Experiment

    Science.gov (United States)

    Euler, William B.; Kirschenbaum, Louis J.; Ruekberg, Ben

    2000-08-01

    The molar solubility of sparingly soluble calcium hydroxide in water at room temperature and in boiling water is easily determined by titration of filtered saturated solutions with standardized hydrochloric acid solution. The apparent equilibrium constant, Ksp, can be calculated from the molar solubility of calcium hydroxide: Ksp = [Ca2+][OH-]2. The ? for the dissolution of calcium hydroxide at each temperature is calculated from the formula ? = -RT ln(Kc). ? values at two temperatures permit the calculation of ? and ?. This exercise utilizes low-cost, relatively nonhazardous materials presenting few disposal problems. It reinforces the students' understanding of the interrelationship of solubility, Ksp, ? , ? and ?. The significant extent of Ca(OH)2 solubility and its favorable temperature variation provide unique conditions for the success of this experiment.

  6. Lack of genotoxicity of formocresol, paramonochlorophenol, and calcium hydroxide on mammalian cells by comet assay.

    Science.gov (United States)

    Ribeiro, Daniel Araki; Marques, Mariângela Esther Alencar; Salvadori, Daisy Maria Fávero

    2004-08-01

    Formocresol, paramonochlorophenol, and calcium hydroxide are widely used in dentistry because of their antibacterial activities in root canal disinfection. However, the results of genotoxicity studies using these materials are inconsistent in literature. The goal of this study was to examine the genotoxic potential of formocresol, paramonochlorophenol, and calcium hydroxide using mouse lymphoma cells and human fibroblasts cells in vitro by the comet assay. Data were assessed by Kruskal-Wallis nonparametric test. The results showed that all compounds tested did not cause DNA damage for the tail moment or tail intensity parameters. These findings suggest that formocresol, paramonochlorophenol, and calcium hydroxide do not promote DNA damage in mammalian cells and that the comet assay is a suitable tool to investigate genotoxicity.

  7. Aluminum phosphate shows more adjuvanticity than Aluminum hydroxide in recombinant hepatitis –B vaccine formulation

    Directory of Open Access Journals (Sweden)

    2008-08-01

    Full Text Available Background: Although a number of investigation have been carried out to find alternative adjuvants to aluminum salts in vaccine formulations, they are still extensively used due to their good track record of safety, low cost and proper adjuvanticity with a variety of antigens. Adsorption of antigens onto aluminum compounds depends heavily on electrostatic forces between adjuvant and antigen. Commercial recombinant protein hepatitis B vaccines containing aluminum hydroxide as adjuvant is facing low induction of immunity in some sections of the vaccinated population. To follow the current global efforts in finding more potent hepatitis B vaccine formulation, adjuvanticity of aluminum phosphate has been compared to aluminum hydroxide. Materials and methods: The adjuvant properties of aluminum hydroxide and aluminum phosphate in a vaccine formulation containing a locally manufactured hepatitis B (HBs surface antigen was evaluated in Balb/C mice. The formulations were administered intra peritoneally (i.p. and the titers of antibody which was induced after 28 days were determined using ELISA technique. The geometric mean of antibody titer (GMT, seroconversion and seroprotection rates, ED50 and relative potency of different formulations were determined. Results: All the adjuvanicity markers obtained in aluminum phosphate formulation were significantly higher than aluminum hydroxide. The geometric mean of antibody titer of aluminum phosphate was approximately three folds more than aluminum hydroxide. Conclusion: Aluminum phosphate showed more adjuvanticity than aluminum hydroxide in hepatitis B vaccine. Therefore the use of aluminum phosphate as adjuvant in this vaccine may lead to higher immunity with longer duration of effects in vaccinated groups.

  8. Process optimization of reaction of acid leaching residue of asbestos tailing and sodium hydroxide aqueous solution

    Institute of Scientific and Technical Information of China (English)

    DU GaoXiang; ZHENG ShuiLin; DING Hao

    2009-01-01

    Silica is the major component of the acid leaching residue of asbestos tailing. The waterglass solution can be prepared by the reaction of the residue with sodium hydroxide aqueous solution. Compared to the high temperature reaction method, this process is environmental friendly and low cost. In this paper, the reaction process of the residue and the sodium hydroxide aqueous solution is optimized. The op-timum reaction process parameters are as follows: the usage of sodium hydroxide is 26.4 g/100 g acid leaching residue, the reaction temperature is 90℃, the reaction time is 1 h, and the ratio of the liq-uid/solid is 2.0. The significance sequence of the process parameters to the alkali leaching reaction effect is the usage of sodium hydroxide > the ratio of the liquid/solid > the reaction time > the reaction temperature. The significance sequence to the leaching ratio of SiO2 is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. The significance sequence to the modulus of the sodium silicate is the ratio of the liquid/solid > the usage of sodium hydroxide > the reaction time > the reaction temperature. Under the optimum conditions, the leaching ratio of the SiO2 is 77.5%, and the modulus of the sodium silicate is 3.15. The XRD analysis result indicates that the major components of the alkali leaching residue are serpentine, talc, quartz and some albite.

  9. Determination of Ultra-trace Amounts of Arsenic(III) by Flow Injection Hydride Generation Atomic Absorption Spectrometry with On-line Preconcentration by Coprecipitation with Lanthanum Hydroxide or Hafnium Hydroxide

    DEFF Research Database (Denmark)

    Nielsen, Steffen; Sloth, Jens Jørgen; Hansen, Elo Harald

    1996-01-01

    (III) is more effectively collected by lanthanum hydroxide than by hafnium hydroxide, the sensitivity achieved by the former being ca. 25% better. With optimal experimental conditions and with a sample consumption of 6.7 ml per assay, an enrichment factor of 32 was obtained at a sample frequency of 33 samples...

  10. Cobalt hydroxide/oxide hexagonal ring-graphene hybrids through chemical etching of metal hydroxide platelets by graphene oxide: energy storage applications.

    Science.gov (United States)

    Nethravathi, C; Rajamathi, Catherine R; Rajamathi, Michael; Wang, Xi; Gautam, Ujjal K; Golberg, Dmitri; Bando, Yoshio

    2014-03-25

    The reaction of β-Co(OH)2 hexagonal platelets with graphite oxide in an aqueous colloidal dispersion results in the formation of β-Co(OH)2 hexagonal rings anchored to graphene oxide layers. The interaction between the basic hydroxide layers and the acidic groups on graphene oxide induces chemical etching of the hexagonal platelets, forming β-Co(OH)2 hexagonal rings. On heating in air or N2, the hydroxide hybrid is morphotactically converted to porous Co3O4/CoO hexagonal ring-graphene hybrids. Porous NiCo2O4 hexagonal ring-graphene hybrid is also obtained through a similar process starting from β-Ni0.33Co0.67(OH)2 platelets. As electrode materials for supercapacitors or lithium-ion batteries, these materials exhibit a large capacity, high rate capability, and excellent cycling stability.

  11. Preparation of hydroxide ion conductive KOH–layered double hydroxide electrolytes for an all-solid-state iron–air secondary battery

    Directory of Open Access Journals (Sweden)

    Taku Tsuneishi

    2014-06-01

    Full Text Available Anion conductive solid electrolytes based on Mg–Al layered double hydroxide (LDH were prepared for application in an all-solid-state Fe–air battery. The ionic conductivity and the conducting ion species were evaluated from impedance and electromotive force measurements. The ion conductivity of LDH was markedly enhanced upon addition of KOH. The electromotive force in a water vapor concentration cell was similar to that of an anion-conducting polymer membrane. The KOH–LDH obtained was used as a hydroxide ion conductive electrolyte for all-solid-state Fe–air batteries. The cell performance of the Fe–air batteries was examined using a mixture of KOH–LDH and iron-oxide-supported carbon as the negative electrode.

  12. Antimycobacterial, antimicrobial, and biocompatibility properties of para-aminosalicylic acid with zinc layered hydroxide and Zn/Al layered double hydroxide nanocomposites.

    Science.gov (United States)

    Saifullah, Bullo; El Zowalaty, Mohamed E; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin M; Hussein, Mohd Zobir

    2014-01-01

    The treatment of tuberculosis by chemotherapy is complicated due to multiple drug prescriptions, long treatment duration, and adverse side effects. We report here for the first time an in vitro therapeutic effect of nanocomposites based on para-aminosalicylic acid with zinc layered hydroxide (PAS-ZLH) and zinc-aluminum layered double hydroxides (PAS-Zn/Al LDH), against mycobacteria, Gram-positive bacteria, and Gram-negative bacteria. The nanocomposites demonstrated good antimycobacterial activity and were found to be effective in killing Gram-positive and Gram-negative bacteria. A biocompatibility study revealed good biocompatibility of the PAS-ZLH nanocomposites against normal human MRC-5 lung cells. The para-aminosalicylic acid loading was quantified with high-performance liquid chromatography analysis. In summary, the present preliminary in vitro studies are highly encouraging for further in vivo studies of PAS-ZLH and PAS-Zn/Al LDH nanocomposites to treat tuberculosis.

  13. Double-Shelled Nanocages with Cobalt Hydroxide Inner Shell and Layered Double Hydroxides Outer Shell as High-Efficiency Polysulfide Mediator for Lithium-Sulfur Batteries.

    Science.gov (United States)

    Zhang, Jintao; Hu, Han; Li, Zhen; Lou, Xiong Wen David

    2016-03-14

    Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li-S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li-S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li-S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance.

  14. Development of Drug Delivery Systems Based on Layered Hydroxides for Nanomedicine

    Directory of Open Access Journals (Sweden)

    Farahnaz Barahuie

    2014-05-01

    Full Text Available Layered hydroxides (LHs have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.

  15. Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides.

    Science.gov (United States)

    Papassiopi, N; Vaxevanidou, K; Christou, C; Karagianni, E; Antipas, G S E

    2014-01-15

    Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH)3·xH2O whereas in the presence of iron the precipitate is a mixed Fe(1-x)Crx(OH)3 phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fex,Cr1-x)(OH)3 hydroxides as compared to the stability of Cr(OH)3. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH)3·3H2O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH)3(am) phase. Mixed Fe0.75Cr0.25(OH)3 hydroxides were found to be of the ferrihydrite structure, Fe(OH)3, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)-Cr(III) hydroxides are more effective enhancers of groundwater quality, in comparison to the plain amorphous or crystalline Cr(III) hydroxides, the latter found to have a solubility typically higher than 50μg/l (maximum EU permitted Cr level in drinking water), while the amorphous Cr(OH)3(am) phase was within the drinking water threshold in the range 5.7hydroxides studied were of extended stability in the 4.8

  16. Synthesis and characterization of laurate-intercalated Mg–Al layered double hydroxide prepared by coprecipitation

    DEFF Research Database (Denmark)

    Gerds, Nathalie Christiane; Katiyar, Vimal; Koch, Christian Bender

    2012-01-01

    Effective utilization of layered double hydroxides (LDH) for industrial applications requires the synthesis of pure and well-defined LDH phases. In the present study, dodecanoate (laurate) anions were intercalated into Mg–Al-layered double hydroxide (LDH-C12) by coprecipitation in the presence...... intercalated structure, but we here demonstrate it to be magnesium laurate (Mg-C12). The LDH-C12 compound showed high structural order with a basal spacing of 2.41nm. Fourier-transform IR-spectra confirmed the intercalation of the laurate anions in the interlayer. Transmission electron microscopy showed plate...

  17. Synthesis and Characterization of Layered Double Hydroxides Containing Optically Active Transition Metal Ion

    Science.gov (United States)

    Tyagi, S. B.; Kharkwal, Aneeta; Nitu; Kharkwal, Mamta; Sharma, Raghunandan

    2017-01-01

    The acetate intercalated layered double hydroxides of Zn and Mn, have been synthesized by chimie douce method. The materials were characterized by XRD, TGA, CHN, IR, XPS, SEM-EDX and UV-visible spectroscopy. The photoluminescence properties was also studied. The optical properties of layered hydroxides are active transition metal ion dependent, particularly d1-10 system plays an important role. Simultaneously the role of host - guest orientation has been considered the basis of photoluminescence. Acetate ion can be exchanged with iodide and sulphate ions. The decomposed product resulted the pure phase Mn doped zinc oxide are also reported.

  18. Sulfur removal from Gediz lignite using aqueous sodium hydroxide solutions under mild oxidative conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, S.; Kuecuekbayrak, S. [Istanbul Technical Univ. (Turkey). Chemical and Metallurgical Engineering Faculty

    1999-11-01

    Sulfur removal from a high-sulfur Turkish lignite (Gediz) using aqueous sodium hydroxide solutions having dissolved oxygen was investigated under mild oxidative conditions. Effects of the parameters such as sodium hydroxide/lignite weight ratio, temperature, and partial pressure of oxygen were investigated within the ranges of 0.05--0.8, 423--498 K, and 1--2 MPa, respectively. Optimum values of these parameters were determined regarding sulfur removal and coal recovery. Influences of dry oxidation of the lignite sample as a pretreatment at 573 K and subsequent washing of some treated lignite samples with 1 N HCl were investigated.

  19. Studies on Thorium Adsorption Characteristics upon Activated Titanium Hydroxide Prepared from Rosetta Ilmenite Concentrate

    Energy Technology Data Exchange (ETDEWEB)

    Gado, M, E-mail: parq28@yahoo.com; Zaki, S [Nuclear Materials Authority, P. O. Box 530 El Maadi, Cairo (Egypt)

    2016-01-01

    The titanium hydroxide prepared from Rosetta ilmenite concentrate has been applied for Th (IV) adsorption from its acid aqueous solutions. The prepared hydroxide is first characterized by both Fourier transform infrared (FT-IR) spectrum and thermogravimetric analysis. The relevant factors affecting the adsorption process have been studied. The obtained equilibrium data fits well with the Langmuir isotherm rather than Freundlich isotherm, while the adsorption kinetic data follow the pseudo-second order model. The different thermodynamic parameters have also been calculated and indicate that the adsorption process is spontaneous.

  20. Hydrothermal Synthesis of Nickel Hydroxide Nanostructures and Flame Retardant Poly Vinyl Alcohol and Cellulose Acetate Nanocomposites

    Directory of Open Access Journals (Sweden)

    S. R. Yousefi

    2016-01-01

    Full Text Available Nickel hydroxide nanostructures were synthesized by a hydrothermal reaction. The effect of different precursors and surfactants on the morphology of nickel hydroxide nanostructures was investigated. Nanostructures were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and Fourier transform infrared  spectroscopy. The influence of Ni(OH2 nanostructures on the thermal stability and flame retardancy of the poly vinyl alcohol and cellulose acetate matrix was studied using UL-94 analysis. The enhancement of thermal stability and flame retardancy of nanocomposites is due to the endothermic decomposition of Ni(OH2 and release of water which dilutes combustible gases.

  1. Antimycobacterial, antimicrobial, and biocompatibility properties of para-aminosalicylic acid with zinc layered hydroxide and Zn/Al layered double hydroxide nanocomposites

    Directory of Open Access Journals (Sweden)

    Saifullah B

    2014-07-01

    Full Text Available Bullo Saifullah,1 Mohamed E El Zowalaty,2,3 Palanisamy Arulselvan,2 Sharida Fakurazi,2,4 Thomas J Webster,5,6 Benjamin M Geilich,5 Mohd Zobir Hussein1 1Materials Synthesis and Characterization Laboratory, Institute of Advanced Technology (ITMA, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 2Laboratory of Vaccines and Immunotherapeutics, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 3Department of Environmental Health, Faculty of Public Health and Tropical Medicine, Jazan University, Jazan, Saudi Arabia; 4Department of Human Anatomy, Faculty of Medicine and Health Science, Universiti Putra Malaysia, Serdang, Selangor, Malaysia; 5Department of Chemical Engineering and Program in Bioengineering, Northeastern University, Boston, MA, USA; 6Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia Abstract: The treatment of tuberculosis by chemotherapy is complicated due to multiple drug prescriptions, long treatment duration, and adverse side effects. We report here for the first time an in vitro therapeutic effect of nanocomposites based on para-aminosalicylic acid with zinc layered hydroxide (PAS-ZLH and zinc-aluminum layered double hydroxides (PAS-Zn/Al LDH, against mycobacteria, Gram-positive bacteria, and Gram-negative bacteria. The nanocomposites demonstrated good antimycobacterial activity and were found to be effective in killing Gram-positive and Gram-negative bacteria. A biocompatibility study revealed good biocompatibility of the PAS-ZLH nanocomposites against normal human MRC-5 lung cells. The para-aminosalicylic acid loading was quantified with high-performance liquid chromatography analysis. In summary, the present preliminary in vitro studies are highly encouraging for further in vivo studies of PAS-ZLH and PAS-Zn/Al LDH nanocomposites to treat tuberculosis.  Keywords: Zn/Al-layered double hydroxides, zinc layered hydroxides, tuberculosis, para

  2. Large-scale simulations of layered double hydroxide nanocomposite materials

    Science.gov (United States)

    Thyveetil, Mary-Ann

    Layered double hydroxides (LDHs) have the ability to intercalate a multitude of anionic species. Atomistic simulation techniques such as molecular dynamics have provided considerable insight into the behaviour of these materials. We review these techniques and recent algorithmic advances which considerably improve the performance of MD applications. In particular, we discuss how the advent of high performance computing and computational grids has allowed us to explore large scale models with considerable ease. Our simulations have been heavily reliant on computational resources on the UK's NGS (National Grid Service), the US TeraGrid and the Distributed European Infrastructure for Supercomputing Applications (DEISA). In order to utilise computational grids we rely on grid middleware to launch, computationally steer and visualise our simulations. We have integrated the RealityGrid steering library into the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) 1 . which has enabled us to perform re mote computational steering and visualisation of molecular dynamics simulations on grid infrastruc tures. We also use the Application Hosting Environment (AHE) 2 in order to launch simulations on remote supercomputing resources and we show that data transfer rates between local clusters and super- computing resources can be considerably enhanced by using optically switched networks. We perform large scale molecular dynamics simulations of MgiAl-LDHs intercalated with either chloride ions or a mixture of DNA and chloride ions. The systems exhibit undulatory modes, which are suppressed in smaller scale simulations, caused by the collective thermal motion of atoms in the LDH layers. Thermal undulations provide elastic properties of the system including the bending modulus, Young's moduli and Poisson's ratios. To explore the interaction between LDHs and DNA. we use molecular dynamics techniques to per form simulations of double stranded, linear and plasmid DNA up

  3. A facile one-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica: Aqueous hydration of nitriles to amides

    Science.gov (United States)

    One-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium hydroxide immobilization; the hydration of nitriles occurs in high yield and excellent selectivity using this...

  4. A facile one-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica: Aqueous hydration of nitriles to amides

    Science.gov (United States)

    One-pot synthesis of ruthenium hydroxide nanoparticles on magnetic silica is described which involve the in situ generation of magnetic silica (Fe3O4@ SiO2) and ruthenium hydroxide immobilization; the hydration of nitriles occurs in high yield and excellent selectivity using this...

  5. Catalytic wet peroxide oxidation of azo dye (Direct Blue 15) using solvothermally synthesized copper hydroxide nitrate as catalyst.

    Science.gov (United States)

    Zhan, Yuzhong; Zhou, Xiang; Fu, Bei; Chen, Yiliang

    2011-03-15

    Copper hydroxide nitrate (Cu(2)(OH)(3)NO(3)) was synthesized solvothermally in anhydrous ethanol and characterized by XRD, FTIR, TG-DTA and SEM. The peroxide degradation of an azo dye (Direct Blue 15) on this material was evaluated by examining catalyst loading, initial pH, hydrogen peroxide dosage, initial dye concentration and temperature. The leaching of Cu from the copper hydroxide nitrate during the reaction was also measured. The copper hydroxide nitrate synthesized solvothermally, which was of a novel spherical morphology with complex secondary structures and contained high-dispersed Cu(2)O impurity, showed good performance for oxidation degradation of the azo dye, especially high catalytic activity, high utilization of hydrogen peroxide and a wide pH range, whereas the copper hydroxide nitrate synthesized by the direct reaction of copper nitrate and sodium hydroxide showed low catalytic activity. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Utilization of Magnesium Hydroxide Produced by Magnesia Hydration as Fire Retardant for Nylon 6-6,6

    Directory of Open Access Journals (Sweden)

    Rocha Sônia D.F.

    2001-01-01

    Full Text Available The present work investigates the use of magnesium hydroxide, produced by magnesia hydration, as a fire retardant in polymers. The hydration was carried out in an autoclave, at temperature of 130°C for 1 hour, and the product was further submitted to cominution in a jet mill. The solids were characterized with regard to their chemical composition, particle size distribution, surface area and morphology. The performance evaluation of the hydroxide as a flame retardant for a copolymer of nylon 6-6,6 was carried out according to the UL94 specifications for vertical burning tests. V-0 flammability rating at 1.6 mm (60% magnesium hydroxide-filled nylon composite and at 3.2 mm (40% magnesium hydroxide filled nylon composite were achieved. Mechanical properties were maintained at the desired values. These results indicate that the hydroxide obtained from magnesia hydration can be successfully employed as a fire retardant for nylon 6-6,6.

  7. 双(羟基)金属复合氧化物的表面改性%Surface Modification of Layered Double Hydroxide

    Institute of Scientific and Technical Information of China (English)

    冯春瑶; 矫庆泽; 李蕾; 张春英; 段雪

    2001-01-01

    Mg/Al layered double hydroxide(LDH) was treated with stearic acid by a wet method. The modified double hydroxide showed good dispersion and floatation property with their layer structure being remained almost unchanged.

  8. Selectivity of the highly preorganized tetradentate ligand 2,9-di(pyrid-2-yl)-1,10-phenanthroline for metal ions in aqueous solution, including lanthanide(III) ions and the uranyl(VI) cation.

    Science.gov (United States)

    Carolan, Ashley N; Cockrell, Gregory M; Williams, Neil J; Zhang, Gang; VanDerveer, Donald G; Lee, Hee-Seung; Thummel, Randolph P; Hancock, Robert D

    2013-01-01

    Some metal ion complexing properties of DPP (2,9-Di(pyrid-2-yl)-1,10-phenanthroline) are reported with a variety of Ln(III) (Lanthanide(III)) ions and alkali earth metal ions, as well as the uranyl(VI) cation. The intense π-π* transitions in the absorption spectra of aqueous solutions of 10(-5) M DPP were monitored as a function of pH and metal ion concentration to determine formation constants of the alkali-earth metal ions and Ln(III) (Ln = lanthanide) ions. It was found that log K(1)(DPP) for the Ln(III) ions has a peak at Ln(III) = Sm(III) in a plot of log K(1) versus 1/r(+) (r(+) = ionic radius for 8-coordination). For Ln(III) ions larger than Sm(III), there is a steady rise in log K(1) from La(III) to Sm(III), while for Ln(III) ions smaller than Sm(III), log K(1) decreases slightly to the smallest Ln(III) ion, Lu(III). This pattern of variation of log K(1) with varying size of Ln(III) ion was analyzed using MM (molecular mechanics) and DFT (density functional theory) calculations. Values of strain energy (∑U) were calculated for the [Ln(DPP)(H(2)O)(5)](3+) and [Ln(qpy)(H(2)O)(5)](3+) (qpy = quaterpyrdine) complexes of all the Ln(III) ions. The ideal M-N bond lengths used for the Ln(III) ions were the average of those found in the CSD (Cambridge Structural Database) for the complexes of each of the Ln(III) ions with polypyridyl ligands. Similarly, the ideal M-O bond lengths were those for complexes of the Ln(III) ions with coordinated aqua ligands in the CSD. The MM calculations suggested that in a plot of ∑U versus ideal M-N length, a minimum in ∑U occurred at Pm(III), adjacent in the series to Sm(III). The significance of this result is that (1) MM calculations suggest that a similar metal ion size preference will occur for all polypyridyl-type ligands, including those containing triazine groups, that are being developed as solvent extractants in the separation of Am(III) and Ln(III) ions in the treatment of nuclear waste, and (2) Am(III) is very

  9. The contribution of polyhydroxyl aromatic compounds to tetramethylammonium hydroxide lignin-based proxies

    NARCIS (Netherlands)

    Filley, T.R.; Nierop, K.G.J.; Wang, Y.

    2006-01-01

    A problem inherent in analytical procedures where thermochemolyis or pyrolysis is coupled with in situ methylation by tetramethylammonium hydroxide is the inability to determine if an observed aromatic methoxyl group was originally present as a hydroxyl or a methoxyl functionality. This analytical i

  10. Molecular dynamic simulations of iron (II) hydroxide in high temperature and supercritical water

    Science.gov (United States)

    Meng, Yuanliang

    In this study, the iron (II) hydroxide -- water system has been investigated at high temperatures by using molecular dynamics (MD) simulations. The simulation results reveal that at infinite dilution both Fe2+ cation and OH- anion have 6 water molecules within their first hydration shell and both types of ionic species experience a dramatic increase in their diffusion coefficients at near and supercritical conditions. The process of iron (II) hydroxide cluster formation has been simulated. The nano-clusters of larger sizes formed in supercritical water tend to be in an amorphous state. After having been quenched by an inert gas bath, iron (II) hydroxide nano-clusters with various structures have been produced. The geometries and associated binding energies of these species are given in detail. The vibrational spectra of iron (II) hydroxide clusters are also derived and compared with the spectrum of a bulk solid. The obtained results have a practical value for the analysis of potential corrosion products in supercritical water-cooled reactor (SCWR) which is employed in the new generation nuclear power plant design (GEN IV). This work also illustrates the process of hydrothermal synthesis of oxide nano-particles.

  11. Effect of the smear layer in the removal of calcium hydroxide from root canal walls

    Directory of Open Access Journals (Sweden)

    Hakan Arslan

    2012-01-01

    Full Text Available Background: The aim of this study was to investigate whether the smear layer influences the removal of calcium hydroxide from the root canal with manual or rotary instruments. Materials and Methods: The root canals of 48 freshly extracted single-rooted maxillary incisors were prepared to apical size 40 (n=40 and finally irrigated with sodium hypochlorite (group A, or ethylene diamine tetra acetic acid (EDTA followed by sodium hypo chlorite (group B. 20 teeth were assigned to each group, while the remaining eight teeth served as positive and negative controls. Each group was divided into two subgroups of 10 teeth (subgroup I - calcium hydroxide was removed with master apical file; subgroup II - with profile file; and, in all removal procedures, citric acid was used for irrigation. The percentage of calcium hydroxide-[Ca(OH [Ca(OH 2 ] coated surface area was calculated by image processing analysis. Results: Considering the root canal as a whole, the removal of Ca(OH 2 from the dentinal walls in group B showed significantly better results (P<0.05 as compared to group A. Conclusions: Under the conditions of this study, it can be concluded that the smear layer is important in the removal of calcium hydroxide.

  12. Speciation of heavy metal ions as influenced by interactions with montmorillonite, Al hydroxide polymers and citrate.

    NARCIS (Netherlands)

    Janssen, R.P.T.

    1995-01-01

    Clay minerals, metal-hydroxides and organic matter can bind metal ions; moreover they also interact with each other. These mutual interactions influence the metal binding to a significant extent. In this study, the speciation of the heavy metal ions Zn and Ph was investigated in model systems consis

  13. Flame retardancy effect of surface-modified metal hydroxides on linear low density polyethylene

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Metal hydroxides (MAH) consisting of magnesium hydroxide and aluminum hydroxide with a mass ratio of 1:2 were surface-modified by γ-diethoxyphosphorous ester propyldiethoxymethylsilane,boric acid and diphenylsilanediol in xylene under dibutyl tin dilaurate catalyst at 140 ℃.Phosphorus,silicon and boron elements covalently bonded to metal hydroxide particles were detected by X-ray photoelectron spectroscopy.The degradation behavior of the surface-modified MAH was characterized by thermogravimetric analysis.The results show that linear low density polyethylene (LLDPE) composite,filled with 50% (mass fraction) of MAH modified by 5.0% (mass fraction) of modifiers,passes the V-O rating of UL-94 test and shows the limited oxygen index of 34%,and its heat release rate and average effective heat combustion in a cone calorimeter measurement decrease obviously;The mechanical properties of MAH can be improved by surface-modification.The uniform dispersion of particles and strong interfacial bonding between particles and matrix are obtained.

  14. Comparison of the Winograd method and chemical cauterization with 10% sodium hydroxide for treating ingrown toenails

    Directory of Open Access Journals (Sweden)

    Nebahat Demet Akpolat

    2016-09-01

    Full Text Available Background and Design: This study was performed to assess the therapeutic outcomes of the surgical method, described by Winograd and chemical cauterization with sodium hydroxide in patients with Heifetz stage 2 and 3 ingrown toenail (recurrence, complication, improvement and time to regain activity. Materials and Methods: One-hundred patients who presented to the outpatient clinics of orthopedics, general surgery and dermatology with the complaints of pain, redness and discharge in the toenail between January 2010 and January 2012 and who failed to respond to conservative treatment and were diagnosed with Heifetz stage 2 and 3 ingrown toenail. Fifty patients underwent chemical cauterization with sodium hydroxide while 50 underwent Winograd surgery. Results: The patients were followed up for a year at 2-month intervals. While no recurrence was observed in patients who received chemical cauterization, five patients who underwent Winograd surgery had recurrence (p=0.022. Three patients receiving Winograd surgery were found to have superficial wound side infection on postoperative follow-up (p=0.08. Patients, who underwent chemical cauterization with sodium hydroxide, were detected to improve and return to normal activity in a shorter period. Conclusion: Chemical cauterization of the germinal matrix with 10% sodium hydroxide is a convenient method with a low rate of complication and recurrence compared to the Winograd surgery in the treatment of ingrown toenails.

  15. Clinical Survey of Successfulness of DPC with MTA and Calcium Hydroxide

    Directory of Open Access Journals (Sweden)

    E.Yasini

    2005-02-01

    Full Text Available Statement of Problem: The pulp may be exposed during remove of caries or by traumatic and iatrogenicinjuries. The material used to DPC, must be biocompatible, scalable and prevent bacterial leakage.Furthermore, it is better to stimulate dentinogenesis. Calcium hydroxide is most usual material for DPC. But itcannot provide a suitablcbiologic seal. Mineral irioxide aggregate (MTA is also a suitable material for DPC.Purpose: The aim of this study was to compare the clinical success of DPC done with MTA or calciumhydroxide cement.Materials and Methods: In this study eighteen posterior teeth without previous spontaneous pain thatinvolved mechanicaly exposure was randomly selected and capped with MTA or calcium hydroxide. These teeth were evaluated by clinical vitality test and radiograph after 3 and 12 months, and patients werequestioned about irritative or spontancus pain in this period. Statistical analysis was carried out by Usher exacttest (a-0.05.Results: This study showed that in calcium hydroxid groud three had irreversible pulpitis and two teeth had symptom and signs of reversible pulpitis. While, In MTA group all cases were normaL and no clinical sign was evident.Conclusion: MTA exhibited better results than calcium hydroxide cement for the capping of the pulp in human

  16. Different approaches to the analysis of small angle scattering experiments on porous aluminum-hydroxide

    DEFF Research Database (Denmark)

    Rasmussen, F.B.

    2001-01-01

    Different approaches to the analysis of Small Angle X-ray Scattering experiments on the porous aluminum-hydroxide pseudo-boehmite are compared. Experimental data is analyzed both as scattering from mass fractal aggregates and polydisperse collections of anisotropic particles. Both types of analys...

  17. Preparation of magnesium hydroxide nanoflowers from boron mud via anti-drop precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xi [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Blue Sky Technology Corporation, Beijing 100083 (China); Ma, Hongwen, E-mail: mahw@cugb.edu.cn [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Jiang, Xiaoqian [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Jiang, Zhouqing [School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Blue Sky Technology Corporation, Beijing 100083 (China)

    2014-08-15

    Highlights: • We use the anti-drop precipitation method for synthesis of magnesium hydroxide. • Boron mud which is solid waste from a borax factory is used as the magnesium source. • The magnesium hydroxide nanoflowers are prepared in a short time. • The as-prepared magnesium hydroxide can be used as an effective flame retardant. - Abstract: Using boron mud as the starting material, the flower-like magnesium hydroxide (MH) has been successfully prepared via anti-drop precipitation method. The effect of NH{sub 3}·H{sub 2}O concentration, aging time, and surfactant on the morphology of MH was investigated. The optimum precipitation conditions are dropping MgSO{sub 4} solution in 5% NH{sub 3}·H{sub 2}O solution, with 3% polyethylene glycol as surfactant, aging for 30 min. XRD, SEM, FI-IR, and TG/DTA have been employed to characterize the as-prepared samples. XRD reveals that MH with high purity has the brucite structure. SEM images show that the flower-like MH exists in the form of mono-disperse well uniform spherical aggregation with diameter of 3–5 μm. TG/DTA shows a total percentage of weight loss 33.6% with a well-defined endothermic peak near 381.3 °C corresponding to the decomposition of MH. Furthermore, it reports that the extremely fast primary nucleation is of significance for crystal growth of MH.

  18. Comparison of Calcium Hydroxide and Bioactive Glass after Direct Pulp Capping in Primary Teeth

    Directory of Open Access Journals (Sweden)

    R. Haghgoo

    2007-12-01

    Full Text Available Objective: Bioactive glass is often used as a filler material for repair of dental bone defects.In different studies osteogenic potential of this material was proved, but its dentinogenesisproperty is in doubt. The purpose of this study was to evaluate the histological pulp responses of Calcium hydroxide and Bioactive glass placed directly on exposed pulp tissues.Materials and Methods: Twenty teeth to be extracted due to orthodontic reasons were selected. These teeth were divided into two groups and treated with direct pulp capping.Calcium hydroxide was used for 10 teeth and Bioactive glass for 10 teeth. After 60 daysthe teeth were extracted and prepared for histological evaluation. Finally the data was analyzed with exact Fisher test.Results: All teeth treated with Calcium hydroxide showed inflammation. Internal resorption was seen in six teeth, abscess in five teeth and dentinal bridge in two teeth. Inflammationwas seen in three Bioactive glass samples and dentinal bridge in seven teeth, but internal resorption and abscess were not seen.Conclusion: Bioactive glass appears to be superior to Calcium hydroxide as a pulp capping agent in primary teeth.

  19. Adsorption and surface oxidation of Fe(II) on metal (hydr)oxides.

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2007-01-01

    The Fe(II) adsorption by non-ferric and ferric (hydr)oxides has been analyzed with surface complexation modeling. The CD model has been used to derive the interfacial distribution of charge. The fitted CD coefficients have been linked to the mechanism of adsorption. The Fe(II) adsorption is

  20. Efficacy of different irrigants in the removal of calcium hydroxide from root canals.

    Science.gov (United States)

    Rödig, T; Vogel, S; Zapf, A; Hülsmann, M

    2010-06-01

    To compare the efficacy of different solutions (1% sodium hypochlorite, 10% citric acid and 20% EDTA) in the removal of calcium hydroxide from root canals. One hundred single-rooted maxillary incisors were prepared to size 50 and split longitudinally. Two standardized grooves were cut into the apical and coronal part of the root canal dentine and filled with calcium hydroxide. The reassembled teeth were irrigated with a syringe and a size 30 needle using the following irrigants: (i) 20% EDTA, (ii) 10% citric acid, (iii) 1% NaOCl, (iv) 10% citric acid + 1% NaOCl, (v) 20% EDTA + 1% NaOCl and (vi) water (control). Volume of irrigant was 20 mL in each group, and irrigation time was 5 min. Evaluation of cleanliness of the blinded specimens was performed by two calibrated observers under a microscope with 30x magnification using a four-grade scoring system as described by van der Sluis et al. (2007). Statistical evaluation was performed using a SAS-macro for non-parametric multifactorial analysis (P irrigation with EDTA and citric acid, whereas NaOCl and water showed the least effect. The combinations of irrigants did not result in improvement in terms of cleanliness. None of the irrigants nor their respective combinations were able to completely remove the calcium hydroxide. Chelating agents such as citric acid and EDTA showed the best results. The combination of chelators and NaOCl did not result in significant improvement of calcium hydroxide removal.

  1. Hydrothermal Synthesis and Characterization of 3R Polytypes of Mg-Al Layered Double Hydroxides

    NARCIS (Netherlands)

    Budhysutanto, W.N.

    2010-01-01

    Layered Double Hydroxides (LDH) is a unique group of clays that have an anionic exchange capability. This research explored the hydrothermal method as an alternative method to synthesize Mg-Al LDH. It is a simple and more environmentally friendly compared to the conventional method of co-precipitati

  2. Synthesis of aluminum oxy-hydroxide nanofibers from porous anodic alumina.

    Science.gov (United States)

    Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki

    2008-10-01

    A novel method for the synthesis of aluminum oxy-hydroxide nanofibers from a porous anodic oxide film of aluminum is demonstrated. In the present method, the porous anodic alumina not only acts as a template, but also serves as the starting material for the synthesis. The porous anodic alumina film is hydrothermally treated for pore-sealing, which forms aluminum oxy-hydroxide inside the pores of the oxide film as well as on the surface of the film. The hydrothermally sealed porous oxide film is immersed in the sodium citrate solution, which selectively etches the porous aluminum oxide from the film, leaving the oxy-hydroxide intact. The method is simple and gives highly uniform aluminum oxy-hydroxide nanofibers. Moreover, the diameter of the nanofibers can be controlled by controlling the pore size of the porous anodic alumina film, which depends on the anodizing conditions. Nanofibers with diameters of about 38-85 nm, having uniform shape and size, were successfully synthesized using the present method.

  3. Inhibition of pH fronts in corrosion cells due to the formation of cerium hydroxide

    NARCIS (Netherlands)

    Soestbergen, M. van; Erich, S.J.F.; Huinink, H.P.; Adan, O.C.G.

    2013-01-01

    The effect of cerium-based corrosion inhibitors on the pH front between the alkaline cathode and acidic anode in corrosion cells has been studied. The cerium component of these inhibitors can affect the pH front since it precipitates in an alkaline environment as cerium hydroxide, which is important

  4. Studies on Synthesis and Properties of Mg-Al-nitrate Layered Double Hydroxides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A positive Mg-Al-nitrate layered double hydroxides (LDHs) has been synthesized using a non-steady coprccipitation method. The shape, size, chemical composition, electrical property and anion exchange property of the positive nanoparticle were studied by SEM, XRD, FTIR,chemical analysis, spectroanalysis and measuring of electrophoretic mobilities. Preliminary results show the positive nanopartiele is a promising precursor ofpolymer/LDHs nanocomposite.

  5. Formation of nematic liquid crystals of sterically stabilized layered double hydroxide platelets

    NARCIS (Netherlands)

    Mourad, M.C.D.; Devid, E.J.; van Schooneveld, M.M.; Vonk, Ch.; Lekkerkerker, H.N.W.

    2008-01-01

    Colloidal platelets of hydrotalcite, a layered double hydroxide, have been prepared by coprecipitation at pH 11−12 of magnesium nitrate and aluminum nitrate at two different magnesium to aluminum ratios. Changing the temperature and ionic strength during hydrothermal treatment, the platelets were ta

  6. Device to generate high purity hydroxide solution in-line for ion chromatography.

    Science.gov (United States)

    Masunaga, Hiroto; Higo, Yuji; Ishii, Mizuo; Maruyama, Noboru; Yamazaki, Shigeo

    2016-05-06

    Herein, we report a new device that generates a high-purity hydroxide solution in line. The device's container has three compartments that are isolated from each other by two cation exchange (CE) membranes. In each end of the container, an electrode is installed. The three compartments are filled with ion exchange resins. A bipolar boundary is a composite boundary comprising anion- and cation-exchangers. This device has two bipolar boundaries, which are used to separate the location of hydroxide solution generation from the location where water is electrolyzed. Therefore, it can produce high-purity hydroxide solutions that are free from gases and anionic impurities. The hydroxide solution is generated on the basis of an electrokinetic phenomenon at the surfaces of ion-exchange resins and membranes in an electric field; NaOH concentration can be controlled at rates from 0.01 to 100mM per 1mL/min by adjusting the electrical current (0-200mA) applied to the device. As the generated solution is used as an eluent for a suppressed anion chromatography, the electrical conductivity of the effluent from the suppressor is as low as that of ultra-pure water. Thus, the noise of the base-line electrical conductivity is improved, and so the detection limit of anions on the sub-ng/mL order can be achieved.

  7. The determination of hydroxide and carbonate in concentrated sodium chloride solutions

    NARCIS (Netherlands)

    Roolvink, W.B.; Bos, M.

    1980-01-01

    A computer method for the determination of carbonate and hydroxide in concentrated (2.89 M) sodium chloride solutions is described. The method is based on multiparametric curve-fitting and can also be applied to salts of dibasic acids with unknown equilibrium constants. The systematic error is not m

  8. Ion Association versus Ion Interaction Models in Examining Electrolyte Solutions: Application to Calcium Hydroxide Solubility Equilibrium

    Science.gov (United States)

    Menéndez, M. Isabel; Borge, Javier

    2014-01-01

    The heterogeneous equilibrium of the solubility of calcium hydroxide in water is used to predict both its solubility product from solubility and solubility values from solubility product when inert salts, in any concentration, are present. Accepting the necessity of including activity coefficients to treat the saturated solution of calcium…

  9. Structure and properties of alizarin complex formed with alkali metal hydroxides in methanol solution.

    Science.gov (United States)

    Jeliński, Tomasz; Cysewski, Piotr

    2016-06-01

    Quantum chemical computations were used for prediction of the structure and color of alizarin complex with alkali metal hydroxides in methanolic solutions. The color prediction relying on the single Gaussian-like band once again proved the usefulness of the PBE0 density functional due to the observed smallest color difference between computed and experimentally derived values. It was found that the alkali metal hydroxide molecules can bind to the two oxygen atoms of both hydroxyl groups of alizarin or to one of these atoms and the oxygen atom from the keto group in a complex with three methanol molecules. This means that two electronic transitions need to be taken into account when considering the spectra of the studied complexes. The resulting bond lengths and angles are correlated with the properties of the alkali metal atoms. The molar mass, the atomic radius, and the Pauling electronegativity of studied metals are quite accurate predictors of the geometric properties of hydroxide complexes with alizarin in methanol solution. Graphical abstract The spectra of the neutral and monoanionic form of alizarin together with color changes resulting from addition of different metal hydroxides and represented in CIE color space.

  10. Electrocatalysis and electroanalysis of nickel, its oxides, hydroxides and oxyhydroxides toward small molecules.

    Science.gov (United States)

    Miao, Yuqing; Ouyang, Lei; Zhou, Shilin; Xu, Lina; Yang, Zhuoyuan; Xiao, Mingshu; Ouyang, Ruizhuo

    2014-03-15

    The electrocatalysis toward small molecules, especially small organic compounds, is of importance in a variety of areas. Nickel based materials such as nickel, its oxides, hydroxides as well as oxyhydroxides exhibit excellent electrocatalysis performances toward many small molecules, which are widely used for fuel cells, energy storage, organic synthesis, wastewater treatment, and electrochemical sensors for pharmaceutical, medical, food or environmental analysis. Their electrocatalytic mechanisms are proposed from three aspects such as Ni(OH)2/NiOOH mediated electrolysis, direct electrocatalysis of Ni(OH)2 or NiOOH. Under exposure to air or aqueous solution, two distinct layers form on the Ni surface with a Ni hydroxide layer at the air-oxide interface and an oxide layer between the metal substrate and the outer hydroxide layer. The transformation from nickel or its oxides to hydroxides or oxyhydroxides could be further speeded up in the strong alkaline solution under the cyclic scanning at relatively high positive potential. The redox transition between Ni(OH)2 and NiOOH is also contributed to the electrocatalytic oxidation of Ni and its oxides toward small molecules in alkaline media. In addition, nickel based materials or nanomaterials, their preparations and applications are also overviewed here.

  11. Effect of supplementation with barley and calcium hydroxide on intake of Mediterranean shrubs

    Directory of Open Access Journals (Sweden)

    Dragan Skobic

    2011-04-01

    Full Text Available Maquis plant communities are one of the most varied vegetation types in the Mediterranean region and an important habitat for wild and domestic herbivores. Although the majority of these shrubs are nutritious, the secondary compounds are main impediments that reduce their forage value. In five experiments we determined the effect of supplementing goats with calcium hydroxide plus barley, and barley alone on intake of five dominant shrubs (Quercus ilex, Erica multiflora, Arbutus unedo, Viburnum tinus and Pistacia lentiscus of the Mediterranean maquis community. The combination of calcium hydroxide plus barley and barley alone increased utilization of all five investigated Mediterranean shrubs; therewith that intake of Arbutus unedo and Viburnum tinus was not statistically significant. Supplemented goats with calcium hydroxide plus barley or barley alone could be effective in controlling secondary compounds-rich Mediterranean shrubs where their abundance threatens biodiversity. This control can be facilitated by browsing dominant Mediterranean shrubs, which has been shown to be effective in managing Mediterranean maquis density. Calcium hydroxide and barley (energy enhance use of secondary compounds-containing plants, which may increase production of alternate forages and create a more diverse mix of plant species in the Mediterranean maquis plant community.

  12. Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

    NARCIS (Netherlands)

    Schouten, Natasja; Ham, Louis G.J. van der; Euverink, Gert-Jan W.; Haan, André B. de

    2007-01-01

    Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents, layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) which is the main contamina

  13. Glycine buffered synthesis of layered iron(II)-iron(III) hydroxides (green rusts)

    DEFF Research Database (Denmark)

    Yin, Weizhao; Huang, Lizhi; Pedersen, Emil Bjerglund;

    2016-01-01

    Layered Fe(II)-Fe(III) hydroxides (green rusts, GRs) are efficient reducing agents against oxidizing contaminants such as chromate, nitrate, selenite, and nitroaromatic compounds and chlorinated solvents. In this study, we adopted a buffered precipitation approach where glycine (GLY) was used in ...

  14. Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

    NARCIS (Netherlands)

    Schouten, Natasja; Ham, van der Louis G.J.; Euverink, Gert-Jan W.; Haan, de André B.

    2007-01-01

    Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents (Schouten et al. 2007), layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) whic

  15. ADSORPTION OF PITCH AND STICKIES ON MAGNESIUM ALUMINUM HYDROXIDES TREATED AT DIFFERENT TEMPERAURES

    Directory of Open Access Journals (Sweden)

    Guodong Li

    2011-04-01

    Full Text Available Magnesium aluminum hydroxides (MAH of nitrate and carbonate forms were prepared by co-precipitation, dried at different temperatures, and employed as an adsorbent for pitch and stickies in papermaking. Results indicated that MAH that had been heat-treated had higher adsorption capacity to model pitch and stickies at neutral pH. Low-temperature-dried magnesium aluminum hydroxides of nitrate form (MAH-NO3 had higher adsorption capacity to model pitch and model stickies than those of the carbonate form (MAH-CO3. Increasing the drying temperature of MAH reduced the difference of adsorption capacity between MAH-NO3 and MAH-CO3. Higher-temperature-dried magnesium aluminum hydroxides also showed higher adsorption capacity to model pitch and stickies when the drying temperature was lower than 550 oC. MAH displayed higher adsorption capacity while a lower initial adsorption rate of model stickies than of model pitch. The model pitch and stickies were adsorbed on MAH significantly by charge neutralization and distributed mainly on the surface of the platelets of magnesium aluminum hydroxides. The experimental isothermal adsorption data of model pitch and stickies on MAH dried at 500 oC fit well to the Freundlich and Dubinin–Radushkevich isotherm equations.

  16. An Aluminum Magnesium Hydroxide Stearate-based Skin Barrier Protection Cream Used for the Management of Eczematous Dermatitis: A Summary of Completed Studies.

    Science.gov (United States)

    Del Rosso, James Q; Bhambri, Sanjay; Michaels, Brent

    2008-11-01

    Eczematous dermatoses can often be very difficult to treat. An aluminum magnesium hydroxide stearate-based cream has recently become available for clinical use. Aluminum magnesium hydroxide stearate-based cream provides an alternative option in treating these dermatoses while providing barrier protection against external allergens and irritants. This article reviews various studies evaluating aluminum magnesium hydroxide stearate-based cream.

  17. Effective Production of Sorbitol and Mannitol from Sugars Catalyzed by Ni Nanoparticles Supported on Aluminium Hydroxide

    Directory of Open Access Journals (Sweden)

    Rodiansono Rodiansono

    2013-06-01

    Full Text Available Effective production of hexitols (sorbitol and mannitol was achieved from sugars by means of nickel nanoparticles supported on aluminium hydroxide (NiNPs/AlOH catalyst. NiNPs/AlOH catalyst was prepared by a simple and benign environmentally procedure using less amount of sodium hydroxide. ICP-AES and XRD analyses confirmed that the NiNPs/AlOH catalysts comprised a large amount of remained aluminium hydroxide (i.e. bayerite and gibbsite. The presence of aluminium hydroxide caused a high dispersion Ni metal species. The average Ni crystallite sizes that derived from the Scherrer`s equation for former R-Ni and NiNPs/AlOH were 8.6 nm and 4.1 nm, respectively. The catalyst exhibited high activity and selectivity both hydrogenolysis of disaccharides (sucrose and cellobiose and monosaccharides (glucose, fructose, and xylose at 403 K for 24 h. The NiNPs/AlOH catalyst was found to be reusable for at least five consecutive runs without any significant loss of activity and selectivity. © 2013 BCREC UNDIP. All rights reservedReceived: 21st December 2012; Revised: 7th February 2013; Accepted: 10th February 2013[How to Cite: Rodiansono, R., Shimazu, S. (2013. Effective Production of Sorbitol and Mannitol from Sug-ars Catalyzed by Ni Nanoparticles Supported on Aluminium Hydroxide. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 40-46. (doi:10.9767/bcrec.8.1.4290.40-46][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4290.40-46] | View in  |

  18. Adsorption characteristics of U(VI) on Fe(III)Cr(III) (oxy)hydroxides synthesized at different temperatures.

    Science.gov (United States)

    Ahn, Hyangsig; Jo, Ho Young; Lee, Young Jae; Kim, Geon-Young

    2016-07-01

    In this study, the adsorption behavior of U(VI) on (oxy)hydroxides synthesized at different temperatures (25 and 75 °C) was investigated. Four (oxy)hydroxides were synthesized by drying slurries of Fe(III) and Fe(III)Cr(III) (oxy)hydroxide in a vacuum desiccator (25 °C) or in an oven (75 °C). Batch adsorption tests were conducted using the (oxy)hydroxides thus synthesized and groundwater containing uranium ions. In general, the U(VI) removal fraction significantly increased with increasing pH from 3 to 5, remained constant with increasing pH from 5 to 9, and decreased at pH greater than 9, regardless of the type of (oxy)hydroxides and solid-to-liquid ratio. The effect of pH on the U(VI) removal fraction was more significant at a low solid-to-liquid ratio. The oven-dried Fe(III) (oxy)hydroxide exhibited a U(VI) removal fraction lower than that of the vacuum-dried one, whereas the oven-dried Fe(III)Cr(III) (oxy)hydroxide exhibited a U(VI) removal fraction higher than that exhibited by the vacuum-dried one. X-ray photoelectron spectroscopy (XPS) analysis results indicated that the difference in the U(VI) removal fraction is attributed to the dissolution and precipitation of the Fe(III) (oxy)hydroxide during oven drying and dehydration of the Fe(III)Cr(III) (oxy)hydroxide during oven drying.

  19. Fabrication of functional transition metal oxide and hydroxide used as catalysts and battery materials

    Science.gov (United States)

    Xu, Linping

    My research is focused on developing metal oxide and hydroxide nanomaterials which can be used as battery materials, organic transformation catalysts, and photocatalysts. This research involves studying ZnO with different morphologies as photocatalysts for phenol degradation, producing CuO as olefin epoxidation catalysts, developing V and Cu incorporated manganese oxides as cathode materials for Li-ion batteries, and fabricating alpha-nickel hydroxide for Li-air battery materials. The first part includes producing ZnO as a photocatalyst for phenol degradation. The goal of this study is the synthesis of ZnO with different morphologies using the solvothermal method. The influence of solvents has been studied in detail. Their properties and photocatalytic performances have been explored as well. The second part of the research is concerned with developing novel urchin-like CuO as an olefin epoxidation catalyst. The purpose of this study is to develop a new catalyst, CuO, for olefin epoxidation. The copper source and precipitators were optimized, and the possible self-assembly mechanism of the urchin-like morphology was proposed. The catalytic activity of CuO for olefin epoxidation was studied. The third part of this work includes developing V, Cu incorporated manganese oxide (V-Cu-OMS-2) as cathode materials for Li-ion batteries. The purpose of this project is to develop a new material with enhanced battery performance. V and Cu incorporated manganese oxide were developed using hydrothermal methods. Octahedral molecular sieve (OMS) materials show mixed valences of Mn 3+ and Mn4+, which produces novel properties in battery applications. Inexpensive starting materials make OMS materials more promising for commercial applications. How the incorporation of V and Cu affected OMS-2 materials was investigated in terms of their crystal structure, morphologies, and surface areas. The battery performance of the incorporated OMS-2 materials with different loading amounts of V

  20. Synthesis, characterization and stability of Cr(III) and Fe(III) hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Papassiopi, N.; Vaxevanidou, K.; Christou, C.; Karagianni, E.; Antipas, G.S.E., E-mail: gantipas@metal.ntua.gr

    2014-01-15

    Highlights: • Fe(III)–Cr(III) hydroxides enhance groundwater quality better than pure Cr(III) compounds. • Crystalline Cr(OH){sub 3}·3H{sub 2}O was unstable, with a solubility higher than 50 μg/l. • Amorphous Cr(OH){sub 3}(am) was stable with a solubility lower than 50 μg/l in the range 5.7 < pH < 11. • For mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3}, the stability region was extended to 4.8 < pH < 13.5. -- Abstract: Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH){sub 3}·xH{sub 2}O whereas in the presence of iron the precipitate is a mixed Fe{sub (1−x)}Cr{sub x}(OH){sub 3} phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fe{sub x},Cr{sub 1−x})(OH){sub 3} hydroxides as compared to the stability of Cr(OH){sub 3}. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH){sub 3}·3H{sub 2}O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH){sub 3}(am) phase. Mixed Fe{sub 0.75}Cr{sub 0.25}(OH){sub 3} hydroxides were found to be of the ferrihydrite structure, Fe(OH){sub 3}, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe

  1. Synthetic Applications and Mechanistic Studies of the Hydroxide-Mediated Cleavage of Carbon-Carbon Bonds in Ketones

    DEFF Research Database (Denmark)

    Mazziotta, Andrea; Makarov, Ilya S.; Fristrup, Peter

    2017-01-01

    The hydroxide-mediated cleavage of ketones into alkanes and carboxylic acids has been reinvestigated and the substrate scope extended to benzyl carbonyl compounds. The transformation is performed with a 0.05 M ketone solution in refluxing xylene in the presence of 10 equiv of potassium hydroxide....... The studies were complemented by a theoretical investigation where two possible pathways were characterized by DFT/M06-2X. The calculations showed that the scission takes place by nucleophilic attack of hydroxide on the ketone followed by fragmentation of the resulting oxyanion into the carboxylic acid...

  2. Dynamics of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of CdAl Layered Double Hydroxide to the Brucite-Like Cadmium Hydroxide

    KAUST Repository

    Saliba, Daniel

    2016-06-23

    Cadmium-Aluminum layered double hydroxide (CdAl LDH) is thermodynamically unstable and transforms to Cd(OH)2 and Al(OH)3 in a short period of time. We present a reaction-diffusion framework that enables us to use in situ steady-state fluorescence spectroscopy to study the kinetics of intercalation of a fluorescent probe (Rhodamine B (RhB)) during the formation of the CdAl LDH and its de-intercalation upon the conversion of the LDH phase to the β phase (Cd(OH)2). The method involves the diffusion of sodium hydroxide into a hydrogel gel matrix containing the aluminum and cadmium ions as well as the species we wish to incorporate in the interlayers of the LDH. The existence of RhB between the LDH layers and its expel during the transition into the β phase are proved via fluorescence microscopy, XRD and ssNMR. The activation energies of intercalation and de-intercalation of RhB are computed and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de- intercalation are systematically higher than those of intercalation proving that the dyes are stabilized due to the probe-brucite sheets interactions.

  3. Evaluation of the Magnesium Hydroxide Treatment Process for Stabilizing PFP Plutonium/Nitric Acid Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gerber, Mark A.; Schmidt, Andrew J.; Delegard, Calvin H.; Silvers, Kurt L.; Baker, Aaron B.; Gano, Susan R.; Thornton, Brenda M.

    2000-09-28

    This document summarizes an evaluation of the magnesium hydroxide [Mg(OH)2] process to be used at the Hanford Plutonium Finishing Plant (PFP) for stabilizing plutonium/nitric acid solutions to meet the goal of stabilizing the plutonium in an oxide form suitable for storage under DOE-STD-3013-99. During the treatment process, nitric acid solutions bearing plutonium nitrate are neutralized with Mg(OH)2 in an air sparge reactor. The resulting slurry, containing plutonium hydroxide, is filtered and calcined. The process evaluation included a literature review and extensive laboratory- and bench-scale testing. The testing was conducted using cerium as a surrogate for plutonium to identify and quantify the effects of key processing variables on processing time (primarily neutralization and filtration time) and calcined product properties.

  4. Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2Reduction

    KAUST Repository

    Saliba, Daniel

    2016-03-30

    We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Extraction of starch from hulled and hull-less barley with papain and aqueous sodium hydroxide

    OpenAIRE

    2013-01-01

    Starch was isolated from hulled (VJM 201) and hull-less (BL 134) barley with papain and aqueous sodium hydroxide treatments. For enzyme-assisted extraction, barley was steeped in water containing 0.2 % SO2 + 0.55 % lactic acid at 50° ± 2 °C for 4–5 h. The slurry was mixed with 0.4–2.0 g papain/kg barley and incubated at 50° ± 2 °C for 1–5 h. Aqueous sodium hydroxide (0.01–0.05 M) was added to the finely ground barley meal. The alkaline slurry was incubated at ambient temperature (25° ± 2 °C) ...

  6. Potassium hydroxide catalyst supported on palm shell activated carbon for transesterification of palm oil

    Energy Technology Data Exchange (ETDEWEB)

    Baroutian, Saeid; Aroua, Mohamed Kheireddine; Raman, Abdul Aziz Abdul; Sulaiman, Nik Meriam Nik [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2010-11-15

    In this study, potassium hydroxide catalyst supported on palm shell activated carbon was developed for transesterification of palm oil. The Central Composite Design (CCD) of the Response Surface Methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst loading and methanol to oil molar ratio on the production of biodiesel using activated carbon supported catalyst. The highest yield was obtained at 64.1 C reaction temperature, 30.3 wt.% catalyst loading and 24:1 methanol to oil molar ratio. The physical and chemical properties of the produced biodiesel met the standard specifications. This study proves that activated carbon supported potassium hydroxide is an effective catalyst for transesterification of palm oil. (author)

  7. Pore size distribution, strength, and microstructure of portland cement paste containing metal hydroxide waste

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Z.A.; Mahmud, H.; Shaaban, M.G.

    1996-12-31

    Stabilization/solidification of hazardous wastes is used to convert hazardous metal hydroxide waste sludge into a solid mass with better handling properties. This study investigated the pore size development of ordinary portland cement pastes containing metal hydroxide waste sludge and rice husk ash using mercury intrusion porosimetry. The effects of acre and the addition of rice husk ash on pore size development and strength were studied. It was found that the pore structures of mixes changed significantly with curing acre. The pore size shifted from 1,204 to 324 {angstrom} for 3-day old cement paste, and from 956 to 263 {angstrom} for a 7-day old sample. A reduction in pore size distribution for different curing ages was also observed in the other mixtures. From this limited study, no conclusion could be made as to any correlation between strength development and porosity. 10 refs., 6 figs., 3 tabs.

  8. Removal of Anionic Metal Ions from Wastewater by Hydroxide-type Adsorbents

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Generally speaking, anionic metal concentrations in wastewater from industries and mineral processing plants are well above the allowed limits for effluent set by the Ministry of Environment of Japan. Nowadays, the removal of anionic ions has been considered difficult and development of new process is desperately needed. In this paper, we report the development of three hydroxide-type adsorbents, illustrating their adsorption efficiency in removing As, Se, Mo and Sb ions from aqueous solutions. The main finding of this work was that the adsorption behavior was influenced very much by both the pH and the adsorbent concentration. Nevertheless, the newly developed hydroxide-type adsorbents were very effective in reducing the concentration of those anionic ions.

  9. Anion exchange kinetics of nanodimensional layered metal hydroxides: use of isoconversional analysis.

    Science.gov (United States)

    Majoni, Stephen; Hossenlopp, Jeanne M

    2010-12-16

    Anion exchange reactions of nanodimensional layered metal hydroxide compounds are utilized to create materials with targeted physical and chemical properties and also as a means for controlled release of intercalated anions. The kinetics of this important class of reaction are generally characterized by model-based approaches. In this work, a different approach based on isothermal, isoconversional analysis was utilized to determine effective activation energies with respect to extent of reaction. Two different layered metal hydroxide materials were chosen for reaction with chloride anions, using a temperature range of 30-60 °C. The concentrations of anions released into solution and the changes in polycrystalline solid phases were evaluated using model-based (Avrami-Erofe'ev nucleation-growth model) and model-free (integral isoconversional) methods. The results demonstrate the utility of the isoconversional approach for identifying when fitting to a single model is not appropriate, particularly for characterizing the temperature dependence of the reaction kinetics.

  10. A Strategy for Hydroxide Exclusion in Nanocrystalline Solid-State Metathesis Products

    Directory of Open Access Journals (Sweden)

    Jiaqi Cheng

    2013-06-01

    Full Text Available We demonstrate a simple strategy to either prevent or enhance hydroxide incorporation in nanocrystalline solid-state metathesis reaction products prepared in ambient environments. As an example, we show that ZnCO3 (smithsonite or Zn5(CO32(OH6 (hydrozincite forms extremely rapidly, in less than two minutes, to form crystalline domains of 11 ±  2 nm and 6 ± 2 nm, respectively. The phase selectivity between these nanocrystalline products is dominated by the alkalinity of the hydrated precursor salts, which may in turn affect the availability of carbon dioxide during the reaction. Thus, unlike traditional aqueous precipitation reactions, our solid-state method offers a way to produce hydroxide-free, nanocrystalline products without active pH control.

  11. Temperature-induced control over phase selection among hydroxides of nickel

    Indian Academy of Sciences (India)

    T N Ramesh; P Vishnu Kamath

    2008-04-01

    While at low (4°C) temperatures, addition of ammonia to aqueous metal nitrate solutions induces the precipitation of -nickel hydroxide and at high (25–65°C) temperatures, -Ni(OH)2 is formed. The crystallinity of the product improves at higher temperatures of precipitation and the product obtained at 65°C is devoid of various disorders such as stacking faults, turbostraticity and interstratification. This provides a simple and efficient alternative to the hydrothermal synthesis of crystalline -Ni(OH)2. The temperature induced control over phase selection provides direct experimental evidence for the metastability of -nickel hydroxide. Crystalline -Ni(OH)2 is, however, a poor electrode material for alkaline secondary cells and exhibits a capacity of only 75 ± 10 mAh/g, against the theoretically expected 289 mAh/g.

  12. Inclusion of poly-aromatic hydrocarbon (PAH) molecules in a functionalized layered double hydroxide

    Indian Academy of Sciences (India)

    L Mohanambe; S Vasudevan

    2006-01-01

    The internal surface of an Mg-Al layered double hydroxide has been functionalized by anchoring carboxy-methyl derivatized -cyclodextrin cavities to the gallery walls. Neutral polyaromatic hydrocarbon (PAH) molecules have been included within the functionalized solid by driving the hydrophobic aromatic molecules from a polar solvent into the less polar interior of the anchored cyclodextrin cavities by a partitioning process. The optical (absorption and emission) properties of the PAH molecules included within the functionalized Mg-Al layered double hydroxide solid are similar to that of dilute solutions of the PAH in non-polar solvents. The unique feature of these hybrid materials is that they are thermally stable over a wide temperature range with their emission properties practically unaltered.

  13. Cementing properties of steel slag activated by sodium silicates and sodium hydroxide

    Institute of Scientific and Technical Information of China (English)

    Wen Ni; En Wang; Jianping Li; Han Sun

    2005-01-01

    Steel slag which is mainly composed of γ-CasSiO4 and other silicates or alumino-silicates is activated by sodium silicates and sodium hydroxide. The powders of such steel slag are usually inert to hydrate and subsequently have very low ability of cementing. But when sodium silicates and sodium hydroxide are used as activators the steel slag shows very good properties of cementing. When activated with NaOH solution the hardened slurry of the steel slag has a compressive strength of 11.13 MPa after being cured for 28 days. When activated with Na2SiO3 solution the samples after being cured for 28 days have an average compressive strength of 40.23 MPa. While the steel slag slurry which is only mixed with water has a compressive of 0.88 MPa after being cured for 28 days.

  14. Alternative Sodium Recovery Technology—High Hydroxide Leaching: FY10 Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, Lenna A.; Neiner, Doinita; Peterson, Reid A.; Rapko, Brian M.; Russell, Renee L.; Schonewill, Philip P.

    2011-02-04

    Boehmite leaching tests were carried out at NaOH concentrations of 10 M and 12 M, temperatures of 85°C and 60°C, and a range of initial aluminate concentrations. These data, and data obtained during earlier 100°C tests using 1 M and 5 M NaOH, were used to establish the dependence of the boehmite dissolution rate on hydroxide concentration, temperature, and initial aluminate concentration. A semi-empirical kinetic model for boehmite leaching was fitted to the data and used to calculate the NaOH additions required for leaching at different hydroxide concentrations. The optimal NaOH concentration for boehmite leaching at 85°C was estimated, based on minimizing the amount of Na that had to be added in NaOH to produce a given boehmite conversion.

  15. Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

    Science.gov (United States)

    Saliba, Daniel; Ezzeddine, Alaa; Sougrat, Rachid; Khashab, Niveen M; Hmadeh, Mohamad; Al-Ghoul, Mazen

    2016-04-21

    We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature.

  16. Strategy for synthesizing quantum dot-layered double hydroxide nanocomposites and their enhanced photoluminescence and photostability.

    Science.gov (United States)

    Cho, Seungho; Jung, Sungwook; Jeong, Sanghwa; Bang, Jiwon; Park, Joonhyuck; Park, Youngrong; Kim, Sungjee

    2013-01-08

    Layered double hydroxide-quantum dot (LDH-QD) composites are synthesized via a room temperature LDH formation reaction in the presence of QDs. InP/ZnS (core/shell) QD, a heavy metal free QD, is used as a model constituent. Interactions between QDs (with negative zeta potentials), decorated with dihydrolipoic acids, and inherently positively charged metal hydroxide layers of LDH during the LDH formations are induced to form the LDH-QD composites. The formation of the LDH-QD composites affords significantly enhanced photoluminescence quantum yields and thermal- and photostabilities compared to their QD counterparts. In addition, the fluorescence from the solid LDH-QD composite preserved the initial optical properties of the QD colloid solution without noticeable deteriorations such as red-shift or deep trap emission. Based on their advantageous optical properties, we also demonstrate the pseudo white light emitting diode, down-converted by the LDH-QD composites.

  17. Electrochemical characteristics and impedance spectroscopy studies of nano-cobalt silicate hydroxide for supercapacitor

    Science.gov (United States)

    Zhang, Guo-Qing; Zhao, Yong-Qing; Tao, Feng; Li, Hu-Lin

    Cobalt silicate hydroxide (Co 3[Si 2O 5] 2[OH] 2) was prepared by chemical method for use in electrochemical capacitors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) tests indicate that the material was pure hexagonal phase with uniform nanometer size distribution. Cyclic voltammeter (CV) and galvanostatic charge/discharge measurements show that the cobalt silicate hydroxide-based electrode has stable electrochemical capacitor properties between potential range of 0.1-0.55 V with a maximum specific capacitance of 237 F g -1 in alkaline solution and 95% of capacity efficiency was reached after 150 cycles. Electrochemical impedance spectra (EIS) investigation illustrates that the capacitance of the test electrode was mainly consisted of pseudo-capacitance, which was caused by underpotential deposition of H 3O + at the electrode surface.

  18. Synthesis and carbon dioxide sorption of layered double hydroxide/silica foam nanocomposites with hierarchical mesostructure

    KAUST Repository

    Fu, Liling

    2014-03-05

    Layered double hydroxides (LDHs) with a hierarchical mesostructure are successfully synthesized on mesoporous silica foams by simple impregnation and hydrothermal treatment. The as-synthesized LDH/silica foam nanocomposites show well-defined mesostructures with high surface areas, large pore volumes, and mesopores of 6-7 nm. The nanocomposites act as carbon dioxide (CO2) sorbents under simulated flue gas conditions. They also exhibit significantly enhanced CO2 capacities under high-pressure conditions and high CO2/N2 and CO2/CH4 selectivities. Respect the hierarchy: Hierarchical mesoporous layered double hydroxide (LDH) nanocomposites with high surface areas and large pore volumes are synthesized by controlled hydrothermal growth of LDH precursors on a mesoporous silica foam. The as-synthesized nanocomposites exhibit a significantly enhanced capacity and selectivity towards carbon dioxide, making them very promising candidates for carbon dioxide (CO2) separation applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

    Institute of Scientific and Technical Information of China (English)

    李永绣; 周雪珍; 王志强

    2002-01-01

    The preparation of nano sized La2O3 powder by mechanochemical reaction of lanthanum carbonate with sodium hydroxide and subsequent heat treatment was studied using X-ray diffraction, differential thermal and thermo gravimetric analysis and transmission electron microscopy. It was found that the mechanochemical reaction process can be divided into two steps: the first step is the multi-phases mechanochemical reaction of lanthanum carbonate with NaOH to form amorphous lanthanum basic carbonate and lanthanum hydroxide, and the second step is the crystallization of basic lanthanum carbonate with the formula of La2(OH)2(CO3)2*H2O under a quasi-hydrothermal synthesis condition caused by the mechanical ball-milling. The synthesized La2O3 powder appears clearly separated spherical-like monodisperse nano-size particles in which particle size ranges from 30 to 50 nm.

  20. Interaction of pristine hydrotalcite-like layered double hydroxides with CO2: a thermogravimetric study

    Indian Academy of Sciences (India)

    Shivanna Marappa; P Vishnu Kamath

    2015-12-01

    Metal oxides in general have surface acidic sites, but for exceptional circumstances, are not expected to mineralize CO2. Given their intrinsic basicity and an expandable interlayer gallery, the hydrotalcite-like layered double hydroxides (LDHs) are expected to be superior candidate materials for CO2 mineralization. However, the incorporation of Al3+ adversely impacts the ability of the metal hydroxide layer to interact with CO2 in the gas phase in comparison with the unitary Mg(OH)2. Thermogravimetric analysis shows that the decomposition reaction of the [Mg–Al–CO3] LDH is only marginally delayed in flowing CO2 in comparison with flowing N2, showing only an apparent marginal CO2 uptake. Al3+ ion severely attenuates the surface basicity of the LDHs, as the unitary Al(OH)3 is acidic in comparison with Mg(OH)2 and shows little or no interaction with CO2 in the gas phase.

  1. A NEW PROCESS DEVELOPED FOR SEPARATION OF LIGNIN FROM AMMONIUM HYDROXIDE PRETREATMENT SOLUTIONS

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, S.; Gorensek, M.; Milliken, C.

    2010-12-14

    A method is described for separating lignin from liquid solutions resulting from the pretreatment of lignocellulosic materials such as switchgrass with ammonium hydroxide. The method involves a sequence of steps including acidification, evaporation, and precipitation or centrifugation that are performed under defined conditions, and results in a relatively pure, solid lignin product. The method is tested on ammonium hydroxide solutions containing lignin extracted from switchgrass. Experimental results show that the method is capable of recovering between 66-95% of dissolved lignin as a precipitated solid. Cost estimates of pilot-scale and industrial-scale expressions of the process indicate that breakeven lignin prices of $2.36/kg and $0.78/kg, respectively, may be obtainable with this recovery method.

  2. Homogeneous precipitation of α-phase Co-Ni hydroxides hexagonal platelets

    Institute of Scientific and Technical Information of China (English)

    Juanjuan Liu; Xuyang Wang; Xiayin Yao; Jun wang; Zhaoping Liu

    2012-01-01

    This paper describes the synthesis of α-phase Co-Ni hydroxides hexagonal platelets through homogeneous precipitation,using hexamethylenetetramine (HMT) or urea as a hydrolytic agent.In the CoCl2-NiCl2-HMT system,pure α-phase can be synthesized at the concentrations of both metal ions higher than 20 mM,while in the CoCl2-NiCl2-urea system,the formation of pure α-phase is independent of the concentrations of the metal ions.When using HMT,monodisperse hexagonal platelets of α-phase Co-Ni hydroxides can be produced in the presence of polyvinylpyrrolidone (PVP).Cyclic voltammogram curve of the hexagonal platelets prepared with HMT demonstrates electrochemical performance superior to that of urea.

  3. Degradation of l-polylactide during melt processing with layered double hydroxides

    DEFF Research Database (Denmark)

    Gerds, Nathalie; Katiyar, Vimal; Koch, Christian Bender;

    2012-01-01

    PLA was melt compounded in small-scale batches with two forms of laurate-modified magnesium–aluminum layered double hydroxide (Mg-Al-LDH-C12), the corresponding carbonate form (Mg-Al-LDH-CO3) and a series of other additives. Various methods were then adopted to characterize the resulting compounds...... in an effort to gain greater insights into PLA degradation during melt processing. PLA molecular weight reduction was found to vary according to the type of LDH additive. It is considered that the degree of particle dispersion and LDH exfoliation, and hence the accessibility of the hydroxide layer surfaces...... may be active degrading agents. Phosphate treatment of laurate-modified LDH was investigated and this may be a promising way of reducing PLA degradation, thereby making such processes more practically realistic....

  4. Formocresol versus calcium hydroxide direct pulp capping of human primary molars: two year follow-up.

    Science.gov (United States)

    Aminabadi, Naser Asl; Farahani, Ramin Mostofi Zadeh; Oskouei, Sina Ghertasi

    2010-01-01

    Clinical and radiographic evaluation of the premedicated direct pulp capping using formocresol (PDC) versus conventional direct pulp capping using calcium hydroxide (CDC) in human carious primary molars. A total of 120 vital primary molars with pinpoint exposure during caries removal in 84 patients aged 4-5 years were selected. In the PDC group (n = 60), 20% Buckley's formocresol solution, and in the CDC group (n = 60), calcium hydroxide powder were applied to the exposure sites followed by placement of zinc oxide-eugenol base. Teeth were restored with preformed stainless steel crowns. Clinical and radiographic evaluations of the treatment outcomes were performed at regular intervals of 6 and 12 months, respectively, for two years post-operatively. The prevalence of spontaneous pain, sensitivity on percussion, and fistula were significantly higher in the CDC group compared to the PDC group (P formocresol premedicated direct pulp capping could safely be used as a substitute for conventional direct pulp capping.

  5. Stabilization of tetanus toxoid formulation containing aluminium hydroxide adjuvant against freeze-thawing.

    Science.gov (United States)

    Solanki, Vipul A; Jain, Nishant K; Roy, Ipsita

    2011-07-29

    Exposure to subzero temperature leads to loss of vaccine potency. This can happen due to degradation of adjuvant surface and/or inactivation of the antigen. When adsorbed on aluminium hydroxide and subjected to freeze-thawing, tetanus toxoid was desorbed from the gel matrix and the preparation was found to lose its antigenicity. Analyses showed that the gel particles were denatured after freezing. When freeze-thawing was carried out in the presence of glucose, sorbitol and arginine, the degradation of gel particles was inhibited. A higher fraction of the protein could be retained on the gel. However, the antigenicity of these preparations was quite low. In the presence of trehalose, the protein could be partially retained on aluminium hydroxide. Being a cryoprotectant, trehalose was also able to inhibit the freezing-induced denaturation of tetanus toxoid, which resulted in retention of antigenicity of the adjuvanted toxoid.

  6. Determination of adsorbed protein concentration in aluminum hydroxide suspensions by near-infrared transmittance Spectroscopy

    DEFF Research Database (Denmark)

    Lai, Xuxin; Zheng, Yiwu; Jacobsen, Susanne

    2008-01-01

    Analysis of aluminum hydroxide based vaccines is difficult after antigen adsorption. Adsorbed protein is often assessed by measuring residual unadsorbed protein for quality control. A new method for the direct determination of adsorbed protein concentration in suspension using near-infrared (NIR......) transmittance spectroscopy is proposed here. A simple adsorption system using albumin from bovine serum (BSA) and aluminum hydroxide as a model system is employed. The results show that the NIR absorbance at 700-1300 nm is correlated to the adsorbed BSA concentration, measured by the ultraviolet (UV) method...... reduce the batch influence, and the NIR predicted results show good agreement with the reference values. The NIR method might be the only direct method for the determination of adsorbed protein concentration in suspension so far. It is a nondestructive method, and it has great advantage for use...

  7. REGIOSELECTIVE REACTIONS OF 3-ALKYL-1-PHENYL-2-PYRAZOLIN-5-ONES WITH ACYL HALIDES IN THE PRECENCE OF NONOSIZED MAGNESIUM HYDROXIDE AS A HIGHLY EFFECTIVE HETEROGENOUS BASE CATALYST Regioselektive Reaktionen von 3-Alkyl-1-PHENYL-2-pyrazolin-5-ONES Mit Acylhalogeniden IN DER PRECENCE DER NONOSIZED MAGNESIUM HYDROXIDE als hochwirksame heterogene BASE CATALYST

    Directory of Open Access Journals (Sweden)

    Hassan Sheibani and Bahman Massomi Nejad

    2012-07-01

    Full Text Available 4-Acyl-3-alkyl-1-phenyl-2-pyrazolin-5-one derivatives were prepared by the regioselective acylation of 3-alkyl-1-phenyl-2-pyrazolin-5-ones in the presence of base catalysts such as calcium hydroxide [Ca(OH2], magnesium hydroxide [Mg(OH2] and nanosized magnesium hydroxide. In the presence of nanosized magnesium hydroxide, excellent yields of products were obtained and reaction times were significantly reduced.

  8. A comparative study on dental pulp response to calcium hydroxide, white and grey mineral trioxide aggregate as pulp capping agents

    Directory of Open Access Journals (Sweden)

    Ali Eskandarizadeh

    2011-01-01

    Conclusions : Based on the result of this study, both types of MTA can be suggested as the materials of choice for direct pulp capping procedure instead of Dycal as hard setting calcium hydroxide cement.

  9. Corrosion Resistance of the Superhydrophobic Mg(OH)2/Mg-Al Layered Double Hydroxide Coatings on Magnesium Alloys

    National Research Council Canada - National Science Library

    Zhang, Fen; Zhang, Changlei; Zeng, Rongchang; Song, Liang; Guo, Lian; Huang, Xiaowen

    2016-01-01

      Coatings of the Mg(OH)2/Mg-Al layered double hydroxide (LDH) composite were formed by a combined co-precipitation method and hydrothermal process on the AZ31 alloy substrate in alkaline condition...

  10. The significance of oxygen as oxides and hydroxides in controlling the abundance and residence times of elements in seawater

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.

    A model is presented which signifies the role of oxygen (as oxides and hydroxides) in controlling the composition of seawater. respective concentration and residence times for the unknown elements can be estimated. Geometric and statistical indices...

  11. Hybrid magnetic materials based on layered double hydroxides: from the chemistry towards the applications

    OpenAIRE

    ABELLÁN SÁEZ, GONZALO

    2014-01-01

    Layered double hydroxides (LDHs) are the leitmotiv of this dissertation. Contradicting the assertion that “any past was better”, LDHs have been continuously revisited from the middle of the twentieth century, and represent an excellent example of the never-ending beauty of Chemistry. New synthetic perspectives are giving a new impetus to LDH chemistry, which among hybrid materials, are finding their heyday. This is resulting in novel materials and also paving the way for new fundamental and p...

  12. Tunable Electronic Transport Properties of 2D Layered Double Hydroxide Crystalline Microsheets with Varied Chemical Compositions.

    Science.gov (United States)

    Zhao, Yibing; Hu, Hai; Yang, Xiaoxia; Yan, Dongpeng; Dai, Qing

    2016-09-01

    Transistors based on layered double hydroxides (LDH) single microcrystal are fabricated, whose conductivity of LDH can be tuned by varying metal cations or interlayer anions, but weakly affected by external electric field. The carrier mobility can reach about 1 × 10(-5) cm(2) V(-1) s(-1) , a value comparable to that of organic C60-based transistors. This work paves a way for future electrical applications of LDH.

  13. Structural Investigation of Zn(II) Insertion in Bayerite, an Aluminum Hydroxide

    DEFF Research Database (Denmark)

    Pushparaj, Suraj Shiv Charan; Jensen, Nicholai Daugaard; Forano, Claude

    2016-01-01

    Bayerite was treated under hydrothermal conditions (120, 130, 140, and 150 °C) in order to prepare a series of layered double hydroxides (LDHs) with an ideal composition of ZnAl4(OH)12(SO4)0.5nH2O (ZnAl4-LDHs). These products were investigated by both bulk techniques (PXRD, TEM, and elemental an...

  14. Functionalized layered double hydroxide-based epoxy nanocomposites with improved flame retardancy and mechanical properties

    OpenAIRE

    Ehsan Naderi Kalali; Xin Wanga; De-Yi Wang

    2015-01-01

    Functionalized layered double hydroxides (LDHs) based on a multi-modifier system composed of hydroxypropyl-sulfobutyl-beta-cyclodextrin sodium (sCD), dodecylbenzenesulfonate (DBS) and taurine (T) have been designed and fabricated in this paper, aiming at developing high performance fire retardant epoxy nanocomposites. In this multi-modifier system, sCD was utilized to improve the char yield, DBS was used to enlarge the inter-layer distance of LDH and T was used to enhance the interaction betw...

  15. Nanoparticles for cultural heritage conservation: calcium and barium hydroxide nanoparticles for wall painting consolidation.

    Science.gov (United States)

    Giorgi, Rodorico; Ambrosi, Moira; Toccafondi, Nicola; Baglioni, Piero

    2010-08-16

    Nanotechnology provides new concepts and materials for the consolidation and protection of wall paintings. In particular, humble calcium and barium hydroxide nanoparticles offer a versatile and highly efficient tool to combat the main degradation processes altering wall paintings. Clear example of the efficacy and potentiality of nanotechnology is represented by the conservation in situ of Maya wall paintings in the archaeological area in Calakmul (Mexico).

  16. Extraction of starch from hulled and hull-less barley with papain and aqueous sodium hydroxide.

    Science.gov (United States)

    Sharma, Priyanka; Tejinder, S

    2014-12-01

    Starch was isolated from hulled (VJM 201) and hull-less (BL 134) barley with papain and aqueous sodium hydroxide treatments. For enzyme-assisted extraction, barley was steeped in water containing 0.2 % SO2 + 0.55 % lactic acid at 50° ± 2 °C for 4-5 h. The slurry was mixed with 0.4-2.0 g papain/kg barley and incubated at 50° ± 2 °C for 1-5 h. Aqueous sodium hydroxide (0.01-0.05 M) was added to the finely ground barley meal. The alkaline slurry was incubated at ambient temperature (25° ± 2 °C) for 15-60 min. The starch and grain fractions were isolated by screening and centrifugation. Increases in the time of treatment significantly affected the fiber, centrifugation and non-starch residue losses. Concentration of papain and sodium hydroxide had negligible effect on extraction losses. The enzyme-assisted extraction efficiency of starch was higher (80.7-84.6 %) than the alkaline method (70.9-83.7 %). The hulled barley showed higher extraction efficiency than the hull-less barley. The slurry treated with 0.4 g papain/kg barley for 5 h and 0.03 M sodium hydroxide for 60 min produced maximal yield of starch. Barley starch showed desirably high pasting temperature, water binding capacity and hold viscosity; and low final and setback viscosity compared with the commercial corn starch. The alkaline extracted hull-less barley starch showed exceptionally high peak and hold viscosities.

  17. Contrasting effects of Al substitution on microbial reduction of Fe(III) (hydr)oxides

    Science.gov (United States)

    Ekstrom, Eileen B.; Learman, Deric R.; Madden, Andrew S.; Hansel, Colleen M.

    2010-12-01

    Aluminum, one of the most abundant elements in soils and sediments, is commonly found co-precipitated with Fe in natural Fe(III) (hydr)oxides; yet, little is known about how Al substitution impacts bacterial Fe(III) reduction. Accordingly, we investigated the reduction of Al substituted (0-13 mol% Al) goethite, lepidocrocite, and ferrihydrite by the model dissimilatory Fe(III)-reducing bacterium (DIRB), Shewanella putrefaciens CN32. Here we reveal that the impact of Al on microbial reduction varies with Fe(III) (hydr)oxide type. No significant difference in Fe(III) reduction was observed for either goethite or lepidocrocite as a function of Al substitution. In contrast, Fe(III) reduction rates significantly decreased with increasing Al substitution of ferrihydrite, with reduction rates of 13% Al-ferrihydrite more than 50% lower than pure ferrihydrite. Although Al substitution changed the minerals' surface area, particle size, structural disorder, and abiotic dissolution rates, we did not observe a direct correlation between any of these physiochemical properties and the trends in bacterial Fe(III) reduction. Based on projected Al-dependent Fe(III) reduction rates, reduction rates of ferrihydrite fall below those of lepidocrocite and goethite at substitution levels equal to or greater than 18 mol% Al. Given the prevalence of Al substitution in natural Fe(III) (hydr)oxides, our results bring into question the conventional assumptions about Fe (hydr)oxide bioavailability and suggest a more prominent role of natural lepidocrocite and goethite phases in impacting DIRB activity in soils and sediments.

  18. Understanding surface interactions in aqueous miscible organic solvent treated layered double hydroxides.

    OpenAIRE

    Erastova, Valentina; Degiacomi, Matteo T.; O'Hare, Dermot; Greenwell, H. Chris

    2016-01-01

    Layered materials are of interest for use in a wealth of technological applications, many of which require a high surface area for optimal properties and performance. Recently, an industrially scalable method to create high surface area layered double hydroxide (LDH) materials, which may be readily dispersed in non-polar solvents, has been developed. This method involves treatment of LDHs with aqueous miscible organic (AMO) solvents. Here, molecular modeling is exploited to elucidate the AMO ...

  19. Comparison of the Winograd method and chemical cauterization with 10% sodium hydroxide for treating ingrown toenails

    OpenAIRE

    Nebahat Demet Akpolat; Ahmet Onur Akpolat; Ozan Namdaroğlu; Ayşe Akkuş

    2016-01-01

    Background and Design: This study was performed to assess the therapeutic outcomes of the surgical method, described by Winograd and chemical cauterization with sodium hydroxide in patients with Heifetz stage 2 and 3 ingrown toenail (recurrence, complication, improvement and time to regain activity). Materials and Methods: One-hundred patients who presented to the outpatient clinics of orthopedics, general surgery and dermatology with the complaints of pain, redness and discharge in the to...

  20. A XAFS study of plain and composite iron(III) and chromium(III) hydroxides.

    Science.gov (United States)

    Papassiopi, N; Pinakidou, F; Katsikini, M; Antipas, G S E; Christou, C; Xenidis, A; Paloura, E C

    2014-09-01

    Reduction of hexavalent Cr(VI) to the trivalent state is the common strategy for remediation of Cr(VI) contaminated waters and soils. In the presence of Fe the resulting compounds are usually mixed Fe(III)-Cr(III) phases, while, under iron-free conditions, reduction leads to formation of plain Cr(III) hydroxides. Environmental stability of these compounds depends on their structure and is important to understand how different precipitation conditions affect the local atomic order of resulting compounds and thus their long term stability. In current study, typical Cr(VI) environmental remediation products, i.e. plain and mixed Fe(III)-Cr(III) hydroxides, were synthesized by hydrolysis and redox reactions and their structure was studied by X ray diffraction and X ray absorption fine structure techniques. Plain Cr(III) hydroxide was found to correspond to the molecular formula Cr(OH)3·3H2O and was identified as crystalline in XRD. However, the same compound when examined by EXAFS did not exhibit any clear local order in the range of EXAFS detectable distances, i.e. between 0 and 5Å. Namely, EXAFS spectroscopy detected only contribution from the first nearest neighboring (Cr-O) shell, suggesting that CrO6 octahedra interconnection is loose, in accordance with the suggested anti-bayerite structure of this compound. Mixed Fe(III)-Cr(III) systems resembled 2-line ferrihydrite irrespective of the synthesis route. Analysis of Fe-K-EXAFS and Cr-K-EXAFS spectra indicated that FeO6 octahedra are bonded by sharing both edges and corners, while CrO6 octahedra seem to prefer edge sharing linkage. EXAFS data also suggest that Fe-Cr hydroxide produced by hydrolysis presents a better arrangement of CrO6 octahedra compared to the redox product.

  1. Oxygen isotope indicators of selenate reaction with Fe(II) and Fe(III) hydroxides.

    Science.gov (United States)

    Schellenger, Alexandra E P; Larese-Casanova, Philip

    2013-06-18

    Selenate (SeO(4)(2-)) reduction to elemental selenium is an important Se immobilization process in subsurface environments that could be mediated by Fe(II)-rich minerals or selenate-respiring microorganisms. We report the kinetic isotope effects for (18)O within selenate during abiotic reactions with iron-bearing hydroxides within laboratory experiments. Selenate was reduced to Se(0) by a green rust (chloride interlayer type) and ferrous hydroxide, the two known environmentally relevant mineral reductants for selenate. Reaction kinetics are described by a rapid, low-fractionating uptake step caused by diffusive exchange between selenate and chloride followed by a slower, high-fractionating reduction step caused by electron transfer from structural Fe(II). The dual-phase kinetics cannot be described with the traditional Rayleigh fractionation model; however, well after the initial uptake step, the extent of selenate reaction is well correlated with δ(18)O values in accordance with the Rayleigh model. Selenate-(18)O enrichment (εO) was nearly identical for reaction with chloride green rust (22.7 ± 2.2‰) and ferrous hydroxide (22.1 ± 1.1‰) which suggests a common reduction mechanism by structural Fe(II). The minor enrichment due to anion exchange alone (1.4 ± 0.2‰) was confirmed using iowaite, a nonredox active Mg(II)-Fe(III) layered double hydroxide. Our εO results may contribute to Se isotope forensics to identify selenate reduction within field sites and to possibly distinguish between abiotic and biotic reduction processes.

  2. Thermodynamic Analysis on the Coprecipitation of Ni-Co-Mn Hydroxide

    Science.gov (United States)

    Li, Ling; Li, Yunjiao; Li, Lin; Chen, Nanxiong; Han, Qiang; Zhang, Xianzhen; Xu, Hu

    2017-10-01

    The thermodynamic data of various species in Ni-H2O, Co-H2O, Mn-H2O, and Ni-Co-Mn-H2O systems were obtained by thermodynamic calculation. The potential-pH diagrams for Ni-H2O, Co-H2O, and Mn-H2O systems at different ion activities at 323 K (50 °C), as well as Ni-Co-Mn-H2O complex systems at activity 1.00 at 298 K, 323 K, and 373 K (25 °C, 50 °C, and 100 °C) were constructed, respectively. The costable regions of Ni(OH)2, Co(OH)2, and Mn(OH)2 are verified to be thermodynamically stable in aqueous solution, which indicates the thermodynamic possibility of Ni-Co-Mn hydroxide coprecipitation. The potential-pH diagrams show that the temperature and ion activity have significant effects on the coprecipitation process. As the temperature increases or the ion activity decreases, the coprecipitation region of the Ni-Co-Mn hydroxide narrows. Moreover, the metal oxides, rather than the metal hydroxide, are more easily formed when the temperature increases. Experimental confirmation was performed to further verify the constructed potential-pH diagrams. The Ni-Co-Mn hydroxide with typical hexagonal CdI2 structure and quasi-spherical morphology was successfully obtained, and the SEM results show the uniform distribution of the elements Ni, Co, and Mn. The experimental results confirm the reliability of the prediction of thermodynamics analysis.

  3. Synthesis of ACECLOFENAC/HYDROXYPROPYL-β-CYCLODEXTRIN Intercalated Layered Double Hydroxides and Controlled Release Properties

    Science.gov (United States)

    Li, Shifeng; Shen, Yanming; Liu, Dongbin; Fan, Lihui; Wu, Keke; Xiao, Min

    2013-04-01

    Aceclofenac (AC)/hydroxypropyl-β-cyclodextrin (HP-β-CD) complex intercalated layered double hydroxides (LDHs) have been synthesized by reconstruction method. X-ray diffraction, Fourier transform infrared and thermal gravimetric analyses indicated a successful intercalation of AC/HP-β-CD complex into the LDHs gallery. The AC release properties were also studied in different pH values buffer solution. The results indicate that the AC/HP-β-CD intercalated LDH has a potential application in drug delivery agent.

  4. Nanotube synthesis from reaction of 4-chloro phenoxy acetate with zinc layered hydroxide

    OpenAIRE

    2015-01-01

    Objective Intercalations of plant growth regulator 4-chloro phenoxy acetate (4CPA) with zinc oxide (ZnO), developed using ZnO-layered hydroxide (ZLH) as host material and 4CPA as a guest. Methods Ion exchange technique via sol-gel method synthesized under aqueous environment, resulted in the formation of inorganic– organic nanotube materials. Results The release of 4CPA from its nanohybrid was found to occur in a controlled manner, governed by pseudo-second order kinetics model...

  5. Comparison of different irrigants on calcium hydroxide medication removal: microscopic cleanliness evaluation.

    Science.gov (United States)

    Salgado, Ricardo Julio Cabrales; Moura-Netto, Cacio; Yamazaki, Andrea Kanako; Cardoso, Luciano Natividade; de Moura, Abílio Albuquerque Maranhão; Prokopowitsch, Igor

    2009-04-01

    Calcium hydroxide dressing residuals can compromise endodontic sealing. This study evaluated the cleaning efficacy of different endodontic irrigants in removing calcium hydroxide by SEM image analysis. Fifty-four single-rooted mandibular premolars were instrumented to a master apical file #60 and dressed with calcium hydroxide. After 36 hours, the teeth were reopened and Ca(OH)(2) medication was removed by 5 different experimental groups: 0.5% NaOCl (G1), EDTA-C (G2), citric acid (G3), EDTA-T (G4), and re-instrumentation with MAF using NaOCl and lubrificant, followed by EDTA-T (G5). The roots were split in the buccal-lingual direction and prepared for SEM analysis in cervical, middle, and apical thirds (9, 6, and 3mm from the apex). Five blinded examiners evaluated the wall cleanliness using a scale from 1 to 5. Statistical analysis was performed using Kruskal-Wallis at 5% level of significance. Group G5 had the best results in all thirds, with significant statistical differences compared to all other groups in the middle and coronal third, and to G1 in the apical third. On the other hand, G1, only flushed with NaOCl, had the worst results, with statistical differences in all thirds compared to the other groups. The best cleanliness was achieved by G4 and G5 groups. The recapitulation of MAF in combination with irrigants improved the removal of calcium hydroxide medication better than an irrigant flush alone.

  6. Morphologies, Preparations and Applications of Layered Double Hydroxide Micro-/Nanostructures

    Directory of Open Access Journals (Sweden)

    Mingdong Dong

    2010-12-01

    Full Text Available Layered double hydroxides (LDHs, also well-known as hydrotalcite-like layered clays, have been widely investigated in the fields of catalysts and catalyst support, anion exchanger, electrical and optical functional materials, flame retardants and nanoadditives. This feature article focuses on the progress in micro-/nanostructured LDHs in terms of morphology, and also on the preparations, applications, and perspectives of the LDHs with different morphologies.

  7. Preparation of Monodisperse Nanoparticle of Layered Double Hydroxides and Polyoxyethylene Sulfate

    Institute of Scientific and Technical Information of China (English)

    XU Huizhong; QIN Lianjie; ZHANG Hong; YANG Qinzheng; YANG Jing

    2005-01-01

    In order to obtain the bio-molecule/ LDHs nanocomposites having regular crystal structure,three nanocomposites of layered double hydroxides and polyoxyethylene sulfates were prepared by ion-exchange method. TEM analysis reveals that the monodisperse rigid .sphere of approximately 200 nm in diameter could be gotten when the intergallery anion was PEGS-400. Such monodisperse nanoparticle could be used as a promising precursor for preparing bio-molecule/LDHs nanocomposites.

  8. Modification of nano-sized layered double hydroxides by long-chain organic aliphatic surfactants

    OpenAIRE

    RAMASAMY ANBARASAN; SEUNG SOON IM; WANDUC LEE

    2008-01-01

    The inter-layer anion of layered double hydroxides (LDH) with a hydrotalcite (HT)-like structure was ion-exchanged with various organic surfactants, particularly with long chain aliphatic surfactants. After the ion-exchange process, the basal spacing of the LDH was increased and the increase of the basal spacing depended on various factors, such as the intercalation capacity functionality and orientation capability of the surfactant. Of the employed surfactants, stearic acid intercalated LDH ...

  9. Study of organo-hybrid layered double hydroxides by medium and near infrared spectroscopy

    Science.gov (United States)

    Mora, Manuel; López, M. Isabel; Jiménez-Sanchidrián, César; Ruiz, J. Rafael

    2011-03-01

    An Mg/Al layered double hydroxide (LDH) containing carbonate ion in its interlayer region was examined by medium infrared (MIR) and near infrared reflectance spectroscopy (NIRS). The MIR and NIR spectroscopy techniques was also used to study two organo-hybrid LDHs containing interlayer dodecylbenzenesulphonate (DBS) and dodecylsulphate (DS) ions, respectively. The NIR spectra for the latter solids were found to exhibit the overtone and combination bands for the hydroxyl groups in addition to those typical bands of the organic host functions.

  10. Magnetic behavior of Mg-Al-Zn-Fe mixed oxides from precursors layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, M.I., E-mail: marcosivanoliva@gmail.com [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); IFFAM AF (CONICET - FaMAF UNC), M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina); Heredia, A. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Zandalazini, C.I. [Centro Laser de Ciencias Moleculares. INFIQC-FCQ-Grupo de Ciencia de Materiales-FaMAF-Universidad Nacional de Cordoba, Ciudad Universitaria, CP5000 Cordoba, Argentina CONICET (Argentina); Crivello, M. [CITeQ - Facultad R. Cordoba, Universidad Tecnologica Nacional Maestro Lopez esq. Cruz Roja Argentina, CP 5016 Cordoba (Argentina); Corchero, E. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, M. Allende y H. de la Torre Ciudad Universitaria, 5000 Cordoba (Argentina)

    2012-08-15

    Mixed oxides of Mg-Al-Zn-Fe were obtained by calcination of layered double hydroxides (LDH) prepared by coprecipitation reaction with hydrothermal treatment. The structural characterization of precursors and oxides was carried out by X rays diffraction, showing increases of ZnO phase with the increase of the zinc content. Magnetic behavior was studied by vibrating sample magnetometer (VSM) and by a superconducting quantum interference device (SQUID) showing both paramagnetic and super paramagnetic behavior depending on both particles size and composition.

  11. Optimization of layered double hydroxide stability and adsorption capacity for anionic surfactants

    OpenAIRE

    2007-01-01

    Low cost adsorption technology offers high potential to clean up laundry rinsing water. From an earlier selection of adsorbents, layered double hydroxide (LDH) proved to be an interesting material for the removal of anionic surfactant, linear alkyl benzene sulfonate (LAS) which is the main contaminant in rinsing water. The main research question was to identify the effect of process parameters of the LDH synthesis on the stability of the LDH structure and the adsorption capacity of LAS. LDH w...

  12. Insights into the Synthesis of Layered Double Hydroxide (LDH) Nanoparticles: Part 2. Formation Mechanisms of LDH

    OpenAIRE

    Sun, Xiaodi; Dey, Sandwip K.

    2015-01-01

    This study demonstrates the effect of (co)intercalated anion compositions on nanostructure evolution to understand the formation mechanisms of layered double hydroxide (LDH) nanoparticles following coprecipitation and hydrothermal treatments (HT). Initially, the room temperature coprecipitation resulted in amorphous primary nanoparticles that agglomerated at the edges due to low surface charge densities. The reversibility of such agglomeration was determined by the crystalline quality upon HT...

  13. Synthesis of graphene oxide-intercalated alpha-hydroxides by metathesis and their decomposition to graphene/metal oxide composites

    OpenAIRE

    2010-01-01

    Graphene oxide-intercalated alpha-metal hydroxides were prepared using layers from the delaminated colloidal dispersions of cetyltrimethylammonium-intercalated graphene oxide and dodecylsulfate-intercalated alpha-hydroxide of nickel/cobalt as precursors. The reaction of the two dispersions leads to de-intercalation of the interlayer ions from both the layered solids and the intercalation of the negatively charged graphene oxide sheets between the positively charged layers of the alpha-hydroxi...

  14. Influence of tebuconazole and copper hydroxide on phosphatase and urease activities in red sandy loam and black clay soils

    OpenAIRE

    B. Anuradha; Rekhapadmini, A.; Rangaswamy, V.

    2016-01-01

    The efficacy of two selected fungicides i.e., tebuconazole and coppoer hydroxide, was conducted experiments in laboratory and copper hydroxide on the two specific enzymes phosphatase and urease were determined in two different soil samples (red sandy loam and black clay soils) of groundnut (Arachis hypogaea L.) from cultivated fields of Anantapuramu District, Andhra Pradesh. The activities of the selected soil enzymes were determined by incubating the selected fungicides-treated (1.0, 2.5, 5....

  15. Difference of Mullite Whiskers between Ytterbia-Doped Aluminum Hydroxide-Silica Gel and Mechanochemical Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mullite whiskers from Al2O3-SiO2 oxide mixtures by mechanochemical method was encountered by chance. The method of ytterbia-doped aluminum hydroxide-silica was used to enhance mullite formation from gel. For adding ytterbia, mullite formation can take place at 1000 ℃ and almost single-phase mullite can be achieved at 1150 ℃, which is a significantly lower temperature than mechanochemical method. This enhancement of mullite formation is also attributed to refinement of aluminum hydroxide-silica by gel. Furthermore, well-developed single-crystal mullite whiskers were produced from the gel powder instead of normal-shaped grains. The presence of YbO might have promoted the formation of nanosized Al2O3 particles, which then acted as a template leading to mullite whiskers at higher sintering temperature.

  16. Microbial mediated iron redox cycling in Fe (hydr)oxides for nitrite removal.

    Science.gov (United States)

    Lu, Yongsheng; Xu, Lu; Shu, Weikang; Zhou, Jizhi; Chen, Xueping; Xu, Yunfeng; Qian, Guangren

    2017-01-01

    Nitrite, at an environmentally relevant concentration, was significantly reduced with iron (hydr)oxides mediated by Shewanella oneidensis MR-1. The average nitrite removal rates of 1.28±0.08 and 0.65±0.02(mgL(-1))h(-1) were achieved with ferrihydrite and magnetite, respectively. The results showed that nitrite removal was able to undergo multiple redox cycles with iron (hydr)oxides mediated by Shewanella oneidensis MR-1. During the bioreduction of the following cycles, biogenic Fe(II) was subsequently chemically oxidized to Fe(III), which is associated with nitrite reduction. There was 11.18±1.26mgL(-1) of NH4(+)-N generated in the process of redox cycling of ferrihydrite. Additionally, results obtained by using X-ray diffraction showed that ferrihydrite and magnetite remained mainly stable in the system. This study indicated that redox cycling of Fe in iron (hydr)oxides was a potential process associated with NO2(-)-N removal from solution, and reduced most nitrite abiotically to gaseous nitrogen species.

  17. Role of sodium hydroxide in the production of hydrogen gas from the hydrothermal gasification of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Onwudili, Jude A.; Williams, Paul T. [Energy and Resources Research Institute, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2009-07-15

    The role of sodium hydroxide as a promoter of hydrogen gas production during the hydrothermal gasification of glucose and other biomass samples has been investigated. Experiments were carried out in a batch reactor with glucose and also in the presence of the alkali from 200 C, 2 MPa to 450 C, 34 MPa at constant water loading. Without sodium hydroxide, glucose decomposed to produce mainly carbon dioxide, water, char and tar. Furfural, its derivatives and reaction products dominated the ethyl acetate extract of the water (organic fraction) at lower reaction conditions. This indicated that the dehydration of glucose to yield these products was unfavourable to hydrogen gas production. In the presence of sodium hydroxide however, glucose initially decomposed to form mostly alkylated and hydroxylated carbonyl compounds, whose further decomposition yielded hydrogen gas. It was observed that at 350 C, 21.5 MPa, half of the optimum hydrogen gas yield had formed and at 450 C, 34 MPa, more than 80 volume percent of the gaseous effluent was hydrogen gas, while the balance was hydrocarbon gases, mostly methane ({>=}10 volume percent). Other biomass samples were also comparably reacted at the optimum conditions observed for glucose. The rate of hydrogen production for the biomass samples was in the following order; glucose > cellulose, starch, rice straw > potato > rice husk. (author)

  18. OPTIMIZATION OF TIME REACTION AND HYDROXIDE ION CONCENTRATION ON FLAVONOID SYNTHESIS FROM BENZALDEHYDE AND ITS DERIVATIVES

    Directory of Open Access Journals (Sweden)

    Sri Handayani

    2010-06-01

    Full Text Available The aim of this research is to determine the optimum time of reaction and concentration of hydroxide ion on chalcone, 4-methoxychalcone and 3,4-dimethoxychalcone synthesis. Chalcone and its derivatives were synthesized by dissolving KOH in ethanol followed by dropwise addition of acetophenone and benzaldehyde. Then, the mixture was stirred for several hours. Three benzaldehydes has been used, i.e : benzaldehyde, p-anysaldehyde and veratraldehyde. The time of reaction was varied for, 12, 18, 24, 30 and 36 hours. Furthermore, on the optimum reaction time for each benzaldehyde the hydroxyl ion concentration was varied from 5,7,9,11 and 13%(w/v. The results of this research suggested that the optimum time of chalchone synthesis was 12 hours, while, 4-methoxychalcone and 3,4-dimethoxychalcone were 30 hours. The optimum concentration of hydroxide ion of chalcone synthesis was 13% and for 4-methoxychalcone and 3,4-dimethoxychalcone were 11%. Keywords: Chalcone synthesis, time of reaction, hydroxide ion concentration.

  19. Hydroxide Self-Feeding High-Temperature Alkaline Direct Formate Fuel Cells.

    Science.gov (United States)

    Li, Yinshi; Sun, Xianda; Feng, Ying

    2017-03-11

    Conventionally, both the thermal degradation of the anion-exchange membrane and the requirement of additional hydroxide for fuel oxidation reaction hinder the development of the high-temperature alkaline direct liquid fuel cells. The present work addresses these two issues by reporting a polybenzimidazole-membrane-based direct formate fuel cell (DFFC). Theoretically, the cell voltage of the high-temperature alkaline DFFC can be as high as 1.45 V at 90 °C. It has been demonstrated that a proof-of-concept alkaline DFFC without adding additional hydroxide yields a peak power density of 20.9 mW cm(-2) , an order of magnitude higher than both alkaline direct ethanol fuel cells and alkaline direct methanol fuel cells, mainly because the hydrolysis of formate provides enough OH(-) ions for formate oxidation reaction. It was also found that this hydroxide self-feeding high-temperature alkaline DFFC shows a stable 100 min constant-current discharge at 90 °C, proving the conceptual feasibility.

  20. Synthesis and characterization of branched yttrium hydroxide fluoride microcrystals with hierarchical tubular structure

    Institute of Scientific and Technical Information of China (English)

    TIAN Li; JIANG Wentao; SUN Qiliang; LIU Jin

    2012-01-01

    Hexagonal yttrium hydroxide fluoride microcrystals were prepared by a two-step hydrothermal route using yttrium nitrate,sodium hydroxide and sodium fluoride as raw materials to react in propanetriol solvent.The samples were characterized by powder X-ray diffraction (XRD),energy dispersive spectrum (EDS),scanning electron microscopy (SEM),transmission electron microscopy (TEM),Fourier transform infrared spectroscopy (FT-IR),thermogravimetre and differential-thermogravimetric analysis (TG-DTA),which revealed that Y(OH)2.14F0.86 microcrystals were multi-branched and that the branches of Y(OH)2.14F0.86 microcrystals were composed of hierarchical tubes.This novel multi-branched and intriguing hierarchical tubular structure of yttrium hydroxide fluoride maybe has a potential application in photoelectric crystals.The formation of branched Y(OH)2.14F0.86 microcrystals with hierarchical tubular structure were due to the substitution reaction and Oswald ripening.

  1. Effect of hydroxide and carbonate alkaline media on anion exchange membranes

    Energy Technology Data Exchange (ETDEWEB)

    Vega, Jose A.; Chartier, Casey; Mustain, William E. [Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 191 Auditorium Rd., Unit 3222, Storrs, CT 06269 (United States)

    2010-11-01

    The effect of hydroxide and carbonate alkaline environments on the chemical stability and ionic conductivity of five commercially available anion exchange membranes was investigated. Exposure of the membranes to concentrated hydroxide environments (1 M) had a detrimental effect on ionic conductivity with time. Over a 30-day period, decreases in conductivity ranged from 27% to 6%, depending on the membrane. The decrease in ionic conductivity is attributed to the loss of stationary cationic sites due to the Hofmann elimination and nucleophilic displacement mechanisms. Exposure of the membranes to low concentration hydroxide (10{sup -4} M) or carbonate/bicarbonate (0.5 M Na{sub 2}CO{sub 3}/0.5 M NaHCO{sub 3}) environments had no measurable effect on the ionic conductivity over a 30-day period. ATR-FTIR spectroscopy confirmed degradation of membranes soaked in 1 M KOH. Apparition of a doublet peak in the region between 1600 cm{sup -1} and 1675 cm{sup -1} confirms formation of carbon-carbon double bonds due to Hofmann elimination. Membranes soaked in mild alkaline environments did not show formation of carbon-carbon double bonds. (author)

  2. THE DIGESTION OPERATION IN THE ALKALI ALUMINAT SOLUTIONS OF ALUMINUM HYDROXIDES IN THE BOEHMITIC BAUXITES

    Directory of Open Access Journals (Sweden)

    Sami ŞAHİN

    1999-01-01

    Full Text Available At present more than 90 per cent of the world's alumina is produced by the Bayer process, a simple technology providing high purity final product. A part from some exceptional local conditions, bauxite is processed almost solely by this technology. As a benefication process, alumina production releases the aluminum oxide content of bauxite from other accompanying oxides thus providing alumina suitable for electrolysis in a cryolite melt. The basic theory of the Bayer process was elaborated by K.J. Bayer and described in his patents in 1887 and 1892. The first patent refers to the aid of seed crystals of aluminum hydroxide or of carbonic acid, that is, to the precipitation and carbonation processes. The second patent formulates the concept that the aluminum oxide content of bauxites can be dissolved in sodium hydroxide solutions, with the formulation of sodium aluminate, a process called digestion nowadays. The most important operations of the Bayer technology are bauxite preparation, crushing, grinding, digestion, red mud separation, thickening, washing, filtration, precipitation, calcination and evaporation. In spite of its great significance as regards the complete Bayer technology, the structure of sodium aluminate solutions has not been cleared up definitely yet. Boehmite is the most important aluminum mineral of karstic bauxites. Some experimental results showing the various effects on aluminum hydroxides by alkali process from boehmitic bauxites and the factors gowerning the digestion operation of aluminate solutions were investigated.

  3. Synthesis, characterization, and efficacy of antituberculosis isoniazid zinc aluminum-layered double hydroxide based nanocomposites.

    Science.gov (United States)

    Saifullah, Bullo; El Zowalaty, Mohamed Ezzat; Arulselvan, Palanisamy; Fakurazi, Sharida; Webster, Thomas J; Geilich, Benjamin Mahler; Hussein, Mohd Zobir

    2016-01-01

    The chemotherapy for tuberculosis (TB) is complicated by its long-term treatment, its frequent drug dosing, and the adverse effects of anti-TB drugs. In this study, we have developed two nanocomposites (A and B) by intercalating the anti-TB drug isoniazid (INH) into Zn/Al-layered double hydroxides. The average size of the nanocomposites was found to bê164 nm. The efficacy of the Zn/Al-layered double hydroxides intercalated INH against Mycobacterium tuberculosis was increased by approximately three times more than free INH. The nanocomposites were also found to be active against Gram-positive and -negative bacteria. Compared to the free INH, the nanodelivery formulation was determined to be three times more biocompatible with human normal lung fibroblast MRC-5 cells and 3T3 fibroblast cells at a very high concentration of 50 µg/mL for up to 72 hours. The in vitro release of INH from the Zn/Al-layered double hydroxides was found to be sustained in human body-simulated buffer solutions of pH 4.8 and 7.4. This research is a step forward in making the TB chemotherapy patient friendly.

  4. Toxicity and metabolism of layered double hydroxide intercalated with levodopa in a Parkinson's disease model.

    Science.gov (United States)

    Kura, Aminu Umar; Ain, Nooraini Mohd; Hussein, Mohd Zobir; Fakurazi, Sharida; Hussein-Al-Ali, Samer Hasan

    2014-04-09

    Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL) nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 µg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC50 concentration. Levodopa metabolite (HVA) released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment.

  5. Raman Study on Pompeii Potteries: The Role of Calcium Hydroxide on the Surface Treatment

    Directory of Open Access Journals (Sweden)

    Daniele Chiriu

    2014-01-01

    Full Text Available Pottery samples from the Pompeii archaeological site were investigated by IR Raman spectroscopy and EDAX measurements. The analysis of the Raman spectra of the surfaces reveals the presence calcium hydroxide (peak at about 780 cm−1 while the calcium carbonate is totally absent. The comparative studies on the carbonation effect of the surfaces were performed on laboratory grown samples of calcium hydroxide. The samples were treated at high temperature and exposed to different ambient conditions, and the analysis suggests that the original surfaces of Roman pottery were scattered by calcium hydroxide (limewash before the cooking process in the furnace. The result of this surface treatment not only permits a vitrification of the surfaces but also seems to reduce the content of CO2 in the furnace atmosphere and then obtain a more oxidant ambient during the cooking of the pottery. These results give new insights on the real degree of knowledge of the Romans about the art of ceramics and more generally about chemistry and technologies.

  6. Mechanical and physical characterization of sodium hydroxide treated Borassus fruit fibers

    Institute of Scientific and Technical Information of China (English)

    Obi Reddy K; Shukla M; Uma Maheswari C; Varada Rajulu A

    2012-01-01

    In order to improve the properties by chemical modification and to optimize the alkali concentration,we treated Borassus fruit fine fibers with aqueous sodium hydroxide solutions of different concentrations.In each case,the tensile properties of the fibers were determined.The morphology of the untreated and alkali treated fibers was observed using scanning electron microscope.The surface of the fibers became rough on alkali treatment.The tensile properties of the fibers improved on alkali treatment.The fibers attained maximum tensile properties when treated with 15% aqueous sodium hydroxide solution and decreased thereafter.The crystallinity index of the fibers showed a similar trend.The thermal stability of the alkali treated fibers was found to be higher than that of untreated fibers.Further,the char content was maximum for fibers treated with alkali having concentration of 15% and above.The chemical composition indicated that the percentageof α-cellulose was maximum when the fibers were treated with 15% aqueous sodium hydroxide solution and then decreased thereafter thus indicating the beginning of degradation of the fibers at higher concentrations.Thus,the optimum concentration of NaOH was established as 15% for alkali treatment of the Borassus fibers.

  7. Nutritional value of whole coconut, coconut powder, and coconut fiber treated with sodium hydroxide for sheep

    Directory of Open Access Journals (Sweden)

    José Cardoso de Araújo Neto

    Full Text Available ABSTRACT The growing consumption of green coconut - fresh and industrialized - in Brazil generates a large volume of wastes and coproducts that justifies the search for alternatives for their use in animal feeding. The most limiting factor to the inclusion of these coproducts in ruminant diets is their high fiber content, which may restrict intake and performance. The present study determined the composition and in vitro dry matter degradability of whole coconut, coconut powder, and coconut fiber treated with sodium hydroxide (0%, 3%, and 6% and the effect of including whole coconut hydrolyzed with 6% sodium hydroxide at different concentrations (25%, 30%, 35%, and 40% in the diet on apparent digestibility of nutrients, performance, and feeding behavior of sheep. Alkalinization decreased the hemicellulose, NDF, and ADF contents of the evaluated coproducts. Whole coconut and coconut powder provided greater in vitro degradation of DM compared with coconut fiber, with highest values obtained with the inclusion of 6% sodium hydroxide. Inclusion of whole coconut in the diets did not affect the intakes of DM, CP, NDF, and ADF, but influenced weight gain, feed conversion, and apparent digestibility of DM and NDF. Regarding the feeding behavior of the animals, the inclusion of whole coconut in the diet only affected their rumination time. Whole coconut hydrolyzed with 6% NAOH can be included in diets for feedlot sheep at up to 35% without reducing intake or weight gain.

  8. Adaptation of two different calcium hydroxide bases under a composite restoration.

    Science.gov (United States)

    Papadakou, M; Barnes, I E; Wassell, R W; McCabe, J F

    1990-10-01

    A preliminary scanning electron microscope (SEM) study was carried out to investigate how the adaptation of two calcium hydroxide bases (one chemically cured, one light cured) was affected by the polymerization contraction of a supervening light-cured composite resin restoration. Occlusal cavities were prepared in 40 sound extracted human premolars, divided into two equal groups. In the first group a chemically cured calcium hydroxide (Dycal, De Trey Dentsply, Konstanz, FRG) was placed as a base. In the second group a new light-cured calcium hydroxide product (Prisma VLC Dycal, De Trey Dentsply) was used. The restorations were completed with an acid-etched, incrementally placed composite resin. The specimens were sectioned vertically and debrided. A replica was made of each half-tooth. The interfaces between composite resin/base and base/dentine were viewed and photographed in the SEM. The marginal adaptation at these two interfaces was classified into three categories according to the extent of the gaps that were observed. Prisma VLC Dycal base was found to be pulled away from the dentine floor of the cavity as a result of an apparent adhesion to the composite resin during polymerization contraction. Dycal was better adapted to the cavity floor than Prisma VLC Dycal. Disorganization of the resin-bonded Prisma VLC Dycal was minimal even after acid etching the enamel, sectioning and ultrasonic debridement. Dycal appeared to be more friable, and occasionally exhibited marked disorganization as a result of these procedures.

  9. Studies on MgNi-Based Metal Hydride Electrode with Aqueous Electrolytes Composed of Various Hydroxides

    Directory of Open Access Journals (Sweden)

    Jean Nei

    2016-08-01

    Full Text Available Compositions of MgNi-based amorphous-monocrystalline thin films produced by radio frequency (RF sputtering with a varying composition target have been optimized. The composition Mg52Ni39Co3Mn6 is identified to possess the highest initial discharge capacity of 640 mAh·g−1 with a 50 mA·g−1 discharge current density. Reproduction in bulk form of Mg52Ni39Co3Mn6 alloy composition was prepared through a combination of melt spinning (MS and mechanical alloying (MA, shows a sponge-like microstructure with >95% amorphous content, and is chosen as the metal hydride (MH alloy for a sequence of electrolyte experiments with various hydroxides including LiOH, NaOH, KOH, RbOH, CsOH, and (C2H54N(OH. The electrolyte conductivity is found to be closely related to cation size in the hydroxide compound used as 1 M additive to the 4 M KOH aqueous solution. The degradation performance of Mg52Ni39Co3Mn6 alloy through cycling demonstrates a strong correlation with the redox potential of the cation in the alkali hydroxide compound used as 1 M additive to the 5 M KOH aqueous solution. NaOH, CsOH, and (C2H54N(OH additions are found to achieve a good balance between corrosion and conductivity performances.

  10. Vertical root fracture associated with prolonged use of calcium hydroxide during apexification. A case report.

    Directory of Open Access Journals (Sweden)

    Jennifer Ribadeneira

    2015-04-01

    Full Text Available Apexification is a procedure performed in young permanent teeth to promote apical closure and root elongation if Hertwig’s epithelial sheath has not been irreversibly damaged. The objective of this article is to describe vertical root fracture as a complication during apexification when using calcium hydroxide for extended periods of time. The patient was a 9-year-old female student who went to the Faculty of Dentistry of the Universidad Andres Bello in Concepcion. She presented strong and spontaneous pain and pressure and swelling on the left cheek. Clinically, the vestibule of the lower left first molar (3.6 was edematous and had pus. Radiographically, lesions and open apices were seen in the apical zone. Diagnosis was pulp necrosis and acute apical abscess. The tooth was trephined to perform intracanal drainage and an oral antibiotic was prescribed. Afterwards, she was referred to the endodontic specialty office. The selected treatment was apexification with calcium hydroxide until achieving the formation of an apical barrier. When the apical formation was observed, a vertical root fracture was discovered as well, confirming that the use of calcium hydroxide should not be prolonged because dehydration processes lead to weakening of the walls and therefore of the tooth

  11. Mechanochemical synthesis of finite particle of layered double hydroxide-acetate intercalation compound: Swelling, thin film and ion exchange

    Science.gov (United States)

    Kuramoto, Kyoko; Intasa-Ard, Soontaree (Grace); Bureekaew, Sareeya; Ogawa, Makoto

    2017-09-01

    Acetate intercalated Mg-Al layered double hydroxide was successfully synthesized by the solid-state reactions between magnesium acetate and aluminum hydroxide as the starting materials using a planetary mil. The acetate intercalated Mg-Al layered double hydroxide prepared by the present solid-state reaction was finite particle and was processed into stable aqueous suspension with variable transparency and viscosity depending on the concentration. By drying the suspension on a substrate under nitrogen atmosphere, thin film (with the thickness of several micrometers) of the acetate intercalated Mg-Al layered double hydroxide with the basal plane oriented parallel to the substrate was obtained. The ion exchange ability of the film, which is as an advantage of the acetate form of layered double hydroxide, was shown by the ion exchange with coumarin-3-carboxylate to give a photoluminescent film. The solid-solid reaction is advantageous for the preparation of layered double hydroxides due to the simple and eco-friendly nature (no solvent) of the operation, lower possibility of carbonate contamination and finite particles of the products.

  12. Electroless Co-Zn Surface-modified Nickel Hydroxide as an Active Material for Pasted Nickel Electrodes

    Institute of Scientific and Technical Information of China (English)

    SONG Quan-sheng(宋全生); TANG Zhi-yuan(唐致远); GUO He-tong(郭鹤桐); CHAN S L I

    2004-01-01

    Chemically precipitated β-type nickel hydroxide powder was surface-modified by electroless deposition of Co-Zn coatings,and physical properties of both the modified and unmodified nickel hydroxide were characterized by scanning electron microscopy (SEM), specific surface area (BET), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It has been found that Co and Zn components of the surface electroless coatings exist in the oxidized state. Electrochemical performances of pasted nickel electrodes using the modified nickel hydroxide as an active material were investigated, and compared with those of the electrodes prepared with the unmodified nickel hydroxide. Charge/discharge tests show that the modified nickel hydroxide electrodes exhibit better performances in the charge efficiency, specific discharge capacity and active material utilization. Their resistance to swelling with cycling is also superior to that of the unmodified nickel hydroxide electrodes. Cyclic voltammetric (CV) studies indicate that the modified electrodes have a higher electrochemical activity, and the porous pasted nickel electrodes have some distinguished CV characteristics in comparison with those of the thin film nickel electrodes.

  13. Clinical outcome of direct pulp capping with MTA or calcium hydroxide: a systematic review and meta-analysis.

    Science.gov (United States)

    Zhu, Chenxi; Ju, Bin; Ni, Rong

    2015-01-01

    Direct pulp capping is one of the most common dental practices in endodontic therapy. This systematic review and meta-analysis aim to determine whether the effect of mineral trioxide aggregate (MTA) and calcium hydroxide for direct pulp capping is different, as measured by the clinical and radiographic analysis. The study list was obtained by searching PubMed, Springer Link, Scopus and Cochrane Database. Only those papers that met the inclusion criteria were analyzed. The results indicated that four studies met the inclusion criteria. Statistically significant difference was found between the success rates of MTA and calcium hydroxide treated teeth that needed direct pulp capping (P=0.002). Clinical assessments of the MTA versus calcium hydroxide for direct pulp capping suggested that MTA was superior to calcium hydroxide in direct pulp capping resulting in a lower failure rate (risk difference 0.1 [95% CI 0.04 to 0.16]). In conclusion, MTA has a higher clinical success rate for direct pulp capping comparing to calcium hydroxide, and might be a suitable replacement for calcium hydroxide.

  14. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes.

    Science.gov (United States)

    Shi, Liang; Squier, Thomas C; Zachara, John M; Fredrickson, James K

    2007-07-01

    Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1- and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.

  15. Iron and aluminum hydroxide nanoparticles in the environment: from nano-scale to the field processes

    Science.gov (United States)

    Bazilevskaya, Ekaterina

    The objective of this doctoral research was to increase scientific understanding of the behavior of Fe and Al hydroxide nanoparticles in soils. These particles are of great environmental importance due to their ability to retain and transport nutrients and contaminants. Three studies were undertaken at different scales, which are documented in three manuscripts included in this dissertation. The first study examined the rate constants for goethite (alpha-FeOOH) crystallization from nano-particulate Fe hydroxide suspensions in the absence (0% Al) and presence (2% Al) of aluminum. One of the merits of this study was the application of a multivariate curve resolution analysis (MCR) of infrared spectra to environmentally important mixed Fe-Al hydroxide colloids in order to quantify goethite content in poorly-crystalline mixtures. Obtained rate constants were found to be equal to (7.64+/-0.67)x10-7 s-1 for 0% Al and (4.5+/-0.21) x10-7 s-1 for 2% Al hydroxides. Dissolution-precipitation mechanism was dominant in the process of goethite transformation to ferrihydrite. Further growth of goethite crystals took place either by aggregation mechanism to form polycrystalline agglomerates or alternatively by Oswald ripening to form large single crystals. The presence of aqueous Al species "poisoned" goethite's surface by disrupting the formation of hydrogen bonds thus increasing the number of non-stoichiometric hydroxyls. The second study addressed changes of mineral composition in mixed Fe-Al hydroxide nanoparticles as a function of Al-substitution and reaction time. It was found that low Al concentrations (2-8 mol. %) lead to formation of moderately crystalline Al-goethite upon ageing, while at medium Al concentrations (10-20%) colloidal suspensions remained stable for the duration of the whole experiment (54 days), goethite formation was completely retarded, and less crystalline intermediate structure were formed. At 25% Al substitution, gibbsite Al(OH)3 microcrystalline

  16. Studies on the dominant-lethal and fertility effects of the heavy metal compounds methylmercuric hydroxide, mercuric hydroxide, mercuric chloride, and cadmium chloride in male and female mice

    Energy Technology Data Exchange (ETDEWEB)

    Suter, K.E.

    1975-01-01

    Dominant-lethal effects of 10 mg/kg methylmercuric hydroxide were studied in male mice from two hybrid stocks and in females from one of these stocks. Two other compounds, mercuric chloride (2 mg/kg) and cadmium chloride (2 mg/kg), were studied only in females for dominant-lethal (in one hybrid stock) and reproductive capacity effects (in two hybrid and one mixed stocks). All compounds were administered in a single intraperitoneal injection. When males of one of the two stocks studied were treated with methylmercuric hydroxide, the females to which they were mated exhibited a slight reduction in the total number of implantations and in the number of living embryos. These reductions were accompanied by a very small increase in the incidence of dead implantations. In females, cadmium chloride had no detectable dominant-lethal or other fertility effects, except superovulation. On the other hand, the two mercury compounds slightly reduced the numbers of implants and living embryos in females subjected to dominant-lethal studies. The two mercury compounds also induced a slight reduction in the long-term reproductive performance of one stock of females. These results, and those reported earlier by others, indicate that the mercury compounds studied so far are not potent inducers of dominant-lethal mutations in male and female mice. It is not clear whether the small effects on male or female fertility induced in some cases, particularly the increase in dead implantations and reductions in the number of living embryos, were attributable to dominant-lethal mutations or to nongenetic causes. (auth)

  17. Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate.

    Science.gov (United States)

    Song, Jia; Jia, Shao-Yi; Yu, Bo; Wu, Song-Hai; Han, Xu

    2015-08-30

    Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. ATR-FTIR and XPS study on the structure of complexes formed upon the adsorption of simple organic acids on aluminum hydroxide

    Institute of Scientific and Technical Information of China (English)

    GUAN Xiao-hong; CHEN Guang-hao; SHANG Chii

    2007-01-01

    Information on the binding of organic ligands to metal (hydr)oxide surfaces is useful for understanding the adsorption behaviour of natural organic matter (NOM) on metal (hydr)oxide. In this study, benzoate and salicylate were employed as the model organic ligands and aluminum hydroxide as the metal hydroxide. The attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectra revealed that the ligands benzoate and salicylate do coordinate directly with the surface of hydrous aluminum hydroxide, thereby forming inner-sphere surface complexes. It is concluded that when the initial pH is acidic or neutral, monodentate and bridging complexes are to be formed between benzoate and aluminum hydroxide while bridging complexes predominate when the initial pH is alkalic. Monodentate and bridging complexes can be formed at pH 5 while precipitate and bridging complexes are formed at pH 7 when salicylate anions are adsorbed on aluminum hydroxide. The X-ray photoelectron (XP) spectra demonstrated the variation of C 1s binding energy in the salicyate and phenolic groups before and after adsorption. It implied that the benzoate ligands are adsorbed through the complexation between carboxylate moieties and the aluminum hydroxide surface, while both carboxylate group and phenolic group are involved in the complexation reaction when salicylate is adsorbed onto aluminum hydroxide. The information offered by the XPS confirmed the findings obtained with ATR-FTIR.

  19. Thermal Characterization of the Gelatinization of Corn Starch Suspensions with Added Sodium Hydroxide or Urea as a Main Component of Corrugating Adhesives

    National Research Council Canada - National Science Library

    Koyakumaru, Takatoshi; Nakano, Hirofumi

    2016-01-01

    The effects of sodium hydroxide and urea on the gelatinization of corn starch suspensions, a main component of corrugating starch adhesives, were studied using differential scanning calorimetry (DSC...

  20. Improving Corrosion Resistance and Biocompatibility of Magnesium Alloy by Sodium Hydroxide and Hydrofluoric Acid Treatments

    Directory of Open Access Journals (Sweden)

    Chang-Jiang Pan

    2016-12-01

    Full Text Available Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH and hydrogen fluoride (HF solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR and X-ray photoelectron spectroscopy (XPS indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility.

  1. Hydroxide precursors to produce nanometric YCrO{sub 3}: Characterization and conductivity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Durán, A., E-mail: dural@cnyn.unam.mx [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800, Ensenada, B.C. (Mexico); Meza F, C. [Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km. 107 Carretera Tijuana-Ensenada, Apartado Postal 14, C.P. 22800, Ensenada, B.C. (Mexico); Arizaga, Gregorio Guadalupe Carbajal, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2012-06-15

    Highlights: ► Y/Cr mixed hydroxide was precipitated with gaseous ammonia. ► The hydroxide treated at 1373 K formed YCrO{sub 3} crystals with 20 nm diameter. ► Electrical properties were different than those found in other methods of synthesis. ► E{sub act} suggests small-polarons as conduction mechanisms. -- Abstract: A precursor to produce perovskite-type YCrO{sub 3} was precipitated by bubbling gaseous ammonia into an yttrium/chromium salts solution. X-ray diffraction showed that the as-prepared powders were amorphous. Thermal treatment between 1273 and 1373 K, leads to formation of polycrystalline YCrO{sub 3} with crystal sizes around 20 nm. High resolution X-ray photoelectron spectra showed uniform chemical environment for yttrium and chromium in the amorphous hydroxide and crystalline YCrO{sub 3}. Shifts between Y 3d{sub 5/2} and Cr 2p{sub 3/2} binding energy suggest redistribution or charge transfer between yttrium and chromium ions in the YCrO{sub 3} structure. The electrical properties of YCrO{sub 3}, whose precursors were precipitated with gaseous ammonia are different than those prepared by combustion synthesis. Electrical conductivity presents a sudden increase at ∼473 K, which is associated to the grain size and morphology of the crystallites. The redistribution of charge between Y(III) and Cr(III) is thermally activated by the hopping of small-polarons, which are characterized by the Arrhenius law as the conductive mechanism.

  2. Evaluation of pH and calcium ion diffusion from calcium hydroxide pastes and MTA.

    Science.gov (United States)

    Sáez, María Del M; López, Gabriela L; Atlas, Diana; de la Casa, María L

    2017-04-01

    The aim of this ex vivo study was to evaluate changes in pH and calcium ion diffusion through root dentin from calcium hydroxide (Ca (OH) 2) and mineral trioxide aggregate (MTA) pastes at 7, 30 and 60 days; and the relationship between pH and ion diffusion. Thirty-two human premolars were used. Crowns were sectioned and root canals instrumented and filled in with the following preparations: 1) Ca(OH) 2 + distilled water (n=7); 2) Ca(OH) 2 + 0.1% chlorhexidine gluconate (n=7); 3) MTA + distilled water (n=7); 4) MTA + 0.1% chlorhexidine gluconate (CHX) (n=7); 5) distilled water (n=2) (control); 6) 0.1% chlorhexidine gluconate (n=2) (control). The apex and coronary opening were sealed with IRM. Roots were placed in Eppendorf tubes with 1 ml distilled water at 37°C and 100% humidity. At baseline, 7, 30 and 60 days, pH was measured with pH meter, and calcium ion content in the solution was analyzed by atomic absorption spectrophotometry. The data were statistically analyzed using ANOVA, simple linear regression analysis and Pearson's correlation test. The highest pH values were achieved with calcium hydroxide pastes at 60 days (p ≤ 0.05). Calcium ions were released in all groups. The calcium hydroxide paste with distilled water at 60 days had the highest calcium ion value (p ≤ 0.01). There was a positive correlation between calcium and pH values. Sociedad Argentina de Investigación Odontológica.

  3. Hydrophilic block copolymer-directed growth of lanthanum hydroxide nano-particles

    Energy Technology Data Exchange (ETDEWEB)

    Bouyer, F.; Sanson, N.; Gerardin, C. [Laboratoire de Materiaux Catalytiques et Catalyse en Chimie Organique, UMR 5618 CNRS-ENSCM-UM1, FR 1878, Institut Gerhardt, 34 - Montpellier (France); Destarac, M. [Centre de Recherches Rhodia Aubervilliers, 93 - Aubervilliers (France)

    2006-03-15

    Stable hairy lanthanum hydroxide nano-particles were synthesized in water by performing hydrolysis and condensation reactions of lanthanum cations in the presence of double hydrophilic poly-acrylic acid-b-polyacrylamide block copolymers (PAA-b-PAM). In the first step, the addition of asymmetric PAA-b-PAM copolymers (M{sub w,PAA} {<=} M{sub w,PAM}) to lanthanum salt solutions, both at pH = 5.5, induces the formation of monodispersed micellar aggregates, which are predominantly isotropic. The core of the hybrid aggregates is constituted of a lanthanum polyacrylate complex whose formation is due to bidentate coordination bonding between La{sup 3+} and acrylate groups, as shown by ATR-FTIR experiments and pH measurements. The size of the micellar aggregates depends on the molecular weight of the copolymer but is independent of the copolymer to metal ratio in solution. In the second step, the hydrolysis of lanthanum ions is induced by addition of a strong base such as sodium hydroxide. Either flocculated suspensions or stable anisotropic or spherical nano-particles of lanthanum hydrolysis products were obtained depending on the metal complexation ratio [acrylate]/[La]. The variation of that parameter also enables the control of the size of the core-corona nano-particles obtained by lanthanum hydroxylation. The asymmetry degree of the copolymer was shown to influence both the size and the shape of the particles. Elongated particles with a high aspect ratio, up to 10, were obtained with very asymmetric copolymers (M{sub w,PAM}/M{sub w,PAA}{>=}10) while shorter rice grain-like particles were obtained with a less asymmetric copolymer. The asymmetry degree also influences the value of the critical metal complexation degree required to obtain stable colloidal suspensions of polymer-stabilized lanthanum hydroxide. (authors)

  4. Pharmacokinetics of iron(III)-hydroxide sucrose complex after a single intravenous dose in healthy volunteers.

    Science.gov (United States)

    Danielson, B G; Salmonson, T; Derendorf, H; Geisser, P

    1996-06-01

    The pharmacokinetics of iron were investigated after intravenous administration to 12 healthy volunteers of iron(III)-hydroxide sucrose complex (Venofer) as a single i.v. dose containing 100 mg Fe. The average predose concentration was 35.7 +/- 12.5 mumol/l. There was no statistically significant difference between the serum iron level before injection (0 h) and the level at 24 h after the injection. The compartment model used includes a Michaelis-Menten term and is in excellent agreement with the observed exchange of iron to transferrin and with the daily iron turnover by transferrin. The intravenously injected iron(III)-hydroxide sucrose complex led rapidly to high serum iron levels. Maximum measured levels averaged 538 mumol/l (30.0 mg/l) at 10 min after the injection. The terminal half-life of the injected iron was calculated to be 5.3 h. Mean total area under the curve (AUC) was 1491 mumol/l h, the mean residence time (MRT) was 5.5 h. The total body clearance was 20.5 ml/min. The volume of distribution of the central compartment (Vc) was 3.21, hence close to the volume of the serum; the volume of distribution at steady state (Vdss) was 7.31; and the volume of distribution during elimination (Vdarea) was 9.21. The calculated amount of iron transported by transferrin was 31.0 +/- 6.6 mg Fe/ 24h. In summary, the data show that the injected iron(III)-hydroxide sucrose complex is quickly cleared from the serum with a terminal half-life of approximately 5-6 h. Renal elimination of iron contributed very little to the overall elimination (in average sucrose averaged about 68 +/- 10% and 75 +/- 11% of the administered dose after 4 h and 24 h, respectively.

  5. Synthesis of Tetrabutylammonium Hydroxide%四丁基氢氧化铵的合成

    Institute of Scientific and Technical Information of China (English)

    高彦春; 杨座国; 陈建华; 储消和

    2012-01-01

    Tetrabutylammonium hydroxide was prepared by the ion exchange between gel type strong basic anion exchange resin(OH-) and aqueous solution of tetrabutylammonium bromide. The suitable synthesis conditions were investigated by the experiments conducted in the laboratory. The results of the research show that, when the concentration of tetrabutylammonium hydroxide 27.0%, the temperature 15 ℃, the concentration of regeneration liquid NaOH 5.0% and the ratio of height to diameter of the exchange column 15, the degree of exchange greater than 86.0%, and the concentration of tetrabutylammonium hydroxide solution more than 10.0% can be achieved. The column exchange method is simple and the used ion exchange resin can be conveniently regenerated.%采用凝胶型强碱性阴离子交换树脂与四丁基溴化铵溶液进行离子交换制取四丁基氢氧化铵溶液,考察了适宜的合成工艺条件.结果表明,四丁基溴化铵的浓度为27.0%,温度为15℃,再生液NaOH浓度为5.0%,交换柱内离子交换树脂的高径比为15时,交换度大于86.0%,产品(C4H9)4NOH(四丁基氢氧化铵)的溶液浓度大于10.0%.方法简单,离子交换树脂可再生.

  6. Structural characterization of nickel oxide/hydroxide nanosheets produced by CBD technique

    Energy Technology Data Exchange (ETDEWEB)

    Taşköprü, T., E-mail: ttaskopru@anadolu.edu.tr [Department of Physics, Anadolu University, Eskişehir 26470 (Turkey); Department of Physics, Çankırı Karatekin University, Çankırı 18100 (Turkey); Zor, M.; Turan, E. [Department of Physics, Anadolu University, Eskişehir 26470 (Turkey)

    2015-10-15

    Graphical abstract: SEM images of (a) as deposited β-Ni(OH)2 and (b) NiO samples deposited with pH 10 solution. The inset figures shows the absorbance spectra of (a) β-Ni(OH)2 and (b) NiO samples. - Highlights: • The formation of β-Ni(OH){sub 2} and NiO were confirmed with XRD, SEM, FT-IR and Raman. • Porous nickel oxide was synthesized after heat treatment of nickel hydroxide. • The increase in pH value changes the nanoflake structure to hexagonal nanosheet. • On increasing the pH from 8 to 11, the band gap decreases from 3.52 to 3.37 eV. - Abstract: Nickel hydroxide samples were deposited onto glass substrates using Ni(NO{sub 3}){sub 2}·6H{sub 2}O and aqueous ammonia by chemical bath deposition technique. The influence of pH of solution was investigated by means of X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, Raman spectroscopy, optical absorption and BET analysis. The as-deposited samples were identified as β-Ni(OH){sub 2}, were transformed into NiO after heat treatment in air at 500 °C for 2 h. Porous nickel oxide nanosheets are obtained by heating nickel hydroxide nanosheets. The optical transitions observed in the absorbance spectra below optical band gap is due to defects or Ni{sup 2+} vacancies in NiO samples. The band gap energy of NiO samples changes between 3.37 and 3.52 eV depending on the pH values.

  7. Hydroxide stabilization as a new tool for ballast disinfection: Efficacy of treatment on zooplankton

    Science.gov (United States)

    Moffitt, Christine M.; Watten, Barnaby J.; Barenburg, Amber; Henquinet, Jeffrey

    2015-01-01

    Effective and economical tools are needed for treating ship ballast to meet new regulatory requirements designed to reduce the introduction of invasive aquatic species from ship traffic. We tested the efficacy of hydroxide stabilization as a ballast disinfection tool in replicated, sequential field trials on board the M/V Ranger III in waters of Lake Superior. Ballast water was introduced into each of four identical 1,320 L stainless steel tanks during a simulated ballasting operation. Two tanks were treated with NaOH to elevate the pH to 11.7 and the remaining two tanks were held as controls without pH alteration. After retention on board for 14–18 h, CO2-rich gas recovered from one of two diesel propulsion engines was sparged into tanks treated with NaOH for 2 h to force conversion of NaOH ultimately to sodium bicarbonate, thereby lowering pH to about 7.1. Prior to gas sparging, the engine exhaust was treated by a unique catalytic converter/wet scrubber process train to remove unwanted combustion byproducts and to provide cooling. The contents of each tank were then drained and filtered through 35-µm mesh plankton nets to collect all zooplankton. The composition and relative survival of zooplankton in each tank were evaluated by microscopy. Zooplankton populations were dominated by rotifers, but copepods and cladocerans were also observed. Hydroxide stabilization was 100% effective in killing all zooplankton present at the start of the tests. Our results suggest hydroxide stabilization has potential to be an effective and practical tool to disinfect ship ballast. Further, using CO2 released from the ship engine reduces emissions and the neutralized by product, sodium bicarbonate, can have beneficial impacts on the aquatic environment.

  8. Diode Laser and Calcium Hydroxide for Elimination of Enterococcus Faecalis in Root Canal

    Directory of Open Access Journals (Sweden)

    Neda Naghavi

    2014-06-01

    Full Text Available Introduction: The ultimate goal of endodontic treatment is to eliminate the bacterial infection in the root canal system. While mechanical debridement combined with chemical irrigation removes the bulk of microorganisms, residual bacteria are readily detectable in approximately one-half of teeth just prior to obturation. Laser light can be used to destroy bacteria. This in vitro study was performed to evaluate the effect of diode laser and calcium hydroxide on mono-infected dental canals.Methods: Fifty five single-rooted human premolars were prepared and contaminated with Enterococcus faecalis. After three weeks of incubation, the samples were divided into three experimental groups (n = 15 and two control groups (n = 5. In the first and second groups, the teeth were rinsed for 5 min with either sterile saline or 5.25% NaOCl and irradiated with a 810-nm diode laser at 1.5 W output for 5 × 4s. In the third group, the teeth were rinsed with 5.25% NaOCl and then Ca(OH2 paste was inserted in the canals for 1 week. Intracanal bacterial sampling was done and the samples were plated to determine the CFU count. Results: 5.25% NaOCl plus laser was as effective as calcium hydroxide and significantly more effective than sterile saline (P>0.05 in elimination of E. faecalis. Complete elimination of E. faecalis was seen only for the one week calcium hydroxide treatment. Conclusion: Combination therapy with NaOCl irrigation and diode laser irradiation can be recommended as an effective treatment option for elimination of E. faecalis from the root canal system.

  9. Effect of Fe/Al Hydroxides on Desorption of K+ and NH4+ from Two Soils and Kaolinite

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-Ping; XU Ren-Kou; LI Jiu-Yu

    2013-01-01

    Potassium (K) and nitrogen (N) are essential nutrients for plants.Adsorption and desorption in soils affect K+ and NH4+ availabilities to plants and can be affected by the interaction between the electrical double layers on oppositely charged particles because the interaction can decrease the surface charge density of the particles by neutralization of positive and negative charges.We studied the effect of iron (Fe)/aluminum (Al) hydroxides on desorption of K+ and NH4+ from soils and kaolinite and proposed desorption mechanisms based on the overlapping of diffuse layers between negatively charged soils and mineral particles and the positively charged Fe/Al hydroxide particles.Our results indicated that the overlapping of diffuse layers of electrical double layers between positively charged Fe/Al hydroxides,as amorphous Al(OH)3 or Fe(OH)3,and negatively charged surfaces from an Ultisol,an Alfisol,and a kaolinite standard caused the effective negative surface charge density on the soils and kaolinite to become less negative.Thus the adsorption affinity of these negatively charged surfaces for K+ and NH4+ declined as a result of the incorporation of the Fe/Al hydroxides.Consequently,the release of exchangeable K+ and NH4+ from the surfaces of the soils and kaolinite increased with the amount of the Fe/Al hydroxides added.The greater the positive charge on the surfaces of Fe/Al hydroxides,the stronger was the interactive effect between the hydroxides and soils or kaolinite,and thus the more release of K+ and NH4+.A decrease in pH led to increased positive surface charge on the Fe/Al hydroxides and enhanced interactive effects between the hydroxides and soils/kaolinite.As a result,more K+ and NH4+ were desorbed from the soils and kaolinite.This study suggests that the interaction between oppositely charged particles of variable charge soils can enhance the mobility of K+ and NH4+ in the soils and thus increase their leaching loss.

  10. [Effects of the treatment of coffee pulp, fresh or ensilaged, with calcium hydroxide, on its nutritive value].

    Science.gov (United States)

    Gómez-Brenes, R; Bendaña, G; González, J M; Jarquín, R; Braham, J E; Bressani, R

    1988-03-01

    This study was carried out to determine the effects of the addition of calcium hydroxide on the chemical composition and nutritive value of fresh or ensilaged coffee pulp. Fresh or ensilaged pulp were mixed with 1, 2 and 3% of calcium hydroxide. The process was carried out during 0 and 16 hr, after which time the treated pulp was sun-dried for 36 hr until moisture content reached 12%. These samples were then analyzed for their proximate chemical composition and for some minerals (Ca, P, Na, K), as well as for caffeine, tannins and chlorogenic and caffeic acids content. Diets were then prepared from these materials, containing 15% protein and 15 or 30% fresh or ensilaged coffee pulp, and offered to weanling rats during six weeks. Information required on weight gain, food conversion, apparent digestibility and toxicity of the diets was recorded. Results of the chemical analysis revealed that the main changes found in both types of pulp as a result of the calcium hydroxide treatment were the following: a decrease in ether extract (from 4.0 to 2.5 g/100 g), crude fiber (from 18.3 to 11.9 g/100 g) and protein content (from 12.3 to 8.6 g/100 g) in an inverse relation to the amount of calcium hydroxide used. The amount of ash increased, fluctuated between 5.5 and 15.4%, depending on the amount of calcium hydroxide used. The latter affected the Ca:P ratio in the diets, where an average ratio of 7.2:1 was found in the control pulp (0% calcium hydroxide) and 59.0:1 in those treated with the highest amount of calcium hydroxide (3%). Regarding the caffeine, tannins and chlorogenic and caffeic acids contents, calcium hydroxide was effective in decreasing only tannins, more so in the fresh than in the ensilaged pulp; the decrease was in direct proportion to the amount of calcium hydroxide added and to the length of the Ca(OH)2 treatment. The results of the biological assays showed that the addition of Ca(OH)2 in either of the two time periods used and at either of the

  11. Incorporation of fluorophosphate into zinc–aluminium–nitrate layered double hydroxide by ion exchange

    Indian Academy of Sciences (India)

    El Hassan Elkhattabi; Mohamed Badreddine; Moha Berraho; Ahmed Legrouri

    2012-08-01

    The intercalation of fluorophosphate (PO3F2-, FP) in the [Zn–Al] layered double hydroxides (LDHs) was investigated. A nitrate precursor was prepared by coprecipitaion at pH 9. An attempt to intercalate FP by direct coprecipitation reaction led to a poorly crystalline LDH phase. The effects of pH, aging time and anion concentration were studied and allowed to confirm that the best crystalline material, with high exchange extent, was obtained by carrying out the exchange at 25 °C in 0.1 M FP solution at pH 9 with at least 20 h of aging time.

  12. Synthesis of Dimethyl Carbonate from Methanol and Carbon Dioxide Catalyzed by Potassium Hydroxide under Mild Conditions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide using potassium hydroxide as catalyst in the presence of CH3I and the effect of ionic liquid on the reaction were investigated. The results showed that KOH is an effective catalyst; the high selectivity and raised yield of DMC formation under mild conditions were achieved. However,the addition of the ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), can evidently accelerate the conversion of methanol and yield of the product.

  13. Mössbauer and XRD study of intercalated CaFe-layered double hydroxides

    Science.gov (United States)

    Sipiczki, Mónika; Kuzmann, Ernő; Pálinkó, István; Homonnay, Zoltán; Sipos, Pál; Kukovecz, Ákos; Kónya, Zoltán

    2014-04-01

    N-containing fully saturated (L-prolinate) or aromatic (indole-2-carboxylate) heterocyclic anions were immobilised in CaFe-layered double hydroxide with the dehydration-rehydration method from aqueous ethanol or acetone. The structure of the resulting organic-inorganic hybrids was characterised mainly with powder X-ray diffraction and 57Fe Mössbauer spectroscopy, and as supplementary analysis scanning electron microscopy, energy dispersive X-ray spectroscopy with elemental mapping and molecular modelling were also applied. It was found that the solvent mixture used for the synthesis caused enormous difference in the interlayer spacings of the obtained inorganic-organic hybrids.

  14. Ruthenium redox equilibria 1. Thermodynamic stability of Ru(III) and Ru(IV) hydroxides

    OpenAIRE

    Igor Povar; Oxana Spinu

    2016-01-01

    On the basis of the selected thermodynamic data for Ru(III) and Ru(IV) compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the ΔG–pH diagrams, the areas of therm...

  15. Removal of borate by coprecipitation with Mg/Al layered double hydroxide

    Science.gov (United States)

    Kurashina, Masashi; Inoue, Tatsuki; Tajima, Chihiro; Kanezaki, Eiji

    2015-03-01

    Borate has been used for various industrial products and excessive dose of boron is harmful to humans. We investigated the removal of borate by direct coprecipitation with Mg/Al layered double hydroxide. In this study, the maximum removal of boron was 90% when Mg 30 mmol and Al 15 mmol at pH = 10 were used for 498 mg/l as B. The boron adsorption isotherms could be fitted to Langmuir model. The calculated constant Ws, saturation limit of boron adsorption, is 25 ± 2 mg/g and it is larger than that of ion exchange reaction (Ws = 15±1 mg/g).

  16. Structure and thermal decomposition of sulfated β-cyclodextrin intercalated in a layered double hydroxide

    Science.gov (United States)

    Wang, Ji; Wei, Min; Rao, Guoying; Evans, David G.; Duan, Xue

    2004-01-01

    The sodium salt of hexasulfated β-cyclodextrin has been synthesized and intercalated into a magnesium-aluminum layered double hydroxide by ion exchange. The structure, composition and thermal decomposition behavior of the intercalated material have been studied by variable temperature X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma emission spectroscopy (ICP), and thermal analysis (TG-DTA) and a model for the structure has been proposed. The thermal stability of the intercalated sulfated β-cyclodextrin is significantly enhanced compared with the pure form before intercalation.

  17. Ab initio studies of ionization potentials of hydrated hydroxide and hydronium

    CERN Document Server

    Swartz, Charles W

    2013-01-01

    The ionization potential distributions of hydrated hydroxide and hydronium are computed with many-body approach for electron excitations with configurations generated by {\\it ab initio} molecular dynamics. The experimental features are well reproduced and found to be closely related to the molecular excitations. In the stable configurations, the ionization potential is mainly perturbed by water molecules within the first solvation shell. On the other hand, electron excitation is delocalized on both proton receiving and donating complex during proton transfer, which shifts the excitation energies and broadens the spectra for both hydrated ions.

  18. Anion-exchange membranes derived from quaternized polysulfone and exfoliated layered double hydroxide for fuel cells

    Science.gov (United States)

    Liu, Wan; Liang, Na; Peng, Pai; Qu, Rong; Chen, Dongzhi; Zhang, Hongwei

    2017-02-01

    Layered double hydroxides (LDH) are prepared by controlling urea assisted homogeneous precipitation conditions. Morphology and crystallinity of LDHs are confirmed by X-ray diffraction and scanning electron microscope. After LDHs are incorporated into quaternized polysulfone membranes, transmission electron microscope is used to observe the exfoliated morphology of LDH sheets in the membranes. The properties of the nanocomposite membranes, including water uptake, swelling ratio, mechanical property and ionic conductivity are investigated. The nanocomposite membrane containing 5% LDH sheets shows more balanced performances, exhibiting an ionic conductivity of 2.36×10-2 S cm-1 at 60 °C.

  19. Citrate influences microbial Fe hydroxide reduction via a dissolution-disaggregation mechanism

    Science.gov (United States)

    Braunschweig, Juliane; Klier, Christine; Schröder, Christian; Händel, Matthias; Bosch, Julian; Totsche, Kai U.; Meckenstock, Rainer U.

    2014-08-01

    Microbial reduction of ferric iron is partly dependent on Fe hydroxide particle size: nanosized Fe hydroxides greatly exceed the bioavailability of their counterparts larger than 1 μm. Citrate as a low molecular weight organic acid can likewise stabilize colloidal suspensions against aggregation by electrostatic repulsion but also increase Fe bioavailability by enhancing Fe hydroxide solubility. The aim of this study was to see whether adsorption of citrate onto surfaces of large ferrihydrite aggregates results in the formation of a stable colloidal suspension by electrostatic repulsion and how this effect influences microbial Fe reduction. Furthermore, we wanted to discriminate between citrate-mediated colloid stabilization out of larger aggregates and ferrihydrite dissolution and their influence on microbial Fe hydroxide reduction. Dissolution kinetics of ferrihydrite aggregates induced by different concentrations of citrate and humic acids were compared to microbial reduction kinetics with Geobacter sulfurreducens. Dynamic light scattering results showed the formation of a stable colloidal suspension and colloids with hydrodynamic diameters of 69 (±37) to 165 (± 65) nm for molar citrate:Fe ratios of 0.1 to 0.5 and partial dissolution of ferrihydrite at citrate:Fe ratios ⩾ 0.1. No dissolution or colloid stabilization was detected in the presence of humic acids. Adsorption of citrate, necessary for dissolution, reversed the surface charge and led to electrostatic repulsion between sub-aggregates of ferrihydrite and colloid stabilization when the citrate:Fe ratio was above a critical value (⩽ 0.1). Lower ratios resulted in stronger ferrihydrite aggregation instead of formation of a stable colloidal suspension, owing to neutralization of the positive surface charge. At the same time, microbial ferrihydrite reduction increased from 0.029 to 0.184 mM h-1 indicating that colloids stabilized by citrate addition enhanced microbial Fe reduction. Modelling of

  20. Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

    Directory of Open Access Journals (Sweden)

    Hongbo Y.

    2015-06-01

    Full Text Available The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

  1. The conditions for electrodeposition of insoluble hydroxides at a cathode surface

    DEFF Research Database (Denmark)

    Hansen, P.Gregers

    1959-01-01

    The pH values obtained in the vicinity of a cathode surface where hydrogen evolution takes place are discussed using the concept of a diffusion layer. It is shown that a given current density I determines a hydrogen ion concentration Cmax in the solution, above which no hydroxide deposition...... at the cathode can be expected to take place. The shape of the pH distribution makes it possible to define a hydroxyl ion layer, the thickness of which approaches zero as the hydrogen ion concentration approaches Cmax. It is found that relatively high pH values (11–13) are easily obtained at a cathode surface...

  2. Influence of pH on the thixotropy of magnesium aluminum hydroxide-kaolinite suspension

    Institute of Scientific and Technical Information of China (English)

    DAI; Xiaonan

    2001-01-01

    [1]Chen Zongqi, Shi Lin, Wu Shiying et al., The negative thixotropy, Chemistry (in Chinese), 1991, 54(2): 31-34.[2]Hou Wanguo, Sun Dejun, Han Shuhua et al., A novel thixotropic phenomenon-complex thixotropic behavior, Chem. Res. Chin. Univ., 1997, 13(1): 86-88.[3]Mo 2+ Al3+[4]Constantino. V. R. L., Pinnavaia, T. J., Basic properties of Mg2+l-x Ai3+x layered double hydroxides intercalated by carbonate. hydroxide, chloride, and sulfate anions, Inorg. Chem., 1995, 34(4): 883-892.[5]Albiston, L., Frankin, K. R., Lee, E. et al., Rheology and microstructure of aqueous layered double hydroxide dispersions, J. Mater. Chem., 1996, 6(5): 871-877.[6]Abend, S., Bonnke, N., Gutschner, U. et al., Stabilization of emulsions by heterocoagulation of clay minerals and layered double hydroxides, Colloid Polym. Sci., 1998, 276(8): 730-737.[7]Heckroodt, R. O., Ryan, W., Clay suspensions with negative thixotropy, Trans. J. Brit. Ceram. Sci., 1978, 77(2): 180- 183.[8]Chen Zongqi, Yu Wanglin, Hao Ce et al., The rheological properties of SiO2 suspension and PHPA system, Acta Chimica Sinica, 1990, 48(7): 666-72.[9]Benna, M., Kbir-Ariguib, N., Magnin, A. et al., Effect of pH on rheological properties of purified sodium bentonite suspensions, J. Colloid Interface Sci., 1999, 218(4): 442-445.[10]Sohm, R., Tadros, T. F., Viscoelastic Properties of sodium montmorillonite (Gelwhite H) suspensions, J. Colloid Interface Sci.. 1989, 132(1): 62-71.[11]Torrance, K. J., Pirmat, M., Effect of pH on the rheology of marine clay from the site of the south Nation River, Clays Clay Miner, 1984, 32(5): 384-390.[12]Heath, D., Tadros, T. F., Influence of pH, electrolyte, and poly (vinyl alcohol) addition on the rheological characteristics of aqueous dispersions of sodium montmorillonite, J. Colloid Interface Sci., 1983, 93(2): 307-319.

  3. Preparation of Layered Double Hydroxide-Immobilized Lipase for High Yield and Optically Active (-)-Menthyl butyrate

    Institute of Scientific and Technical Information of China (English)

    Siti; Salhah; Othman; Mahiran; Basri; Mohd.Zobir; Hussein; Mohd; Basyaruddin; Abdul; Rahman; Raja; Noor; Zaliha; Raja; Abdul; Rahman; Abu; Bakar; Salleh; Salina; Mat; Radzi; Azwani; Sofia; Ahmad; Khiar

    2007-01-01

    1 Results Layered Double Hydroxide (LDH) finds extensive usage in the areas of pharmaceutical sciences and catalysis. In this study, a member of the LDH family, Mg/Al-hydrotalcite (HT), or the so-called anionic clay, was prepared at ratio 4 (HT) by co-precipitating through continuous agitation. X-ray diffraction pattern and thermogravimetric analysis of the material indicated that a pure HT had been successfully synthesized. This matrix was then used as support in the immobilization of lipase from Cand...

  4. Preparation and evaluation of PEGylated phospholipid membrane coated layered double hydroxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Mina Yan

    2016-06-01

    Full Text Available The aim of the present study was to develop layered double hydroxide (LDH nanoparticles coated with PEGylated phospholipid membrane. By comparing the size distribution and zeta potential, the weight ratio of LDH to lipid materials which constitute the outside membrane was identified as 2:1. Transmission electron microscopy photographs confirmed the core-shell structure of PEGylated phospholipid membrane coated LDH (PEG-PLDH nanoparticles, and cell cytotoxicity assay showed their good cell viability on Hela and BALB/C-3T3 cells over the concentration range from 0.5 to 50 μg/mL.

  5. Direct decarbonation of micrometer-scale layered double hydroxides without morphology damage

    Institute of Scientific and Technical Information of China (English)

    Kong Li Xu; Guang Ming Chen; Jian Quan Shen

    2012-01-01

    A direct decarbonation route without obvious morphology damage was developed for large micrometer-scale layered double hydroxides (LDHs).First,we synthesized pure,hexagonal-shaped LDHs with lateral dimension of micrometer-size by the recently reported urea hydrolysis method.Then,using HNO3-NaNO3 mixed solution,the obtained LDH with carbonate anions in the interlayer (LDH_CO3) was directly decarbonated to its nitrate form,LDH_NO3,its morphology and particle size were still unchanged.Compared with the recently published two-step decarbonation method,the direct decarbonation reported herein is very convenient.

  6. Aerobic Oxidation of 5-(Hydroxymethyl)furfural in Ionic Liquids with Solid Ruthenium Hydroxide Catalysts

    DEFF Research Database (Denmark)

    Ståhlberg, Tim Johannes Bjarki; Eyjolfsdottir, Ester; Gorbanev, Yury

    2012-01-01

    ][OAc] at 100 °C with 30 bar of oxygen over Ru(OH) x /La2O3 which afforded 48 % of 2,5-furandicarboxylic acid and 12 % of 5-hydroxymethyl-2-furancarboxylic acid. During use the catalysts were found to leach some of the metal inventory. However, the leached Ru species did not contribute to the catalytic activity......The aerobic oxidation of 5-(hydroxymethyl)furfural was investigated over solid ruthenium hydroxide catalysts in ionic liquids at elevated temperatures and pressures. Several different catalyst supports were tested in combination with various ionic liquids. The best result was obtained in [EMIm...

  7. Anodic stripping voltammetry of nickel ions and nickel hydroxide nanoparticles at boron-doped diamond electrodes

    Science.gov (United States)

    Musyarofah, N. R. R.; Gunlazuardi, J.; Einaga, Y.; Ivandini, T. A.

    2017-04-01

    Anodic stripping voltammetry (ASV) of nickel ions in phosphate buffer solution (PBS) have been investigated at boron-doped diamond (BDD) electrodes. The deposition potential at 0.1 V (vs. Ag/AgCl) for 300 s in 0.1 M PBS pH 3 was found as the optimum condition. The condition was applied for the determination of nickel contained in nickel hydroxide nanoparticles. A linear calibration curve can be achieved of Ni(OH)2-NPs in the concentration range of x to x mM with an estimated limit of detection (LOD) of 5.73 × 10-6 mol/L.

  8. Cobalt-based layered double hydroxides as oxygen evolving electrocatalysts in neutral electrolyte

    Science.gov (United States)

    Lin, Hong; Zhang, Ye; Wang, Gang; Li, Jian-Bao

    2012-06-01

    Co-M (M= Co, Ni, Fe, Mn) layered double hydroxides (LDHs) were successfully fabricated by a hexamethylenetetramine (HMT) pyrolysis method. Composite electrodes were made using a self-assembly fashion at inorganic/organic surface binder-free and were used to catalyze oxygen evolution reaction. Water oxidation can take place in neutral electrolyte operating with modest overpotential. The doping of other transitional metal cations affords mix valences and thus more intimate electronic interactions for reversible chemisorption of dioxygen molecules. The application of employing LDH materials in water oxidation process bodes well to facilitate future hydrogen utilization.

  9. Preparation and inhibition properties of molybdate intercalated ZnAlCe layered double hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Huajie; Wang, Jihui, E-mail: jhwang@tju.edu.cn; Zhang, Yu; Hu, Wenbin

    2016-09-05

    ZnAlCe layered double hydroxide intercalated by molybdate (ZnAlCe−MoO{sub 4} LDH) was successfully synthesized by using co-precipitation method, and the morphology, structure of ZnAlCe−MoO{sub 4} LDH were observed and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. The inhibition behavior of ZnAlCe−MoO{sub 4} LDH for Q235 steel in 3.5%NaCl solution was determined by polarization curves, electrochemical impedance spectroscopy (EIS), inductively coupled plasma mass spectrometer (ICP-MS) and X-ray photoelectron spectrometer (XPS) methods. The results shows that the synthesized ZnAlCe−MoO{sub 4} LDH has a lamellar structure with a particle size of 0.1–2.0 μm, an average thickness of 30 nm, and a basal plane spacing of 0.898 nm. Compared with the addition of ZnAl layered double hydroxide intercalated by nitrate (ZnAl−NO{sub 3} LDH) and ZnAl layered double hydroxide intercalated by molybdate (ZnAl−MoO{sub 4} LDH) in 3.5% NaCl solution, Q235 steel in 3.5%NaCl + ZnAlCe−MoO{sub 4} LDH solution has a lower corrosion current density, larger polarization resistance and a higher inhibition efficiency. The addition of ZnAlCe−MoO{sub 4} LDH will reduce the chloride concentration in 3.5% NaCl solution by the anion exchanged with molybdate, and improve the corrosion resistance of Q235 steel owing to the formation of passive film with the composition of ferrous or iron molybdate and deposition film with zinc and cerium hydroxides. - Highlights: • ZnAlCe−MoO{sub 4} LDH compound was successfully synthesized by co-precipitation method. • ZnAlCe−MoO{sub 4} LDH has a better inhibition effect to Q235 steel in 3.5%NaCl solution. • The Cl{sup −} ions in solution was partially exchanged with MoO{sub 4}{sup 2−} ions in host layers. • The passive film and deposition film were formed by the release of LDH compound.

  10. Determination of Aluminium Content in Aluminium Hydroxide Formulation by FT-NIR Transmittance Spectroscopy

    DEFF Research Database (Denmark)

    Lai, Xuxin; Zheng, Yiwu; Søndergaard, Ib

    2007-01-01

    A method for determining the aluminium content of an aluminium hydroxide suspension using near infrared (NIR) transmittance spectroscopy has been developed. Inductively coupled plasma-atomic emission spectroscopy (ICP-AES) was used as reference method. The factors influencing the NIR analysis......-AES and NIR transmittance spectroscopy exhibit comparable precision and accuracy. The NIR method provides several advantages: no complicated sample preparation; easy to operate; fast and non-destructive. In conclusion, NIR transmittance spectroscopy can be an alternative analytical method for determining...

  11. Ionic Strength-Controlled Mn (Hydr)oxide Nanoparticle Nucleation on Quartz: Effect of Aqueous Mn(OH)2.

    Science.gov (United States)

    Jung, Haesung; Jun, Young-Shin

    2016-01-05

    The early formation of manganese (hydr)oxide nanoparticles at mineral-water interfaces is crucial in understanding how Mn oxides control the fate and transport of heavy metals and the cycling of nutrients. Using atomic force microscopy, we investigated the heterogeneous nucleation and growth of Mn (hydr)oxide under varied ionic strengths (IS; 1-100 mM NaNO3). Experimental conditions (i.e., 0.1 mM Mn(2+) (aq) concentration and pH 10.1) were chosen to be relevant to Mn remediation sites. We found that IS controls Mn(OH)2 (aq) formation, and that the controlled Mn(OH)2 (aq) formation can affect the system's saturation and subsequent Mn(OH)2 (s) and further Mn3O4 (s) nanoparticle formation. In 100 mM IS system, nucleated Mn (hydr)oxide particles had more coverage on the quartz substrate than those in 1 mM and 10 mM IS systems. This high IS also resulted in low supersaturation ratio and thus favor heterogeneous nucleation, having better structural matching between nucleating Mn (hydr)oxides and quartz. The unique information obtained in this work improves our understanding of Mn (hydr)oxide formation in natural as well as engineered aqueous environments, such as groundwater contaminated by natural leachate and acid mine drainage remediation.

  12. Coagulation-adsorption of reactive orange from aqueous solution by freshly formed magnesium hydroxide: mixing time and mechanistic study.

    Science.gov (United States)

    Zhao, Jianhai; Shi, Huanhuan; Liu, Meile; Lu, Jingfang; Li, Wenpu

    2017-04-01

    The utilization of magnesium hydroxide was successfully carried out to remove reactive orange by coagulation-adsorption from aqueous solution. The coagulation-adsorption mechanisms and magnesium hydroxide-reactive orange floc property were analyzed through zeta potential, scanning electron microscope (SEM), X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR). Flocculation Index was then discussed with controlled experiments using intelligent Particle Dispersion Analyzer (iPDA) and optimum rapid mixing time of 90 s was obtained for pH 12. The results of this study indicate that charge neutralization and adsorption are proposed to be the main coagulation mechanisms. The FT-IR spectra and SEM showed that reactive orange was adsorbed on the magnesium hydroxide surface during coagulation and adsorption. Freshly generated magnesium hydroxide can effectively remove reactive orange and the removal efficiency can reach 96.7% and 46.3% for coagulation and adsorption, respectively. Adsorption process accounts for 48% of the whole coagulation experiment. The removal efficiency decreased significantly with increasing magnesium hydroxide formation time.

  13. Improving the quality of rice straw by urea and calcium hydroxide on rumen ecology, microbial protein synthesis in beef cattle.

    Science.gov (United States)

    Polyorach, S; Wanapat, M

    2015-06-01

    Four rumen-fistulated beef cattle were randomly assigned to four treatments according to a 4 × 4 Latin square design to study the influence of urea and calcium hydroxide [Ca(OH)2 ] treatment of rice straw to improve the nutritive value of rice straw. Four dietary treatments were as follows: untreated rice straw, 50 g/kg urea-treated rice straw, 20 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw and 30 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw. All animals were kept in individual pens and fed with concentrate at 0.5 g/kg of BW (DM), rice straw was fed ad libitum. The experiment was conducted for four periods, and each period lasted for 21 days. During the first 14 days, DM feed intake measurements were made while during the last 7 days, all cattle were moved to metabolism crates for total faeces and urine collections. The results revealed that 20 g/kg urea + 20 g/kg calcium hydroxide-treated rice straw improved the nutritive value of rice straw, in terms of dry matter intake, digestibility, ruminal volatile fatty acids, population of bacteria and fungi, nitrogen retention and microbial protein synthesis. Based on this study, it could be concluded that using urea plus calcium hydroxide was one alternative method to improve the nutritive value of rice straw, rumen ecology and fermentation and thus a reduction of treatment cost.

  14. Bacterial reduction and release of adsorbed arsenate on Fe(Ⅲ)-, Al-and coprecipitated Fe(Ⅲ)/Al-hydroxides

    Institute of Scientific and Technical Information of China (English)

    Xuexia Zhang; Yongfeng Jia; Shaofeng Wang; Rongrong Pan; Xudong Zhang

    2012-01-01

    Mobilization of arsenic under anaerobic conditions is of great concern in arsenic contaminated soils and sediments.Bacterial reduction of As(Ⅴ)and Fe(Ⅲ)influences the cycling and partitioning of arsenic between solid and aqueous phase.We investigated the impact of bacterially mediated reductions of Fe(Ⅲ)/A1 hydroxides-bound arsenic(Ⅴ)and iron(Ⅲ)oxides on arsenic release.Our results suggested that As(Ⅴ)reduction occurred prior to Fe(Ⅲ)reduction,and Fe(Ⅲ)reduction did not enhance the release of arsenic.Instead,Fe(Ⅲ)hydroxides retained their dissolved concentrations during the experimental process,even though the new iron mineral-magnetite formed.In contrast,the release of reduced As(Ⅲ)was promoted greatly when aluminum hydroxides was incorporated.Thus,the substitution of aluminum hydroxides may be responsible for the release of arsenic in the contaminated soils and sediments,since aluminum substitution of Fe(Ⅲ)hydroxides universally occurs under natural conditions.

  15. EFFECT OF SODIUM HYDROXIDE CONCENTRATION ON FRESH PROPERTIES AND COMPRESSIVE STRENGTH OF SELF-COMPACTING GEOPOLYMER CONCRETE

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2013-02-01

    Full Text Available This paper reports the results of the laboratory tests conducted to investigate the effect of sodium hydroxide concentration on the fresh properties and compressive strength of self-compacting geopolymer concrete (SCGC. The experiments were conducted by varying the concentration of sodium hydroxide from 8 M to 14 M. Test methods such as Slump flow, V-Funnel, L-box and J-Ring were used to assess the workability characteristics of SCGC. The test specimens were cured at 70°C for a period of 48 hours and then kept in room temperature until the day of testing. Compressive strength test was carried out at the ages of 1, 3, 7 and 28 days. Test results indicate that concentration variation of sodium hydroxide had least effect on the fresh properties of SCGC. With the increase in sodium hydroxide concentration, the workability of fresh concrete was slightly reduced; however, the corresponding compressive strength was increased. Concrete samples with sodium hydroxide concentration of 12 M produced maximum compressive strength.

  16. Protective Activity of the Mixtures of Pine Oil and Copper Hydroxide against Bacterial Spot and Anthracnose on Red Pepper

    Directory of Open Access Journals (Sweden)

    Jae-Woo Soh

    2014-09-01

    Full Text Available This research was performed to examine the protective activities of the mixtures of pine oil and copper hydroxide against bacterial spot and anthracnose on pepper plants. As for bacterial spot, the treatment of pine oil alone displayed high disease incidence (59.6% and low protective effect (28.9%. In comparison, the treatments of mixtures and copper hydroxide alone showed protective activities of 66.8-76.1%. The mixture of pine oil and copper hydroxide (4:1 suppressed the most effectively bacterial spot on pepper. On the other hand, the mixture of pine oil and copper hydroxide (4:1 also showed the strongest protective effect against pepper anthracnose among the 4 treatments tested; its disease incidence and disease control value were 49.8% and 41.7%, respectively. The other treatments showed low protective activities with control values of 7.4-17.1%. These results suggested that the mixture of pine oil and copper hydroxide (4:1 can be used for the environmental-friendly disease control of bacterial spot and anthracnose on pepper.

  17. Synthesis of nanocomposite 2-methyl-4-chlorophenoxyacetic acid with layered double hydroxide: physicochemical characterization and controlled release properties

    Energy Technology Data Exchange (ETDEWEB)

    Sarijo, Siti Halimah, E-mail: izaddinizaddin@yahoo.com; Ghazali, Sheikh Ahmad Izaddin Sheikh Mohd [Faculty of Applied Sciences, Universiti Teknologi MARA (Malaysia); Hussein, Mohd Zobir [Universiti Putra Malaysia, Department of Chemistry, Faculty of Science (Malaysia); Sidek, Norizzah Jaafar [Faculty of Applied Sciences, Universiti Teknologi MARA (Malaysia)

    2013-01-15

    A new organic-inorganic hybrid nanocomposite Zn-Al-MCPA-layered double hydroxide (ZAM) was prepared by intercalation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into Zn-Al-layered double hydroxide (ZAL) at various concentration of MCPA ranging from 0.1 to 0.7 M. The pH of the synthesis was kept constant at 7.5. Well-ordered hybrid nanocomposite was obtained with 0.4 M MCPA with an expansion of basal spacing from 8.9 Angstrom-Sign in the ZAL to 19.7 Angstrom-Sign in the resulting nanocomposite. The FTIR spectra of the nanocomposite show resemblance peaks of the MCPA and Zn-Al-layered double hydroxide indicating the inclusion of MCPA into the layered double hydroxide. The average particle size of ZAL and ZAM in this study was 115 and 128 nm, respectively. Percentage loading of MCPA was found to be 45.0 % (w/w), calculated based on the percentage of carbon in the sample. The release of MCPA into various aqueous solution was found to be dependent to the anion in the aqueous solution in the order of phosphate > sulfate > chloride with the percentage release of 80, 44, and 8%, respectively. This study shows that Zn-Al-layered double hydroxide can be used as a host carrier for herbicide, MCPA, with controlled release capability.

  18. Synthesis of nanocomposite 2-methyl-4-chlorophenoxyacetic acid with layered double hydroxide: physicochemical characterization and controlled release properties

    Science.gov (United States)

    Sarijo, Siti Halimah; Ghazali, Sheikh Ahmad Izaddin Sheikh Mohd; Hussein, Mohd Zobir; Sidek, Norizzah Jaafar

    2013-01-01

    A new organic-inorganic hybrid nanocomposite Zn-Al-MCPA-layered double hydroxide (ZAM) was prepared by intercalation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) into Zn-Al-layered double hydroxide (ZAL) at various concentration of MCPA ranging from 0.1 to 0.7 M. The pH of the synthesis was kept constant at 7.5. Well-ordered hybrid nanocomposite was obtained with 0.4 M MCPA with an expansion of basal spacing from 8.9 Å in the ZAL to 19.7 Å in the resulting nanocomposite. The FTIR spectra of the nanocomposite show resemblance peaks of the MCPA and Zn-Al-layered double hydroxide indicating the inclusion of MCPA into the layered double hydroxide. The average particle size of ZAL and ZAM in this study was 115 and 128 nm, respectively. Percentage loading of MCPA was found to be 45.0 % (w/w), calculated based on the percentage of carbon in the sample. The release of MCPA into various aqueous solution was found to be dependent to the anion in the aqueous solution in the order of phosphate > sulfate > chloride with the percentage release of 80, 44, and 8 %, respectively. This study shows that Zn-Al-layered double hydroxide can be used as a host carrier for herbicide, MCPA, with controlled release capability.

  19. Rare earth and zinc layered hydroxide salts intercalated with the 2-aminobenzoate anion as organic luminescent sensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Cursino, Ana Cristina Trindade, E-mail: anacursino@ufpr.br [CEPESQ – Research Centre of Applied Chemistry, Department of Chemistry, Universidade Federal do Paraná – P.O. Box 19081, 81531-980 Curitiba, PR (Brazil); Rives, Vicente, E-mail: vrives@usal.es [GIR-QUESCAT – Department of Inorganic Chemistry, Universidad de Salamanca, Plaza de la Merced S/N, 37998 Salamanca (Spain); Arizaga, Gregorio Guadalupe Carbajal, E-mail: gregoriocarbajal@yahoo.com.mx [Universidad de Guadalajara, Department of Chemistry, Boulevard Marcelino García Barragán 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Trujillano, Raquel, E-mail: rakel@usal.es [GIR-QUESCAT – Department of Inorganic Chemistry, Universidad de Salamanca, Plaza de la Merced S/N, 37998 Salamanca (Spain); Wypych, Fernando, E-mail: wypych@ufpr.br [CEPESQ – Research Centre of Applied Chemistry, Department of Chemistry, Universidade Federal do Paraná – P.O. Box 19081, 81531-980 Curitiba, PR (Brazil)

    2015-10-15

    Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The UV absorption ability was improved after intercalation/grafting in relation to that shown by the parent material. - Highlights: • Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide were synthesized. • Intercalated nitrate anions were exchanged by 2-aminobenzoate. • In all the 2-aminobenzoate containing compounds, the grafting reaction was detected. • The UV absorption ability was improved after the exchange reactions. • Rare earth hydroxide salts are potential matrixes to produce luminescent materials. - Abstract: Rare earth (RE = Eu, Y and Tb) and zinc layered hydroxide salts intercalated with nitrate anions were synthesized, followed by exchange with 2-aminobenzoate. The obtained compounds were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and ultraviolet visible (UV–vis) spectroscopies, fluorescence measurements and thermal analysis (TGA/DTA). The results from FTIR spectroscopy suggest a direct coordination of 2-aminobenzoate to the metal cations of the inorganic layered structure. The organic derivative products from the intercalation reactions absorb a broader range of UV-light in relation to that shown by the parent material; the photoluminescence measurements present a strong violet, blue and green luminescence under UV-light excitation for layered compounds with, Zn, Y and Tb, respectively. Rare earth hydroxide salts (RE-LHS) are potential alternative matrices for the immobilization of organic species to produce luminescent materials.

  20. Aluminum Hydroxide

    Science.gov (United States)

    ... and others), chloroquine (Aralen), cimetidine (Tagamet), clonazepam (Klonopin), clorazepate, dexamethasone (Decadron and others), diazepam (Valium, Valrelease, and Zetran), diflunisal (Dolobid), digoxin (Lanoxin), ...

  1. New metal phthalocyanines/metal simple hydroxide multilayers: experimental evidence of dipolar field-driven magnetic behavior.

    Science.gov (United States)

    Bourzami, Riadh; Eyele-Mezui, Séraphin; Delahaye, Emilie; Drillon, Marc; Rabu, Pierre; Parizel, Nathalie; Choua, Sylvie; Turek, Philippe; Rogez, Guillaume

    2014-01-21

    A series of new hybrid multilayers has been synthesized by insertion-grafting of transition metal (Cu(II), Co(II), Ni(II), and Zn(II)) tetrasulfonato phthalocyanines between layers of Cu(II) and Co(II) simple hydroxides. The structural and spectroscopic investigations confirm the formation of new layered hybrid materials in which the phthalocyanines act as pillars between the inorganic layers. The magnetic investigations show that all copper hydroxide-based compounds behave similarly, presenting an overall antiferromagnetic behavior with no ordering down to 1.8 K. On the contrary, the cobalt hydroxide-based compounds present a ferrimagnetic ordering around 6 K, regardless of the nature of the metal phthalocyanine between the inorganic layers. The latter observation points to strictly dipolar interactions between the inorganic layers. The amplitude of the dipolar field has been evaluated from X-band and Q-band EPR spectroscopy investigation (Bdipolar ≈ 30 mT).

  2. Accidental contamination of a German town's drinking water with sodium hydroxide.

    Science.gov (United States)

    Lendowski, Luba; Färber, Harald; Holy, Andreas; Darius, Anke; Ehrich, Bernd; Wippermann, Christine; Küfner, Bernd; Exner, Martin

    2015-05-01

    Case report of a very serious drinking water incident putting up to 50,000 inhabitants of a town near Bonn in North Rhine-Westphalia, Germany at risk. A concentrated solution of highly alkaline water by sodium hydroxide was accidentally washed into the town's drinking water at a pumping station and increased the pH-value of the water to 12. Residents who came into contact with the contaminated water immediately had a toxic reaction. The incident was detected by complaints from customers and after that was stopped within several hours. The pipes were flushed and the customers were warned not to use the water till the all clear. After this immediate management there was an investigation and the cause of the incident was detected as an accidental release of accumulated sodium hydroxide (NaOH) solution. The lack of a network alarm system and the automatic cut-off mechanisms as deficiencies in the design of the station were rectified by the water company immediately after the incident.

  3. Adsorption of phosphonate antiscalant from reverse osmosis membrane concentrate onto granular ferric hydroxide.

    Science.gov (United States)

    Boels, Luciaan; Keesman, Karel J; Witkamp, Geert-Jan

    2012-09-04

    Adsorptive removal of antiscalants offers a promising way to improve current reverse osmosis (RO) concentrate treatment processes and enables the reuse of the antiscalant in the RO desalination process. This work investigates the adsorption and desorption of the phosphonate antiscalant nitrilotris(methylenephosphonic acid) (NTMP) from RO membrane concentrate onto granular ferric hydroxide (GFH), a material that consists predominantly of akaganéite. The kinetics of the adsorption of NTMP onto GFH was predicted fairly well with two models that consider either combined film-pore or combined film-surface diffusion as the main mechanism for mass transport. It is also demonstrated that NTMP is preferentially adsorbed over sulfate by GFH at pH 7.85. The presence of calcium causes a transformation in the equilibrium adsorption isotherm from a Langmuir type to a Freundlich type with much higher adsorption capacities. Furthermore, calcium also increases the rate of adsorption substantially. GFH is reusable after regeneration with sodium hydroxide solution, indicating that NTMP can be potentially recovered from the RO concentrate. This work shows that GFH is a promising adsorbent for the removal and recovery of NTMP antiscalant from RO membrane concentrates.

  4. Generation of Hydrogen, Lignin and Sodium Hydroxide from Pulping Black Liquor by Electrolysis

    Directory of Open Access Journals (Sweden)

    Guangzai Nong

    2015-12-01

    Full Text Available Black liquor is generated in Kraft pulping of wood or non-wood raw material in pulp mills, and regarded as a renewable resource. The objective of this paper was to develop an effective means to remove the water pollutants by recovery of both lignin and sodium hydroxide from black liquor, based on electrolysis. The treatment of a 1000 mL of black liquor (122 g/L solid contents consumed 345.6 kJ of electric energy, and led to the generation of 30.7 g of sodium hydroxide, 0.82 g of hydrogen gas and 52.1 g of biomass solids. Therefore, the recovery ratios of elemental sodium and biomass solids are 80.4% and 76%, respectively. Treating black liquor by electrolysis is an environmentally friendly technology that can, in particular, be an alternative process in addressing the environmental issues of pulping waste liquor to the small-scale mills without black liquor recovery.

  5. Synthesis of Platinum-Nickel Hydroxide Nanocomposites for Electrocatalytic Reduction of Water

    KAUST Repository

    Wang, Lei

    2016-11-25

    Water electrolysis represents a promising solution for storage of renewable but intermittent electrical energy in hydrogen molecules. This technology is however challenged by the lack of efficient electrocatalysts for the hydrogen and oxygen evolution reactions. Here we report on the synthesis of platinum-nickel hydroxide nanocomposites and their electrocatalytic applications for water reduction. An in situ reduction strategy taking advantage of the Ni(II)/Ni(III) redox has been developed to enable and regulate the epitaxial growth of Pt nanocrystals on single-layer Ni(OH)2 nanosheets. The obtained nanocomposites (denoted as Pt@2D-Ni(OH)2) exhibit an improvement factor of 5 in catalytic activity and a reduction of up to 130 mV in overpotential compared to Pt for the hydrogen evolution reaction (HER). A combination of electron microscopy/spectroscopy characterization, electrochemical studies and density functional calculations was employed to uncover the structures of the metal-hydroxide interface and understand the mechanisms of catalytic enhancement.

  6. Organo-layered double hydroxides composite thin films deposited by laser techniques

    Energy Technology Data Exchange (ETDEWEB)

    Birjega, R. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Vlad, A., E-mail: angela.vlad@gmail.com [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Matei, A.; Dumitru, M.; Stokker-Cheregi, F.; Dinescu, M. [National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Str., 77125 Bucharest-Magurele (Romania); Zavoianu, R. [University of Bucharest, Faculty of Chemistry, Department of Chemical Technology and Catalysis, 4-12 Regina Elisabeta Bd., Bucharest 030018 (Romania); Raditoiu, V.; Corobea, M.C. [National R.& D. Institute for Chemistry and Petrochemistry, ICECHIM, 202 Splaiul Independentei Str., CP-35-274, 060021 Bucharest (Romania)

    2016-06-30

    Highlights: • PLD and MAPLE was successfully used to produce organo-layered double hydroxides. • The organic anions (dodecyl sulfate-DS) were intercalated in co-precipitation step. • Zn2.5Al-LDH (Zn/Al = 2.5) and Zn2.5Al-DS thin films obtained in this work could be suitable for further applications as hydrophobic surfaces. - Abstract: We used laser techniques to create hydrophobic thin films of layered double hydroxides (LDHs) and organo-modified LDHs. A LDH based on Zn-Al with Zn{sup 2+}/Al{sup 3+} ratio of 2.5 was used as host material, while dodecyl sulfate (DS), which is an organic surfactant, acted as guest material. Pulsed laser deposition (PLD) and matrix assisted pulsed laser evaporation (MAPLE) were employed for the growth of the films. The organic anions were intercalated in co-precipitation step. The powders were subsequently used either as materials for MAPLE, or they were pressed and used as targets for PLD. The surface topography of the thin films was investigated by atomic force microscopy (AFM), the crystallographic structure of the powders and films was checked by X-ray diffraction. FTIR spectroscopy was used to evidence DS interlayer intercalation, both for powders and the derived films. Contact angle measurements were performed in order to establish the wettability properties of the as-prepared thin films, in view of functionalization applications as hydrophobic surfaces, owing to the effect of DS intercalation.

  7. Ruthenium redox equilibria: 1. Thermodynamic stability of Ru(III and Ru(IV hydroxides

    Directory of Open Access Journals (Sweden)

    Igor Povar

    2016-04-01

    Full Text Available On the basis of the selected thermodynamic data for Ru(III and Ru(IV compounds in addition to original thermodynamic and graphical approach used in this paper, the thermodynamic stability areas of sparingly soluble hydroxides as well as the repartition of their soluble and insoluble chemical species towards the solution pH and initial concentrations of ruthenium in heterogeneous mixture solid phase–saturated solution have been investigated. By means of the ΔG–pH diagrams, the areas of thermodynamic stability of Ru(III and Ru(IV hydroxides have been established for a number of analytical concentrations in heterogeneous mixtures. The diagrams of heterogeneous and homogeneous chemical equilibria have been used for graphical representation of complex equilibria in aqueous solutions containing Ru(III and Ru(IV. The obtained results, based on the thermodynamic analysis and graphic design of the calculated data in the form of the diagrams of heterogeneous chemical equilibria, are in good agre­ement with the available experimental data.

  8. Synthesis and controlled release properties of 2,4-dichlorophenoxy acetate–zinc layered hydroxide nanohybrid

    Energy Technology Data Exchange (ETDEWEB)

    Bashi, Abbas M., E-mail: abbasmatrood@yahoo.com [Department of Medical Analysis, Faculty of Medical Science, Karbala University (Iraq); Hussein, Mohd Zobir; Zainal, Zulkarnain [Chemistry Department Faculty of Science-UPM (Malaysia); Tichit, Didier [Institut Charles Gerhardt UMR 5253 CNRS/UM2/ENSCM/UM1, Matériaux Avancés pour la Catalyse et la Santé, 8 rue Ecole Normale, 34296 Montpellier Cedex 5 (France)

    2013-07-15

    Direct reaction of ZnO with 2,4-dichlorophenoxyacetic acid (24D) solutions of different concentrations allows obtaining new organic–inorganic nanohybrid materials formed by intercalation of 24D into interlayers of zinc layered hydroxide (ZLH). XRD patterns show a progressive evolution of the structure as 24D concentration increases. The nanohybrid obtained at higher 24D concentration (24D–ZLH(0.4)) reveals a well ordered layered structure with two different basal spacings at 25.2 Å and 24 Å. The FTIR spectrum showing the vibrations bands of the functional groups of 24D and of the ZLH confirms the intercalation. SEM images are in agreement with the structural evolution observed by XRD and reveal the ribbon morphology of the nanohybrids. The release studies of 24D showed a rapid release of 94% for the first 100 min governed by the pseudo-second order kinetic model. - Graphical abstract: The phenomenon indicates that the optical energy gap is enlarged with the increase of molar concentrations in 2,4-dichlorophenoxy acetate anion content into ZnO to create a ZLH–24D nanohybrid. - Highlights: • Nanohybrid was synthesized from 2,4-dichlorophenoxy acetate with-Zinc LHD, using wet chemistry. • Characterized using SEM, TEM, EDX, FTIR, XRD and TGA. • Ribbon-shaped 24D–Zn-layered hydroxide nanoparticles with (003) diffractions of 2.5 nm phase were synthesized.

  9. Sandwich-like graphene/polypyrrole/layered double hydroxide nanowires for high-performance supercapacitors

    Science.gov (United States)

    Li, Xuejin; Zhang, Yu; Xing, Wei; Li, Li; Xue, Qingzhong; Yan, Zifeng

    2016-11-01

    Electrode design in nanoscale is considered to be ultra-important to construct a superb capacitor. Herein, a sandwich-like composite was made by combining graphene/polypyrrole (GPPY) with nickel-aluminum layered double hydroxide nanowires (NiAl-NWs) via a facile hydrothermal method. This sandwich-like architecture is promising in energy storage applications due to three unique features: (1) the conductive GPPY substrate not only effectively prevents the layered double hydroxides species from aggregating, but also considerably facilitates the electron transmission; (2) the ultrathin NiAl-NWs ensure a maximum exposure of active Ni2+, which can improve the efficiency of rapid redox reactions even at high current densities; (3) the sufficient space between anisotropic NiAl-NWs can accommodate a large volume change of the nanowires to avoid their collapse or distortion during the reduplicative redox reactions. Keeping all these unique features in mind, when the as-prepared composite was applied to supercapacitors, it presented an enhanced capacitive performance in terms of high specific capacitance (845 F g-1), excellent rate performance (67% retained at 30 A g-1), remarkable cyclic stability (92% maintained after 5000 cycles) and large energy density (40.1 Wh·Kg-1). This accomplishment in the present work inspires an innovative strategy of nanoscale electrode design for high-rate performance supercapacitor electrodes containing pseuducapacitive metal oxide.

  10. OptimalParameters of Response Surface Methodology for Preparation of Magnesium Hydroxide Flame Retardant

    Institute of Scientific and Technical Information of China (English)

    刘志启; 李丽娟; 陈运法; 李晓昆; 张艳灵; 沈根利

    2011-01-01

    The yield of magnesium hydroxide was investigated via response surface methodology using bischofite and aqueous ammonia as raw materials.The experimental results indicated that the effects of reaction temperature,magnesium ion and aqueous ammonia concentrations on the yield of magnesium hydroxide gradually decreased.In particular,reaction temperature and magnesium ion concentration had a significant influence on the yield.After the regression and fitting of the response value and each factor,the regression equation was obtained.As proven by experiments,the predicted value and actual value showed a good fit.The products of the center experiment were characterized by particle size analysis,scanning electron microscopy,and X-ray diffraction.The results show that the morphology is irregular and shows a lamellar structure.The particles have a narrow size distribution ranging from 0.64 to 0.68 μm of D50 size.The difference in particle size of D10and D90 is less than 0.91 μm,and the purity very high.

  11. Chloride adsorption by calcined layered double hydroxides in hardened Portland cement paste

    KAUST Repository

    Yoon, Seyoon

    2014-06-01

    This study investigated the feasibility of using calcined layered double hydroxides (CLDHs) to prevent chloride-induced deterioration in reinforced concrete. CLDHs not only adsorbed chloride ions in aqueous solution with a memory effect but also had a much higher binding capacity than the original layered double hydroxides (LDHs) in the cement matrix. We investigated this adsorption in hardened cement paste in batch cultures to determine adsorption isotherms. The measured and theoretical binding capacities (153 mg g -1 and 257 mg g-1, respectively) of the CLDHs were comparable to the theoretical capacity of Friedel\\'s salt (2 mol mol-1 or 121 mg g-1), which belongs to the LDH family among cementitious phases. We simulated chloride adsorption by CLDHs through the cement matrix using the Fickian model and compared the simulation result to the X-ray fluorescence (XRF) chlorine map. Based on our results, it is proposed that the adsorption process is governed by the chloride transport through the cement matrix; this process differs from that in an aqueous solution. X-ray diffraction (XRD) analysis showed that the CLDH rebuilds the layered structure in a cementitious environment, thereby demonstrating the feasibility of applying CLDHs to the cement and concrete industries. © 2014 Published by Elsevier B.V. All rights reserved.

  12. On the dielectric response of complex layered oxides: Mica-type silicates and layered double hydroxides

    Science.gov (United States)

    Mehrotra, Vivek; Giannelis, Emmanuel P.

    1992-08-01

    The dielectric properties of mica-type silicates and layered double hydroxides have been studied in the pristine and various intercalated forms in the frequency range 101-107 Hz. A relaxation peak has been observed for the pristine silicate, whereas the pristine layered double hydroxide exhibits an anomalous low-frequency dispersion. The dielectric response is rationalized in terms of structural ordering and fluctuation of charge carriers as well as models invoking fractal time processes and fractal structure. The response is also related to the structure and mobility of the intercalated water molecules. In both pristine hosts, the predominant conduction mechanism is proton hopping between sites generated by a network of intercalated water molecules. Silicate intercalated with the insulating form of polyaniline exhibits an almost frequency-independent response. In the case of conducting polyaniline intercalated silicate, where polarons are the majority charge carriers, an anomalous low-frequency dispersion is observed and the response is typical of a metal-insulator composite. Finally, impedance measurements have been used to calculate the spatial disorder and/or surface irregularity of the host layers, expressed by the fractal dimension ds. The changes observed in ds upon intercalation of high-charge ions are correlated to the stacking disorder of the host layers.

  13. Mg-Al layered double hydroxide intercalated with porphyrin anions: molecular simulations and experiments.

    Science.gov (United States)

    Kovár, Petr; Pospísil, Miroslav; Káfunková, Eva; Lang, Kamil; Kovanda, Frantisek

    2010-02-01

    Molecular modeling in combination with powder X-ray diffraction (XRD) provided new information on the organization of the interlayer space of Mg-Al layered double hydroxide (LDH) containing intercalated porphyrin anions [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS)]. Anion-exchange and rehydration procedures were used for the preparation of TPPS-containing LDH with an Mg/Al molar ratio of 2. Molecular modeling was carried out in the Cerius(2) and Materials Studio modeling environment. Three types of models were created in order to simulate the experimental XRD patterns of LDH intercalates with a TPPS loading of 70-80% with respect to the theoretical anion exchange capacity (AEC). The models represent single-phase systems with a 100% TPPS loading in the interlayer space (Type 1) and models represent the coexistence of two phases corresponding to the total exchange from 75 to 92% (Type 2). To cover other possible arrangements, models with the coexistence of both TPPS and NO(3)(-) anions in the same interlayer space were calculated (Type 3). The models are described and compared with experimental data. In all cases, guest TPPS anions are tilted with respect to the hydroxide layers, and are horizontally shifted to each other by up to one-half of the TPPS diameter. According to the energy characteristics and simulated XRD, the most probable arrangement is of Type 2, where some layers are saturated with TPPS anions and others are filled with original NO(3)(-) anions.

  14. Evaluation of preservative effectiveness of gallic acid derivatives in aluminum hydroxide gel-USP

    Directory of Open Access Journals (Sweden)

    Anurag Khatkar

    2013-01-01

    Full Text Available Background: Preservatives are added to most of the pharmaceutical preparations to prevent them from deterioration throughout their shelf life. Literature reveals that the common synthetic preservatives have many limitations, such as development of microbial resistance (in due course of time and several serious side-effects. Aim: The aim of this study is to find out new preservatives synthesized from natural sources, which may have better efficiency than the existing synthetic preservatives. The derivatives of naturally occurring gallic acid were subjected for their preservative efficacy study. Their preservative efficiency was evaluated and compared with the standard parabens. Materials and Methods: The selected amide, anilide and ester derivatives of gallic acid were subjected to preservative efficacy testing in an official antacid preparation, {aluminum hydroxide gel-USP (United States Pharmacopoeia} against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans, and Aspergillus niger as representative challenging microorganisms as per USP 2004 guidelines. Results: The selected derivatives were found to be effective against all selected strains and showed preservative efficacy comparable to that of standard and even better in case E. coli, C. albicans and A. niger. The 8-hydroxy quinoline ester derivative showed better preservative efficacy than standard as well as other derivatives. Conclusion: The newly synthesized gallic acid preservatives were found to be effective in the proposed pharmaceutical preparation (Aluminium Hydroxide Gel - USP. Also, the synthesized preservatives have shown comparative and even better efficacy than the existing parabens and hence they have potential for use in pharmaceutical preparations.

  15. Evaluation of preservative effectiveness of p-coumaric acid derivatives in aluminium hydroxide gel-USP

    Directory of Open Access Journals (Sweden)

    Anurag Khatkar

    2013-01-01

    Full Text Available Background: Deterioration of pharmaceutical preparations due to growth of microorganisms is a great challenge and need of preservation becomes very important. Literature reports about various problems associated with the existing synthetic preservatives such as development of microbial resistance (in due course of time and several serious side effects. Aim: The aim of the present study is to find out new preservatives synthesized from natural sources, which may have better efficiency than the existing synthetic preservatives. The derivatives of naturally occurring p-coumaric acid were subjected for their preservative efficacy study. Their preservative efficiency was evaluated and compared with the standard parabens. Materials and Methods: The selected amide, anilide and ester derivatives of p-coumaric acid were subjected to preservative efficacy testing in an official antacid preparation, (aluminium hydroxide gel-USP against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Candida albicans and Aspergillus niger as representative challenging microorganisms as per USP 2004 guidelines. Results: The selected derivatives were found to be effective against all selected strains and showed preservative efficacy comparable to that of standard and even better in case E. coli, C. albicans and A. niger. The 8-hydroxy quinoline ester derivative showed better preservative efficacy than standard as well as other derivatives. Conclusion: The newly synthesized p- coumaric acid preservatives were found to be effective in the proposed pharmaceutical preparation (Aluminium Hydroxide Gel - USP. Also, the synthesized preservatives have shown comparative and even better efficacy than the existing parabens and hence they have potential for use in pharmaceutical preparations.

  16. Double layered hydroxides as potential anti-cancer drug delivery agents.

    Science.gov (United States)

    Riaz, Ufana; Ashraf, S M

    2013-04-01

    The emergence of nanotechnology has changed the scenario of the medical world by revolutionizing the diagnosis, monitoring and treatment of cancer. This nanotechnology has been proved miraculous in detecting cancer cells, delivering chemotherapeutic agents and monitoring treatment from non-specific to highly targeted killing of tumor cells. In the past few decades, a number of inorganic materials have been investigated such as calcium phosphate, gold, carbon materials, silicon oxide, iron oxide, and layered double hydroxide (LDH) for examining their efficacy in targeting drug delivery. The reason behind the selection of these inorganic materials was their versatile and unique features efficient in drug delivery, such as wide availability, rich surface functionality, good biocompatibility, potential for target delivery, and controlled release of the drug from these inorganic nanomaterials. Although, the drug-LDH hybrids are found to be quite instrumental because of their application as advanced anti-cancer drug delivery systems, there has not been much research on them. This mini review is set to highlight the advancement made in the use of layered double hydroxides (LDHs) as anti-cancer drug delivery agents. Along with the advantages of LDHs as anti-cancer drug delivery agents, the process of interaction of some of the common anti-cancer drugs with LDH has also been discussed.

  17. Structure and Magnetic Property Control of Copper Hydroxide Acetate by Non-Classical Crystallization.

    Science.gov (United States)

    Song, RuiQi; Krasia-Christoforou, Theodora; Debus, Christian; Cölfen, Helmut

    2017-03-01

    Copper hydroxide acetate (CHA), one layered hydroxide compound with tunable magnetism, attracts great interest because of its potential applications in memory devices. However, ferromagnetism for CHA is only demonstrated by means of GPa pressure. Herein, a new method is reported, involving the combination of different crystallization pathways to control crystallization of amorphous CHA toward the formation of CHA/polymer composites with tunable magnetic properties and even a tunability that can be tested at room temperature. By using poly[(ethylene glycol)6 methyl ether methacrylate]-block-poly[2-(acetoacetoxy) ethyl methacrylate] (PEGMA-b-PAEMA) diblock copolymers as additives in combination with a post-treatment process by ultracentrifugation, it is demonstrated that CHA and PEGMA-b-PAEMA form composites exhibiting different magnetic properties, depending on CHA in-plane nanostructures. Analytical characterization reveals that crystallization of CHA is induced by ultracentrifugation, during which CHA nanostructures can be well controlled by changing the degrees of polymerization of the PEGMA and PAEMA blocks and their block length ratios. These findings not only present the first example of using crystallization from polymer stabilized amorphous precursors toward the generation of magnetic nanomaterials with tunable magnetism but also pave the way for the future design of functional composite materials.

  18. A study of thermally activated Mg–Fe layered double hydroxides as potential environmental catalysts

    Directory of Open Access Journals (Sweden)

    MILICA S. HADNAĐEV-KOSTIĆ

    2010-09-01

    Full Text Available Layered double hydroxides (LDHs and mixed oxides derived after thermal decomposition of LDHs with different Mg–Fe contents were investigated. These materials were chosen because of the possibility to tailor their various properties, such as ion-exchange capability, redox and acid–base and surface area. Layered double hydroxides, [Mg1-xFex(OH2](CO3x/2×mH2O (where x presents the content of trivalent ions, x = M(III/(M(II + M(III were synthesized using the low supersaturation precipitation method. The influence of different Mg/Fe ratios on the structure and surface properties of the LDH and derived mixed oxides was investigated in correlation to their catalytic properties in the chosen test reaction (Fischer–Tropsch synthesis. It was determined that the presence of active sites in the mixed oxides is influenced by the structural properties of the initial LDH and by the presence of additional Fe phases. Furthermore, a synthesis outside the optimal range for the synthesis of single phase LDHs leads to the formation of metastable, multiphase systems with specific characteristics and active sites.

  19. Cobalt hydroxide nanoflakes and their application as supercapacitors and oxygen evolution catalysts

    Science.gov (United States)

    Rovetta, A. A. S.; Browne, M. P.; Harvey, A.; Godwin, I. J.; Coleman, J. N.; Lyons, M. E. G.

    2017-09-01

    Finding alternative routes to access and store energy has become a major issue recently. Transition metal oxides have shown promising behaviour as catalysts and supercapacitors. Recently, liquid exfoliation of bulk metal oxides appears to be an effective route which provides access to two-dimensional (2D) nano-flakes, the size of which can be easily selected. These 2D materials exhibit excellent electrochemical charge storage and catalytic activity for the oxygen evolution reaction. In this study, various sized selected cobalt hydroxide nano-flake materials are fabricated by this time efficient and highly reproducible process. Subsquently, the electrochemical properties of the standard size Co(OH)2 nanoflakes were investigated. The oxide modified electrodes were prepared by spraying the metal oxide flake suspension onto a porous conductive support electrode foam, either glassy carbon or nickel. The cobalt hydroxide/nickel foam system was found to have an overpotential value at 10 mA cm-2 in 1 M NaOH as low as 280 mV and an associated redox capacitance exhibiting numerical values up to 1500 F g-1, thereby making it a viable dual use electrode.

  20. Oxidation states of molybdenum in oxide films formed in sulphuric acid and sodium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Okonkwo, I.A.; Doff, J.; Baron-Wiechec, A. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Jones, G. [Waters Corporation, Floats Rd, Roundthorn Ind. Est., Manchester M23 9LZ (United Kingdom); Koroleva, E.V. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Skeldon, P., E-mail: p.skeldon@manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom); Thompson, G.E. [Corrosion and Protection Centre, School of Materials, The University of Manchester, Manchester M13 9PL (United Kingdom)

    2012-07-31

    X-ray photoelectron spectroscopy is used to investigate the oxidation states of molybdenum in thin films formed potentiostatically, over a range of potentials, in either 1 mol dm{sup -3} H{sub 2}SO{sub 4} or 10 mol dm{sup -3} NaOH at 20 Degree-Sign C. Mo 3d spectra suggested that MoO{sub 2} and Mo(OH){sub 2} were the main components of the films, with smaller amounts of MoO{sub 3} and possibly Mo{sub 2}O{sub 5}. O 1s spectra indicated the presence of oxygen as oxide and hydroxide species and as bound water. Ion beam analysis revealed the formation of thin films at all potentials, with significant losses of oxidized molybdenum to the electrolyte. - Highlights: Black-Right-Pointing-Pointer Oxides are formed on molybdenum in sulphuric acid and sodium hydroxide solutions. Black-Right-Pointing-Pointer Molybdenum IV and VI are identified by XPS, with MoO2 species dominating. Black-Right-Pointing-Pointer Thicknesses of films are determined by ion beam analysis for a range of potentials. Black-Right-Pointing-Pointer Films form at low efficiency due to loss of molybdenum species to electrolyte.

  1. Radiopacity evaluation of root canal sealers containing calcium hydroxide and MTA

    Directory of Open Access Journals (Sweden)

    Juliane Maria Guerreiro- Tanomaru

    2009-06-01

    Full Text Available The purpose of this study was to evaluate the radiopacity of root canal sealers containing calcium hydroxide and MTA (Acroseal, Sealer 26, Sealapex, Endo CPM Sealer, Epiphany and Intrafill. Five disc-shaped specimens (10 x 1 mm were fabricated from each material, according to the ISO 6876/2001 standard. After setting of the materials, radiographs were taken using occlusal film and a graduated aluminum stepwedge varying from 2 to 16 mm in thickness. The dental X-ray unit (GE1000 was set at 50 kVp, 10 mA, 18 pulses/s and distance of 33.5 cm. The radiographs were digitized and the radiopacity compared to that of the aluminum stepwedge using VIXWIN-2000 software (Gendex. The data (mmAl were analyzed statistically by ANOVA and Tukey's test at the 5% significance level. Epiphany and Intrafill presented the highest radiopacity values (8.3 mmAl and 7.5 mmAl respectively, p < 0.05 followed by Sealer 26 (6.3 mmAl, Sealapex (6.1 mmAl and Endo CPM Sealer (6 mmAl. Acroseal was the least radiopaque material (4 mmAl, p < 0.05. In conclusion, the calcium hydroxide- and MTA-containing root canal sealers had different radiopacities. However, all materials presented radiopacity values above the minimum recommended by the ISO standard.

  2. Synthesis of layered double hydroxide nanosheets by coprecipitation using a T-type microchannel reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Xiujiang; Sun, Meiyu; Ma, Xiuming [State Key Laboratory Base of Eco-chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Hou, Wanguo, E-mail: wghou@sdu.edu.cn [Key Laboratory of Colloid and Interface Chemistry (Ministry of Education), Shandong University, Jinan 250100 (China)

    2014-02-15

    The synthesis of Mg{sub 2}Al–NO{sub 3} layered double hydroxide (LDH) nanosheets by coprecipitation using a T-type microchannel reactor is reported. Aqueous LDH nanosheet dispersions were obtained. The LDH nanosheets were characterized by X-ray diffraction, transmission electron microscopy, atomic force microscopy and particle size analysis, and the transmittance and viscosity of LDH nanosheet dispersions were examined. The two-dimensional LDH nanosheets consisted of 1–2 brucite-like layers and were stable for ca. 16 h at room temperature. In addition, the co-assembly between LDH nanosheets and dodecyl sulfate (DS) anions was carried out, and a DS intercalated LDH nanohybrid was obtained. To the best of our knowledge, this is the first report of LDH nanosheets being directly prepared in bulk aqueous solution. This simple, cheap method can provide naked LDH nanosheets in high quantities, which can be used as building blocks for functional materials. - Graphical abstract: Layered double hydroxide (LDH) nanosheets were synthesized by coprecipitation using a T-type microchannel reactor, and could be used as basic building blocks for LDH-based functional materials. Display Omitted - Highlights: • LDH nanosheets were synthesized by coprecipitation using a T-type microchannel reactor. • Naked LDH nanosheets were dispersed in aqueous media. • LDH nanosheets can be used as building blocks for functional materials.

  3. Preparation and properties of blends composed of lignosulfonated layered double hydroxide/plasticized starch and thermoplastics.

    Science.gov (United States)

    Privas, Edwige; Leroux, Fabrice; Navard, Patrick

    2013-07-01

    Layered double hydroxide prepared with lignosulfonate (LDH/LS) can be easily dispersed down to the nanometric scale in thermoplastic starch, at concentration of 1 up to 4 wt% of LDH/LS. They can thus be used as a bio-based reinforcing agent of thermoplastic starch. Incorporation of LDH/LS in starch must be done using LDH/LS slurry instead of powder on order to avoid secondary particles aggregation, the water of the paste being used as the starch plasticizer. This reinforced starch was used for preparing a starch-polyolefine composite. LDH/LS-starch nanocomposites were mixed in a random terpolymer of ethylene, butyl acrylate (6%) and maleic anhydride (3%) at concentrations of 20 wt% and 40 wt%. With a 20% loading of (1 wt% LDH/LS in thermoplastic starch), the ternary copolymer is partially bio-based while keeping nearly its original processability and mechanical properties and improving oxygen barrier properties. The use of layered double hydroxides is also removing most odours linked to the lignin phase.

  4. Organo/layered double hydroxide nanohybrids used to remove non ionic pesticides.

    Science.gov (United States)

    Chaara, D; Bruna, F; Ulibarri, M A; Draoui, K; Barriga, C; Pavlovic, I

    2011-11-30

    The preparation and characterization of organo/layered double hydroxide nanohybrids with dodecylsulfate and sebacate as interlayer anion were studied in detail. The aim of the modification of the layered double hydroxides (LDHs) was to change the hydrophilic character of the interlayer to hydrophobic to improve the ability of the nanohybrids to adsorb non-ionic pesticides such as alachlor and metolachlor from water. Adsorption tests were conducted on organo/LDHs using variable pH values, contact times and initial pesticide concentrations (adsorption isotherms) in order to identify the optimum conditions for the intended purpose. Adsorbents and adsorption products were characterized several physicochemical techniques. The adsorption test showed that a noticeable increase of the adsorption of the non-ionic herbicides was produced. Based on the results, the organo/LDHs could be good adsorbents to remove alachlor and metolachlor from water. Different organo/LDHs complexes were prepared by a mechanical mixture and by adsorption. The results show that HTSEB-based complex displays controlled release properties that reduce metolachlor leaching in soil columns compared to a technical product and the other formulations. The release was dependent on the nature of the adsorbent used to prepare the complexes. Thus, it can be concluded that organo/LDHs might act as suitable supports for the design of pesticide slow release formulations with the aim of reducing the adverse effects derived from rapid transport losses of the chemical once applied to soils.

  5. Accessing the biocompatibility of layered double hydroxide by intramuscular implantation: histological and microcirculation evaluation

    Science.gov (United States)

    Cunha, Vanessa Roberta Rodrigues; de Souza, Rodrigo Barbosa; da Fonseca Martins, Ana Maria Cristina Rebello Pinto; Koh, Ivan Hong Jun; Constantino, Vera Regina Leopoldo

    2016-01-01

    Biocompatibility of layered double hydroxides (LDHs), also known as hydrotalcite-like materials or double metal hydroxides, was investigated by in vivo assays via intramuscular tablets implantation in rat abdominal wall. The tablets were composed by chloride ions intercalated into LDH of magnesium/aluminum (Mg2Al-Cl) and zinc/aluminum (Zn2Al-Cl). The antigenicity and tissue integration capacity of LDHs were assessed histologically after 7 and 28 days post-implantation. No fibrous capsule nearby the LDH was noticed for both materials as well any sign of inflammatory reactions. Sidestream Dark Field imaging, used to monitor in real time the microcirculation in tissues, revealed overall integrity of the microcirculatory network neighboring the tablets, with no blood flow obstruction, bleeding and/or increasing of leukocyte endothelial adhesion. After 28 days Mg2Al-Cl promoted multiple collagen invaginations (mostly collagen type-I) among its fragments while Zn2Al-Cl induced predominantly collagen type–III. This work supports previous results in the literature about LDHs compatibility with living matter, endorsing them as functional materials for biomedical applications. PMID:27480483

  6. A kinetic and mechanistic study into the formation of the Cu-Cr layered double hydroxide.

    Science.gov (United States)

    Williams, Gareth R; Clout, Alexander; Burley, Jonathan C

    2013-06-14

    The formation of the layered double hydroxide [Cu2Cr(OH)6]Cl·yH2O from the reaction between CuO and aqueous CrCl3·6H2O was explored using synchrotron X-ray diffraction and ex situ analyses. The use of hard X-rays permitted time-resolved in situ studies to be performed as the reaction proceeded under a range of conditions. Additional information was obtained from ex situ experiments in which aliquots of the reaction mixture were removed, quenched, and subsequently analysed by laboratory X-ray diffraction, IR, UV-visible, and atomic emission spectroscopies. On the basis of these data, it is proposed that the reaction involves three steps. First, the solid CuO starting material is hydrolysed to give Cu(OH)2 chains, releasing Cu(2+) ions into solution. The Cu hydroxide chains subsequently condense with aqueous Cr(3+) species, Cl(-) ions and water molecules to give a hydrated form of the LDH. This material then extrudes some water to form a phase with a reduced interlayer spacing.

  7. Efficient drug delivery using SiO2-layered double hydroxide nanocomposites.

    Science.gov (United States)

    Li, Li; Gu, Zi; Gu, Wenyi; Liu, Jian; Xu, Zhi Ping

    2016-05-15

    MgAl-layered double hydroxide (MgAl-LDH) nanoparticles have great potentials in drug and siRNA delivery. In this work, we used a nanodot-coating strategy to prepare SiO2 dot-coated layered double hydroxide (SiO2@MgAl-LDH) nanocomposites with good dispersibility and controllable size for drug delivery. The optimal SiO2@MgAl-LDH nanocomposite was obtained by adjusting synthetic parameters including the mass ratio of MgAl-LDH to SiO2, the mixing temperature and time. The optimal SiO2@MgAl-LDH nanocomposite was shown to have SiO2 nanodots (10-15nm in diameter) evenly deposited on the surface of MgAl-LDHs (110nm in diameter) with the plate-like morphology and the average hydrodynamic diameter of 170nm. We further employed SiO2@MgAl-LDH nanocomposite as a nanocarrier to deliver methotrexate (MTX), a chemotherapy drug, to the human osteosarcoma cell (U2OS) and found that MTX delivered by SiO2@MgAl-LDH nanocomposite apparently inhibited the U2OS cell growth.

  8. A chiroptical switch based on DNA/layered double hydroxide ultrathin films.

    Science.gov (United States)

    Shi, Wenying; Jia, Yankun; Xu, Simin; Li, Zhixiong; Fu, Yi; Wei, Min; Shi, Shuxian

    2014-11-04

    A highly oriented film was fabricated by layer-by-layer self-assembly of DNA and MgAl-layered double hydroxide nanosheets, and its application in chiroptical switch was demonstrated via intercalation and deintercalation of an achiral molecule into the DNA cavity. DNA molecules are prone to forming an ordered and dispersive state in the interlayer region of rigid layered double hydroxide (LDH) nanosheets as confirmed by scanning electron microscopy and atomic force microscopy. The induced chiroptical ultrathin film (UTF) is achieved via the intercalation of an achiral chromophore [5,10,15,20-tetrakis(4-N-methylpyridyl)porphine tetra(p-toluenesulfonate) (TMPyP)] into the spiral cavity of DNA stabilized in the LDH matrix [denoted as TMPyP-(DNA/LDH)20]. Fluorescence and circular dichroism spectroscopy are utilized to testify the intercalation of TMPyP into (DNA/LDH)20 UTF that involves two steps: the electrostatic binding of TMPyP onto the surface of (DNA/LDH)20 followed by intercalation into base pairs of DNA. In addition, the TMPyP-(DNA/LDH)20 UTF exhibits good reversibility and repeatability in induced optical chirality, based on the intercalation and deintercalation of TMPyP by alternate exposure to HCl and NH3/H2O vapor, which can be potentially used as a chiroptical switch in data storage.

  9. Advanced phosphorus removal from membrane filtrates by adsorption on activated aluminium oxide and granulated ferric hydroxide.

    Science.gov (United States)

    Genz, Arne; Kornmüller, Anja; Jekel, Martin

    2004-09-01

    The advanced phosphorus (P) removal by adsorption was studied for its suitability as a post-treatment step for membrane bioreactor (MBR) effluents low in P concentration and particle content. Two commercial adsorbents, granulated ferric hydroxide (GFH) and activated aluminium oxide (AA), were studied in batch tests and lab-scale filter tests for P adsorption in MBR filtrates. GFH showed a higher maximum capacity for phosphate and a higher affinity at low P concentrations compared to AA. Competition by inorganic ions was negligible for both adsorbents at the original pH (8.2). When equilibrium P concentrations exceeded 2 mg L(-1) in the spiked MBR filtrates, a precipitation of calcium phosphates occurred additionally to adsorption. During column studies the effluent criteria of 50 microgL(-1) P was reached after a throughput of 8000 bed volumes for GFH and 4000 for AA. Dissolved organic carbon appears to be the strongest competitor for adsorption sites. A partial regeneration and reloading of both adsorbents could be achieved by the use of sodium hydroxide.

  10. Thermodynamic studies of cobalt and cadmium additions to nickel hydroxide as material for positive electrodes

    Science.gov (United States)

    Watanabe, Ken-ichi; Kumagai, Naoaki

    Nickel oxide is used as the positive electrode in nickel-cadmium and nickel-metal-hydride batteries. The physical and the electrochemical effects due to the addition of cobalt and cadmium to nickel hydroxide powders are investigated. X-ray diffraction analysis shows that the d001 value (interlayer distance in the nickel hydroxide) decreases with increase in cobalt content, while the d100 value increases with increase in cadmium content. The open-circuit potential in discharge follows an S-shaped curve in 3 M KOH electrolyte. The results are discussed with respect to thermodynamic theory. The experimentally obtained OCP variation is in good agreement with calculated data using thermodynamic theory with one fitting parameter, φ/ RT; φ is an interaction energy parameter (J mol -1) and RT is the product of the gas constant and absolute temperature. The φ/ RT and E0 (standard electrode potential) values are found to decrease with increase in cobalt content, while the addition of cadmium has little effect on the φ/ RT and E0 values. A difference between the OCP data and the calculated value occurs at the end of discharge; this difference tends to increase with increase in cobalt content.

  11. Mechanochemical synthesis of Cu-Al and methyl orange intercalated Cu-Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jun, E-mail: forsjun@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); He, Xiaoman; Chen, Min; Hu, Huimin [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Zhang, Qiwu, E-mail: zhangqw@whut.edu.cn [School of Resources and Environmental Engineering, Wuhan University of Technology, Luoshi Road 122, Wuhan, Hubei 430070 (China); Liu, Xinzhong [College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou 350118 China (China)

    2017-04-15

    In this study, a mechanochemical route to synthesize a Cu-Al layered double hydroxide (LDH) and a methyl orange (MO) intercalated one (MO-LDH) was introduced, in which basic cupric carbonate (Cu{sub 2}(OH){sub 2}CO{sub 3}) and aluminum hydroxide (Al(OH){sub 3}) with Cu/Al molar ratio at 2/1 was first dry ground for 2 h and then agitated in water or methyl orange solution for another 4 h to obtain the LDH and MO-LDH products without any heating operation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Thermogravimetry (TG), Differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). The products showed high crystallinity phase of Cu-Al and MO intercalated Cu-Al LDH with no evident impurities, proving that the craft introduced here was facile and effective. The new idea can be applied in other fields to produce organic-inorganic composites. - Highlights: • A facile mechanochemical route to synthesize Cu-Al and MO intercalated Cu-Al LDH. • The products possesses high crystalline of LDH phase with no impure phases. • The dry milling process induces the element substitution between the raw materials. • The agitation operation helps the grain growth of LDH.

  12. The Effect of Sodium Hydroxide on Drag Reduction using a Biopolymer.

    Directory of Open Access Journals (Sweden)

    Singh Harvin Kaur A/P Gurchran

    2014-07-01

    Full Text Available Drag reduction is observed as reduced frictional pressure losses under turbulent flow conditions and hence, substantially increases the flowrate of the fluid. Practical application includes water flooding system, pipeline transport and drainage system. Drag reduction agent, such as polymers, can be introduced to increase the flowrate of water flowing, reducing the water accumulation in the system and subsequently lesser possibility of heavy flooding. Currently used polymer as drag reduction agents is carboxymethylcellulose, to name one. This is a synthetic polymer which will seep into the ground and further harm our environment in excessive use of accumulation. A more environmentally-friendly drag reduction agent, such as the polymer derived from natural sources or biopolymer, is then required for such purpose. As opposed to the synthetic polymers, the potential of biopolymers as drag reduction agents, especially those derived from a local plant source, are not extensively explored. The drag reduction of a polymer produced from a local plant source within the turbulent regime will be explored and assessed in this study using a rheometer where a reduced a torque produced can be perceived as a reduction of drag. The cellulose powder was converted to carboxymethylcellulose (CMC by etherification process using sodium monochloroacetate and sodium hydroxide. The carboxymethylation reaction then was optimized against concentration of NaOH. The research is structured to focus on producing the biopolymer and also assess the drag reduction ability of the biopolymer produced against concentration of sodium hydroxide.

  13. Pilot-scale production of biodiesel from waste fats and oils using tetramethylammonium hydroxide.

    Science.gov (United States)

    Šánek, Lubomír; Pecha, Jiří; Kolomazník, Karel; Bařinová, Michaela

    2016-02-01

    Annually, a great amount of waste fats and oils not suitable for human consumption or which cannot be further treated are produced around the world. A potential way of utilizing this low-cost feedstock is its conversion into biodiesel. The majority of biodiesel production processes today are based on the utilization of inorganic alkali catalysts. However, it has been proved that an organic base - tetramethylammonium hydroxide - can be used as a very efficient transesterification catalyst. Furthermore, it can be employed for the esterification of free fatty acids - reducing even high free fatty acid contents to the required level in just one step. The work presented herein, is focused on biodiesel production from waste frying oils and animal fats using tetramethylammonium hydroxide at the pilot-plant level. The results showed that the process performance in the pilot unit - using methanol and TMAH as a catalyst, is comparable to the laboratory procedure, even when the biodiesel is produced from waste vegetable oils or animal fats with high free fatty acid content. The reaction conditions were set at: 1.5% w/w of TMAH, reaction temperature 65°C, the feedstock to methanol molar ratio to 1:6, and the reaction time to 120min. The conversion of triglycerides to FAME was approximately 98%. The cloud point of the biodiesel obtained from waste animal fat was also determined.

  14. Evidence of pulpotomy in primary teeth comparing MTA, calcium hydroxide, ferric sulphate, and electrosurgery with formocresol.

    Science.gov (United States)

    Stringhini Junior, E; Vitcel, M E B; Oliveira, L B

    2015-08-01

    The aim of this study was to evaluate the scientific evidence of pulpotomy in primary teeth comparing mineral troxide aggregate (MTA), calcium hydroxide, ferric sulphate, and electrosurgery with formocresol. A systematic search using key words was conducted using seven databases up to December 10, 2013. Clinical articles in English, Portuguese and Spanish were selected, which were in accordance with the inclusion and exclusion criteria and the research objective of comparing whether pulpotomy performed with formocresol in primary teeth is more effective than other medicaments or techniques. Out of the 12,515 publication initially identified, 30 clinical articles were included in the systematic review and analysed by four meta-analyses. The success rate of MTA (94.6 %) was higher than that of formocresol (87.4 %), with a statistically significant difference (OR = 0.39; 95 % CI = 0.25-0.62). Formocresol pulpotomy success was not statistically different from ferric sulphate or electrosurgery. MTA was clinically and radiographically superior to formocresol for pulpotomy of primary teeth. The other alternatives to formocresol such as electrosurgery and ferric sulphate can be used instead of formocresol since they showed success similar to formocresol. In addition, there is no evidence to support calcium hydroxide for pulpotomies in primary teeth.

  15. The sensitized reaction of non-ionic surfactant to acetylacetone spectrophotometry in the determination of trace formaldehyde in marine products%非离子表面活性剂OP增敏乙酰丙酮光度法测定海产品中的痕量甲醛

    Institute of Scientific and Technical Information of China (English)

    任淑华; 郭振良

    2013-01-01

    目的:建立快速、准确、灵敏测定海产品中甲醛的新方法.方法:在沸水浴中,痕量甲醛与乙酰丙酮能发生微弱的显色反应.实验发现,非离子表面活性剂OP对上述反应有较强的增敏作用,由此建立了一种测定痕量甲醛的新方法.结果:在测定条件下,溶液的最大吸收波长在412 nm,方法的检出限为0.11 μg/ml,相关系数为0.9993,九次空白实验的标准偏差为S=0.00365,相对标准偏差为RSD为0.376%,回收率在100% ~ 105%.结论:方法简单快速、选择性好,用于测定海产品中的甲醛时,测得结果与非增敏乙酰丙酮光度法及HPLC法的结果一致.%Objective: To develop a simple, exact and sensitive method for determination of trace formaldehyde in marine products. Methods: In boiling water bath, acetylacetone and formaldehyde could have a feeble colour reaction. The experiment was found that non - ionic surfactant OP could sensitize the colour reaction. Results: The maximum absorption wavelength was 412 nm. The detection limit was 0. 11 μg/ml. The correlation coefficient was 0.9993. The standard deviation and the relative standard deviation for nine blank were 0.00365 and 0.376%. The recoveries were in the range of 100% to 105% . Conclusion: The results obtained in the application of this method to the analysis of marine products were in consistency with those obtained by the acetylacetone spectrophotometry and the HPLC method.

  16. Structural and electrochemical studies on the utilization of Cerium (Ce3+ as an additive for nickel hydroxide electrode

    Directory of Open Access Journals (Sweden)

    Marcio Vidotti

    2007-03-01

    Full Text Available This paper describes electrochemical and spectroscopic studies on the utilization of cerium atoms as additives for nickel hydroxide electrodes. Thin films were galvanostatically grown with different amounts of cerium and mixed electrodes were studied by electrochemical measurements and the spectroscopic technique. The electrochromic behavior was investigated by “in situ” experiments , while the amount of species was determined by ICP-OES. The addition of cerium to nickel hydroxide electrodes increases durability, due to modifications in the structural properties, as seen by Raman spectras.

  17. Preparation of poly(ethylene terephthalate/layered double hydroxide nanocomposites by in-situ polymerization and their thermal property

    Directory of Open Access Journals (Sweden)

    Q. Jiao

    2012-06-01

    Full Text Available Terephthalate (TA intercalated layered double hydroxides (LDHs were synthesized using hydroxides as raw materials, and poly(ethylene terephthalate (PET/LDH nanocomposites with different contents of TA intercalated LDHs were prepared by in-situ polymerization. The structure, morphology and thermal property of PET/LDH nanocomposites were investigated. The TA intercalated LDHs were partially exfoliated and well dispersed in PET matrix. The PET/LDH nanocomposites exhibit enhanced thermal stability relative to pure PET, confirmed by the thermogravimetric analysis results. The results of differential scanning calorimetry suggest that LDH nanoparticles could effectively promote the nucleation and crystallization of PET.

  18. Development of magnesium hydroxide flame retardant%氢氧化镁阻燃剂发展概述

    Institute of Scientific and Technical Information of China (English)

    郝建文; 杨保俊

    2012-01-01

    介绍Mg(OH)2阻燃剂的优势以及阻燃抑烟机理,评述了Mg(OH)2阻燃剂的制备方法,提出了新的制备工艺以及有针对性的发展方向与建议.%The advantages and fire resistant of magnesium hydroxide flame retardant are introduced. The method for preparation of magnesium hydroxide flame retardant is also emphatically estimated. A new preparation technology as well as targeted development direction and suggestion are put forward.

  19. Preparation of Magnesium Hydroxide and Nanofiber Polymer Composites to Reduce the Flammability and Melt Dripping Behaviour of Polymers

    Directory of Open Access Journals (Sweden)

    S. S. Raza

    2014-12-01

    Full Text Available Nanoscale alumina fibers reduce the flammability and melt dripping behaviour of polymers. Magnesium hydroxide breaks the agglomerates by generating shear and iterative forces. Mixing was done with Brabender Plasticoder. The temperature and time of mixing greatly affects the mixing behaviour. At higher temperatures blow holes were observed. By increasing the mixing time agglomerates were broken to a greater extent. Different concentrations of nanofibers, Magnesium hydroxide and surface treatments are used to investigate the properties of polymer. Thermogravimetric analysis (TGA, optical microscopy and flame test was done to see the effect of different parameters on mixing and flame retardancy behaviour.

  20. Respiration of metal (hydr)oxides by Shewanella and Geobacter: a key role for multihaem c-type cytochromes

    OpenAIRE

    Shi, Liang; Squier, Thomas C.; Zachara, John M.; Fredrickson, James K.

    2007-01-01

    Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer ...