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Hydrotalcite-like Compounds (hydrotalcite-like + compound)

Distribution by Scientific Domains

Chemistry	85%

Selected Abstracts

Lactate Biosensor Based on Hydrotalcite-Like Compounds: Performances and Application to Serum Samples

ELECTROANALYSIS, Issue 22 2009
Irene Carpani
Abstract A lactate biosensor based on lactate oxidase supported onto a hydrotalcite, electrochemically deposited on a platinum surface, was developed for the first time. For the best electrode configuration, a linear response up to 0.8,mM, with a limit of detection of 14,,M and a sensitivity of 91,mA M,1,cm,2, was obtained. The influence of some interferents due to the oxidation of hydrogen peroxide (at +0.35,V vs. SCE) was also studied. By controlling carefully the experimental conditions, the determination of lactate in a commercial serum sample in the presence of interferents was successfully accomplished. [source]

Evaluation of Intrinsic Ionization and Complexation Constants of TiO2 and Mg-Fe Hydrotalcite-like Compounds

CHINESE JOURNAL OF CHEMISTRY, Issue 10 2006
Wan-Guo Hou
Abstract The intrinsic surface reaction constants, pKinta1, pKinta2, p*KintC and p*KintA, were evaluated by a modified double extrapolation (MDE) for TiO2 without structural charge and Mg-Fe hydrotalcite-like compounds (HTlc) with structural charge, respectively. The results of intrinsic surface reaction constants for TiO2 were compared with those obtained by class double extrapolation (CDE) in literature. Furthermore, the values of intrinsic surface reaction constants obtained by MDE were used to simulate the charging behaviors of the materials. The following conclusions were obtained. For TiO2 without structural charge, the pKinta1 and pKinta2 evaluated by MDE are equal to those by CDE, however the p*KintC and p*KintA evaluated by MDE are much different from those by CDE. In principle, the results of the p*KintC and p*KintA evaluated by MDE are more accurate than those by CDE. The values of intrinsic surface reaction constants obtained by MDE can excellently simulate the charging curves for TiO2 with the triple layer model (TLM). For HTlc with positive structural charge, the results of *KintC=0 and *KintA,, were obtained by MDE, which means the inert electrolyte chemical binding does not exist; the point of zero net charge (PZNC) of c -independence also exist as the same as solid without structural charge, and the pHPZNC obtained by the acid-base titration can excellently be simulated and the surface charging tendency can be simulated to a great extent using the pKinta1 and pKinta2 evaluated by MDE and the diffuse layer model (DLM). [source]

Synthetic hydrotalcites from different routes and their application as catalysts and gas adsorbents: a review

APPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2009
M. R. Othman
Abstract In this paper, widely accepted methods of hydrotalcite preparation such as co-precipitation, urea hydrolysis, hydrothermal, sol,gel, microwave irradiation, steam activation and solvothermal have been selected and reviewed. Our review indicates that the nature of the divalent cations, the synthesis method, the calcination temperature and the nature of the interlayer species are determinant factors in shaping the surface properties of the layered double hydoxides. The basic strength of the surface base site and structural changes produced in the mixed oxides can be adjusted conveniently by varying the Al content during the synthesis. The combination of sol,gel with microwave irradiation during the gelling and crystallization steps has also been found to increase the surface area of the hydrotalcite-like compound. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Novel Multi-functional Mixed-oxide Catalysts for Effective NOx Capture, Decomposition, and Reduction,

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2007
J. Yu
Abstract In this paper, novel multi-functional mixed-oxide catalysts have been rationally designed and developed for the effective abatement of NOx. CaxCo3,,,xAl hydrotalcite-like compounds (where x,=,0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0) are first synthesized by co-precipitation and calcined at 800,°C for 4,h in air to derive the mixed oxides. The resultant mixed oxides are generally of spinel phase, where the CaO phase is segregated when x,,,2.5. It has subsequently been found that the derived oxides are catalytically multi-functional for NOx decomposition, capture, and reduction. For example, the mixed Ca2Co1Al1 -oxide can decompose 55,% NO at 300,°C in 8,% oxygen, completely trap NO for 750,s, and capture 12.88,and 18.06,mg,g,1 NO within 30,and 60,min, respectively. The catalytic activities of the Ca2Co1Al1 -oxide catalyst have been further improved by incorporating La to form a quaternary catalyst Ca2Co1La0.1Al0.9 -oxide. This catalyst significantly enhances the NO decomposition to 75,%, extends the complete trapping time to 1100,s, and captures more NO at 300,°C in 8,% O2 (19.02,mg,g,1 NO within 60,min). The in-situ IR spectra of the catalysts with adsorbed NO indicates that the major nitrogen species formed on the catalysts are various kinds of nitrites and nitrates, which can be readily reduced by H2 within 6,min at 350,°C. Therefore, the excellent catalytic activity of layered double hydroxide (LDH)-based mixed oxides for NO decomposition, storage, and reduction can be achieved by the elegant combination of normal transition metals. [source]

High-performance HTLcs-derived CuZnAl catalysts for hydrogen production via methanol steam reforming

AICHE JOURNAL, Issue 5 2009
Ying Tang
Abstract A series of CuZnAl oxide-composite catalysts were prepared via decomposition of CuZnAl hydrotalcite-like compounds (HTLcs). The catalysts derived from CuZnAl HTLcs (Cu: 37%, Zn: 15%, Al: 48% mol; using metal nitrate or acetate precursors) at 600°C provided excellent activity and stability for the methanol steam reforming. CuZnAl HTLcs were almost decomposed completely at 600°C to form highly dispersed CuO with large specific surface area while forming CuAl2O4 spinel that played a key role in separating and stabilizing the nano-sized Cu and ZnO during the reaction. The CuZnAl catalyst prepared from metal acetates could highly convert H2O/MeOH (1.3/1, mol/mol) mixture into hydrogen with only ,0.05% CO at 250°C or ,0.005% at 210°C. It is evidenced that the former afforded stronger Cu-ZnO interaction, which might be the intrinsic reason for the significant promotion of catalyst selectivity. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Controlled-release of Avermectin from Organically Modified Hydrotalcite-like Compound Nanohybrids

CHINESE JOURNAL OF CHEMISTRY, Issue 3 2009
Depeng QIU
Abstract The intercalation of avermectin (AVM) into sodium dodecyl sulfate (SDS) modified hydrotalcite-like compounds (HTlc) was carried out using an evaporating solvent enhanced intercalation method to obtain AVM-SDS-HTlc nanohybrids. It was found that the nanohybrids could well control the release of avermectin, showing the nanohybrids are a potential pesticide controlled-release formulation. The release of avermectin from AVM-SDS-HTlc nanohybrids is dependent on the pH, temperature and the presence of electrolyte in release medium. Acidic medium and higher temperature and the presence of electrolytes may induce the higher release rate of avermectin. The release process of avermectin from AVM-SDS-HTlc nanohybrids can be described by pseudo-first-order release kinetics, and the activation energy of release is 279 kJ/mol. [source]