An oxygen scavenging agent and compositions capable of providing good oxygen absorption capabilities which contain said agent, wherein the agent is a modified anionic hydrotalcite particulate material.

Oxygen scavenging hydrotalcite and compositions containing same

Magnesium–aluminum layered double hydroxide containing polysulfide anions was prepared by a hydrothermal reaction from magnesium and aluminum hydroxides. Thioacetamide was used as the sulfide sourc...

Easily Oxidizable Polysulfide Anion Occluded in the Interlayer Space of Mg/Al Layered Double Hydroxide

Novel Ca–Al–Zn layered double hydroxide (LDH) was synthesized by co-precipitation method and its calcined product (calcined Ca–Al–Zn LDH) was obtained by heating at 450°C for 4.0 h. The calcined and uncalcined products of Ca–Al–Zn LDHs were used as adsorbents to remove copper ions from aqueous solutions. The structure, composition, and morphology of the synthesized calcined and uncalcined products were approved by X-ray diffraction, FT-IR, N2 adsorption–desorption isotherm, and scanning electron microscopy. The removal capacities of calcined layered double hydroxide are higher than that of uncalcined LDH at ambient temperature, different pH, constant shaking rate 160 rpm, and different copper/adsorbent ratios. According to the analytical results and the experimental data, we were successful to prepare a novel LDH adsorbent for the Cu(II) removal, where the removal of the copper ions reached a maximum value at pH 6.0, shaking, 160 rpm, adsorbent mass 0.25 g/l and after 120 min to be 15.4 and 20.5 m...

Copper ions removal from aqueous solutions by novel Ca–Al–Zn layered double hydroxides

Intercalation of naphthalene-2,6-disulfonate between layers of Mg and Al double hydroxide: preparation, powder X-Ray diffraction, fourier transform infrared spectra and X-Ray photoelectron spectra

Difficulties related to handling gases are a common bottleneck for applications. Although solid materials that release gas molecules under external stimuli exist, they require an external energy or a device for reliable operation. Herein, we report a CO2 stimulus for controlled release of p.p.m.-level functional gases from solid materials. A CO2-preferential anion-exchange property of layered double hydroxides and redox reactions in gas molecules are combined to release various gases (including H2S and NO) under ambient air from HS− and NO2−-incorporated layered double hydroxides, respectively. The profiles of gas release are mainly governed by the difference of pKa between H2CO3 and resulting acids (formed through protonation of interlayer anions), and are not so susceptible to the variation of relative humidity in air. Moreover, structural modulation of solid materials enables fine control of the gas release profiles. The use of safe, ubiquitous, and nearly constant (~400 p.p.m. in atmosphere) CO2 stimulus offers broad applications for functional gases. Solid materials releasing gas molecules under external stimuli usually require external energy for reliable operation. Here the authors synthesize layered double hydroxides for the autonomous release of H2S and NO gases in response to CO2-stimulus.

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Controlled release of H2S and NO gases through CO2-stimulated anion exchange.

Anion exchanged hydrotalcites have been characterized by means of X-ray, thermal and infrared spectroscopic methods. The sample has been treated in the solution containing various anions such as S 2− , SO 4 2− , SO 3 2− , HSO 3 − , S 2 O 3 2− , S 2 O 4 2− , S 2 O 5 2− , SCN − . The dehydration temperature of structural OH as well as the CO 3 remarkably shifts from 400 to 480°C in the samples exchanged with anions such as SO 4 2− , HSO 3 2− , S 2 O 5 2− , which suggests the presence of some interactions between the anions and the structural OH. All the sulfur atoms exchanged are retained in the temperature up to 980°C. Infrared spectroscopic and thermogravimetric data show that the exchanged SO 4 occupy the site of CO 3

Hideaki Kuwabara

Papers

Characterization of anion exchanged hydrotalcite and determination of the site of exchanged so4 group