The formation of Fe colloids and layered double hydroxides as sequestration agents in the natural remediation of mine drainage

Calcined layered double hydroxides (LDHs) can be used to remove Sb(V), in the Sb(OH)6− form, from aqueous solutions. Sorption batch experiments showed that the mixed MgAlFe oxides, obtained from calcined hydrotalcite-like compound (3HT-cal), removed Sb(OH)6− through the formation of a non-LDH brandholzite-like compound, whereas the mixed ZnAl oxides, resulting from calcined zaccagnaite-like compound (2ZC-cal), trapped Sb(OH)6− in the interlayer during the formation of a Sb(V)-bearing LDH (the zincalstibite-like compound). The competition effect of coexistent anions on Sb(OH)6− removal was HAsO42− >> HCO3− ≥ SO42− for 2ZC-cal and HAsO42− >> HCO3− >> SO42− for 3HT-cal. Considering the importance of assessing the practical use of calcined LDHs, batch experiments were also carried out with a slag drainage affected by serious Sb(V) pollution (Sb = 9900 μg/L) sampled at the abandoned Su Suergiu mine (Sardinia, Italy). Results showed that, due to the complex chemical composition of the slag drainage, dissolved Sb(OH)6− was removed by intercalation in the interlayer of carbonate LDHs rather than through the formation of brandholzite-like or zincalstibite-like compounds. Both 2ZC-cal and 3HT-cal efficiently removed very high percentages (up to 90–99%) of Sb(V) from the Su Suergiu mine drainage, and thus can have a potential application for real polluted waters.

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EFFICIENT REMOVAL OF ANIONIC DYE POLLUTANT BY NIMGAL LAYERED DOUBLE HYDROXIDES OF VARIABLE COMPOSITION

Catalysis in Green Chemistry and Engineering ◽

10.1615/catalgreenchemeng.2018028634 ◽

2018 ◽

Vol 1 (4) ◽

pp. 307-323

Author(s):

Dipshikha Bharali ◽

Pankaj Bharali ◽

Ramesh Ch. Deka

Keyword(s):

Layered Double Hydroxides ◽

Variable Composition ◽

Efficient Removal ◽

Anionic Dye ◽

Double Hydroxides

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Acceptorless amine dehydrogenation and transamination using Pd-doped layered double hydroxides

10.26434/chemrxiv.6998204.v2 ◽

2018 ◽

Author(s):

Diana Ainembabazi ◽

Nan An ◽

Jinesh Manayil ◽

Kare Wilson ◽

Adam Lee ◽

...

Keyword(s):

Layered Double Hydroxides ◽

Oxidation States ◽

Secondary Amines ◽

Primary Amines ◽

Acid Dissolution ◽

Oxidative Amination ◽

Strong Function ◽

Excellent Activity ◽

High Yields ◽

Double Hydroxides

<div> <p>The synthesis, characterization, and activity of Pd-doped layered double hydroxides (Pd-LDHs) for for acceptorless amine dehydrogenation is reported. These multifunctional catalysts comprise Brønsted basic and Lewis acidic surface sites that stabilize Pd species in 0, 2+, and 4+ oxidation states. Pd speciation and corresponding cataytic performance is a strong function of metal loading. Excellent activity is observed for the oxidative transamination of primary amines and acceptorless dehydrogenation of secondary amines to secondary imines using a low Pd loading (0.5 mol%), without the need for oxidants. N-heterocycles, such as indoline, 1,2,3,4-tetrahydroquinoline, and piperidine, are dehydrogenated to the corresponding aromatics with high yields. The relative yields of secondary imines are proportional to the calculated free energy of reaction, while yields for oxidative amination correlate with the electrophilicity of primary imine intermediates. Reversible amine dehydrogenation and imine hydrogenation determine the relative imine:amine selectivity. Poisoning tests evidence that Pd-LDHs operate heterogeneously, with negligible metal leaching; catalysts can be regenerated by acid dissolution and re-precipitation.</p> </div> <br>

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Carbonate Form of Mg,Al-Layered Double Hydroxides for Concentrating Eu(III) and Its Subsequent Analytical Determination in Natural Aqueous Media

Journal of Water Chemistry and Technology ◽

10.3103/s1063455x20050094 ◽

2020 ◽

Vol 42 (5) ◽

pp. 365-372

Author(s):

G. N. Pshinko ◽

L. N. Puzyrnaya ◽

V. S. Shunkov ◽

B. P. Yatsik

Keyword(s):

Layered Double Hydroxides ◽

Aqueous Media ◽

Analytical Determination ◽

Double Hydroxides

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Antibiotic-anionic Clay Matrix Used for Drug Controlled Release

Revista de Chimie ◽

10.37358/rc.18.2.6098 ◽

2018 ◽

Vol 69 (2) ◽

pp. 321-323

Author(s):

Georgeta Zegan ◽

Elena Mihaela Carausu ◽

Loredana Golovcencu ◽

Alina Sodor Botezatu ◽

Eduard Radu Cernei ◽

...

Keyword(s):

Controlled Release ◽

Layered Double Hydroxides ◽

Bioactive Molecules ◽

Drug Controlled Release ◽

Anionic Clays ◽

Anionic Clay ◽

Toxicological Studies ◽

High Efficient ◽

Clay Matrix ◽

Double Hydroxides

Anionic clay matrix acting as drug controlled release system have shown in last years a great potential for delivery of bioactive molecules and chemical therapeutics. This organic-inorganic nanohybrid system is high efficient offering an excellent protection of intercalated compounds from degradation. Compared to other nanoparticles used in medical area, anionic clays type layered double hydroxides have found to be biocompatible according to toxicological studies. Ampicillin containing MgAlLDHs and ZnAlLDH samples have been prepared following two routes: anion-exchange procedure and reconstruction from calcined layered double hydroxides. Solid samples have been characterized by FTIR and SEM-EDX highlighting the alteration of pristine LDHs structure when the antibiotic is introduced in the interlayer gallery.

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