The urea method for the direct synthesis of ZnAl layered double hydroxides with nitrate as the interlayer anion

2011 ◽  
Vol 51 (4) ◽  
pp. 452-459 ◽  
Author(s):  
Alexandra Inayat ◽  
Michael Klumpp ◽  
Wilhelm Schwieger
Keyword(s):  
Layered Double Hydroxides ◽  
Direct Synthesis ◽  
Interlayer Anion ◽  
Double Hydroxides ◽  
Urea Method

scholarly journals Nanohybrid Layered Double Hydroxides Used to Remove Several Dyes from Water

2019 ◽  
Vol 3 (2) ◽  
pp. 41 ◽  
Author(s):  
Karima Abdellaoui ◽  
Ivana Pavlovic ◽  
Cristobalina Barriga
Keyword(s):  
Layered Double Hydroxides ◽  
Wide Spectrum ◽  
Dodecylbenzene Sulfonate ◽  
Hydrophilic Nature ◽  
Interlayer Anion ◽  
Hydrophilic Character ◽  
Dyes Adsorption ◽  
Layer Double Hydroxides ◽  
Double Hydroxides

For the preparation and characterization of several layer double hydroxides (LDH) with inorganic interlayer anions (carbonate and nitrate) and nanohybrids, two organo-LDHs were studied in detail. The dodecylbenzene sulfonate (DBS) was used as an organic interlayer anion to modify the hydrophilic nature of the interlayer. The aim of the modification of the layered double hydroxides (LDH) was to change the hydrophilic character of the interlayer to hydrophobic with the purpose of improving its ability to adsorb several (anionic and cationic) dyes from water. These compounds have been used as adsorbents of amaranth (Am), diamine green B (DGB) and brilliant green (BG) dyes. Adsorption tests were conducted using variable pH values, contact times and initial dye concentrations (adsorption isotherms) to identify the optimum conditions for the intended purpose. Adsorbents and adsorption products were characterized by several physicochemical techniques. The results of the adsorption tests showed that the organo-LDH nanohybrids could be efficient adsorbents in the removal of studied dyes from water. Thus, it can be concluded that nanohybrids studied in this work might act as suitable supports in the design of adsorbents for the removal of a wide spectrum of dyes with the aim of reducing the adverse effects on water resources.

Direct Synthesis and Anion Exchange of Noncarbonate-Intercalated NiFe-Layered Double Hydroxides and the Influence on Electrocatalysis

2018 ◽  
Vol 30 (13) ◽  
pp. 4321-4330 ◽  
Author(s):  
Lianna Dang ◽  
Hanfeng Liang ◽  
Junqiao Zhuo ◽  
Brandon K. Lamb ◽  
Hongyuan Sheng ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Layered Double Hydroxides ◽  
Direct Synthesis ◽  
Double Hydroxides

The effect of interlayer anion on the reactivity of Mg–Al layered double hydroxides: Improving and extending the customization capacity of anionic clays

2011 ◽  
Vol 359 (1) ◽  
pp. 136-141 ◽  
Author(s):  
Ricardo Rojas ◽  
Felipe Bruna ◽  
Carlos P. de Pauli ◽  
M. Ángeles Ulibarri ◽  
Carla E. Giacomelli
Keyword(s):  
Layered Double Hydroxides ◽  
Anionic Clays ◽  
Interlayer Anion ◽  
Double Hydroxides

Pathways of phosphate uptake from aqueous solution by ZnAl layered double hydroxides

2013 ◽  
Vol 67 (8) ◽  
pp. 1757-1763 ◽  
Author(s):  
X. Cheng ◽  
Y. Wang ◽  
Z. Sun ◽  
D. Sun ◽  
A. Wang
Keyword(s):  
Ion Exchange ◽  
Layered Double Hydroxides ◽  
Surface Adsorption ◽  
Chloride Ion ◽  
Bulk Solution ◽  
Entire Study ◽  
Pseudo Second Order ◽  
Interlayer Anion ◽  
Acidic Conditions ◽  
Double Hydroxides

ZnAl layered double hydroxides (LDHs) were prepared by urea hydrolysis-based coprecipitation for removing phosphate from aqueous solutions. The chemical formula of the product was determined as Zn5.54Al3.02(OH)8.73(CO3)0.57Cl5.66·7.84H2O. Chloride ion was the major interlayer anion of the ZnAl LDHs. Adsorption of phosphate onto the ZnAl sorbent over the entire study period was not in close agreement with pseudo-first-order or pseudo-second-order models. The adsorption can be divided into two steps. A fast adsorption was observed during the first 10 h with a marked increase in the concentration of Cl− in the bulk solution. This indicated that the adsorption of phosphate was largely attributed to the ion exchange between phosphate and the interlayer Cl−. A second fast adsorption of phosphate occurred after 10 h. During this period, the pH increased slowly, whereas the Cl− concentration was stable. The uptake of phosphate was likely attributed to OH−–H2PO4−/HPO42− ion exchange as well as surface adsorption/complexation. Acidic conditions favored adsorption of phosphate by ZnAl LDHs, which is consistent with the pH increases during the adsorption. Coexisting anions, e.g., SO42− and CO32−, are competitive ions for the adsorption of phosphate. The results verify the contribution of ion exchange and surface adsorption/complexation in the removal of phosphate by ZnAl LDHs.

scholarly journals Investigation of layered double hydroxides type ZnMgAl-carbonate and derivates.

2014 ◽  
Vol 70 (a1) ◽  
pp. C1100-C1100
Author(s):  
Weberton do Carmo ◽  
Gustavo de Carvalho ◽  
Juliana da Silva ◽  
Luciano Chagas ◽  
Alexandre Leitão ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Mixed Oxides ◽  
Inorganic Materials ◽  
Precipitation Method ◽  
Trivalent Cation ◽  
Catalyst Precursor ◽  
Step Size ◽  
Co Precipitation ◽  
Double Hydroxides ◽  
Urea Method

Layered double hydroxides (LDHs) or hydrotalite-like compounds belong to a class of synthetic two-dimensional inorganic materials with lamellar structures, where the hydroxyl-hydrated compounds are formed by chemical substitution of divalent ion of the brucite-like octahedral layers by trivalent ions [1]. The LDH are represented by the general formula, Figure a , where M2+, M3+ are divalent and trivalent cation and Am- is interlayer anion responsible by charge balancing, the range of divalent and trivalent ions (x) varies normally between 0.17 a 0.33. According Montanari and co-works [2] compounds type ZnAl-hydrotalcites (ZnAl-HT) have relevant industrial interest; however the scientific literature concerning this material as catalysts or catalyst precursor is scarce. Based on this fact, in the present communication we will present a studied on how the variation in percentage of Zinc in a ZnMgAl-HT catalyst precursor can influence the formation of mixed oxides after calcination. The ZnMgAl-HTs, Figure b , y=5, 10,15,20,25,50,75 and 100% were prepared by co-precipitation and urea method. Mg-Zn/Al mixed oxides were prepared from calcinations of hydrotalcites precursors at 5000C for 4 hours. The material synthesized were characterized by X-ray powder diffraction, the measurements were carried out in Bruker D8 DaVinci diffractometer, equipped with CuKα radiation , LynxEye linear Position Sensitive Detector, Ni-filter. Data was collect between 8 and 800in 2θ with step size of 0.020and the count time of 0.05 per step. Soller slit 2.50of divergence and 0.2 mm primary slit were used. For the ZnMgAl-HT samples the measurements were performed at different temperatures, range 25-12000C, heating rate 50C/min. It was observed differences among XRD patterns for y greater than 25% of Zn in urea method at 5000C, and for co-precipitation method just for the substitution at 50 and 75% of Zn. These results suggested that the increase in Zn percentage change the structure of calcinated samples.

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