Nitrogen removal by modified zeolites coated with Zn-layered double hydroxides (Zn-LDHs) prepared at different molar ratios

2018 ◽  
Vol 87 ◽  
pp. 73-82 ◽  
Author(s):  
Ye Yuan ◽  
Xiangling Zhang ◽  
Yu Lei ◽  
Yinghe Jiang ◽  
Zhouying Xu ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Layered Double Hydroxides ◽  
Molar Ratios ◽  
Modified Zeolites ◽  
Double Hydroxides

Co-Cr bimetallic oxide derived from layered double hydroxides with high catalytic performance for chlorinated aromatics oxidation

2021 ◽  
Author(s):  
Wei Deng ◽  
Biao Gao ◽  
Ziye Jia ◽  
Dongqi Liu ◽  
Limin Guo
Keyword(s):  
Physicochemical Properties ◽  
Layered Double Hydroxides ◽  
Catalytic Performance ◽  
Chlorinated Aromatics ◽  
Molar Ratios ◽  
Double Hydroxides

Co-Cr bimetallic oxide with different Co/Cr molar ratios were prepared through a layered double hydroxides (LDHs) derived method. Their physicochemical properties together with catalytic performance for chlorinated aromatics (1, 2-dichlorobenzene...

Adsorption of Ink-Jet Inks and Anionic Dyes onto Mg-Al-NO3 Layered Double Hydroxides of Variable Mg:Al Molar Ratio

2010 ◽  
Vol 63 (1) ◽  
pp. 83 ◽  
Author(s):  
Anthony R. Auxilio ◽  
Philip C. Andrews ◽  
Peter C. Junk ◽  
Leone Spiccia
Keyword(s):  
Layered Double Hydroxides ◽  
Molar Ratio ◽  
Anionic Dyes ◽  
Type Curves ◽  
Molar Ratios ◽  
High Affinity ◽  
Ink Jet ◽  
Jet Printing ◽  
Double Hydroxides ◽  
Adsorption Desorption

Layered double hydroxides are materials that show promise as adsorbing media for ink-jet printing. In this work, layered double hydroxides with nitrate as interlayer anions and with variable Mg:Al molar ratios ranging from 2.2 to 8.1 have been synthesized at constant pH by the coprecipitation method and characterized by powder X-ray diffraction, N2 adsorption–desorption, scanning electron microscopy, and helium pycnometry techniques. The ability of these materials to adsorb ink-jet inks (BCI-Cyan, BCI-Yellow, and BCI-Magenta) and anionic dyes (CI Acid Blue 9 (AB9), CI Acid Yellow 23 (AY23), and CI Acid Red 37 (AR37)) were investigated. BCI-Yellow was found to have high affinity for material with an Mg:Al molar ratio between 2.2 and 4.0, whereas BCI-Cyan and BCI-Magenta showed a high affinity when the Mg:Al molar ratio was between 4.8 and 5.5. The adsorption isotherms for AB9, AY23, and AR37 on the material with Mg:Al molar ratios 2.2–5.5 exhibited H-type curves, indicating a very strong interaction between the adsorbate and adsorbent. Although there was no clear systematic correlation between the MgsAl molar ratio and the Cm (dye capacity) and Ka (dye affinity), the optimum Mg:Al molar ratio was 4.0, and this material has the potential to be used in Ink-Receptive Layer formulation.

Photocatalytic decolourization of methylene blue using [Zn-Al] layered double hydroxides synthesized at different molar cationic ratios

Clay Minerals ◽  
2017 ◽  
Vol 52 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Kaouther Abderrazek ◽  
Najoua Frini Srasra ◽  
Ezzeddine Srasra
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Layered Double Hydroxides ◽  
Diffuse Reflectance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Molar Ratios ◽  
Constant Ph ◽  
Double Hydroxides

Abstract[Zn-Al] layered double hydroxides (LDH) with cationic molar ratios of R = Zn/Al 1–5 were synthesized by the coprecipitation method at constant pH = 10. The samples synthesized and their derived forms obtained after calcination at 500°C and at 900°C (denoted Zn-Al-R, Zn-Al-R-500 and Zn-Al-R-900, respectively), were characterized by X-ray diffraction (XRD), inductively coupled plasmamass spectrometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy and nitrogen physisorption at −196°C. The XRD study showed: (1) the presence of accessory ZnO with the LDH in samples synthesized with R ≥ 3; and (2) the lamellar structure was destroyed at 500°C which made room for a poorly ordered ZnO phase, while calcination at 900°C yielded well crystallized ZnO and ZnAl2O4. The photocatalytic activity of the calcined and the unheated samples was evaluated for the decolourization of methylene blue. The photocatalytic activity was dependent on the cationic ratio R and on the calcination temperature. The sample Zn-Al-3 displayed maximum photocatalytic activity. Calcination at 500 and 900°C improved the photocatalytic activity of LDH synthesized at R = 1 and 2.

Preparation and Characterization of Nanocrystalline Ce-Containing Layered Double Hydroxides

2011 ◽  
Vol 239-242 ◽  
pp. 375-379 ◽  
Author(s):  
Chun Xia Chen ◽  
Yu Zhang ◽  
Han Qing Zhao ◽  
Jin Song Peng ◽  
Bin Li
Keyword(s):  
Particle Size ◽  
Reaction Temperature ◽  
Layered Double Hydroxides ◽  
Crystallization Time ◽  
Molar Ratios ◽  
Microwave Assisted ◽  
Crystallization Method ◽  
Double Hydroxides ◽  
Better Than

Ce-containing Layered Double Hydroxides (Ce-LDHs) were prepared by conventional and microwave-assisted crystallization method, which were denoted as Ce-LDHs-A and Ce-LDHs-B, respectively. The dispersibility of Ce-LDHs-B is much better than that of Ce-LDHs-A; the particles of Ce-LDHs-B with particle size ranging from 20 to 70 nm are smaller than that of Ce-LDHs-A with sizes around 50-300 nm. The effect of the cerium to aluminum molar ratios, microwave crystallization time and reaction temperature on the structure of Ce-LDHs was also investigated. The results show the excessive Ce into LDHs causes distortion of the samdwich, the damage of the LDHs structure becomes more and more serious with increasing the proportion of Ce/Al. The structure of Ce-LDHs becomes more and more perfect with the increasing of the microwave crystallization time and reaction temperature.

scholarly journals Fabrication of Zinc-Iron-Aluminum Layered Double Hydroxides with Controlled Micromorphology in a Tailored Aqueous - Organic Synthesis Medium

2020 ◽  
Vol 71 (7) ◽  
pp. 137-144
Author(s):  
Dorina Stanciulescu ◽  
Gabriela Carja ◽  
Doina Lutic
Keyword(s):  
Organic Solvent ◽  
Ethyl Acetate ◽  
Organic Synthesis ◽  
Layered Double Hydroxides ◽  
Structural Features ◽  
Environmental Cleanup ◽  
Molar Ratios ◽  
Iron Aluminum ◽  
Double Hydroxides ◽  
Synthesis Medium

Micromorphology characteristics of layered double hydroxides are important to establish their performances to act as adsorbents and catalysts/photocatalysts. Herein, we report the fabrication of ZnFeAl layered double hydroxides (LDHs) (defined by a molar ratios Zn/Fe/Al 2/0.5/0.5), in a tailored aqueous-organic synthesis medium, by using the coprecipitation method. The nature of the organic solvent (e.g.: ethanol, ethyl acetate, glycerol and toluene) was used as a controlled variable for obtaining specific morphology characteristics of ZnFeAl. XRD, FTIR, UV-Vis-DR spectroscopy and SEM microscopy have been used to characterize the structural, optical and textural features of ZnFeAl. Results show that the controlled aqueous-organic synthesis medium established important changes in the structural features and the micromorphology characteristics (e.g.: particle sizes and their interconnection patterns) of ZnFeAl, as indicated by the results of XRD and SEM analyses. The FTIR spectra revealed that most of the interlayer anions are carbonate, even though the initial salts precursors contain nitrates or sulfates anions. Furthermore, the UV-Vis-DR results underline that the band gaps of the LDH derived oxides changed in a significant manner, as a function of the nature of the organic solvent. Such that, ZnFeAl prepared in the presence of ethanol and ethyl acetate show band gap values lower than 3 eV and thus could be better activated under visible light. These results should be inspiring for fabricating layered double hydroxides with a controlled micromorphology for specific applications for environmental cleanup.

Zn-Cr Layered Double Hydroxides Composites for Methyl Orange (MO) Absorption

2018 ◽  
Vol 281 ◽  
pp. 836-841
Author(s):  
Tao Zhou ◽  
Jian Ping Ai ◽  
Wei Xiu Liao ◽  
Li Hong Cheng ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Layered Double Hydroxides ◽  
Adsorption Property ◽  
Bet Surface Area ◽  
Molar Ratio ◽  
Light Illumination ◽  
X Ray Diffraction ◽  
Anionic Dyes ◽  
Molar Ratios ◽  
Double Hydroxides

In this study, The Zn-Cr nanocomposite was synthesized using the hydrothermal method show good adsorption property. The as-prepared LDHs absorbent were characterized by Powder X-ray Diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier Transform Infrared (FT-IR), BET surface area, and simultaneously UV-visible spectrophotometer. The nanocomposites of Zn-Cr layered double hydroxides, the strong adsorptive adsorbents for anions. Zn-Cr LDHs with various Zn/Cr molar ratios for 2, 3, 4. The nanocomposites quickly adsorbed the anionic dyes such as methyl orange (MO) without the light illumination. The effects of Zn/Cr molar ratio on the adsorption performance of Zn-Cr LDHs were investigated.

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