Zn-M-CO3 Layered Double Hydroxides (M=Fe, Cr, or Al): Synthesis, Characterization, and Removal of Aqueous Indigo Carmine

In this approach, Zn-M+3 layered double hydroxides (LDHs) with M+3 = Fe, Cr, or Al were synthesized by the co-precipitation method from the aqueous solution at a constant solution pH. The as-synthesized samples were characterized by XRD analysis, FTIR spectra, BET techniques and simultaneous thermogravimetric-differential scanning calorimetry (TGA/DSC). XRD analysis showed that Zn-Fe-CO3 had the greatest lattices parameters. BET surface area of Zn-Fe-CO3 was calculated as 52.24 m2.g-1 and was higher than Zn-Cr-CO3 and Zn-Al-CO3 with 46.70 and 49.99 m2.g-1, respectively. The FTIR spectra clearly confirmed the presence of carbonate anions in the structure of the LDHs. Adsorption experiments for Indigo Carmine (IC), as the main model organic pollutant in this study from aqueous solution onto synthetized samples were carried out in terms of solution pH, contact time and initial dye concentration. Experimental results indicate that the capacity of dye uptake augmented rapidly within the first 15, 40, and 55 minuts for Zn-Fe-CO3, Zn-Cr-CO3 and Zn-Al-CO3 respectively and then stayed practically the same regardless of the concentration. Adsorption kinetics studies revealed that the adsorption process followed pseudo-second order kinetics model instead of a pseudo-first-order model. The adsorption isotherm data follow the Langmuir equation in which parameters are calculated. The maximum Langmuir monolayer adsorption capacities were 94.87, 21.79, and 66.71 mg.g-1, respectively, for Zn-Fe-CO3, Zn-Cr-CO3, and Zn-Al-CO3. The adsorption capacities were slightly influenced by the pH variations from 5 to 10, showing the advantage of using these materials in water treatments in a wide pH range. Finally, the IC removal is proven by the presence of IC functional groups in IR spectra and thermograms. TGA/DSC of Zn-Fe-CO3 obtained after removal of IC indicate that the LDHs stabilizes IC and delays the combustion of adsorbed molecules. Copyright © 2020 BCREC Group. All rights reserved

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Uptake of chloride ion from aqueous solution by calcined layered double hydroxides: Equilibrium and kinetic studies

Water Research ◽

10.1016/j.watres.2005.11.043 ◽

2006 ◽

Vol 40 (4) ◽

pp. 735-743 ◽

Cited By ~ 145

Author(s):

Liang Lv ◽

Jing He ◽

Min Wei ◽

D.G. Evans ◽

Xue Duan

Keyword(s):

Aqueous Solution ◽

Layered Double Hydroxides ◽

Chloride Ion ◽

Kinetic Studies ◽

Double Hydroxides

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Mixed Oxide Layered Double Hydroxide Materials: Synthesis, Characterization and Efficient Application for Mn2+ Removal from Synthetic Wastewater

Materials ◽

10.3390/ma13184089 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4089

Author(s):

Cristina Modrogan ◽

Simona Cǎprǎrescu ◽

Annette Madelene Dǎncilǎ ◽

Oanamari Daniela Orbuleț ◽

Eugeniu Vasile ◽

...

Keyword(s):

Adsorption Capacity ◽

Layered Double Hydroxides ◽

Synthetic Wastewater ◽

Precipitation Method ◽

Metallic Ions ◽

Materials Synthesis ◽

Experimental Conditions ◽

Edx Analysis ◽

Co Precipitation ◽

Double Hydroxides

Magnesium–aluminum (Mg-Al) and magnesium–aluminum–nickel (Mg-Al-Ni) layered double hydroxides (LDHs) were synthesized by the co-precipitation method. The adsorption process of Mn2+ from synthetic wastewater was investigated. Formation of the layered double hydroxides and adsorption of Mn2+ on both Mg-Al and Mg-Ni-Al LDHs were observed by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometry (EDX) analysis. XRD patterns for prepared LDHs presented sharp and symmetrical peaks. SEM studies revealed that Mg-Al LDH and Mg-Al-Ni LDH exhibit a non-porous structure. EDX analysis showed that the prepared LDHs present uniformly spread elements. The adsorption equilibrium on these LDHs was investigated at different experimental conditions such as: Shaking time, initial Mn2+ concentration, and temperatures (10 and 20 °C). The parameters were controlled and optimized to remove the Mn2+ from synthetic wastewater. Adsorption isotherms of Mn2+ were fitted by Langmuir and Freundlich models. The obtained results indicated that the isotherm data fitted better into the Freundlich model than the Langmuir model. Adsorption capacity of Mn2+ gradually increased with temperature. The Langmuir constant (KL) value of Mg-Al LDH (0.9529 ± 0.007 L/mg) was higher than Mg-Al-Ni LDH (0.1819 ± 0.004 L/mg), at 20 °C. The final adsorption capacity was higher for Mg-Al LDH (91.85 ± 0.087%) in comparison with Mg-Al-Ni LDH (35.97 ± 0.093%), at 20 °C. It was found that the adsorption kinetics is best described by the pseudo-second-order model. The results indicated that LDHs can be considered as a potential material for adsorption of other metallic ions from wastewater.

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