scholarly journals Synthesis of nanocomposite coating based on TiO2/ZnAl layer double hydroxides

2017 ◽  
Vol 67 (325) ◽  
pp. 112 ◽  
Author(s):  
V. Jovanov ◽  
O. Rudic ◽  
J. Ranogajec ◽  
E. Fidanchevska
Keyword(s):  
Mechanical Activation ◽  
Catalyst Support ◽  
Xrd Analysis ◽  
Nanocomposite Coating ◽  
Precipitation Method ◽  
Cleaning Efficiency ◽  
Co Precipitation ◽  
Layer Double Hydroxides ◽  
Double Hydroxides ◽  
Water Rinsing

The aim of this investigation was the synthesis of nanocomposite coatings based on Zn-Al layered double hydroxides (Zn-Al LDH) and TiO2. The Zn-Al LDH material, which acted as the catalyst support of the active TiO2 component (in the content of 3 and 10 wt. %), was synthesized by a low super saturation co-precipitation method. The interaction between the Zn-Al LDH and the active TiO2 component was accomplished by using vacuum evaporation prior to the mechanical activation and only by mechanical activation. The final suspension based on Zn-Al LDH and 10wt. % TiO2, impregnated only by mechanical activation, showed the optimal characteristics from the aspect of particle size distribution and XRD analysis. These properties had a positive effect on the functional properties of the coatings (photocatalytic activity and self-cleaning efficiency) after the water rinsing procedure.

scholarly journals Dielectric properties of Bi-substituted LDHs synthesized by co-precipitation and sol-gel methods

2019 ◽  
Vol 37 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Denis Sokol ◽  
Maksim Ivanov ◽  
Andrei N. Salak ◽  
Robertas Grigalaitis ◽  
Juras Banys ◽  
...  
Keyword(s):  
Sol Gel ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
Complexing Agent ◽  
Mixed Metal Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Double Hydroxides ◽  
Gel Processing

AbstractMagnesium-aluminum-bismuth layered double hydroxides (Mg3Al1−xBix; LDHs) were prepared using both coprecipitation and sol-gel methods. For the preparation of Mg/Al/Bi LDH by the co-precipitation method, the appropriate amounts of dissolved starting materials (Al(NO3)3 · 9H2O, Mg(NO3)2 · 6H2O and Bi(NO3)3 · 5H2O) were mixed with a solution of NaHCO3:NaOH. In the sol-gel processing, the precursor Mg–Al–Bi–O gels were synthesized using the same starting materials and ethylene glycol as complexing agent. The mixed-metal oxides obtained by subsequent heating of Mg–Al–Bi–O gels at 650 °C were reconstructed to Mg3Al1−xBix LDHs in water at 80 °C. All the synthesized products were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and dielectric measurements.

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

Materials ◽  
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.

scholarly journals Fumonisin B1 Interaction with Mg-Al and Mg-Fe Layered Double Hydroxides: Removal Efficiency and Mechanisms

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4344
Author(s):  
Jakub Matusik ◽  
Youjun Deng
Keyword(s):  
Adsorption Capacity ◽  
Removal Efficiency ◽  
Layered Double Hydroxides ◽  
Lower Layer ◽  
Fumonisin B1 ◽  
Xrd Analysis ◽  
Layer Charge ◽  
Basal Spacing ◽  
Co Precipitation ◽  
Double Hydroxides

Mycotoxins in feed and food are highly toxic and pose a serious danger even at very low concentrations. The use of bentonites in animal diet can reduce toxin bioavailability. However, some mycotoxins like fumonisin B1 (FB1) form anionic species which excludes the use of negatively charged clays. Layered double hydroxides (LDH) with anion-exchange properties, in theory, can be perfect candidates to adsorb FB1. However, fundamental research on the use of LDH for mycotoxins removal is scarce and incomplete. Thus, the presented study was designed to explore such a possibility. The LDH materials with differing chemistry and layer charge were synthesized by co-precipitation both from metal nitrates and chlorides and were then tested for FB1 removal. XRD, FTIR, XPS, and chemical analysis were used for the LDH characterization and to obtain insight into the removal mechanisms. A higher adsorption capacity was observed for the Mg/Al LDH samples (~0.08–0.15 mol/kg) in comparison to the Mg/Fe LDH samples (~0.05–0.09 mol/kg) with no difference in removal efficiency between Cl and NO3 intercalated LDH. The adsorption capacity increased along with lower layer charge of Mg/Al and was attributed to the lower content of bonded carbonates and the increase of non-polar sites which led to matching between the adsorption domains of LDH with FB1. The FTIR analysis confirmed the negative effect of carbonates which hampered the adsorption at pH 7 and led to the highest adsorption at pH 5 (FB1 content ~15.8 ± 0.75 wt.%). The fast surface adsorption (1–2 min) was dominant and XRD analysis of the basal spacing indicated that no FB1 intercalation occurred in the LDH. The XPS confirmed a strong interaction of FB1 with Mg sites of LDH at pH 5 where the interaction with FB1 carboxylate moieties COO− was confirmed. The research confirmed a high affinity and selectivity of LDH structures towards anionic forms of FB1 mycotoxin.

Enhanced catalytic phenol hydroxylation by CuZnFeAl layered double hydroxides: synergistic effects of Cu+ and oxygen vacancies

2021 ◽  
Vol 45 (1) ◽  
pp. 179-188
Author(s):  
Yong Jiang ◽  
Wenlong Xu ◽  
Jinhua Liang ◽  
Jiecan Shen ◽  
Xiaomin Fu ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Oxygen Vacancies ◽  
Synergistic Effects ◽  
Phenol Oxidation ◽  
Precipitation Method ◽  
Phenol Hydroxylation ◽  
Co Precipitation ◽  
Double Hydroxides

In this work, a series of CuZnFeAl-LDH catalysts for phenol oxidation to dihydroxybenzene have been prepared through a co-precipitation method.

scholarly journals Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates

2019 ◽  
Vol 9 (3) ◽  
pp. 598
Author(s):  
Danna Trejo-Arroyo ◽  
Karen Acosta ◽  
Julio Cruz ◽  
Ana Valenzuela-Muñiz ◽  
Ricardo Vega-Azamar ◽  
...  
Keyword(s):  
Xrd Analysis ◽  
Sem Analysis ◽  
Precipitation Method ◽  
Zro2 Nanoparticles ◽  
Microstructural Development ◽  
Cement Ratio ◽  
Cement Mortars ◽  
Crystallite Sizes ◽  
Co Precipitation ◽  
Two Stages

In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO2 additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO2 revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO2 on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates.

scholarly journals Gas-Phase Hydrogenation of Furfural to Furfuryl Alcohol over Cu-ZnO-Al2O3 Catalysts Prepared from Layered Double Hydroxides

Catalysts ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 486
Author(s):  
Guillermo R. Bertolini ◽  
Carmen P. Jiménez-Gómez ◽  
Juan Antonio Cecilia ◽  
Pedro Maireles-Torres
Keyword(s):  
Gas Phase ◽  
Aging Time ◽  
Layered Double Hydroxides ◽  
Furfuryl Alcohol ◽  
Precipitation Method ◽  
Molar Ratio ◽  
X Ray ◽  
General Chemical ◽  
Co Precipitation ◽  
Double Hydroxides

Several layered double hydroxides (LDHs) with general chemical composition (Cu,Zn)1−xAlx(OH)2(CO3)x/2·mH2O have been synthesized by the co-precipitation method, maintaining a (M2+/M3+) molar ratio of 3, and varying the Cu2+/Zn2+ molar ratio between 0.2 and 6.0. After calcination and reduction steps, Cu/ZnO/Al2O3 catalysts were synthesized. These catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), H2 thermoprogrammed reduction (H2-TPR), N2 adsorption-desorption at −196 °C, N2O titration, X-ray photoelectron miscroscopy (XPS), NH3-thermoprogramed desorption (NH3-TPD) and CO2- thermoprogrammed desorption (CO2-TPD). The characterization data revealed that these catalysts are mainly meso-and macroporous, where Cu, ZnO and Al2O3 are well dispersed. The catalytic results show that these catalysts are active in the gas-phase hydrogenation of furfural, being highly selective to furfuryl alcohol (FOL) and reaching the highest FOL yield for the catalyst with a Cu2+/Zn2+ molar ratio of 1. In an additional study, the influence of the aging time on the synthesis of the LDHs was also evaluated. The catalytic data revealed that the use of shorter aging time in the formation of the LDH has a beneficial effect on the catalytic behavior, since more disordered structures with a higher amount of available Cu sites is obtained, leading to a higher yield towards FOL (71% after 5 h of time-on-stream at 210 °C).

Effect of Doped Iron on Fluoride Sorption by Calcined MgAlFe-CO3 Layered Double Hydroxides

2013 ◽  
Vol 681 ◽  
pp. 21-25
Author(s):  
Yu Bing Pu ◽  
Jia Rui Wang ◽  
Hong Zheng ◽  
Peng Cai ◽  
Si Yuan Wu
Keyword(s):  
Layered Double Hydroxides ◽  
Synthetic Wastewater ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Fluoride Removal ◽  
Maximum Sorption Capacity ◽  
Fluoride Adsorption ◽  
Maximum Sorption ◽  
Co Precipitation ◽  
Double Hydroxides

A series of MgAlFe-CO3 layered double hydroxides (LDHs) were successfully prepared by co-precipitation method. With synthetic wastewater, the effect of doped iron on fluoride sorption by calcined MgAlFe-CO3 layered double hydroxides (CLDH) under different pH and contact time conditions was investigated. The sorption isotherm data were fitted well to Langmuir isotherm at 25 °C. The maximum sorption capacity of fluoride on CLDH increases first and then decreases with the increase of Fe/Al molar ratio and attains maximum of 71.94 mg/g when Fe/Al molar ratio is 1:2, although doped iron is unfavorable to the regeneration of original layered structure for CLDH after fluoride adsorption. No aluminium in the solution after fluoride adsorption was detected when Fe/Al molar ratio is equal to or larger than 1:2. The results indicate that CLDH with proper Fe/Al molar ratio is a promising candidate as an adsorbent material for fluoride removal from aqueous solutions.

The Preparation and Characterization of LiFe0.98Mn0.02PO4/C by Spray-Drying and Low Temperature Reduction Route

2012 ◽  
Vol 581-582 ◽  
pp. 525-528
Author(s):  
Jia Feng Zhang ◽  
Bao Zhang ◽  
Xue Yi Guo ◽  
He Zhang Chen ◽  
Jian Long Wang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Spray Drying ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Sem Images ◽  
Temperature Reduction ◽  
Co Precipitation ◽  
Low Temperature Reduction

The LiFe0.98Mn0.02PO4/C was synthesized by spray-drying and low temperature reduction route using FePO4•2H2O as precursor, which was prepared by a simple co-precipitation method. The LiFe0.98Mn0.02PO4/C sample was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and electrochemical measurements. The XRD analysis and SEM images show that sample has the good ordered structure and spherical particle. The charge-discharge tests demonstrate that the powder has the better electrochemical properties, with an initial discharge capacity of 162.1 mAh•g−1 and 155.8 mAh•g−1 at current density of 0.1 C and 1C, respectively. The capacity retention reaches 99.4% after 100 cycles at 1C.

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