Structural, Textural and Thermal Characterization of Nano-Mg/Al Hydrotalcite before and after Cr (VI) Removal

In this work there was studied the structural, textural and effect that has treat thermal on the removal of Cr (VI) of nanoMg/Al hydrotalcite (NHT) synthesized by the sol-gel method with a ratio of Mg/Al=3. These present the characterization of the nanoMg/Al hydrotalcite before and after Cr (VI) removal, as well as the kinetic studies and of balance. In agreement with the results, when the NHT are thermal treated to 350 °C the hydrotalcite crystalline structure remains but the textural properties are improved and structural. The NHT synthesized by the sol-gel method present a good capacity of removal with values of 91 mg of Cr (VI) removed / g of NHT. The above mentioned capacity of removal gets improved after thermal treating the material, reaching values of removal of 124 mg of Cr (VI) removed / g of NHT. The NHT with the Cr (VI) absorbed show decrease of the crystalline structure, as well as a saturation of the pores that annuls the porosity due to the fact that the Cr (VI) lodges both at the pores and at the intersheets. The time that him takes the HLM to remove the Cr (VI) of the watery solution is alone of 2 minutes, with which it is possible to conclude that the NHT have an excellent aptitude to remove Cr (VI) of watery solutions in an interval of very short time.

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Effect of the Thermal Treatment on the Capacity of Removal of Cr (VI) of Sol-Gel Hydrotalcite-like Materials

MRS Proceedings ◽

10.1557/opl.2012.120 ◽

2012 ◽

Vol 1372 ◽

Author(s):

E. Ramos ◽

N. L. Gutiérrez ◽

C. A. Contreras ◽

G. A. del Angel

Keyword(s):

Adsorption Capacity ◽

Contact Time ◽

Interlayer Space ◽

Sol Gel ◽

Textural Properties ◽

Kinetic Studies ◽

Before And After ◽

Short Time ◽

Thermally Treated

ABSTRACTIn this work the effect on the adsorption of Cr (VI) by thermally treated Hydrotalcite-like Material (HTM) synthesized by the sol-gel method with a Mg/Al = 2 was studied. The characterization of the HTM before and after Cr (VI) removal, as well as the kinetic studies were carried out. When the HTM are thermally treated at 350ºC the hydrotalcite crystalline structure remains and the textural properties improve. The Cr (VI) adsorption capacity of HTM was 125 mg of Cr (VI) / g of HTM. This capacity augments at 132 mg of Cr (VI) / g of HTM after heating HTM at 300°C. The crystallinity as well the porosity of the HTM diminished after adsorption of Cr (VI), due to the obstruction of both the pores and the interlayer space. The adsorption of Cr (VI) occurred before 4 minutes contact time. It can be concluded that HTM exhibits a high Cr (VI) adsorption capacity in a short time.

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Synthesis and Thermal Characterization of Co-Doped ZnO Nanocomposites Prepared by Sol-Gel Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.512-515.1753 ◽

2012 ◽

Vol 512-515 ◽

pp. 1753-1756

Author(s):

Zi Hua Wu ◽

Hua Qing Xie ◽

Qing Feng Zeng

Keyword(s):

Thermal Conductivity ◽

Sol Gel ◽

Thermal Characterization ◽

Sem Images ◽

Additional Absorption ◽

Spin Configuration ◽

Gel Method ◽

Sol Gel Method ◽

Tetrahedral Crystal

Polyparaphenylene/Zn0.925Co0.075O(PPP/Zn0.925Co0.075O) nanocomposites were synthesized by using a sol-gel method and their thermal conductivity properties were measured. The XRD pattern of Zn0.925Co0.075O shows the single phase wurtzite structure. The SEM images show that the lighter-contrast area is PPP and the dark-contrast area is the polycrystalline of Zn0.925Co0.075O. The increase in the band edge is a clear indication for the incorporation of Co inside the ZnO lattice. The observation of three additional absorption peaks provided evidence that the 3d7 high-spin configuration of Co2+ under the tetrahedral crystal field was probably formed by neighboring O2- ions. With the increase of the PPP content, the thermal conductivity of nanocomposite samples is smaller than those of pure Zn0.925Co0.075O. Due to the high density of interfaces and grain boundaries present in the nanocomposites, the scattering of phonon across a broad wavelength spectrum was enhanced. This suppressed the lattice thermal conductivity of the nanocomposites significantly.

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