The crystalline properties of synthesized alumina (γ-Al2O3) are s

The crystalline properties of synthesized alumina (γ-Al2O3) are shown by the XRD pattern in Fig. 2. The XRD spectra presents Epacadostat cell line three main peaks placed at d-spacings of 0.239, 0.197, and 0.140 nm, corresponding respectively to

the d311, d400, d440 reflections of γ-Al2O3 [11], [12] and [13]. However, several other metastable aluminum oxides, so-called transition aluminas (such as κ, γ, δ, η and θ) show similar XRD traces, which make phase identification more difficult [3] and [16]. Fortunately, there are unique values of tetrahedral to octahedral Al ratios that can be utilized for confirming the XRD characteristics of alumina phases [3] and [16]. For this reason 27Al MAS NMR has been used to observe the structural transformations

produced by thermal heating. The 27Al MAS NMR spectrum of the sample calcined at 650 °C is shown in Fig. 3. In the spectrum two signals at 5.5 and 74.5 ppm were identified, which can be related to the octahedrally coordinated AlO6 and the tetrahedrally coordinated AlO4 sites in the alumina matrix, respectively. Penta-coordinated alumina often associated to the presence of amorphous alumina phase is absent. The ratio of tetrahedral to octahedral Al is about 1:3, which is characteristic of γ-Al2O3 phase [3], [10], [11], [12], [13], [14], [15], [16], [17] and [18]. Both the XRD patterns and 27Al MAS NMR spectrum seem to indicate that the formation of alumina using metal alkoxide takes place according to the following reaction scheme: Al(OR)3+2H2O→AlOOH+3ROHAl(OR)3+2H2O→AlOOH+3ROH Thiazovivin purchase 2AlOOH→600°CAl2O3+H2O It is also important to mention that the thermal dehydration of boehmite (AlOOH) can afford

γ, η, δ, or θ phases, depending on the conditions of dehydration, the particle size and degree of crystallinity of the starting boehmite [1] and [11]. For this reason, it is important to perform a thermogravimetric analysis of the sample to evaluate the dehydration process of boehmite. Fig. 4(A–C) shows the TG curves of the pine rosin (A), the sample dried at 80 °C (B) and pure Elongation factor 2 kinase boehmite (C), respectively. Boehmite was synthesized in absence of the extract, for purpose of comparison. The TG curve of rosin showed a total weight loss of 93%. A continuous loss up to about 250 °C was followed by a sharp step at this temperature and a second less intense at 530 °C. This could be attributed to the slow elimination of the water in the crystals, and the stepwise pyrolysis of the rosin. For the boehmite sample, two-step weight loss was observed due to dehydroxylation process. Three steps of weight loss were detected for as-synthesized sample, being thermally stable up to 300 °C, while no changes were evident above 450 °C. The region between 25 °C and 150 °C indicates the desorption of physisorbed water (zone I) [10], [11] and [12]. Weight loss in the range of temperature 150–300 °C (zone II) could be attributed to the decomposition of organic components [10], [11] and [12].

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