BROMURO DE HEXADECILTRIMETILAMONIO PDF

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PDF | In this work, ordered mesoporous silica MCM was prepared by hydrothermal como fuente de sílice, bromuro de hexadeciltrimetilamonio ( CTAB). como fuente de sílice, bromuro de hexadeciltrimetilamonio (CTAB) como surfactante y acetato de etilo como regulador de pH. Se estudió la influencia de la. bromuro de hexadeciltrimetilamonio para adsorber diferentes pdf. Cordovez, M.V.; Miranda, M.R.;Ríos, S.M. and Sosai, G.R. ().


Bromuro De Hexadeciltrimetilamonio Pdf

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su superficie externa con bromuro de hexadeciltrimetilamonio (HDMTA-Br). Se seleccionó un tamaño de grano para realizar experimentos de cinética y. Cloruro de dimetiloctadecil[3-(trimetoxisilil)propil]amonio (DMOTPAC) y 2 para bromuro de hexadeciltrimetilamonio-. Polietilenglicol (CTAB-PEG). Hexadecyltrimethylammonium bromide for molecular biology, ≥99%. SDS. Product Information Sheet (PDF) · Specification Sheet (PDF) · RAMAN FTIR (PDF ).

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However, this result indicates that ordered structure MCM silica can be obtained using relative low hydrothermal temperature and it would be an advantage in the large-scale production of hexagonal mesoporous MCM silica [18] and then further experiments were carried out at 80 C Fig.

The MCM samples synthesized in a range from 0. Both, decreasing or increasing out of this range resulted in a decrease of the pore mesostructure ordering due to the disturbing of the assembly on MCM structure during process of synthesis. In addition, the peaks of the planes and attributed to the 2D hexagonal structure of MCM silica are more defined.

This behavior could be attributed to a thicker pore wall as can be seen in the values of Table 2. This behavior is due to the increase in the surfactant concentration cause prohibition of unit cell growth and decrease in polymerization of silica resulting in poor hexagonal ordered MCM silica.

Influence of ethyl acetate hydrolysis reaction time Intensity a. This figure shows the formation of MCM in all cases. However, when hydrolysis reaction time is increased the pore structure ordering decreases. This behavior is detected by a clear reduction of the intensity of the reflection peaks and This indicated that the pore structure of the sample become more ordered when the ethyl acetate hydrolysis is carried out for 3 h.

The reason that ethyl acetate affected the pore structure ordering was that ethyl acetate is a good co-solvent for CTAB and when hydrolysis time increases more ethanol and acetic acid are generated and they could destroy the micellar template and make the pore structure less ordered.

Thus, the mixtures prepared at higher hydrolysis reaction time have a lower final ph. Effect of co-surfactant It is well-known that use of co-surfactants in the synthesis of mesoporous materials affects important material properties, such as pore diameter, mesostructure order and phase behavior [20]. For this reason, some co-surfactants were proved in order to know how they affect the mesostructure of the MCM- 41 silica.

From this figure, it can be seen that wellordered mesoporous MCM silica was obtained with i-proh. In this case, typical three diffraction peaks were observed for the planes , , and On the other hand, sample Intensity a. Intensity a. BuOH i-propoh Fig.

This behavior could be explained because when increasing the number of carbon atoms in the chain of co-surfactant the extent of condensation decrease. Thus, the higher condensation rates the better ordered mesoporous silica.

This can be attributed to an increase of the amphiphilic bilayer thickness of the surfactant phase when alcohol chain length increase [20].

Dependence of reaction time Mesoporous MCM silica was prepared at different intervals of time between 48 and h to explore the optimum reaction synthesis time. The XRD patterns are showed in Figure 5. The samples synthesized at 72 and h showed the three characteristic diffraction peaks of the hexagonal-ordered silica MCM while the sample obtained at 48 hours showed Intensity a.

The shifting might be associated with a bigger mesopore size [22]. After the addition of silica source, facilitation of hydrolysis and condensation of Na 2 SiO 3 with longer stirring results in higher-ordered structure MCM silica.

It is interesting to note that no mesophases are formed during aging process as other authors have reported previously [21, 23, 24].

On the other hand, Mendonza et al. In our case, a longer reaction time permits to obtain higher ordered mesostructure MCM silica without degradation. Both samples showed nitrogen adsorption-desorption isotherms typically of type IV with H1 hysteresis loop [25]. Samples exhibited pronounced steep condensation step for relative pressures arising from condensation of nitrogen inside the mesopores and indicating good structural order of MCM This result is in agreement with XRD results described in section 2.

Also, MCMmesoporous molecular sieves exhibited narrow pore size distribution pore sizes from 2 to 3 nm. All these properties make them an attractive molecular sieve for application, such as, catalysis, sorption of organic molecules, chromatographic separations, etc.

The first one, showed a well-defined spherical morphology with particle size range from to nm whereas the other sample exhibited an irregular morphology without defined form and smaller particle size.

Deionized water was obtained from a system of two ionic interchange columns Cole-Parmer Instruments. Preparation of mesoporous MCM silica In a typical procedure, a desired amount of CTAB was mixed with 7 ml of 2-propanol i-proh and ml of deionized water until total dissolution, separately, 3 g of Na 2 SiO 3 solution were dissolved in 33 ml of deionized water and then both solutions were cooled at 4 C.

Subsequently, the resulting mixture was sonicated during 2 h and then 10 ml of ethyl acetate were added, and the solution was sonicated during 5 min again. This solution was kept at 30 C under magnetic stirring during 5 h in order to promote hydrolysis of ethyl acetate. Finally, the solution was kept at 80 C for 72 h. The solid obtained was separated by filtration and washing with deionized water and dried at room temperature. Finally, nitrogen adsorptiondesorption measurements were obtained using a Quantachrome Autosorb-1 analyzer.

For this case, MCM silica samples were first degassed for several h at C. The measurements were carried out a C. Influence of ethyl acetate hydrolysis reaction time Intensity a.

This figure shows the formation of MCM in all cases. However, when hydrolysis reaction time is increased the pore structure ordering decreases. This behavior is detected by a clear reduction of the intensity of the reflection peaks and This indicated that the pore structure of the sample become more ordered when the ethyl acetate hydrolysis is carried out for 3 h.

The reason that ethyl acetate affected the pore structure ordering was that ethyl acetate is a good co-solvent for CTAB and when hydrolysis time increases more ethanol and acetic acid are generated and they could destroy the micellar template and make the pore structure less ordered.

Thus, the mixtures prepared at higher hydrolysis reaction time have a lower final ph. Effect of co-surfactant It is well-known that use of co-surfactants in the synthesis of mesoporous materials affects important material properties, such as pore diameter, mesostructure order and phase behavior [20]. For this reason, some co-surfactants were proved in order to know how they affect the mesostructure of the MCM- 41 silica.

From this figure, it can be seen that wellordered mesoporous MCM silica was obtained with i-proh. In this case, typical three diffraction peaks were observed for the planes , , and On the other hand, sample Intensity a.

Intensity a. BuOH i-propoh Fig. This behavior could be explained because when increasing the number of carbon atoms in the chain of co-surfactant the extent of condensation decrease.

Thus, the higher condensation rates the better ordered mesoporous silica.

This can be attributed to an increase of the amphiphilic bilayer thickness of the surfactant phase when alcohol chain length increase [20]. Dependence of reaction time Mesoporous MCM silica was prepared at different intervals of time between 48 and h to explore the optimum reaction synthesis time. The XRD patterns are showed in Figure 5. The samples synthesized at 72 and h showed the three characteristic diffraction peaks of the hexagonal-ordered silica MCM while the sample obtained at 48 hours showed Intensity a.

The shifting might be associated with a bigger mesopore size [22]. After the addition of silica source, facilitation of hydrolysis and condensation of Na 2 SiO 3 with longer stirring results in higher-ordered structure MCM silica. It is interesting to note that no mesophases are formed during aging process as other authors have reported previously [21, 23, 24]. On the other hand, Mendonza et al.

In our case, a longer reaction time permits to obtain higher ordered mesostructure MCM silica without degradation. Both samples showed nitrogen adsorption-desorption isotherms typically of type IV with H1 hysteresis loop [25]. Samples exhibited pronounced steep condensation step for relative pressures arising from condensation of nitrogen inside the mesopores and indicating good structural order of MCM This result is in agreement with XRD results described in section 2. Also, MCMmesoporous molecular sieves exhibited narrow pore size distribution pore sizes from 2 to 3 nm.

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All these properties make them an attractive molecular sieve for application, such as, catalysis, sorption of organic molecules, chromatographic separations, etc. The first one, showed a well-defined spherical morphology with particle size range from to nm whereas the other sample exhibited an irregular morphology without defined form and smaller particle size. Deionized water was obtained from a system of two ionic interchange columns Cole-Parmer Instruments.

Preparation of mesoporous MCM silica In a typical procedure, a desired amount of CTAB was mixed with 7 ml of 2-propanol i-proh and ml of deionized water until total dissolution, separately, 3 g of Na 2 SiO 3 solution were dissolved in 33 ml of deionized water and then both solutions were cooled at 4 C. Subsequently, the resulting mixture was sonicated during 2 h and then 10 ml of ethyl acetate were added, and the solution was sonicated during 5 min again.

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This solution was kept at 30 C under magnetic stirring during 5 h in order to promote hydrolysis of ethyl acetate. Finally, the solution was kept at 80 C for 72 h. The solid obtained was separated by filtration and washing with deionized water and dried at room temperature. Finally, nitrogen adsorptiondesorption measurements were obtained using a Quantachrome Autosorb-1 analyzer.

For this case, MCM silica samples were first degassed for several h at C. The measurements were carried out a C. The specific surface area and pore size distribution were determined by the BJH method.

Conclusions Ordered mesoporous MCM silica was obtained hydrothermally under the reaction conditions reported in this work without formation of mesophases during aging process. Also, a short ethyl acetate hydrolysis reaction time 3 h is preferred to obtain high quality MCM silica. Mesoporous silica MCM synthesized under these reaction conditions showed a well-ordered hexagonal array with spherical morphology and particle sizes of to nm.

Mesoporous silica MCM could have potential applications in drug delivery systems, catalysis and sorption of organic molecules due to the high specific surface area. Cepeda and H.The solid obtained was separated by filtration and washing with deionized water and dried at room temperature. The homogeneity of the pores, high surface area, and good thermal stability, which make them an attractive molecular sieve for applications in catalysis, sorption of large organic molecules, chromatographic separations, as well as host for quantum confinement of guest molecules [6].

However, this result indicates that ordered structure MCM silica can be obtained using relative low hydrothermal temperature and it would be an advantage in the large-scale production of hexagonal mesoporous MCM silica [18] and then further experiments were carried out at 80 C Fig. Current Science, 9 , Kresge, C.

Conclusions Ordered mesoporous MCM silica was obtained hydrothermally under the reaction conditions reported in this work without formation of mesophases during aging process.

Fungi cell wall composition is highly diverse; therefore optimizing RNA extraction procedures is necessary when studying specific organisms. Molecular Research Center Technical Bulletin, 10, CTAB, due to its relatively high cost, is typically only used in select cosmetics. Conclusions Ordered mesoporous MCM silica was obtained hydrothermally under the reaction conditions reported in this work without formation of mesophases during aging process.

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