Synthesis of High-Quality MCM-48 Mesoporous Silica Using Gemini Surfactant Dimethylene-1,2-bis(dodecyldimethylammonium bromide)

Abstract

Using the Gemini surfactant [C12H25N+(CH3)2-(CH2)2-N+(CH3)2-C12H25]·2Br- (abbreviated as C12-2 - 12) with the short spacer group (s = 2) as structure-directing agent and sodium silicate as precursor, high-quality ordered cubic mesoporous silica (space group Ia3d) was prepared through the S+I- route (S denotes surfactant, I precursor). The samples were characterized by small-angle X-ray diffraction, transmission electron microscopy, and N2 adsorption−desorption techniques. Results showed that the pore structure of the resulting mesoporous silica belonged to the cubic structure (space group Ia3d). The high-quality cubic mesoporous structure was formed at 1:0.33 (molar ratio of sodium silicate to C12-2 - 12), 2:1 (ethyl acetate to sodium silicate), and at 30 °C. The formation conditions of MCM-48 with C12-2 - 12 were milder than those with the corresponding monovalent surfactants, such as alkyltrimethylammonium bromide. N2 adsorption−desorption curves revealed type IV isotherms and H1 hysteresis loops; Brunauer−Emmet−Teller (BET) surface areas increased with the decrease of the molar ratio of sodium silicate to C12-2 - 12 and of ethyl acetate to sodium silicate as well as of the hydrothermal temperatures.

Removal of DDT from aqueous solutions using mesoporous silica materials

“…19 -22 There are two hysteresis loops occurring in the N 2 adsorption-desorption isotherm of MCM-48, which are attributed to two kinds of mesoporous silica pores of different pore sizes. 23 This is reflected in the corresponding pore size distribution in Fig. 2.…”

Surfactant effects on the microstructures of Fe3O4 nanoparticles synthesized by microemulsion method

“…About Gemini surfactants, there have the relevant reports on the application of template synthesis of various materials, such as gold particles and organized mesoporous silica [48][49][50]. Here, a Gemini surfactant dimethylene-1,2-bis(dodecyldimethylammonium bromide), abbreviated as 12-2-12, has been devised as surfactant phase to synthesize the nanosized Fe 3 O 4 particles in water-in-oil microemulsion.…”

Synthesis, characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units

“…Furthermore, the Brunauer Emmett Teller (BET) surface area and pore volume of the MCM-48 sample are as high as 1 200 m 2 · g −1 and 1.0 cm 3 · g −1 , respectively. In contrast, the conventional MCM-48 shows the BET surface area at 1 100 m 2 · g −1 [13,14], which is lower than that of the MCM-48 sample. Figure 4 shows N 2 adsorption-desorption isotherms of the calcined MCM-48 sample, which give typical type-IV isotherms with a sharp inflection at relative pressure P/P 0 >0.5 (characteristic of capillary condensation).…”