Surface Properties of Al-Functionalized Mesoporous MCM-41 and the Melting Behavior of Water in Al-MCM-41 Nanopores

Abstract

We report an experimental investigation of structural and adhesive properties for Al-containing mesoporous MCM-41 and MCM-41 surfaces. In this work, highly ordered hexagonal mesoporous structures of aluminosilica with two different Si/Al molar ratios equal to 50 and 80 and silica samples were studied; Al was incorporated into the MCM-41 structures using the direct synthesis method, with CTAB as a surfactant. The incorporation of aluminum was evidenced simultaneously without any change in the hexagonal arrangement of cylindrical mesopores. The porous materials were examined by techniques such as low-temperature nitrogen sorption, energy-dispersive spectroscopy, and scanning and transmission electron microscopy. Surface properties were determined through X-ray photoelectron spectroscopy, potentiometric titration, and static contact angle measurements. It was shown that an increase in surface acidity leads to an increase in the wetting energy of the surface. To investigate the influence of acidity on the confinement effects, the melting behavior of water in Al-MCM-41 and MCM-41 with the same pore size was determined by using dielectric relaxation spectroscopy and differential scanning calorimetry methods. We found that the melting-point depression of water in pores is larger in the functionalized pores than in pure silica pores of the same pore diameter.

Amine‐impregnated silica zeolite from microalgae ash at different calcination temperatures for CO 2 capture

“…According to Figure 5B, it was found that the pore size was arranged from 3 to 10 nm, also indicating mesoporous materials. Similar results were found in previous literature 29,32,51 . Although similar pore structures were shown, according to the adsorption amount, the order of porosity and specific surface area from high to low was MCM41‐450, MCM41‐500, MCM41‐550, and MCM41‐600.…”

“…Similar results were found in previous literature. 29,32,51 Although similar pore structures were shown, according to the adsorption amount, the order of porosity and specific surface area from high to low was MCM41-450, MCM41-500, MCM41-550, and MCM41-600. It was obvious that with the increase in the calcination temperature, the porosity reduced and the specific surface area decreased.…”

A novel BMSN (biologically synthesized mesoporous silica nanoparticles) material: synthesis using a bacteria-mediated biosurfactant and characterization

“…of the Si 2p 3/2 orbital at 600 °C (102.03 eV) was smaller than that at 550 °C due to less interaction of Si 2p 3/2 with oxygen, where the B.E. of the O 1s orbital was detected 531.26, 531.42, 531.57, and 531.47 eV at calcination temperatures of 450 °C, 500 °C, 550 °C, and 600 °C, respectively, which indicated the coupling of silicon with oxygen to generate SiO 4 4− by Si–O linkage, and this result is comparable with the findings of Sterczyńska et al 37 Likewise, the B.E. of oxygen (O 1s) are intense peaks ( Fig.…”

“…The major peaks of the BMSN particles were observed as Si 2p 3/2 , C 1s and O 1s atoms (Fig. 1d-g temperatures of 450 C, 500 C, 550 C, and 600 C, respectively, which indicated the coupling of silicon with oxygen to generate SiO 4 4À by Si-O linkage, and this result is comparable with the ndings of Sterczyńska et al 37 Likewise, the B.E. of oxygen (O 1s) are intense peaks (Fig.…”

Al-MCM-41 Synthesized from Kaolin via Hydrothermal Route: Structural Characterization and Use as an Efficient Adsorbent of Methylene Blue

“…3,10 The traditional synthesis of this type of ordered mesoporous materials is based on the hydrothermal route that uses an organic source of silica, e.g., tetraethyl orthosilicate (TEOS) and a surfactant, which plays the role of the structure directing agent, and that must be removed after the silica condensation so that the mesopores become available. [11][12][13][14] Such reagents are usually expensive and the MCM-41 materials built with pure-silica are of limited use for some applications, because of the lack of acid sites and poor ion-exchange capacity. 15 Several studies have been devoted to the search of cheaper raw materials that could overcome the high costs associated with the synthesis of MCM-41.…”