Application of ultrasound and methanol for rapid removal of surfactant from MCM-41

Ultrasound waves have been successfully applied for removing template from the mesoporous MCM-41 molecular sieve. The method uses a 28 KHz ultrasound irradiation in a methanol solvent for disrupting micellar aggregation of the surfactant molecules, cetyltrimethylammonium bromide, which have filled the pores of the as-synthesized MCM-41. In 15 min sonication at moderate temperature of 40 °C, a majority of surfactant molecules are removed out from powder MCM-41. The template removal rate using ultrasound irradiation (15 min) is faster than the rate via thermal calcination and a perfect hexagonal pore structure was obtained after the template removal using ultrasound irradiation, according to the characterization using the X-ray diffraction (XRD), and nitrogen adsorption analyses, while high temperatures in calcination will cause shrinkage which is affected on the surface properties of materials. In this procedure, the surfactant molecules are released into methanol and can be recovered for reuse. The effectiveness of the sonicated prepared MCM-41 as an adsorbent has been confirmed using the adsorption reaction with Methylene Blue (MB)

An energy-efficient route to the rapid synthesis of organically-modified SBA-15 via ultrasonic template removal

A low energy route for the removal of Pluronic P123 surfactant template during the synthesis of SBA-15 mesoporous silicas is explored. The conventional reflux of the hybrid inorganic–organic intermediate formed during co-condensation routes to Pr-SO3H-SBA-15 is slow, utilises large solvent volumes, and requires 24 h to remove [similar]90% of the organic template. In contrast, room temperature ultrasonication in a small methanol volume achieves the same degree of template extraction in only 5 min, with a 99.9% energy saving and 90% solvent reduction, without compromising the textural, acidic or catalytic properties of the resultant Pr-SO3H-SBA-15

Effect of the degree of template removal from mesoporous silicate materials on their adsorption of heavy oil from aqueous solution

The key aim of this study is to evaluate the adsorption of heavy oil from aqueous solutions with different oil contents over mesoporous silicate materials having different surfactant template contents. The mesoporous silicate materials have been synthesized from tetraethylorthosilicate as a silica precursor and cetyltrimethylammonium bromide as a template using the sol-gel technique. Four samples were prepared by (1) totally removing the template using the calcination process, (2) partially removing the template via ethanol extraction, (3) partially removing the template via water extraction, and (4) keeping the template as synthesized, respectively. These four samples have been characterized using X-ray diffraction, nitrogen adsorption, thermal gravimetric analysis and Fourier transformed infrared. The effect of the degree of template removal of these mesoporous materials for the oil removal has been investigated. The oil removal is inversely proportional to the surfactant content in the mesoporous material, being highest for the calcined sample but lowest for the as-synthesized sample. The kinetic of oil adsorption over the calcined material has been also studied and the data obtained fit well a second-order model