Influence of functional silanes on hydrophobicity of MCM-41 synthesized from rice husk

Abstract

Mesoporous molecular sieve MCM-41 was synthesized from rice husk and rice husk ash, called RH-MCM-41 and RHA-MCM-41. The sol-gel mixtures were prepared with molar composition of 1.0 SiO 2 : 1.1 NaOH: 0.13 CTAB: 0.12 H 2 O. After calcination, the polarity of MCM-41 still remained on its surface due to the existence of some silanol groups. In this study, both RH-MCM-41 and RHA-MCM-41 were silylated with two different functional silanes trimethylchlorosilane (TMCS) and phenyldimethylchlorosilane (PDMS) in order to reduce the surface polarity. The efficiency of silylation was determined based on the amount of moisture adsorbed using thermogravimetric analysis (TGA). The structure of silylating agents and silica templates were found to be important parameters affecting the hydrophobic property of the MCM-41 surface. The post-grafting silylation with aliphatic silane can decrease the surface polarity better than that with aromatic silane, probably due to less sterric hindrance effect. Thus, the surface hydrophobicity of MCM-41 can be improved by the silylation of small molecular silane on RH-MCM-41. r

Enhancement of Gaseous BTEX Adsorption on RH-MCM-41 by Chlorosilanes

“…Rice husk obtained from rice mill was boiled in 1 MHCl at 80°C for 1 h. Then, the pretreated rice husk was washed with deionized water and then calcined in a muffle furnace at 650°C for 4 h. The extracted rice husk silica was mixed with sodium hydroxide and cetyltrimethylammonium bromide (CTAB), which was used as a cationic template, with the molar composition of 1 SiO 2 : 1.09 NaOH: 0.13 CTAB: 120 H 2 O. The pH of solution was controlled at 10 and then the solution was stirred for 48 h at room temperature under atmospheric condition (Chiarakorn et al 2007;Grisdanurak et al 2003). The white suspended solid was filtered, rinsed with ethanol and distillated water and then calcined at 550°C for 5 h. After the synthesis, the physical and chemical Chiarakorn et al (2007) and Zhao and Lu (1998).…”

“…The pH of solution was controlled at 10 and then the solution was stirred for 48 h at room temperature under atmospheric condition (Chiarakorn et al 2007;Grisdanurak et al 2003). The white suspended solid was filtered, rinsed with ethanol and distillated water and then calcined at 550°C for 5 h. After the synthesis, the physical and chemical Chiarakorn et al (2007) and Zhao and Lu (1998). The 1 g of was degassed at 200°C for 2 h and then placed in 100 mL of 5% v/v of each silane reagent.…”

“…Trimethylchlorosilane (TMCS) and phenyldimethylchlorosilane (PDMCS) were used as silane precursors and the ex-situ silylation was applied in this study. The results indicated that a small silane, like TMCS, could improve the hydrophobicity of RH-MCM-41 better than PDMS due to less steric hindrance effect (Chiarakorn et al 2007). Ketcome et al (2009) also followed our silylation technique and reported that toluene adsorption efficiency could be significantly improved by RH-MCM-41 modified with TMCS (Ketcome et al 2009).…”

“…The RH-MCM-41 is categorized as a nanoporous material containing silicate framework like honey comb. Its pore diameter is ranged between 20-30 Å and its surface area is about 700-900 m 2 g -1 (Chiarakorn et al 2007). This material has been introduced to be an alternative adsorbent for the adsorption of various air pollutants, supporting material for catalytic reaction, ion exchange media and filter (Appaturiet al 2012;Artklaet al 2009;Beck et al 1992;Chumeeet al 2009;Klankawet al 2012;Tong-On et al 2009;Wantalaet al 2010;Yoshitakeet al 2002;Zhao & Lu 1998).…”

Study on Comparison of Boiler Efficiency Using Husk and Coal as Fuel in Rice Mill

“…Partial and uneven combustion of husks in the furnaces of the boilers also would lead to smoke emissions. The disposal of partially burned husks and ash also created environmental hazards [3]. The development of compact, fluidized bed process steam boilers by the boiler manufacturers led to more efficient and environment-friendly utilization of this widely available bio-fuel resource.…”