Influence of aliphatic and aromatic silylating agents on hydrophobicity of RH-MCM – 41

Siriluk Chiarakorn
Division of Environmetal Technology, School of energy and materials, King Mongkut's University Technology Thonburi, Thailand 10140

*Thanita Areerob
Division of Environmetal Technology, School of energy and materials, King Mongkut's University Technology Thonburi, Thailand 10140

*Nurak Grisdanurak
Department of Chemical Engineering, Faculty of Engineering, Thammasat University (Rangsit Campus), Thailand 12120

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     Last modified: February 9, 2006

Abstract
RH-MCM-41, a mesoporous adsorbent, was successfully synthesized from rice husk silica and hexadecyltrimethylammoniumbromind (CTAB) with molar composition of 1.0SiO2: 1.1 NaOH: 0.13 CTAB: 0.12 H2O. The hydrophilic characteristic of RH-MCM-41 was due to the remaining of some silanol groups. The surface tailoring to enhance the hydrophobicity of material surface was carried out by silylation. The effects of silylating condition and silylating agents on the hydrophobicity improvement were studied. Two types of silylating agents, trimethylchlorosilane (TMCS) and phenyldimethylchlorosilane (PDMS), were used in the experiment. The chemical and physical properties of that silylated RH-MCM-41 were examined by XRD and FTIR. It was found that the degree of silylation determined based on the amount of moisture adsorbed using TGA was proportional to concentration of silylating agent. The molecular structure of silylating agent also provided a predominant effect in silylation mechanism.


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