The Heterogenation Of Saccharin, Melamine And Sulfonic Acid Onto Rice Husk Ash Silica And Their Catalytic Activity In Esterification Reaction

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dc.contributor.authorMohammed Hello, Kasim
dc.date.accessioned2018-07-02T07:56:15Z
dc.date.available2018-07-02T07:56:15Z
dc.date.issued2010-12
dc.description.abstractSodium silicate from rice husk ash (RHA) was functionalized with 3– (chloropropyl)triethoxysilane (CPTES), 3–(mercaptopropyl)trimethoxysilane and 3–(aminopropyl)triethoxysilane to give RHACCl, RHAPrSH and RHAPrNH2 via a simple one–pot synthesis. The 29Si MAS NMR of RHACCl showed the presence of T2, T3, Q3 and Q4 silicon centres, while the T1, T2, T3, Q2, Q3 and Q4 silicon centres were present in both RHAPrSH and RHAPrNH2. The 13C MAS NMR showed that RHACCl had three chemical shifts at 10.37, 26.70 and 47.69 ppm, which was attributed to the three carbon atoms of the CPTES moiety. RHAPrNH2 had chemical shifts at 16.59, 32.73 and 14.58, while RHAPrSH showed only two signals at 26.13 and 47.87 ppm instead of the expected three signals. This was due to the superimposition of two signals on each other. The combination of elemental and EDX analysis showed the presence of chlorine in RHACCl, sulfur was found in RHAPrSH and nitrogen was found in RHAPrNH2 as well as the presence of carbon and silicon in the samples confirmed that the silylating agents were incorporated onto RHA silica. Saccharine (Sac) and Melamine (Mela) were immobilized onto RHACCl to form RHAC-Sac and RHAPrMela. Both 29Si MAS NMR spectra of RHAC-Sac and RHAPrMela showed similar chemical shifts to the RHACCl. The 13C MAS NMR showed that RHAC-Sac had a series of chemical shifts consistent with the presence of the aromatic and lactam ring. Two chemical shifts at 161.52 and 169.67 ppm with double spinning side bands were seen in the 13C MAS NMR of RHAPrMela, indicating that the three carbon atoms in the melamine ring were not equivalent. The functionalized –CH2–SH group in RHAPrSH was oxidized to sulfonic acid, –CH2–SO3H with hydrogen peroxide at room temperature. The 29Si MAS NMR showed similar chemical shifts to the RHAPrSH. No overlapping of the C3 and C2 chemical shifts in the 13C MAS NMR was observed after the transformation to RHAPrSO3H. RHAC-Sac, RHAPrMela, RHAPrSO3H, RHA– Blank (as control) as well as homogenous Sac and homogenous Mela were used as catalysts in the esterification reaction. The catalytic activity of the catalysts toward the respective esters was found to follow the sequence below.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/5838
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectThe heterogenation of saccharin, melamine and sulfonic aciden_US
dc.subjectonto rice husk ash silica and their catalytic activity in esterification reactionen_US
dc.titleThe Heterogenation Of Saccharin, Melamine And Sulfonic Acid Onto Rice Husk Ash Silica And Their Catalytic Activity In Esterification Reactionen_US
dc.typeThesisen_US
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