Formation of functionalized mesoporous silicas and factors affecting adsorption of heavy metal from aqueous solution

• Main Authors: Ling-Chu Lin, 林玲珠
• Other Authors: Jiunn-Fwu Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/67818115143132410521

博士 === 國立中央大學 === 環境工程研究所 === 101 === Mesoporous materials lack for uniform pore-size distribution, ordered pore structure, and high surface area. Meosporous materials are also less selectivity toward heavy metal adsorption. This study described the effective synthesis of mesoporous materials by altering different synthesis parameters. Subsequently, the synthesized mesoporous materials were functionalized under different controlling factors, such as water effect, solvent effect, different functional groups and concentration of functional group to enhance the adsorption capacity toward metal ions such as Hg2+ and Ag+. In the same time, the effects of changing pore size, surface area, and morphology of the mesoporous material were also evaluated in this studied. The before and after functionalized mesoporous materials were characterized by TGA, EA, BET, SEM, FT-IR, and 13C NMR to verify the effect of the controlling factors on the functionalized mesoporous material. The C9 and C16 had surface area of 981.62 m2/g and 1013.28 m2/g; pore size of 2.43nm and 3.18nm, respectively. The BET isotherms curve for the unmodified samples were typical type IV. The BET isotherms curve for functionalized samples, which might be caused by blocking pore channel, had been changed to type II. The characteristic FT-IR, and 13C NMR results showed that the functional group had been grafted to the surface of mesoporous successfully. The most important controlling factors for grafting density were pore size and water effect. The EA results showed that the amount of functional group grafted to the surface of mesoporous material were relatively high. The average density was 2.0 mmol SH/g, and C9-SAnC sample had the highest grafting amount (11.37%, 3.55mmol SH/g). The Freundlich model better described the unmodied samples adsorption behavior. However, the adsorption behaviors of the functionalized samples were better delineated by Langmuir model. The pseudo second order fitted the Ag+ adsorption kinetic model better. The adsorption experiments results showed that the C16-SHC had the highest Hg2+ adsorption capacity of 126.58 mg/g (0.63mmol/g). The C16-SHC had the highest Hg2+/S molar ratio of 0.62. The C16-SAnC came in second of 0.44. The factors influence the adsorption capacity the most were solvent effect, and pore size. The average Ag+ adsorption capacity was 1.0 mmol/g. The C16-SHT had the highest adsorption capacity of 250.00 mg/g (2.32mmol/g). The C9-LHT had the lowest adsorption capacity 71.94 mg/g (0.67 mmol/g). The results were higher than those of other researchers’. The adsorption capacity of functionalized mesoporous materials under all control factors were enhanced by two orders. This study developed the synthesis and functionalization method with high affinity toward adsorbing heavy metal successfully. The functionalized mesoporous material can be reused as bacteria inhibitor after adsorbing Hg2+ and Ag+ ions.