Studies of Applying Functionalized Mesoporous SBA-15 in Adsorption of Pollutants in Water
Date Issued
2012
Date
2012
Author(s)
Lee, Jan-Yen
Abstract
The SBA-15 material has attracted great attention in compared with other mesoporous silica such as M41S, due to its relatively large pore diameter (5-8 nm) and better hydrothermal stability. For better molecular diffusion and mass transfer inside the pores during the applications in adsorption and catalysis, the morphology of SBA-15 is important. According to the original paper reported by Zhao et al., SBA-15 materials have fiber-like morphology and channeling pores in the micrometers length, parallel to the long axis of the fibers. The same group later synthesized SBA-15 materals with a rod-like morphology and average pore length of ca. 1-2 μm by adding salts such as KCl and NaCl. Recently, SBA-15 mesoporous silica with very short mesopore channels in the sub-micrometer scale have been synthesized. These short channeled SBA-15 materials offer great advantages in faster speed and larger capacity for adsorption of bulky molecules as well as in enzymes immobilization. To expand the applications in adsorption and catalysis, the functionalization of mesoporous silica with organic groups is important because of the inert nature of the silica surface. Two methods are commonly adapted to prepare organic functionalized SBA-15 materials: one-pot co-condensation or post-grafting method. The co-condensation method is often preferred over the post-grafting pathway because it minimizes processing steps and provides more uniform distribution of organic functionalities without blocking the entrance of the mesopores. This thesis focused on the preparations and adsorptive applications of functionalized mesoporous silica materials using co-polymer P123 as the pore-directing agent in acid condition. In the first part, the amino-functionalized SBA-15 (NH2-SBA-15) materials with different morphologies and the platelet SBA-15 with tailoring different agents are synthesized and used as adsorbents in adsorption of two different anionic dyes (acid red 73 and acid orange 12) in aqueous solutions. The adsorption behaviors of dyes are studied at different experimental conditions including morphologies of adsorbents, pH of solution, the effect of organic functional groups and the content of amino-functional groups on SBA-15 framework. The kinetic parameters are further calculated on amino-functionalized fibrous materials.
Many industries such as textiles, mining, painting, electroplating, plumbing,
Fertilizer, and battery manufacturing are charge their wastewater with various heavy metals such as Pb (II) and Cu (II) into the environment causing serious pollution problems and threatening people’s health. Therefore, removal of these heavy metals from industrial wastewater has been causing more and more attentions. In the second part, amino, thiol and other Schiff base-type groups were incorporated onto the SBA-15 network. Schiff base ligands are known as efficient chelating agent for many metals, easily prepared by condensation between aldehydes and amines. These functionalized SBA-15 materials were used as an adsorbent to investigate the behaviors in removing Cu2+ and Pb2+ from aqueous solutions. The hard and soft acids and bases (HSAB) theory was used to explain the experimental result.
Subjects
platelet-SBA-15；morphology of SBA-15；organic-functionalized-SBA-15；adsorption of acid dye；adsorption of copper and lead ions
Type
thesis
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