Preparation Of Monolith Silica And Preliminary Study On Oil-absorption Performance

Monolith silica is a novel class of monolithic porous materials with a three-dimensional network structure，and the morphology depended on the appearance ofthe mold. The macropores, mesopores and micropores exist in the monolith silicarelying on the preparation process. In the monolith silica, the presence of varioustypes of pores facilitate rapid mass transfer and reduce the back pressure. Theframeworks endow the mechanical strength to the column of monolith silica to acertain degree. Furthermore, a variety of functional groups can be modified andanchored in the pore surface, which makes it show a perfect application inchromatographic separations. In recent years, monolith silica has been explorativeresearched in catalyst field. However, the usual organosilicon source limited itsapplication in industry due to the more expensive price and complicated preparationprocess. Therefore, exploring the cheap sodium silicate instead of organosilicon forpreparing silica monolith and studying a simple drying way to keep cylindermorphology are of practical significance.In this thesis, we used tetraethylorthosilicate (TEOS) and sodium silicate assilica source through the sol-gel method and synthesized the monolith silicarespectively. In our synthetic system, acetic acid was used as catalyst andpolyethylene glycol(PEG) was used to induce phase separation. Meanwhile, weinvestigated the influence factors on the pore structure and morphology of products,such as water bath temperature, polyethylene glycol content, pH, water content anddry conditions. The results showed that the optimum reaction conditions inTEOS-PEG system was TEOS:PEG:H2O:CH3COOH=1:0.09:1.90:0.26at313K for24h. While the Na2SiO3-PEG system mass ratio was N2SiO3:PEG:H2O:CH3COOH=1:0.10:1.67:1.40, at323K for18h. Used the scanning electron microscopy, theresults suggested the as-synthesized monolithic silica had continuous pore structure.The XRD diffraction showed the frameworks was composed of the amorphous silica.Thermal gravimetric analysis showed the loss in weight of the material at different temperatures, and PEG can be effectively removed by calcined at823K.At last, monolith silica was modified by C18, and then used to measure theoil-absorption performance. We contrast the differences between the syntheticmaterials and silica gel on oil-absorption properties. The preliminary experimentresults supported that monolithic silica can adsorb and clean oil film on the watersurface. Contact angle measurement of the two systems products with oil dropletsshowed the contact angle were30°, which indicated that silica monolith wasinfiltrated with oil. The preliminary oil-absorption performance experiment resultssuggested that monolith silica modified by C18can effectively absorb the oil film onthe water surface.