Preparation And Adsorption Properties Of Amino Functionalized Mesoporous Silica And Hybrid Silica Carbon Material

Mesoporous silica materials had been widely applied in adsorption due to the specific pore structure and easily-doped unstructured skeleton.The synthesis method of mesoporous silica materials usually took a long time and high cost.The silica hydroxyl made mesoporous silica charged negatively,which affected the adsorption of anionic ion.For the above problems,this paper used ultrasonic induced assembly of mesoporous silica for shorten the synthesis time,and studied the effect of ultrasonic time on the material.Mesoporous silica material was functionalized by cationic polymer EPI-DMA to improve the surface potential and dispersibility.The dichromate adsorption and the optimum conditions of amino functionalized mesoporous silica were studied.Mesoporous silica carbon materials were prepared by in-situ high temperature carbonization,and the adsorptions of chromate and methylene blue were investigated.The mesoporous materials were measured by N-,adsorption/desorption,SEM,TEM,FTIR,zeta potential and XPS.The main research and relevant conclusions were as follows:1.The ultrasonic induced mesoporous silica material was prepared to shorten the synthesis time.The effect of different ultrasonic time on the pore structure of mesoporous silica was studied.It was found that optimal ultrasonic time was 45 min for ultrasonic induced mesoporous silica material.Under this condition,the average pore diameter was 4.913 nm,the specific surface area was 1040 m2/g and the pore volume was 1.277 cm3/g.2.Amino cationic polymer reagents EPI-DMA was used to functionalized the mesoporous silica to improve the surface potential and dispersibility.The optimal functionalization conditions of mesoporous silica were EPI-DMA concentration of 15%and temperature of 25℃.The pore structure of optimal EPI-DMA functionalized mesoporous silica materials were D=3.011 nm,Sbetr=103 m2/g,Vtot =0.3341 cm3/g.The maximum adsorption capacity of SiO2@EPI-DMA was 102.7 mg/g,and improved 85 times than maximum adsorption capacity of SiO2(1.2 mg/g).From the isotherm and kinetic model studied,it was found that Langmuir was more suitable than Freundlich to fit the adsorption isotherm data.And the pseudo-second kinetic model was more suitable to fit the adsorption kinetic data.3.The mesoporous silica carbon materials were prepared by the in-situ high temperature carbonization.The effects of different washing condition on the mesoporous silica carbonmaterials were investigated.The results showed that the specific surface area and pore diameter could be improved better under alkaline condition than under washing condition.The SiCa13 was optimal material(D=7.732 nm,SBET= 446.5 m2/g,Vtot=0.9331cm3/g).By studying the adsorption isotherms and thermodynamic models of methylene blue and chromate,it was found that Langmuir was more suitable to fit the adsorption isotherm data.The maximum adsorption capacity for methylene blue and chromate were 47.62 and 153.85 mg/g,respectively.The adsorption process of chromate was endothermic,while the adsorption process of methylene blue was exothermic.