Synthesis Of Amidoxime-functionalized KIT-6、SBA-15 And Their Adsorption Performance Of Uranyl Ions In Aqueous Phase

Because of their high surface area, uniform pore size distribution and ordered mesoscale arrangement, mesoporous materials have been widely used in the field of adsorption. Amidoxime groups possess high uranyl selectivities. To graft the amidoxime group onto the surface of the mesoporous silica materials, makes full use of the advantages of mesoporous materials and amidoxime group selectivity for the adsorption of uranyl ions, that can be complementary in its adsorption function. The more details are as follows:Mesoporous silica materials SBA-15 with hexagonal mesostructure, cyano-functionalized SBA-15 was synthetized by co-condensation method, while amidoxime-functionalized SBA-15 (AN-SBA-15) is prepared by a subsequent oximation reaction. Two mesoporous silica SBA-15 and AN-SBA-15 are comparatively studied to investigate their adsorption properties for uranyl. The adsorption results revealed that the maximum adsorption capacity of SBA-15 is 100.2 mg/g and the maximum adsorption capacity of AN-SBA-15 is 149.0 mg/g.Mesoporous silica materials KIT-6 with cubic mesostructure, cyano-functionalized KIT-6 was synthetized by co-condensation method, while amidoxime-functionalized KIT-6 (AN-KIT-6) was prepared by a subsequent oximation reaction.The characterized results revealed that with the addition of siloxane increased the ordered mesopore arrangement was decreased, the surface area of materials are 484.710-706.526 m2/g and pore size are 4.15-4.55 nm, the pore volume are 0.5027-0.8487 cm~3/g. The experiment is studied to investigate their adsorption properties for uranium. The adsorption results reveaedl that the maximum adsorption capacity of AN-KIT-6 is 176.6 mg/g.Two mesoporous silica with different structure were comparatively studied to investigate their adsorption properties for uranyl ions. KIT-6 with cubic mesostructure has better adsorption performance on uranyl ions than SBA-15 with hexagonal mesostructure. The adsorption behavior of two kinds of mesoporous silicas is followed Freundlich model; adsorption kinetic is simulated by pseudo-first order and pseudo-second order equations, related regression analysis results indicated both pseudo-first order and pseudo-second order equations were fitted to describe adsorption process. Desorption results reveaedl that two mesoporous silica could be recycled and reused several times.