不同铁源制备磁性中空介孔硅铁复合微球及应用

Preparation and application of magnetic hollow mesoporous SiO2-FexOy microspheres from different Fe sources

采用一锅溶胶-凝胶法,以酚醛树脂为软模板、十六烷基三甲基溴化铵(CTAB)为制孔剂、四乙氧基硅烷(TEOS)为硅源,通过改变铁源制备了不同形貌的磁性中空介孔硅铁复合微球(FexOy/HMS),并考察了铁源在复合微球形成中的调控作用。利用XRD、SEM、TEM以及振动样品磁强计(VSM)分别对其晶型结构、形貌和磁性进行了表征和分析。结果表明,乙酰丙酮铁(Fe(acac)3)有助于复合微球壳层的形成,合成的复合微球更加光滑规整。对以Fe(acac)3为铁源合成的Fex Oy/HMS复合微球磁性化后进行接枝聚丙烯腈(PAN),并经聚偕胺肟(PAO)化制得FexOy/HMS接枝聚偕胺肟(FexOy/HMS-g-PAO)复合材料,其比饱和磁化强度达8.6 emu/g,可用于水中Cr(Ⅵ)的吸附与快速分离。以浓度为100 mg/L的K2Cr2O7溶液为目标溶液,pH=2时平衡吸附量达123.75 mg/g。

Magnetic hollow mesoporous SiO2-FexOy microspheres(FexOy/HMS) were prepared by changing Fe sources via one-pot sol-gel approach, with phenolic resin as soft template, cetyltrimethylammonium bromide(CTAB) as a pore-forming agent and tetraethylorthosilicate(TEOS) as the silicon source. The effect of Fe sources on the microspheres formation was investigated. The crystal structure, the morphology and the magnetic performance of FexOy/HMS was analyzed by XRD, SEM and TEM as well as vibrating sample magnetometer(VSM),respectively. The results indicate that the as prepared FexOy/HMS obtained from iron acetylacetonate(Fe(acac)3)has more perfect morphology than those from other Fe sources. Fe(acac)3 contributes to the formation of shells and improves the structural stability of the composite microspheres. The FexOy/HMS was magnetized followed by grafting polyacrylonitrile(PAN), which was transformed to polyamidoxime(PAO). The resulting magnetic composite FexOy/HMS-g-PAO, with a saturated magnetization value of 8.6 emu/g, was used in absorbing Cr(Ⅵ) ions in water.Therefore, the FexOy/HMS-g-PAO with the absorbed Cr(Ⅵ) could be separated rapidly by magnetic irons. As K2Cr2O7 solution with the concentration of 100 mg/L used as the target solution, the equilibrium adsorption capacity reaches 123.75 mg/g at pH value of 2.