巯基改性磁性介孔二氧化硅的制备及其对重金属Cd^2＋的吸附研究

Preparation of Thiohydroxy Modified Magnetic Mesoporous Silica from Rice Husk and its Removal Properties for Cd(Ⅱ)

以稻壳灰为硅源、Fe3O4为磁性材料制备磁性介孔二氧化硅(MMS);随后对其进行巯基改性制备巯基改性磁性介孔二氧化硅(TMMS),并考察了搅拌时间、反应温度、氨水添加量对TMMS表面巯基浓度的影响,研究了巯基浓度对Cd^(2+)吸附效果的影响;最后,对MMS与TMMS的结构进行表征,并通过吸附等温线对MMS与TMMS对Cd^(2+)吸附效果进行比较。结果表明:当反应时间8 h、水浴温度80℃、催化剂氨水添加量750μL时,TMMS的表面巯基浓度达到0.131mmol/g;巯基浓度越高,TMMS对Cd^(2+)的吸附效果越好;MMS与TMMS两种材料的骨架均为无定形的SiO2结构,BET多点比表面积分别为581.769 m2/g与405.665 m2/g;MMS与TMMS对Cd^(2+)的等吸附温模型更符合Langmuir模型,都属于单分子层吸附;在Langmuir模型中,TMMS的饱和吸附量为33.33 mg/g,大于MMS的饱和吸附量(21.50 mg/g)。因此,巯基改性有利于TMMS对Cd^(2+)的吸附,可达到有效脱除废水中Cd^(2+)的目的。

In this paper, magnetic mesoporous silica （MMS） was prepared by using rice husk ash as the silica source and Fe3O4 as the magnetic material, and then MMS was modified by TMMPS as the silane coupling agents. The effects of agitation time,reaction temperature and the amount of ammonia on the surface thiohydroxy concentration were investigated during the preparation process and the effect of surface thiohydroxy concentration on the adsorption capacity on Cd^2＋ was investigated during the adsorption process. At last,the end product named thiohydroxy modified magnetic mesoporous silica （TMMS） and MMS was characterized and the adsorption effect of MMS and TMMS for Cd^2＋ was compared by adsorption isotherm. It was found that when the reaction condition was 8 h at 80 ℃ and the amount of ammonia was 750 μL,the surface thiohydroxy concentration of TMMS was 0.131 mmol/g. The adsorption effect was in direct proportion to the surface thiohydroxy concentration. The BET surface area of MMS and TMMS was 581.769 m^2/g and 405.665 m^2/g respectively. The isotherm had a good correlation with Langmuir isotherm model rather than Freundlich isotherm model,which suggesting that the adsorption was monolayer adsorption. When the reaction temperature during the adsorption process was 30 ℃ ,the saturated adsorption capacity of TMMS was 33.33 rag/g, which was bigger than the value of MMS. Therefore, the purpose of effective removal of Cd^2＋ in wastewater can be achieved by modification.