埃洛石原料无模板法制备高比表面积介孔氧化硅及其在亚甲基蓝吸附中的应用（英文）

Template-free Synthesis of Mesoporous Silica with High Specific Surface Area from Natural Halloysite and Its Application in Methylene Blue Adsorption

采用无模板法,以天然的矿物原料制备介孔材料是一种经济有效的制备方法。本研究利用"煅烧-沸石化-酸处理"工艺制备高比表面积的介孔氧化硅颗粒。研究发现,通过长时间的碱处理将煅烧埃洛石转化为沸石,随后通过酸处理,可制备出比表面积高达767 m^2/g的介孔氧化硅材料。该工艺机理为:850℃煅烧使埃洛石转变为无定型态的Si-O-Al网络结构,煅烧埃洛石在长时间的水热碱处理过程中转化为结晶态的LTA沸石硅铝酸钠,在随后的强酸性环境下,沸石的Al-O和Na-O成分被完全溶解,而残余的Si-O纳米碎片在酸环境中相互聚合,生成无定形态的介孔氧化硅颗粒。本实验制备的介孔氧化硅比表面积高达767 m^2/g,最可几孔径为5 nm,其亚甲基蓝平衡吸附量可达741 mg/g,表明其在污染物吸附中具有良好的应用潜力。

Avoiding the use of templates and employing natural minerals as raw materials could promote the cost-efficient preparation of mesoporous materials. This work demonstrated a template-free route to process natural halloysite into mesoporous silica with high specific surface area (SSA) up to 767 m 2 /g and pore size of about 5 nm. The halloysite was successively calcined, alkali-treated and acid-treated. The transformation of calcined halloysite into crystalline sodium aluminosilicate (zeolite LTA) by longtime alkali-treating, was found to be the key for obtaining high-SSA mesoporous silica in the final acid treatment. The optimized mesoporous silica showed a monolayer adsorp- tion capacity as high as 741 mg/g for methylene blue, suggesting its great potential in adsorption applications.