Preparation method of silicon dioxide molecular sieve

Abstract

The invention relates to a preparation method of a silicon dioxide molecular sieve, and belongs to the technical field of porous material preparation. The preparation method comprises the following steps: carrying out thermal treatment on silica fume, then carrying out particle classification and acid leaching treatment, filtering and cleaning; mixing the silica fume subjected to the acid leaching treatment, NaOH, a structure-directing agent and H2O in a molar ratio of SiO2 to NaOH to the structure-directing agent to H2O being 1: (0.2-0.4): (0.1-0.3): (150-200), reacting for 12-48 hours at the temperature of 90-120 DEG C, washing, filtering and drying, thus obtaining an organic-inorganic composite intermediate product; mixing the organic-inorganic composite intermediate product and water in a mass ratio being 1: (30-50), stirring, carrying out hydro-thermal treatment, washing, filtering and drying an obtained solid matter, then baking the obtained solid matter, and removing the structure-directing agent, thus obtaining the spherical mesoporous silicon dioxide molecular sieve. The preparation method has the advantages that the synthetic process and condition of the spherical mesoporous silicon dioxide molecular sieve are greatly simplified, the synthetic cost is reduced, and the prepared mesoporous material has excellent heavy metal adsorption property.

Description

technical field [0001] The invention relates to a preparation method of silica molecular sieve, which belongs to the technical field of porous material preparation. Background technique [0002] Since the scientists of Mobile Company successfully synthesized the M41S series ordered mesoporous silica material in 1992, due to its unique nano-scale ordered pores, high specific surface area and easy-to-modify surface properties, it was born in the field of nanomaterials and molecular sieves. Due to its strong adsorption capacity and large adsorption capacity, MCM-41 has high application value in the field of adsorption treatment of heavy metal ions in wastewater (such as Hg, Ag, Cr, Pb, Ba and Zn, etc.), after self-assembling 3-mercaptopropyltrimethoxysilane on the surface of mesoporous material MCM-41, it has a good adsorption effect on heavy metal ions in water. Shi Jianlin, a researcher at the Shanghai Institute of Ceramics, Chinese Academy of Sciences, found that the mesopo...

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Problems solved by technology

However, this mesoporous material has not been widely used at present, mainly because of the following problems: In order to obtain mesoporous silica molecular sieves with specific shapes, it is necessary to conduct complex and precise self-assembly systems and synthesis processes during the synthesis process. control, and requires the use of more expensive surfactants; the particle size of spherical silica mesoporous molecular sieves prepared by traditional synthesis methods is small (typical particle size range is 0.2-1 μm), which cannot meet the requirements of some fields For example, the requirement for the stationary phase in HPLC is that the particle size is not less than 5 μm, so as to ensure that it is not easy to block during use and reduce the energy consumption of fluid flow. Although non-ionic surfactants can be used to synthesize mesoporous microspheres of 3-17 μm, However, the assembly of mesoporous materials with block copolymers as templates is mostly carried out under strong acidic conditions, and silicon species tend to gel and linearly cross-link in acidic environments, resulting in the monodispersity of the prepared mesoporous microspheres. sex is not ideal

The main component of micro-silica fume is amorphous SiO2, the content is generally 80-95%, and the impurity components include Na2O, CaO, MgO, Fe2O3, Al2O3 and activated carbon. Currently, it is mainly used as an admixture in concrete, refractory materials and cement, etc. field, the industrial added value is low, and even most of the micro-silicon fume in the southwestern region is directly disposed of in landfill or discarded in the open air, resulting in waste of resources and greater environmental pressure

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