Preparation method of nanometer silicon dioxide

Abstract

The invention discloses a preparation method of nanometer silicon dioxide, which comprises the following steps of: adding lauryl sodium sulfate into ammonium fluorosilicate solution as a surfactant; introducing ammonia solution and carrying out ammoniation reaction on the ammonium fluorosilicate solution, wherein the adding quantity of ammonia is 110-150 percent of theoretical amount; reacting at a normal temperature, strictly controlling the agitating speed, the adding speed of the ammonia and the reaction time, controlling the aging time within 60-150 min, adding polypropylene solution as a filter aid and carrying out solid-liquid separation after agitation; and calcining after the silicon dioxide is precipitated, washed and dried to obtain silicon dioxide powder with a median grain size of between 38-55 nm. The preparation method has the beneficial effects that as the ammonium fluorosilicate and the ammonia are taken as raw materials to prepare the nanometer silicon dioxide, and the lauryl sodium sulfate is taken as the surfactant, the surface activity of the silicon dioxide is improved; the reaction conditions are strictly controlled to prepare a silicon dioxide product with excellent performance; and the integrity of silicon dioxide powder crystals is ensured.

Description

technical field [0001] The invention relates to the field of preparation methods of inorganic chemical materials, in particular to a preparation method of nano silicon dioxide. Background technique [0002] Silica is commonly known as white carbon black, and its molecular formula is SiO 2 , Silica is insoluble in water and acids (except hydrofluoric acid), and aggregates into fine particles after absorbing water. It can dissolve in sodium hydroxide and hydrofluoric acid when heated, and is stable to other chemicals. Silica is high temperature resistant, non-combustible, and has good electrical insulation. [0003] The production methods of silica at home and abroad are mainly divided into gas phase method and precipitation method. The gas phase method is prepared by reacting silicon tetrachloride, oxygen (or air) and hydrogen as raw materials at high temperature. The quality of the product obtained by the gas phase method is good, but the preparation process is complicat...

AI Technical Summary

Problems solved by technology

This method is simple in process, but due to the low mixing efficiency of the reactants in the conventional stirred reactor, the precipitation reaction cannot be uniformly and effectively controlled, and the product has quality problems such as coarse particles, wide particle size distribution, serious agglomeration and encapsulation, and cannot meet the requirements. High-end application requirements, low added value