Silica sol acid neutralization method

The acid neutralization method generally uses dilute water glass (Na2O.xSiO2) as the starting material, and inorganic acids such as dilute sulfuric acid as the acidifying agent. Depending on the amount of acid used, acidic or alkaline silica sol can be prepared. The specific process steps include ion exchange to remove sodium ions, preparation of crystal nuclei, acid neutralization reaction, and grain growth. ①Ion exchange to remove sodium ions: Use ion exchange resin to remove sodium ions in the raw material to obtain a dilute solution with a large m(SiO2):m(Na2O), and the content of sodium ions in the dilute solution is already low. ②Preparation of crystal nuclei: the dilute sol prepared in the above steps is heated and left for a period of time to gradually form nano-scale crystal nuclei in the dilute sol. ③Acid neutralization reaction: Add dilute water glass raw materials and acidifying agent continuously to the dilute sol containing crystal nuclei prepared above. During the addition process, care should be taken to control the concentration of sodium ions in the mixed solution, the heating temperature of the mixed solution, pH and the addition process. time and other reaction conditions. ④ Grain growth: The above mixed solution undergoes a grain growth process under controlled conditions. After the continuous grain growth process is completed, the finished silica sol can be obtained. Among them, the sodium salt generated by the acid neutralization reaction can be separated by adding an organic solvent to the system.