Preparation of silica sol
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I used the ion exchange method to prepare silica sol. At the beginning of my experiments, I encountered some problems and was unsure of their causes, so I’m posting them here for everyone’s feedback. Those who know the reasons could please help explain them. If there are any advancements in my experiments, I will also write down my experiences so that everyone can learn from them. Question 1: Why is the solution of sodium silicate milky and translucent rather than clear and transparent? The solution that passes through ion exchange resin is completely transparent, but it still contains some very fine suspended particles – so fine that even a 300-mesh sieve cannot filter them out. If not examined carefully, it might be mistaken for a clear and transparent solution. Is it the silica gel that has been separated out? Question 2: What are the conditions for silica sol to transform into a gel? Is it a slow stirring speed? High temperature? Question 3: What is the principle of action of stabilizers?
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First question: The solution of sodium silicate (water glass) is a colorless, transparent, viscous liquid with a specific gravity of 2.6 and a melting point of 1088°C. It decomposes when exposed to acids (it can also decompose in the presence of carbon dioxide in the air), resulting in the formation of a colloidal precipitate of silicic acid. Therefore, the milky white color is due to the absorption of CO2 from the air, which reacts to form H2SiO3 that is insoluble in water. Na2SiO3 + H2O + CO2 = Na2CO3 + H2SiO3↓ Second question: Refer to http://wenda.tianya.cn/wenda/thread?tid=3067c535616e892d for methods of converting water glass into silica sol; http://www.bokee.net/company/weblog_viewEntry/1981057.html for research on the electrolytes of colloidal batteries and their filling properties; http://www.365powernet.com/UploadFileLibrary/20080117153721.pdf for advances in the study of the properties of colloidal electrolytes; http://kecheng.edu.people.com.cn/database_type/library/g/gggg/y/ggggg1012922/wjjx_72.htm. This post was last edited by zhangyong6404 on 2009-3-26 at 17:25
What type of resin do you use? I need to work on this for my graduation project, and I’m completely confused right now. Maybe we can exchange ideas and that will help me out