Preparation of hydrophobic silica aerogel with kaolin dried at ambient pressure

• A new method for preparing hydrophobic silica aerogel with kaolin as raw material is proposed.
• The method uses the abundant clay kaolin as raw material.
• The method lowers the cost of silica aerogel compared to using organosilane as raw material.
• The concentration of HCl solution affects greatly the pore structure of aerogel with an optimal value of 4 mol/L.
• Hydrophobic modification of aerogel optimizes its pore structure.

A method for preparing hydrophobic silica aerogel with kaolin as raw material and dried at ambient pressure is proposed. The process of preparing the aerogel consists of three stages including activation of kaolin, preparation of wet silica gel and hydrophobic modification. The effects of hydrochloric acid concentration on the physical properties and structures of the silica aerogel are investigated. Effects of removing Na+ from the solvent solution on the structure and properties of aerogel are discussed. The aerogel obtained with kaolin has comparable structure and property to those prepared with other more expensive silica sources. The newly proposed method is expected to simplify the manufacturing technique, to shorten the production time and to reduce the costs of silica aerogel.

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