Patent ID: 8137651

Claim:
A method for preparing an aerogel whose surface has permanent hydrophobicity comprising the steps of: A) adding a water glass to 0.5-2N HCl at room temperature until the pH of solution is adjusted to 3 to 4; B) forming a silica gel by adding 1.5-10% by weight of a non-ionic surfactant to the resulting solution in step A), based on the total weight of the finally prepared silica powder in step F), and by adding water glass so that the solution is under an acidic condition of pH 4-6; C) washing the formed silica gel with distilled water and filtering the washed silica gel; D) adding a mixture solvent of 1-40% by weight of n-pentanol and 99-60% by weight of n-butanol to the filtered silica gel and further adding a silylizing agent; E) putting the mixture solution of the step D) into a reactor, separating the solvent and moisture while maintaining a pressure level of 200 to 30 mmHg at a temperature of 45 to 60° C. in the reactor, and then removing the moisture and refluxing the solvent again, followed by repeating the refluxing until the moisture is completely removed from the silica gel; and F) closing a reflux line when the moisture is removed from the silica gel, and drying the solvent from the silica gel until the silica gel is prepared in powder form.