Hydrophobic silica gel is a kind of highly active inorganic silica adsorption material, which is insoluble in water and any solvent, non-toxic, tasteless, stable in chemical properties, and does not react with other substances except strong alkali and acid. Compared with activated carbon adsorbent, it has the characteristics of low adsorption heat, stable chemical properties, safety and environmental protection, high mechanical strength and long service life.