A method for extracting silica from herbaceous plant capable of extracting
high purity amorphous silica from seed shell of various herbaceous plants
is provided. The method includes carbonizing a herbaceous plant and
pulverizing a carbide of the plant to a size of at least 50 mesh, adding
at least 5% (w/w) aqueous alkaline solution based on 100 weight percents
of the carbide, leaving a reactant of the solution and the carbide for 1
hour at about 45.degree. C. and filtering the reactant, slowly heating the
reactant to a predetermined temperature, dropping sulfuric acid to the
reactant at the predetermined temperature until the sulfuric acid is
neutralized, and evaporating and drying the reactant to produce silica.
