The Collaborative International Dictionary of English v.0.48:

Depurate \Dep"u*rate\, v. t. [imp. & p. p. Depurated; p. pr. &
   vb. n. Depurating.]
   To free from impurities, heterogeneous matter, or feculence;
   to purify; to cleanse.
   [1913 Webster]

         To depurate the mass of blood.           --Boyle.
   [1913 Webster]