The present invention relates, generally, to the art of incorporating hydrated metal oxide compounds into ion exchange resins to provide composites which remove various metal cations from aqueous brine solutions.
For instance, U.S. Pat. No. 4,116,856, U.S. Pat. No. 4,116,858, and U.S. Pat. No. 4,159,311 disclose preferential removal of Li.sup.+ values from brine solutions containing other metal ions, by using an anion exchange resin containing crystalline LiOH.2Al(OH).sub.3, also known as hydrous lithium aluminate. U.S. Pat. No. 4,116,857, U.S. Pat. No. 4,183,900, and U.S. Pat. No. 4,243,555 disclose preferential removal of Mg.sup.++ values from brine by using an anion exchange resin containing crystalline MgCl.sub.2.2Al(OH).sub.3.
U.S. Pat. No. 4,048,283 teaches removal of heavy metals, such as Pb, from aqueous solutions by treatment with chromate or dichromate ions under certain conditions of pH and temperature which precipitate heavy metal chromates. The chromium treating agents are in solution and are not supported on a resin.
USPTO Backgrounds
USPTO Backgrounds