Use of rice milling byproducts (hulls & bran) to remove metal ions from aqueous solution

Rice milling byproducts (hulls and bran) were evaluated for their ability to adsorb metal ions from aqueous solution. Hulls adsorbed low levels (13–27%) of Cr(III), Co(II), Cu(II), Ni(II) and Zn(II) at 100 mg/L metal ion concentration. Several different bran samples, both full‐fat and defatted, were evaluated. A defatted, extrusion stabilized bran was found to have a high adsorption capacity for Cr(III), Cu(II) and Zn(II), but a much lower adsorption capacity for Co(II) and Ni(II). The maximum adsorption capacity of this bran for Cr (III) compared favorably to the total exchange capacity of a commercial resin specifically used to remove transition metals (Zn, Cu, etc.) from aqueous solution.