Biosorption of Pb2+ with Modified Soybean Hulls as Absorbent

Using soybean hull residue after the soluble dietary fiber being removed during the soybean processing industry as crude material, a novel absorbent, modified soybean hulls, is prepared. Its adsorption behavior for Pb2+ is studied. The adsorbent has a large and efficient adsorption capacity for Pb2+, up to 20% of the mass of dry adsorbent. Its maximum adsorption capacity for Pb2+ reaches 217 mg·g−1 at initial Pb2+ concentration of 2000 mg·L−1, which is twice that of yeast absorbent and threefold greater than that of chitosan absorbent. The adsorption ability is sensitive to pH value in the solution and the optimal pH for adsorption of Pb2+ is 7.0. In the presence of other metal ions (Ca2+, Mg2+ and Na+) in the solution, their effect on the adsorption capacity for Pb2+ is not obvious. After 5 cycles of adsorption, 80% adsorption capacity of Pb2+ is maintained. Compared with various available commercial resins, the modified soybean hulls are a plentiful, inexpensive and effective medium for the capture of dissolved Pb2+ from waste streams.