| Research Abstract |
Egg shell membrane (ESM) protein was found to acumulate various precious metal ions (gold and platinum metals) selectively from their dilute aqueous solutions in high yield and in short contact time, depending on pH and characteristics of the individual precious metal ions. Under certain condition, the sequestering level of precious ions, Au (III), Pt(II) and Pd(II) approaches about 55,25 and 22 % of dry wt of ESM,respectively. Gold (I) potassiun cyanide was also accumulated up to 19% at pH 2.0. The presence of 100 folds (mol) of co-existing cations such as Na^+, Fe (III), Cu (II) and Ni (II) did not show a discernible effect on the precious metal uptake rate and capacity of ESM.Experiment suggested ESM is promising to use for the removal/recovery of precious metals.
ESM exhibited a certain degree ofbiosorption of all metal ions tested except Na^+ and K^+. These include Na^+, K^+, Ni^<2+>, Zn^<2+>, Fe^<2+>, Fe^<3+>, Co^<2+>, Ag^+, Hg^<2+>, Cd^<2+>, Pb^<2+>, U^<6+>, (as UO_2^<2+>), La^<3+>, Nd^<3+>, Pr^<3+>, Gd^<3+>, Ce^<3+>, Sm^<3+>, Eu^<3+>, V^<4+>, (as VO^<2+>). Hg and V ions shows the higher adsorption capacity than common transition metals. HgCl_2 shows accumulated up to 50-70mg/g ESM at low pH region. The metal ions not specified were added as sulfate, nitrate or chloride salts. The maximum uptake values for different common metalions were ranging from a few mg/g ESM (Ca^<2+>) to 13mg/g ESM (Fe^<3+>) and were dependent on pH.ESM plays very unique behavior for uranium to have the out-standingly high binding capacity : i.e..under pH 5.0 ESM has binding capacity that is at least 20% of dry wt of ESM.And the binding of uranium is completely reversible by lowering with respect to the pH at 4.0. Egg shell membrane have various positive characters that are an intricate network of stable and water-insoluble protein fibers with high surface area and is an abundant bio-resorce.
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