Recovery of valuable metals and removal of toxic metalions by natural clelate egg shell memblane

研究发现，蛋壳膜蛋白（ESM）可以根据不同的pH值和不同的贵金属离子的特性，在较短的接触时间内，以较高的收率选择性地从其稀水溶液中积累各种贵金属离子（金和铂金属）。在一定条件下，贵金属离子Au （III）、Pt（II）和Pd（II）的固载水平分别接近ESM干质量的55%、25%和22%左右。在pH 2.0条件下，金(I)氰化钾的富集量也高达19%。100倍（mol）的共存阳离子Na^+、Fe （III）、Cu （II）和Ni （II）的存在对ESM的贵金属吸收速率和容量没有明显的影响。实验表明，ESM有望用于贵金属的去除/回收。ESM对除Na^+和K^+外的所有金属离子均有一定程度的生物吸附。这些包括Na ^ +, K ^ +,倪^ < 2 + >,锌^ < 2 + >,Fe ^ < 2 + >, Fe ^ < 3 + >,公司^ < 2 + >,Ag) ^ +, Hg ^ < 2 + >, Cd ^ < 2 + >, Pb ^ < 2 + >, U ^ < 6 + >, (UO_2 ^ < 2 + >),拉^ < 3 + > Nd ^ < 3 + >,公关^ < 3 + >,Gd ^ < 3 + >, Ce ^ < 3 + >, Sm ^ < 3 + >,欧盟^ < 3 + >,V ^ < 4 + >,(如签证官^ < 2 + >)。Hg和V离子的吸附能力高于普通过渡金属。HgCl_2在低pH区累积ESM达50 ~ 70mg/g。未指定的金属离子以硫酸盐、硝酸盐或氯化物盐的形式加入。不同常见金属离子的最大吸收值从几mg/g ESM （Ca^<2+>）到13mg/g ESM (Fe^<3+>)，并依赖于pH值。ESM对铀具有非常高的结合能力具有非常独特的行为：即，在pH 5.0下，ESM的结合能力至少是干重量ESM的20%。铀的结合是完全可逆的因为pH值在4.0时降低了。蛋壳膜具有多种积极的特性，是一个由高表面积的稳定不溶于水的蛋白质纤维组成的复杂网络，是一种丰富的生物资源。

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.