New recovery system of novel metals by earth friendly polymer gel/liquid extraction method

我们成功地开发了一种利用单宁凝胶颗粒回收手机电子部件中所含金（Au）、银（Ag）和钯（Pd）的新型回收系统。单宁凝胶颗粒是通过交联天然缩合单宁分子制备的，天然缩合单宁分子是普遍存在且廉价的具有大量羟基的材料。详细研究了这些新型金属在单宁凝胶颗粒上的吸附机制，以建立聚合物凝胶/液体萃取方法。结果表明：(1)单宁凝胶颗粒对Au、Ag、Pd的吸附是通过两个步骤进行的：Au、Ag、Pd离子被单宁凝胶颗粒表面的金属还原和单宁分子的氧化。(2)金属银的最大吸附量高达930mg-Ag/(g-dry-tannin-gel)。在少量Cu离子存在下，Ag的吸附速率加快，Ag离子在Ag-Cu混合物中被选择性回收。(3)单宁凝胶对Au表现出最高的吸附容量(8000mg-Au/g-dry-tannin gel that)。(4)对于Pd，含有较少Cl的Pd物种，如PdCl^和PdCl_2，比单宁凝胶颗粒更容易吸附在单宁凝胶颗粒上。 PdCl_3^-和PdCl_4^<2->。(5)阐明了Au和Pd的分离完全取决于Au-Pd水溶液的条件。

We succeeded in developing a novel recovery system of gold(Au), silver(Ag), and palladium(Pd) contained in the electric parts of mobile phones, utilizing tannin gel particles. Tannin gel particles were prepared by cross-linking natural condensed tannin molecules which is ubiquitous and inexpensive material having a lot of hydroxyl groups. The adsorption mechanisms of those novel metals onto the tannin gel particles was investigated in detail to establish the polymer gel/liquid extraction method. The following results were obtained.(1)The adsorption of Au, Ag and Pd onto the tannin gel particles was found to take place through the two steps : the reduction of Au, Ag and Pd ions to the metals on the surface of tannin gel particles and the oxidization of tannin molecules.(2)The maximum capacity of metallic silver adsorbed was extremely high as 930mg-Ag/(g-dry-tannin-gel). The adsorption rate of Ag was accelerated in the presence of small amount of Cu ions and Ag ions were recovered selectively in Ag-Cu mixtures.(3)The tannin gel showed the most highest adsorption capacity (8000mg-Au/g-dry-tannin gel that) for Au among the previous reports.(4)As for Pd, the Pd species containing fewer Cl such as PdCl^+ and PdCl_2, were more adsorbable onto the tannin gel particles than PdCl_3^-and PdCl_4^<2->.(5)It was elucidated that the separation of Au and Pd occurred perfectly depending on the conditions of Au-Pd aqueous solution.