光化学分离水溶液中铂族金属元素的研究——Pd(Ⅱ)的光还原

Photochemical Separation of Platinum Group Metals in Aqueous Solution——Photoreduction of Pd(Ⅱ)

采用光化学法将Na2PdCl4水溶液中的二价钯离子(Pd(Ⅱ))还原至钯单质,通过改变照射光波长、自由基清除剂种类、Cl-浓度、pH值等参数以获得光还原Pd(Ⅱ)的最佳条件。采用紫外-可见吸收光谱(UV-vis)和X射线光电子能谱(XPS)等表征手段分别对上清液和生成的沉淀进行表征。结果表明:使用光化学法能成功地还原出水溶液中的钯离子,提取率可达98.4%;相比之下,采用异丙醇作为自由基清除剂时能更有效地提取溶液中的钯元素。高浓度的Cl-抑制Pd(Ⅱ)的还原;适当提高pH值可以促进Pd(Ⅱ)的还原。此外,还验证了从Na2PdCl4和NdCl3混合溶液中光还原并分离Pd(Ⅱ)的可行性。

In present work,the photochemical method was proposed to reduce Pd（Ⅱ）ions in Na2PdCl4 aqueous solution,and the effects of various experimental parameters including the wavelength of light,radical scavengers,concentration of Cl-and pH values were studied.The supernatant and precipitation products have been characterized by the UV-vis spectra and XPS respectively.The results indicate that Pd（Ⅱ）ions in aqueous solution can be extracted by the photoreduction method by a ratio of 98.4%,and the generation of Pd atoms is more efficient in the presence of 2-propanol than ethanol,methanol or tertiary butanol.High concentration Cl-will suppress the reduction of Pd（Ⅱ）,and high pH value can enhance the reduction of Pd（Ⅱ）.In addition,the extraction of palladium metal from themixed solution of Na2PdCl4 and NdCl3 was also demonstrated.