笼形聚偕胺肟树脂的研究──Pd(Ⅱ)在碱式树脂上的吸附动力学

Studies on the "cage" polyamidoxime adsorbents─kinetics of adsorption of Pd (Ⅱ) on alkaline resin

研究了碱式笼形聚偕胺树脂（BCAO）吸附Pd（Ⅱ）的行为．溶液pH值对吸附容量有重要的影响．在一定条件下，BCAO在中性溶液中吸附Pd（Ⅱ）的量是酸性溶液中的一倍以上，但提高溶液的酸性有利于从稀溶液中回收钯．Pd（Ⅱ）在盐酸溶液中显H_2PdCI_4结构．吸附结果生成AO－Pd络合物．当溶液被碱中和至近中性时，Pd（Ⅱ）以Pd^(2+)和[Pd（OH）_2CI_2]2-的形式存在，吸附过程中先后生成AO－Pd，AO-Pd_2和AO_2－Pd_3先等不同组成的给合物．由于AO与Pd（Ⅲ）之间较大的电位差，部分Pd（Ⅱ）被还原成Pd（0），并汇聚在BCAO表面上．

Adsorption behaviors of alkaline 'cage' polyamidoxime adsorbeht (BCAO) for Pd (Ⅱ ) uptake were investigated. The adsorption capacity is affected greatly by the hydrogen ion concentration in solution. Under the given conditions adsorption capacity of BCAO for Pd (Ⅱ) in neutral solution is twice as in acidic solution. However, increase of acidity favors to recover of Pd(Ⅱ ) in dilute solution. In acidic medium, Pd (Ⅱ ) is presented as H_2PdCl_4 and forms AO-Pd complex with an amidoxime group. When the solution is became to neutralization, Pd(Ⅱ ) appear8 in the forms as Pd2+ and [Pd (OH)_2Cl_2]2-, which react with BCAO to yield the complexes with varied compo8itions.Finally, a part of Pd (Ⅱ ) is reduced by amisoxime groups owing to the potential difference. The products accumlate and adhere on the surface of BCAO.