氨基膦酸改性硅胶吸附分离铂和钯

采用化学接枝法合成了氨基膦酸改性硅胶吸附剂，考察了其对溶液中铂（Pt）和钯（Pd）的吸附分离性能，测试了溶液pH值、吸附时间、初始金属离子浓度、离子强度和固液比对吸附的影响，并考察了改性硅胶吸附剂的重复使用性能。改性硅胶吸附剂对Pt和Pd的吸附主要受溶液pH值影响，而离子强度和固液比对吸附的影响不大。吸附过程符合准二级吸附动力学模型和Langmuir等温吸附方程。改性硅胶吸附剂180 min时，pH=2时对Pt的平衡吸附容量为18.5 mg/g，pH=6时对Pd的平衡吸附容量为29.9 mg/g，利用改性硅胶吸附剂不同pH值条件下的吸附行为差异可分离回收溶液中的Pt和Pd。用5 mL 0.1 mol/L HNO₃为基质的6%硫脲溶液可实现Pt和Pd的解吸，解吸率分别为99.3%和99.2%。所合成的氨基膦酸硅胶吸附材料可回收重复使用。

Sorption and Separation of Platinum and Palladium from Aqueous Solution by Aminophosphonic Acid Functionalized Silica

Aminophosphonic acid functionalized silica synthesized by chemical grafting method was utilized as the sorbent for separation of platinum (Pt)and palladium (Pd) from aqueous solution.The effects of pH,contact time,initial metal concentration, ionic strength and solid-liquid ratio on the sorption of Pt and Pd by functionalized silica were investigated.The sorption capacity is strongly dependent on pH but independent on the ionic strength and solid-liquid ratio.The sorption process fits the pseudo-second-order kinetic model and Langmuir isotherm very well.Equilibrium sorption capacities of 18.5 mg/g for Pt at pH=2 and 29.9 mg/g for Pd at pH=6 are achieved respectively. The distinct sorption behavior of functionalized silica for Pt and Pd with pH can be used for separation of these two metal ions in aqueous solution.The sorbed Pt or Pd can be completely eluted using 6% sulfourea in 5 mL 0.1 mol/L HNO3 .The synthesized sor-bent material can be recycled and reused.