聚乙烯亚胺(PEI)改性UiO-66对钯(Ⅱ)吸附性能的影响

Effects of Polyethyleneimine (PEI) Modified UiO-66 on Its Palladium ( Ⅱ )Adsorption Properties

钯是电子、催化、医药、首饰等诸多领域不可或缺的重要原料,但是钯在地壳中的含量十分稀少,并且价格非常昂贵,因而分离和回收钯具有重要意义。本工作采用浸渍后处理法对溶剂热法合成获得的UiO-66进行聚乙烯亚胺(PEI)改性,当PEI含量为UiO-66的20%(质量分数,下同)时,制得的PEI@UiO-66对Pd(Ⅱ)溶液(2 000 mg/L)的吸附量可达145 mg/g,较未改性前提升126.6%;通过在浸渍后处理工艺中引入硅烷偶联剂γ-氨丙基三乙氧基硅烷(KH550)能够有效改善PEI和UiO-66间的界面结合,当KH550含量为UiO-66的5%时,PEI@KH550@UiO-66对Pd(Ⅱ)溶液(2 000 mg/L)的吸附量达到178 mg/g,较PEI@UiO-66提升22.8%,较未改性UiO-66则提升178.1%。PEI@UiO-66和PEI@KH550@UiO-66对Pd(Ⅱ)吸附机理除了锆基团簇同PdCl_(4)^(2-)之间的电子偏移,还存在质子化的氨基同PdCl_(4)^(2-)之间的电子偏移。

Palladium is an indispensable and important raw material in various fields, such as electronics, catalysis, medicine and jewelry. However, palladium has a very rare natural resource on the earth and very high price, so it is of great significance to separate and recover palladium. In this study, the amino active functional group was successfully introduced into UiO-66 by impregnation post-treatment, and its palladium adsorption performance was characterized. It was found that the adsorption capacity of PEI@UiO-66 on Pd(Ⅱ) solution (2 000 mg/L) reached 145 mg/g when PEI content was 20wt% of UIO-66. By further introducing silane coupling agent γ-aminopropyl triethoxysilane (KH550) into the impregnation post-treatment process, PEI@KH550@UIO-66 was finally obtained, and the interface between PEI and UiO-66 was improved effectively. When the KH550 content was 5wt% of UiO-66, the adsorption capacity of PEI@KH550@UIO-66 on Pd(Ⅱ) solution (2 000 mg/L) was up to 178 mg/g. The adsorption mechanism of UiO-66 for Pd(Ⅱ) is mainly the electron migration between zirconium group clusters and PdCl_(4)^(2-) . In addition to the electron migration between the zirconium group cluster and PdCl_(4)^(2-) , there is also the electron migration between the protonated amino group and PdCl_(4)^(2-) in the Pd(Ⅱ) adsorption process for both PEI@UiO-66 and PEI@KH550@UiO-66.