磁性羧甲基化壳聚糖纳米粒子吸附铂和钯

Magnetic carboxymethyl chitosan nanoparticles for palladium and platinum adsorption

壳聚糖经羧甲基化改性以及碳二亚胺活化后接枝在Fe3O4颗粒表面,制备Fe3O4/羧甲基化壳聚糖(MCMCS)磁性纳米粒子,用于吸附贵金属铂和钯.结果表明:MCMCS粒径约20 nm,Fe3O4质量分数为36%,比饱和磁化强度25.74×10-3A.m2.g-1.当pH=2时MCMCS对Pd和Pt的吸附以质子化氨基(+)与Pd(Pt)-Cl络合离子(-)的静电吸引为主要机理.MCMCS对Pd和Pt的饱和吸附容量分别为3.2和2.7 mmol·g-1;Pd和Pt之间存在竞争吸附,二者竞争相同的活性位,MCMCS对Pd的亲和性优于Pt.用0.5 mol·L-1硫脲脱附,脱附率最高(>68%),但用5 mol·L-1氨水对Pd的脱附选择性最好.

Magnetic earboxymethyl chitosan （MCMCS） nanoadsorbent was prepared for adsorption of palladium and platinum. Chitosan was first carboxymethylated and then grafted on the surface of Fe3O4 nanoparticles through carbodiimide activation. The results showed that MCMCS had the diameter of about 20 nm, the mass content of Fe304 of 36 %, and the saturation magnetization of 25.74 × 10^- 3 A· m^2·g^-1. The main adsorption mechanism was the electrostatic attraction of protonated amine groups and Pd（Pt）-Cl anionic complexes at pH 2. The saturated adsorption capacity was 3.2 mmol· g^-1 for Pd and 2.7 mmol·g^-1 for Pt, respectively. The competition adsorption between Pd and Pt was observed, Pd and Pt competed for the same adsorption active sites, and the affinity of MCMCS for Pd was greater than that for Pt. The desorption efficiency of more than 68 % for both Pd and Pt was achieved using 0.5 mol·L^-1 thiourea as eluant, while the highest selectivity was observed with 5 mol· L^- 1 ammonia.