磁性羧甲基化壳聚糖纳米粒子吸附铂和钯_周利民

磁性羧甲基化壳聚糖纳米粒子吸附铂和钯

周利民1,2,3)　王一平3)　黄群武3)　刘峙嵘1)

1)东华理工大学核资源与环境教育部重点实验室,抚州344000　2)东华理工大学化学生物与材料科学学院,抚州3440003)天津大学化工学院,天津300072

摘　要　壳聚糖经羧甲基化改性以及碳二亚胺活化后接枝在F e 3O 4颗粒表面,制备Fe 3O 4/羧甲基化壳聚糖(MCM CS )磁性纳米粒子,用于吸附贵金属铂和钯.结果表明:MCM CS 粒径约20nm ,Fe 3O 4质量分数为36%,比饱和磁化强度25.74×10

-3

A ·m 2·g

-1

.当pH =2时M CM CS 对Pd 和Pt 的吸附以质子化氨基(+)与Pd (P t )-Cl 络合离子(-)的静电吸引为主要

机理.M CMCS 对Pd 和P t 的饱和吸附容量分别为3.2和2.7mmol ·g -1;Pd 和Pt 之间存在竞争吸附,二者竞争相同的活性位,M CM CS 对Pd 的亲和性优于P t .用0.5mol ·L -1硫脲脱附,脱附率最高(>68%),但用5mol ·L -1氨水对Pd 的脱附选择性最好.

关键词　纳米吸附剂;羧甲基化壳聚糖;铂;钯分类号　O 646.8

Magnetic carboxymethyl chitosan nanoparticles for palladium and platinum ad -sorption

Z HOU L i -min 1,2,3),WAN G Y i -ping 3),HUANG Qun -w u 3),LIU Zhi -rong 1)

1)Key Laboratory of the M inistry of Education of China for Nucl ear Resources and Environment ,East China Institute of Technology ,Fuzhou 344000,China

2)School of Chemistry ,Biotechnology and M aterial ,East China Institute of Technol ogy ,Fuzhou 344000,China 3)School of Chemistry and Chemical Engineering ,Tianjin Univers ity ,Tianjin 300072,China

ABSTRAC T M ag netic carbox ymethyl chitosan (M CM CS )nanoadso rbent was prepared fo r adso rption of palladium and platinum .Chitosan was first carboxy methylated and then grafted on the surface of Fe 3O 4nanopar ticles through carbodiimide activation .T he re -sults showed that M CM CS had the diameter of about 20nm ,the mass content of Fe 3O 4of 36%,and the saturation mag netization of 25.74×10-3A ·m 2·g -1.T he main adsorption mechanism w as the electrostatic attraction of pro to nated amine g roups and Pd (P t )-Cl anionic complex es at pH 2.T he saturated adsorption capacity was 3.2mmol ·g -1for Pd and 2.7mmol ·g -1for P t ,respectively .T he competitio n adso rption between Pd and Pt was observed ,Pd and Pt competed fo r the same adsorption active sites ,and the affinity of M CM CS for P d was greater than that for Pt .T he deso rption efficiency of more than 68%for bo th Pd and P t w as achieved using 0.5mol ·L -1thiourea as eluant ,w hile the highest selectivity was observed with 5mol ·L -1ammo nia .KEY W ORDS nanoadso rbent ;carboxy methyl chitosan ;palladium ;platinum

收稿日期:2007-10-31

基金项目:江西省教育厅科技项目(No .GJJ08302);东华理工大学核资源与环境开放基金资助项目(No .070710)作者简介:周利民(1970—),男,副教授,博士,E -mail :minglzh @s ohu .com

壳聚糖的基本组成单位是2-胺基葡萄糖,以β-(1,4)-糖苷键相互连接,具有亲水性、生物相容性和可降解性,因此是一种环境友好的吸附剂.壳

聚糖分子中含有羟基和氨基,可通过络合、离子交换

或静电引力吸附金属或有机物[1-3];但壳聚糖微球

粒径多在亚微米至微米级[4],内扩散阻力较大,导

致吸附速率和吸附容量下降.纳米吸附剂具有扩散阻力小、比表面积大、吸附快和吸附容量大的特点,近年来受到关注[5-6]

.纳米吸附剂难以通过离心或

过滤的方法分离;但磁性吸附剂通过外加磁场易于分离[7-8],因此有效地解决了分离困难的问题.

贵金属铂和钯是重要的催化剂材料,通常采用

第31卷第1期2009年1月北京科技大学学报Journal of University of Science and Technology Beijing

Vol .31No .1

Jan .2009

D OI :10.13374/j .iss n1001-053x .2009.01.011