用于重金属离子预富集的孔功能化聚合物膜

Pore-functionalized polymer membranes for preconcentration of heavy metal ions.

作者信息

Vasudevan T, Das Sadananda, Sodaye Suparna, Pandey A K, Reddy A V R

机构信息

Research Reactor Services Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India.

出版信息

Talanta. 2009 Apr 15;78(1):171-7. doi: 10.1016/j.talanta.2008.10.053. Epub 2008 Nov 7.

DOI:10.1016/j.talanta.2008.10.053

PMID:19174221

Abstract

Functionalized membranes containing carboxylate, phosphate and sulfonate groups were prepared by UV-initiator induced graft polymerization of the functional monomer (acrylic acid, ethylene glycol methacrylate phosphate (EGMP) and 2-acrylamido-2-methyl-1-propane sulfonic acid) with a crosslinker (methylenebisacrylamide) in the pores of poly(propylene) host membranes. The functionalized membranes thus obtained were characterized by gravimetry, FTIR spectroscopy, radiotracers and scanning electron microscopy for the degree of grafting and water uptake, presence of functional groups, ion-exchange capacity, and physical structure of the membranes, respectively. The uptakes of Cs(+), Ag(+), Sr(2+), Cd(2+), Hg(2+), Zn(2+), Eu(3+), Am(3+), Hf(4+) and Pu(4+) ions in the functionalized membranes were studied as a function of acidity of the equilibrating aqueous solution. Among the functionalized membranes prepared in the present work, the EGMP-grafted membrane (with phosphate groups) showed acid concentration dependent selectivity towards multivalent metal ions like Eu(3+), Am(3+), Hf(4+) and Pu(4+). The solvent extraction studies of EGMP monomer in methyl isobutyl ketone (MIBK) solvent indicated that divalent and trivalent metal ions form complexes with EGMP in 1:2 proportion, but the distribution coefficients of trivalent metal ions were significantly higher that for the divalent ions. The uptakes of Eu(3+) ions in monomeric EGMP (dissolved in MIBK) and polymeric EGMP (in the forms of crosslinked gel and membrane) were studied as a function of concentration of H(+) ions in the equilibrating solution. This study indicated that polymeric EGMP has better binding ability towards Eu(3+) as compared to monomeric EGMP. The variation of distribution coefficients of Eu(3+)/Am(3+) in gel and membrane as a function of H(+) ion concentration in the equilibrating aqueous solution indicated that ionic species held in the membrane and gel were not same. These results indicated that proximity of functional groups (phosphate) plays an important role in metal ion binding with polymeric EGMP.

摘要

通过紫外线引发剂诱导功能单体（丙烯酸、甲基丙烯酸乙二醇磷酸酯（EGMP）和2-丙烯酰胺基-2-甲基丙烷磺酸）与交联剂（亚甲基双丙烯酰胺）在聚丙烯主体膜的孔中进行接枝聚合，制备了含有羧酸盐、磷酸盐和磺酸盐基团的功能化膜。通过重量法、傅里叶变换红外光谱法、放射性示踪剂和扫描电子显微镜分别对所得功能化膜的接枝度和吸水率、官能团的存在情况、离子交换容量以及膜的物理结构进行了表征。研究了功能化膜对Cs(+)、Ag(+)、Sr(2+)、Cd(2+)、Hg(2+)、Zn(2+)、Eu(3+)、Am(3+)、Hf(4+)和Pu(4+)离子的吸附情况，考察了平衡水溶液酸度的影响。在本工作制备的功能化膜中，EGMP接枝膜（含磷酸基团）对Eu(3+)、Am(3+)、Hf(4+)和Pu(4+)等多价金属离子表现出与酸浓度相关的选择性。对EGMP单体在甲基异丁基酮（MIBK）溶剂中的溶剂萃取研究表明，二价和三价金属离子与EGMP以1:2的比例形成配合物，但三价金属离子的分配系数明显高于二价离子。研究了Eu(3+)离子在单体EGMP（溶解于MIBK）和聚合EGMP（交联凝胶和膜的形式）中的吸附情况，考察了平衡溶液中H(+)离子浓度的影响。该研究表明，与单体EGMP相比，聚合EGMP对Eu(3+)具有更好的结合能力。Eu(3+)/Am(3+)在凝胶和膜中的分配系数随平衡水溶液中H(+)离子浓度的变化表明，膜和凝胶中保留的离子种类不同。这些结果表明，官能团（磷酸盐）的邻近性在金属离子与聚合EGMP的结合中起重要作用。