Polyethylenimine–polyepichlorohydrin interpolymer for chelating ion-exchange membrane

Abstract

SynopsisPolyethylenimine membranes consisting of linear polyethylenimine (PEI) and polyepichlorohydrin (PECH) were prepared by casting and heating an N,N-dimethylformamide solution of the two polymers under nitrogen at 100°C for 60 min. The membrane was also prepared by a heat-press method in a conventional manner. The cast membrane obtained was transparent. The membrane has a crosslinked structure due to the reaction between the secondary amino groups in PEI and the chloromethyl groups in PECH. Although a larger feed ratio of PEIPECH gave membranes with a larger adsorption capacity for Cu2+ ions, the optimum ratio was 40/100 with respect to mechanical properties. A belt conveyor system using the PEI membrane was able to transport Cu2+ ions from one bath to another. In a diffusion dialysis against 1N HCl, the PEI membrane crosslinked rather tightly showed a specific ion-selective transfer character. For example, in Cu2+-Ca2+ system the permeability ratio PcJPc, was about 3.8. The selectivity arises from the difference between affinities (extractabilities) of PEI toward metal ions. The selectivity was changed depending on the pH value. INTRODUCTIONPolyethylenimine (PEI) is a good complexing agent for heavy metal ions.' Recently we have reported the preparation of a chelating resin containing linear PEI, i.e., poly(styrene-g-ethylenimine).2 The resin was quite effective for the adsorption of metal ions such as Hg2+, Cu2+, and Cd2+. The findings prompted us to prepare elastic chelating ion-exchange materials consisting of PEL Elastic ion-exchange materials are expected to exhibit desired properties in several purposes of applications, e.g., an ion-exchange membrane. The preparation of the elastic materials can be performed by the following two methods: 1. graft polymerization onto an elastomer, and 2. blending PEI with an elastomer followed by crosslinking the two polymers with each other. Graft polymerization of 2-methyl-2-oxazoline onto poly( 1,3-butadiene-co-l-chloro-1,3-butadiene) was carried out as an example of method l.3 The present paper describes an example of method 2, in which polyepichlorohydrin (PECH) was used as an elastomer. Since PECH possesses moderately active chloromethyl groups, the method seems to be convenient to prepare anion-exchange materials by reacting this group with amines such as PEL When the elastic ion-exchange materials containing PEI is used as a membrane, specific ion-selective transfer characteristics might be expected for the PEI membrane. The chemical species extracted more readily by a carrier permeated more rapidly through a liquid membrane of the ~a r r i e r .~ The gel-type PEI membrane will show a similar phenomenon under suitable conditions. The PEI membrane is known to adsorb heavy metal ions, e.g., Cu2+. The adsorbed Cu2+ has low mobility in the membrane and is not permeable through the membrane because of the high stability of PEI-Cu2+ complex. If the complex stability is lowered with a change of pH, the complexed Cu2+ will have a proper mobility in the membrane and wil...

Cyclic Imino Ethers, Polymerization

“…A new chelating membrane obtained by the reaction of (47) with polyepichlorohydrin shows selective ion-transport characteristics (113). A quantitative study of the chelation toward heavy-metal ions reveals a slightly smaller chelating ability of linear polymer (47) than of branched polyethyleneimine (114).…”

CuSO4 nanoparticles loaded onto poly (toluenesulfonic acid‐formaldehyde)/polyethyleneimine composites: An efficient retrievable catalyst for A3/decarboxylative A3 reactions

“…PEI is an amorphous, water‐miscible branched polymer with repeating units of primary, secondary, and tertiary amine moieties. [ 35,36 ] The PEI plays as a strong donor of electron pair and thus effectively enhances the electron density at the center of transit metal and thus accelerate the catalysis. Poly (toluenesulfonic acid‐formaldehyde) (PTSAF) is a novel water‐immiscible strong acidic resin synthesized by the copolymerization of p ‐toluenesulfonic acid and paraformaldehyde in the presence of catalytic amount of sulfuric acid.…”

Kinetics and equilibrium of cobalt ion adsorption on cross‐linked polyethylenimine membrane

“…However, PEI is a hydrophilic polymer and dissolves in water, therefore, it cannot be used repeatedly and effectively in water treatment. Saegusa prepared crosslinked PEI membrane and found that the membrane showed a high adsorption capacity for Cu 2+ ions, and high Cu 2+ /Ca 2+ selectivity 7. Recently, Liu et al found that the adsorption of zinc ions on PEI membrane obeys Langmuir isotherm 8…”

“…The adsorption behavior of cobalt ions on crosslinked PEI membrane is important for water treatment and other areas, therefore, PEI was crosslinked by polyepichlorohydrin (PECH) and crosslinked PEI membrane was prepared according to Ref 7…”