Facile synthesis and properties of a cation exchange membrane with bifunctional groups prepared by pre-irradiation graft copolymerization

Synthesis of Fibrous Metal Adsorbent with a Piperazinyl-Dithiocarbamate Group by Radiation-Induced Grafting and Its Performance

A fibrous grafted metal adsorbent with a piperazinyl-dithiocarbamate (PZ-DTC) group was synthesized by radiation-induced emulsion grafting of glycidyl methacrylate onto a polyethylene-coated polypropylene nonwoven fabric (PE/PP-NF) and subsequent three-step chemical modifications consisting of amination with N-(tert-butoxycarbonyl)piperazine (N-Boc-piperazine, NBPZ), deprotection of the Boc group with HCl, and dithiocarbamation with carbon disulfide (CS2). By using the NBPZ reagent in the amination step, the self-cross-linking of piperazine (PZ) could be completely suppressed, unlike using the PZ reagent. Consequently, the PZ-DTC group density of the fibrous grafted metal adsorbent synthesized through NBPZ attained 2.122 mmol-PZ-DTC/g-adsorbent, which was approximately 6 times higher than that of the metal adsorbent synthesized through PZ. The fibrous grafted metal adsorbent with the PZ-DTC group selectively adsorbed heavy metal ions over light metal ions. Furthermore, it exhibited high adsorption capacity, particularly for Cu2+. The Cu2+ adsorption capacity was determined to be 1.903 mmol-Cu2+/g-adsorbent by a batchwise adsorption test using a single-metal-ion aqueous solution at pH 6. The order of metal ion selectivity of the fibrous grafted metal adsorbent with the PZ-DTC group was Na+ < Mg2+, Ca2+, Co2+, Cd2+ < Pb2+ ≪ Cu2+, and Co2+ ≈ Ni2+ < Zn2+ ≪ Cu2+. In addition, the fibrous grafted metal adsorbent with the PZ-DTC group did not lose its metal adsorption function even under highly alkaline conditions (pH 15). It could recover Cu2+ efficiently and selectively from a high-concentration Na+ aqueous solution at this pH. The Cu2+ adsorption capacity of the fibrous grafted metal adsorbent with the PZ-DTC group was 0.754 mmol-Cu2+/g-adsorbent under a highly alkaline condition, a 10 M NaOH aqueous solution at pH 15. This value was approximately 2.4 times higher than that of the other grafted adsorbent with an amine-type functional group.

Surface hemocompatible modification of polysulfone membrane via covalently grafting acrylic acid and sulfonated hydroxypropyl chitosan

In this study, acrylic acid (AA) and sulfonated hydroxypropyl chitosan (SHPCS) were covalently grafted on the PSf membrane surface to improve its hemocompatibility.