Nano-fibrous sulfonated poly(ether ether ketone) membrane for selective electro-transport of ions

We reported fabrication of electrospun nano-fibrous ion-exchange membrane (IEM) composed of sulfonated poly(ether ether ketone) (SPEEK). Prepared membrane was employed for electro-dialytic separation of Na+ from Mg2+ or Ca2+, which is an urgent problem for the production potable water from brackish water and chlor-alkali industries. Nano-fibrous membrane was successfully fabricated onto spun-bonded non-woven polypropylene fabric. Electrospun SPEEK (ESPEEK) and SPEEK thin film membrane's suitability, for the electro-dialytic separation of cations, was assessed by their conductivity measurements under different electrolytic environment using electrochemical impedance spectroscopy. Counter-ion transport number and membrane permselectivity were strongly depended on the nature of counter-ions. ESPEEK membrane showed very low selectivity (about negligible) for Mg2+ and Ca2+, because formation of nano-fibrous pore or channels, which restricted the migration of bi-valent cations. Additionally, very low flux and electro-transport efficiency for bi-valent cations in compare with Na+ across ESPEEK membrane, suggested its possible application for electro-driven separation of mono-valent and bi-valent electrolytes. Electrospun nano-fibrous IEMs may be the promising candidate for electro-dialytic selective separation of ions depending on their charge and hydrated ionic size.

Figure optionsDownload as PowerPoint slideResearch highlights▶ Electrospun nano−fibrous sulfonated poly (ether ether ketone) (ESPEEK) membrane was fabricated onto spun-bonded non-woven polypropylene fabric. ▶ The fibers were found to be fairly uniform and show a narrow distribution in diameter. ▶ The average diameter was found to be 103 nm and the standard deviation was 20 nm. ▶ The electro-dialytic separation of cations (Na+ from Mg2+ or Ca2+) was achieved using ESPEEK membrane. ▶ ESPEEK membrane may be the promising candidate for electro-dialytic selective separation of ions from their mixture.