How does a Nafion dryer work?
Nafion functions essentially as a highly selective, semi-permeable membrane to water vapor. If gases inside Nafion tubing are wetter than gases surrounding the tubing, drying will occur. If the surrounding gases are wetter, humidification will occur. In the simplest case, a strand of Nafion is suspended in ambient air.
What is Nafion tubing?
Nafion tubing is a highly selective, semi-permeable membrane to water vapor. If gases inside Nafion tubing are wetter than gases surrounding the tubing, drying will occur. In normal use, a portion of Nafion tubing is used as a portion of the tube between a gas sample stream and a sensor.
What is Nafion dryer?
Nafion dryers are built with a tubing of semi-permeable membrane separating an inter- nal sample gas stream from a counterflow purge gas stream contained within a stainless steel outer shell. If the partial pressure of water vapor is lower in the purge gas stream, then water is removed from the sample gas stream.
What is Nafion used for?
Nafion has found use in fuel cells, electrochemical devices, chlor-alkali production, metal-ion recovery, water electrolysis, plating, surface treatment of metals, batteries, sensors, Donnan dialysis cells, drug release, gas drying or humidifaction, and superacid catalysis for the production of fine chemicals.
Is Nafion electrically conductive?
The combination of the stable PTFE backbone with the acidic sulfonic groups gives Nafion its characteristics: It is highly conductive to cations, making it suitable for many membrane applications. It resists chemical attack.
Who invented Nafion?
Walther Grot
Nafion is a brand name for a sulfonated tetrafluoroethylene based fluoropolymer-copolymer discovered in the late 1960s by Walther Grot of DuPont. Nafion is a brand of the Chemours company.
What is Nafion solution used for?
Why is Nafion expensive?
A critical component of RFB is the membrane which separates anode and cathode compartments. The current state-of-the-art membrane, NAFION is too expensive, lacks selectivity, permitting leakage between anode and cathode electrolyte compartments.
What is the burst pressure of Nafion tubing?
The burst pressure of Nafion™ tubing is generally greater than 200 psig (over 13 bar) but it varies with the diameter and wall thickness. An unusual property of Nafion™ is its propensity to change in physical size. As Nafion™ absorbs water, it swells by up to 22%.
How does a nafion membrane transfer water molecules?
The Nafion™ polymer transfers water molecules from one side of the membrane to the other by a first order kinetic reaction. This is unlike a porous membrane that depends on the physical size of molecules. Nafion™ Polymer selectivity is based on chemical reactivity, not the size of the molecule – therefore, not traditional permeation.
What are the physical properties of Nafion polymer?
Nafion™ polymer functions like a very selective, semi-permeable membrane to water vapor. The physical properties of Nafion™ polymer are similar to those of other fluoropolymers. It is translucent plastic. When used as an ion exchange membrane, it operates at temperatures up to 190°C. When used as a dryer, it can operate up to 150°C.
How many molecules of water does Nafion absorb?
Nafion™ polymer very readily absorbs water, from the vapor phase or from the liquid phase. Each sulfonic acid group will absorb up to 13 molecules of water. The sulfonic acid groups form ionic channels through the bulk hydrophobic polymer, and water is very readily transported through these channels.