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Nafion pipe PFSA tubing 

This is a very special and powerful polymer material product.
1. Material
The core material of Nafion tubes is Nafion, a perfluorosulfonic acid proton exchange membrane material developed by DuPont of the United States.
Chemical nature: It is a perfluorosulfonic acid copolymer. It can be understood as a very strong and stable "plastic" (similar to polytetrafluoroethylene, that is, the skeleton of  PTFE), but ether groups with sulfonic acid groups are introduced on the side chains of this skeleton.
Key structure:
The hydrophobic main chain: perfluorocarbon skeleton, provides extremely high chemical stability and thermal stability.
Hydrophilic sulfonic acid groups: These sulfonic acid groups can aggregate within the material to form "ion clusters" or "channels".

Nafion tubes are thin-walled tubes made of this material.

2. Characteristics

The characteristics of Nafion tubes are entirely attributed to their unique chemical structure. The main features are as follows:
 1). Outstanding chemical stability
It can withstand the vast majority of strong acids, strong oxidants, halogens and highly corrosive chemicals.
This is similar to the inertness of  PTFE.
2).Super strong selective permeability - Core feature:
This is the most unique and significant property of Nafion pipes. It has an extremely high selective permeability to water vapor and small molecule protons, while being almost impermeable to most gases, ions and organic molecules.
Working principle: The hydrophilic channels formed by sulfonic acid groups within the tube wall only allow hydrated protons to pass through. When there is a humidity difference or gas concentration difference between the inside and outside of the tube, water molecules will rapidly pass through the tube wall in a proton jumping manner, migrating from the high-concentration side to the low-concentration side until equilibrium is reached.

3).Ion exchange function

The sulfonic acid group is strongly acidic and can dissociate protons, making the Nafion tube a solid cation exchanger. It allows cations to be transported through ion exchange while blocking anions.
4).Good thermal stability
The continuous operating temperature is usually above 130°C, and it can withstand even higher temperatures in the short term.
5).Mechanical strength
As a tubular material, it has certain flexibility and mechanical strength, which is convenient for installation and use.

Main disadvantages:

High cost: Nafion material itself is expensive.
Performance decline under specific conditions: In extremely dry or high-temperature and low-humidity environments, the proton conductivity will significantly decrease because its function depends on a certain degree of hydration.
Poor resistance to reducing substances: It has poor tolerance to hydrogen and some strongly reducing metals under certain conditions.

3. Application
Due to its unique ability to selectively permeate water vapor and protons, Nafion tubes have irreplaceable applications in fields such as analytical chemistry, environmental monitoring, and electrochemistry.
Main application fields
1).Gas drying and humidification
Drying gas: The gas to be dried is introduced into the Nafion tube, and dry purge gas is introduced in the opposite direction outside the tube or it is placed in a vacuum. The moisture inside the tube will selectively seep out of the tube, thereby efficiently drying the gas inside the tube. This method will not introduce new pollutants.
Humidifying gas: The process is reversed. Dry gas is introduced into the tube, and water or moisture is placed outside the tube, which can precisely humidify the gas inside the tube.
2).Sample pretreatment for online gas chromatography and mass spectrometry
In environmental monitoring, it is necessary to analyze volatile organic compounds in the air. However, a large amount of water vapor in the air can interfere with the chromatographic column and detector. Nafion tubes can be used as membrane dryers to efficiently remove water vapor from samples before they enter the instrument, while ensuring that almost no target organic matter is lost.

3).Electrochemical sensors and fuel cells

The electrolyte membrane used as a micro-sensor allows proton conduction while isolating the reactants.
In some fuel cell designs, it is used to manage the moisture content of the membrane to prevent it from being too dry or too wet.
4).Osmotic evaporation
Used for removing trace amounts of water from organic solvents.
5).Isotope analysis
In fields such as hydrology and geology, it is necessary to analyze the ratio of hydrogen and oxygen isotopes in water samples. Nafion tubes can be used to balance the water vapor between water samples and standard gases, achieving efficient and automated sample preparation.

Typical application examples

In the continuous emission monitoring system of flue gas, when measuring sulfur dioxide in flue gas, the water vapor in the flue gas will seriously interfere with the measurement results. A Nafion tube dryer is usually used, allowing the hot and humid sample gas to pass through the tube while dry and pure air is introduced from the outside. The water vapor in the flue gas will be carried away through the tube wall, while the SO₂ gas is retained, thus obtaining dry and clean sample gas and sending it to the analyzer, ensuring the accuracy of the measurement and the service life of the instrument.
Summary
Nafion pipe is a functional pipe material based on perfluorosulfonic acid. Its core value lies in its unique selective permeability to water vapor and protons, combined with its excellent chemical stability. It is mainly used as an efficient and pollution-free gas drying/humidification and sample pretreatment component, and is widely applied in high-end analytical instruments, environmental monitoring and electrochemical research. Although it is costly, in many critical applications, its performance is irreplaceable by other materials.