Dr. Colleen Spiegel

There are numerous methods that have been developed for working with ion exchange materials. In this blog post, we will describe a few basic methods commonly used in ion exchange research to help a student or new scientist to work with these materials.

Conventional ion exchange processes use chemical reactants in solution for the ion exchange process. However, ion exchange processes are not just chemically driven, are also electrically driven. An example of an electrically driven ion exchange process is electrodialysis, (also known as electrodeionization), where ionizable species are removed from liquids using electrically active media and the electrical potential as a driving force for ion transport. Electrodeionization can also be used for water treatment, separation of electrolytes from non-electrolytes, concentrating or depletion of i..

As we saw in the previous blog post, the process of ion exchange is influenced by a very large number of factors. The primary mode of ion transport is diffusion, which is process of the movement of atoms, ions, molecules, or energy from a region of high concentration to a region of low concentration.

The rate of ion exchange depends on the rates of the chemical (ionic) reactions in the ionic exchange material (membranes, dispersions, beads, pellets, etc.), but it is often limited by the diffusion processes. The ion exchange process maybe primarily controlled by diffusion, which is dependent upon the material layers, structure, thickness and reactant rate of contact on the surface of the material. This blog post introduces the factors to consider when thinking about the kinetics of the ion exchange reactions. Mechanism of Ion Exchange Processes A common ion-exchange system is an ..

Ion exchange materials are used to purify, separate, and extract many different types of molecules, including organic and biochemical molecules. When ion exchange materials involve these ion types, there may be additional complexities involved with the interaction.Some of the phenomena that may occur are:

1. Secondary forces between the ionized group and counterion. These forces may consist of coordination, hydrogen, and van der Waals bonding.
2. The pH can affect the percent ionization.
3. The position of the functional groups can affect ion transport.
4. Hydration of organic molecules can be more complex than inorganic ions.
5. Organic ions may be larger than inorganic ions; thus, steric hinderances can reduce ionic interactions.

Therefore, ion exchange phenomena may be able to be explained chemically by stoichiometric reactions, but the actual ionic selectively may be determined by other interactions.

In nature, the majority of gases, liquids, and solids are not charged (in the neutral form). Ion exchange, where free ions are exchanged for different ions, occurs when there is an open network structure to carry the ions through it. There are many natural and man-made mediums that are ion exchangers, including solids, liquids, and gases. The medium needs to be in contact with the ion exchanger and these two entities exchange some of its ions for similarly charged ions. The medium is often a solid ion exchanger in contact with an aqueous solution or gas. If you recall from chemistry, there ..

Cation exchange membranes (CEMs) are frequently referred to as proton exchange membranes (PEMs) because they are often used in chemical reactions that generate protons. CEMs are used in various applications ranging from proton exchange membrane and microbial fuel cells to chlorine and caustic soda production. The cation exchange membrane (CEM) contains negatively charged functional groups (PO3-, COO–, and C6H4O–) in the membrane backbone, which allows cations to pass through. There are many types of CEM that have been used in the literature, including Nafion©, Fumatech, Aquiv..

Zero-gap electrolyzers are similar to fuel cells in design because the heart of the electrolyzer consists of two electrodes pressed against a membrane. These electrolyzers are called “zero-gap” because there is no gap between the cathodes, anodes, and the electrolyte. This design decreases the distance for ion transport because the layers are pressed or bonded together. The zero-gap CO2 electrolyzers can achieve high current densities (≥100 mA/cm2) by delivering gaseous CO2 to the cathode. The efficiency of these electrolyzers depends upon the catalysts used, the operating conditions, and o..

An Introduction to CO2 Capture and Conversion Electrochemical devices that convert CO2 into fuels and valuable compounds have been undergoing extensive research for over a decade now. The research in this area has been driven by the desire to reduce reliance on fossil fuels and reduce greenhouse emissions. As you are probably aware, the majority of the world’s energy used for transportation, industrial, and residential uses are made from coal, petroleum, and natural gas. An Increase in CO2 Emissions As we are all aware, the consumption of fossil fuels has led to an increase in C..

A numerical model was developed to predict the water concentration, temperature, potential and pressure across a Nafion membrane used in proton exchange membrane (PEM) based fuel cells. The numerical model consists of simultaneously calculating the diffusive flux for water and hydrogen, the proton potential and the pressure and temperature at each node...

Ion-exchanges membranes (IEMs) have many applications beyond fuel cells -- they can also be used to synthesize all types of compounds that are used in various industries. The most popular IEMs consist of polymeric resins with charged functional groups based upon their ion selectivity, they are referred to as anion-exchange (AEM) and...

Anion exchange membranes (AEMS) have been an active area of research for over a decade. AEMS can be used for fuel cells, redox flow batteries, electrolyzers, and even water desalination membranes. The electrolyte layer is the “heart” of electrochemical cells such as fuel cells, batteries, and because it transports ions from...

Alkaline fuel cells (AFCs) was one of the first extensively researched fuel cell types and was used by NASA for the Gemini, Apollo, and Space Shuttle missions. The first alkali electrolyte fuel cell was built by Francis Thomas Bacon (1904–1992) in 1939. He used potassium hydroxide for the electrolyte and...

Many countries around the world have been diligently working towards implementing renewable energy plants for over a decade. According to the International Energy Agency (IEA), renewables in the form of hydropower, bioenergy, wind and solar will account for 18% of primary energy by 2035. Since 2013, more electrical grid capacity was added...

If you are considering the installation of a solar system (by yourself or by a solar company), there are several codes and regulations that need to be adhered to. These include the National Electrical Code (NEC), local permits, building codes, fire codes, and grounding systems. In addition, every component in a...