Desiccant Dehumidifier 101: What are Zeolites?

by Vivien Mah    

Ionmax ION612 Dehumidifier Control Panel

If you’ve been shopping around for a desiccant dehumidifier, you would’ve come across the term “zeolite” quite often.

Our top Ionmax desiccant dehumidifiers – the ION612 and ION632 – both use zeolite as the desiccant material to remove excess moisture from the air. Due to an increasing amount of queries from customers on what zeolite actually is, we thought we’d answer some FAQ’s here.


What is a desiccant?

A desiccant is a hygroscopic substance (able to attract and hold water molecules from the surrounding environment) that induces or sustains a state of dryness (desiccation) in its vicinity.

Desiccants remove moisture in three ways:

  1. Absorption – when a substance is chemically integrated into another, for example, salt dissolving in water and becoming salt water.
  2. Adsorption – the physical attraction and adherence of gas or liquid molecules to the surface of a solid. The force of the attraction is very small, van der Waal’s forces, and does not change the physical characteristics of the substance.
  3. Chemical reaction or change – a process that changes the chemical structure of the substance.

There are four main types of desiccants:

  1. Silica gel
  2. Montmorillonite clay
  3. Molecular sieve (zeolites)
  4. Calcium oxide

Some desiccant materials can be regenerated (i.e. purged of contaminants and then re-used), whereas some cannot. This depends on the change in the physical structure of the desiccant and the deleterious effects of regeneration on the material.

Our desiccant dehumidifiers use Zeolite – and for a very good reason, too. Zeolites are highly efficient at removing moisture from the air. They are also capable of regeneration, meaning your Ionmax dehumidifiers need little to no maintenance at all!


So, what are zeolites?

Zeolites are a form of naturally occurring volcanic rock composed of hydrated aluminosilicates of the alkali earth metals. Naturally occurring zeolites are rarely pure and are contaminated to varying degrees by other minerals, metals, quartz, or other zeolites. This is why naturally occurring zeolites are excluded from important commercial applications where uniformity and purity are essential.

For commercial use, synthetic zeolites are used. Produced into a uniform, phase-pure state, synthetic zeolites

and hold some key advantages over their natural form, namely being in a uniform, phase-pure state.

Zeolites have a high affinity for water and are capable of adsorbing and desorbing it without damaging its crystal structure. This property makes them very efficient at removing excess moisture from the air[1].


Are Zeolites safe?

As explained by, zeolites are very stable solids that resist the kinds of environmental conditions that challenge many other materials. Here are some of zeolites’ properties[2]:

  • Can withstand high temperatures. Zeolites don’t burn and they have high melting points (over 1000°C)
  • Resistant to high pressures
  • Don’t dissolve in water or other inorganic solvents
  • Don’t oxidise in air
  • Do not cause health problems through skin contact or inhalation
  • Unreactive and, being based on naturally occurring minerals, they’re not believed to have any harmful environmental impacts


How do zeolites work in the dehumidifier? How do zeolites regenerate?

Zeolites and desiccant wheel of a desiccant dehumidifier

The zeolites are used in the desiccant wheel of our dehumidifiers.

When a zeolite is placed in an air stream, it will absorb moisture up to its maximum capacity (or saturation point) and will not absorb any more moisture.

When the zeolite has reached its saturation point, the dehumidifier runs a stream of hot air through it and vents the moisture away from it. This moisture collects in the dehumidifier’s water tank. This is necessary to prevent the captured moisture from being reintroduced into the conditioned space.

After this, the zeolite can begin to absorb moisture and the cycle is repeated.

This is the process of the zeolite regenerating itself.


Why does a desiccant dehumidifier produce heat?

This is the only way zeolites are used to control humidity levels in conditioned spaces.

Desiccant dehumidifiers need to have a heating element to heat the zeolite in order to regenerate it.

Heating the zeolite discharges the absorbed water into the water tank. The zeolite regenerates itself during the heating process and is then able to adsorb more water.

But the amount of heat produced by the dehumidifiers is not significant – usually only 3 ~ 5°C higher than room temperature at most.


How does a desiccant dehumidifier compare to a compressor type dehumidifier?

A desiccant dehumidifier is a preferred appliance due to its ability to perform at low temperatures, even close to freezing point.

For example, our 7-litre Ionmax ION612 desiccant dehumidifier would be able to extract 7 litres per day even at 5°C, provided there is enough moisture in the air.

Desiccant dehumidifiers are also able to dry to humidity levels below 40%RH if required, something that compressor dehumidifiers can hardly achieve.

Additionally, desiccant dehumidifiers can be quite energy efficient, as most of the energy consumed is returned to the room as warm air.  This can reduce the amount of energy used by other sources to the heat the room.

With a high efficiency in removing moisture from the air, the ability to regenerate itself, and little to no maintenance required, desiccant dehumidifiers are becoming one of the top dehumidifier choices in Australia, especially in cooler climates.

Check out our posts on Dehumidifier Buying Guide and  Desiccant Dehumidifiers vs Compressor Dehumidifiers for more information on their differences.

P.S. Our Ionmax ION612 and ION632 desiccant dehumidifiers were reviewed by CHOICE and both have been recommended again!

CHOICE is formally known as the Australian Consumer’s Association (ACA) and is an independent publisher of consumer information. They conduct rigorous and scientific product reviews across a range of goods and services. With over 160,000 members, CHOICE is the number one advocate of consumer rights in Australia.

Check out the full Choice Dehumidifier Review here and view the Ionmax ION612 and Ionmax ION632 desiccant dehumidifiers on our website.

Ionmax ION632 and ION612 desiccant dehumidifiers



Most viruses and bacteria are fond of humid and cold environments. They are afraid of heat, and could very well be inactivated under high temperature. The higher the temperature is, the shorter the inactivation time.

Due to the nature of zeolite (the main absorption material of the desiccant wheel), it is very good at capturing small molecules in the air- that includes not only vapour but also all kinds of pathogens, allergens, spores, and even formaldehyde.

There is an ultra high temperature core within the desiccant dehumidifier, and it's main purpose to evaporate the vapour absorbed in the zeolite wheel; however, since the core temperature could reach temperatures of 200°-500°C, it also automatically sterilises the wheel while dehumidifying.



Information from this article was researched from the following sites. Please visit the sites below if you’d like to learn more 🙂

[1] Zeolites, Atomic Scale Design Network (ADSN),

[2] Zeolites,,

This article also incorporates public domain material from the United States Geological Survey document: “Zeolites” (PDF):

Disclaimer: The information provided in this article is for general reference only. Please seek advice from professionals according to your needs.