Calcium Chloride Hygroscopic | Some Influencing Factors

Calcium chloride (CaCl₂) is a versatile compound that is used across a wide range of industries due to its unique properties. Calcium chloride can be used as a deicing agent, wastewater treatment, and as a dehumidifier. Calcium chloride desiccant works well in temperatures ranging from freezing to 80°C or higher.

Calcium chloride desiccant

Factors Influencing Hygroscopic Properties

Several factors affect the hygroscopic behavior of calcium chloride. Understanding these factors is crucial for optimizing its use in various applications.

1. Environmental Humidity

The relative humidity of the environment plays a critical role in the hygroscopic behavior of calcium chloride. Relative humidity is the amount of moisture present in the air compared to the maximum amount the air can hold at a given temperature. When the relative humidity is high, calcium chloride absorbs more moisture. Conversely, in low-humidity conditions, the rate of moisture absorption decreases.

Through the data obtained in the network under the best experimental conditions (CaCl2 dissolution temperature 50℃; CaCl2 mass fraction 80%; ambient temperature 30℃), the experimental mixed gel has the largest hygroscopic expansion due to its strong hygroscopicity; the hygroscopic capacity of calcium chloride and the good water retention capacity of polyacrylamide show that the hygroscopic expansion of calcium chloride solution increases with the increase of relative humidity.

Environmental Humidity(%RH)Hygroscopicity(%)
This data is simulated based on experimental conditions and its authenticity is not guaranteed.

2. Temperature

  • When exposed to high temperatures, the Calcium chloride hygroscopic effect is reduced because the moisture is evaporated and released into the air more quickly.
  • In cold environments, calcium chloride’s hygroscopic ability is enhanced because the moisture content in the air is higher and less likely to evaporate.

3. Particle Size and Surface Area

There are differences in the hygroscopic performance of calcium chloride particles of different sizes in practical applications. According to evidence, the shape and size of calcium chloride particles affect their hygroscopic speed and efficiency.

Particle shape: Calcium chloride can be in a variety of forms, including granular, honeycomb block, spherical, irregular granular and powder. Among them, dihydrate spherical calcium chloride is widely used in dehumidification boxes, dehumidification bag desiccants, etc. because of its uniform particle size, smooth and full appearance, high hardness and good hygroscopic performance.

Moisture absorption rate: Powdered calcium chloride absorbs moisture very quickly due to its porous structure, but it is easy to stick to the wall in the drying tower and difficult to discharge. The spherical specification particles have a low moisture absorption rate (≤50%) in high humidity environments, but have a better moisture absorption effect in low humidity environments.

Moisture absorption capacity: Generally speaking, calcium chloride can quickly absorb moisture in the surrounding environment and convert it into solid moisture attached to the surface of the particles. Different forms of calcium chloride show different hygroscopic capacities under different humidity conditions. For example, dihydrate spherical calcium chloride has a strong hygroscopic capacity in high humidity environments and good hygroscopic effect in low humidity environments.

Calcium Chloride Anhydrous Powder

4. Purity and Composition

The purity of calcium chloride can significantly influence its hygroscopic properties. High-purity calcium chloride exhibits better hygroscopic behavior compared to lower purity grades. For example, anhydrous calcium chloride (i.e. calcium chloride without water of crystallization) is more hygroscopic because it can form hydrates with water (e.g. CaCl2*6H2O). When high-purity calcium chloride comes into contact with water, it can quickly absorb moisture and release a large amount of heat, thus maintaining a dry state more effectively.

5. Storage Conditions

How calcium chloride is stored can also impact its hygroscopic properties. Proper storage is essential to prevent premature moisture absorption, which can reduce the effectiveness of the product. Calcium chloride should be stored in airtight containers to protect it from exposure to atmospheric moisture.

Additionally, the storage environment should be cool and dry to minimize the risk of the calcium chloride absorbing moisture and forming a brine solution. This is particularly important for applications where dry calcium chloride is required, such as in certain chemical processes or manufacturing.

Calcium chloride desiccant2

Applications of Hygroscopic Properties

The hygroscopic nature of calcium chloride lends itself to a variety of practical applications across different industries.


Calcium chloride is widely used in dehumidifiers and moisture absorbers. Its ability to attract and hold water molecules makes it an excellent choice for reducing humidity in residential, commercial, and industrial settings. This is particularly useful in preventing mold growth, protecting sensitive equipment, and improving indoor air quality.

Water treatment

Calcium chloride can be used in the sludge dewatering process. In the sewage treatment process, the sludge produced contains a lot of water. Calcium chloride can help remove moisture from the sludge through hygroscopic action, increase the solid content of the sludge, reduce the sludge volume, and reduce transportation and treatment costs. Calcium chloride can also be used to adjust the hardness of water in water treatment. By adding calcium chloride, the concentration of calcium ions in the water can be increased, thereby changing the hardness of the water.

Construction Industry

Adding calcium chloride to concrete can promote the hydration reaction of cement and shorten the setting time of concrete. It can increase the ion concentration in concrete, promote the reaction between cement particles, and speed up the hardening of concrete. Concrete is susceptible to freeze-thaw cycles in low temperature environments, resulting in a decrease in the strength and durability of concrete. Adding calcium chloride can improve the anti-freeze performance of concrete and reduce the damage of freeze-thaw cycles.


The hygroscopic properties of calcium chloride make it a commonly used compound in a variety of industries. Understanding the factors that influence its hygroscopic behavior is crucial for users.

For more information on calcium chloride and its applications, visit our website or contact our team of experts.

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