Basic Characteristics of Ion Exchange Resins

1. Appearance

Ion exchange resins are available in various colors such as yellow, brown, white, brown, black, and gray depending on the structure, group, ionic form, manufacturing process, etc., to meet the needs of different occasions in specific applications.
When the resin is contaminated, its color will also change fundamentally. The degree of color change is generally proportional to the degree of contamination of the resin and is difficult to reverse. Therefore, in the process of using the resin, it is necessary to pay attention to the change in color at any time to judge the degree of resin contamination.
 

2. Particle Size

The particle size and uniformity of the resin affects pressure drop and system operating speed.
 

3. Reversible Swelling

Ion exchange resins are polymers with different degrees of cross-linking, so the volume will vary under different conditions.

When the resin is in a dry state, it will rapidly expand when it meets water. Therefore, when the resin is dehydrated, it cannot be directly contacted with water, but is immersed in saturated saline solution to slow down the expansion speed and prevent cracking of the resin.

The Reversible Swelling is due to ion exchange, resulting in volume shrinkage and expansion. In general, for strong acid cation resin, the volume will swell from Na type to H type; while weak acid cation resin is on the opposite; for strong base anion resin, by the volume will expand from type Cl Converted to OH type, while weak base anion resin is on the opposite.

These data is important to design ion exchange system.
 

4. Moisture

The amount of equilibrium water is an inherent property of the resin, and different ionic forms lead to different moisture.
 

5. Density

Density and shipping weight
Shipping weight is used to calculate the loading and volume, including the porosity between beads. So, it is influenced by the particle size.
Density is specific gravity, not influenced by the particle size. It determines the sedimentation rate of the resin and the backwash expansion rate.it is important item for mixed bed resin.
Porosity: P＝1-d1/d1
Note:
P, Porosity;
d1,Shipping weight;
d2,density;
 

6. Total capacity

Total capacity, can reflect the inherent capacity of the resin, is a fixed value. In addition, there is work exchange capacity, which is an actual capacity in an operation. It is related to many field factors and is a variable.