Zeolite process and ion exchange process are water softening processes. The key difference between zeolite and ion exchange process is that the zeolite process uses the mineral zeolite as the exchanging resin for cations in the hard water whereas the ion exchange process may include several different resins for the ion exchange. Furthermore, the zeolite process is a form of ion exchange process of softening hard water.
Hard water is the water that is rich with calcium or magnesium cations. The presence of these cations in water may cause difficulties such as decreasing the effectiveness of nearly any cleaning task via reacting with heat, metallic plumbing or detergents. Therefore, it is better to remove these ions from hard water; we call it water softening. We can do this removal via ion exchange processes. Zeolite process is one such process.
CONTENTS
1. Overview and Key Difference
2. What is Zeolite Process
3. What is Ion Exchange Process
4. Side by Side Comparison – Zeolite vs Ion Exchange Process in Tabular Form
5. Summary
What is Zeolite Process?
Zeolite process is a process of softening hard water via ion exchange technique using the chemical compound zeolite. It is a chemical compound that has hydrated sodium aluminosilicate. This leads to name this process as zeolite process. Zeolite can exchange its sodium cations reversibly with calcium and magnesium ions in the water softening process.
There are two types of zeolite as natural and synthetic zeolite. The natural form is porous and synthetic form is a non-porous zeolite. Moreover, synthetic form possesses a high exchange capacity per unit weight than the natural form.
Figure 01: Cylinder Containing the Zeolite Bed
Process
In the water softening process, we pass the hard water through a bed of zeolite (inside a cylinder) at a specified rate. Then the cations that cause the water-hardening will retain on the zeolite bed because these cations exchange with the sodium cations of zeolite. Therefore, the water coming out of this cylinder contains sodium cations rather than calcium and magnesium cations.
After some time, the zeolite bed gets exhausted. Then we have to stop the water flow and treat the bed with concentrated brine solution (10%) in order to regenerate the zeolite. When we treat the bed with a brine solution, it washes away all the calcium and magnesium ions, by exchanging them with sodium ions in a brine solution. Therefore, this treatment regenerates the zeolite.
What is Ion Exchange Process?
Ion exchange process is a water softening process in which we use cations or anions in order to soften water. We can do this by exchanging cations or anions with the calcium and magnesium ions in hard water. This process involves a reversible chemical reaction. However, we can use this technique only on dilute solutions. The equipment that we use for this purpose is ion exchangers.
Types
There are two types;
- Cation exchangers – use zeolite, greensand, sulfonated coal, etc. as the exchanging material.
- Anion exchangers – uses metallic oxides, synthetic resins, etc.
The materials we use in cation exchangers include either weak acids or strong acids. Strong acid cation exchangers mainly contain sulfate functional groups. Weak acid cation exchangers mainly contain carboxyl groups. The materials that we use in anion exchangers include either weak bases or strong bases. Moreover, there are several categories of ion exchange process which include softening, dealkalization and demineralization. The ions that involved in the exchange process (the ions that exchange with the calcium and magnesium cations in hard water) include sodium ions, hydrogen cations, chloride anions and hydroxyl anions.
What is the Difference Between Zeolite and Ion Exchange Process?
The zeolite process is a process of softening hard water via ion exchange technique using the chemical compound zeolite whereas the ion exchange process is a water softening process in which we use cations or anions in order to soften water. This is the key difference between zeolite and ion exchange process. However, zeolite process is a form of ion exchange process because this process involves exchanging the sodium ions in zeolite with calcium and magnesium ions in hard water. Moreover, the zeolite process involves the exchange of sodium ions only while the ion exchange process involves different anions and cations such as chloride ion, hydroxyl ion, hydrogen ion and a sodium ion.
The below infographic presents the difference between zeolite and ion exchange process in tabular form.
Summary – Zeolite vs Ion Exchange Process
The ion exchange process involves the exchange of calcium and magnesium ions in hard water with different anions or cations in exchangers. This process is important for the removal of hardness from water. Zeolite process is also a category of ion exchange processes. The difference between zeolite and ion exchange process is that the zeolite process uses the mineral zeolite as the exchanging resin for cations in the hard water whereas the ion exchange process may include several different resins for the ion exchange.
Reference:
1. Chauhan. “Zeolite Process.” LinkedIn SlideShare, 29 Apr. 2016. Available here
2. “Water Softening.” Wikipedia, Wikimedia Foundation, 24 Aug. 2018. Available here