# Demineralised Water: The Purest Form

Introduction

Demineralised water, also known as deionized water, is a type of water that has had its mineral ions removed through a process called demineralization. This process involves using ion exchange resins or electrodialysis to remove positively charged cations (such as sodium, calcium, and magnesium) and negatively charged anions (such as chloride, sulfate, and bicarbonate) from the water.

Benefits of Demineralised Water

Demineralised water is preferred in many applications due to its high purity. Key benefits of demineralised water include:

• Corrosion resistance: Demineralised water is non-corrosive, making it ideal for use in boilers, cooling systems, and other industrial applications where corrosion can be a problem.
• Electrical insulation: The absence of mineral ions in demineralised water makes it an excellent electrical insulator, suitable for use in batteries, semiconductors, and other electronic devices.
• Improved appearance: Demineralised water leaves no mineral deposits, resulting in a cleaner, more aesthetically pleasing appearance in applications such as car washes and window cleaning.
• Reduced scaling: The lack of mineral ions in demineralised water prevents the formation of scale in pipes, boilers, and other equipment, extending their lifespans and reducing maintenance costs.

Applications of Demineralised Water

Due to its unique properties, demineralised water is used in a wide range of applications across various industries:

• Industrial: Boilers, cooling systems, batteries, semiconductors, pharmaceuticals, and chemical processing
• Automotive: Car washes, auto detailing
• Household: Cleaning, cooking, ironing, aquarium maintenance
• Medical: Pharmaceutical production, laboratory testing, medical devices
• Food and beverage: Food processing, beverage production, winemaking

Production of Demineralised Water

Demineralised water is produced through a two-step process:

1. Pretreatment:

• Filtration: Water is passed through filters to remove suspended solids, particles, and organic matter.
• Carbon filtration: Activated carbon filters remove chlorine, organic impurities, and odors.

2. Demineralization:

• Ion exchange: Water is passed through ion exchange resins, which chemically exchange mineral ions for hydrogen ions (H+) and hydroxide ions (OH-).
• Electrodialysis: Water is passed through a series of membranes that selectively allow the passage of ions, separating them from the water.

Types of Demineralised Water

Depending on the application, demineralised water can be classified into three types:

• Type I: The purest form of demineralised water, with a conductivity of
• Type II: Less pure than Type I, with a conductivity of
• Type III: The least pure form of demineralised water, with a conductivity of

Standards and Regulations

The purity of demineralised water is regulated by various standards and organizations, including:

• ASTM International: ASTM D512 and D1193
• ISO: ISO 3696
• World Health Organization (WHO): Guidelines for Drinking-water Quality

Key Figures

• The global market for demineralised water is expected to reach $2.8 billion by 2027.
• Demineralised water accounts for over 80% of the purified water market.
• The United States is the largest consumer of demineralised water, accounting for approximately 40% of global demand.

Health Considerations

Demineralised water is safe to drink, although it may have a slightly flat taste due to the absence of minerals. However, continuous consumption of large amounts of demineralised water can lead to electrolyte imbalances, as the body requires minerals for proper functioning. It is generally recommended to drink mineral-rich water for hydration purposes.

Stories and Lessons Learned

Story 1:

A pharmaceutical company experienced frequent equipment failures and corrosion in its manufacturing process. After switching to demineralised water, the corrosion issues were resolved, resulting in increased efficiency and reduced maintenance costs.

Lesson Learned: Demineralised water's corrosion resistance can save companies money by reducing equipment repair and replacement costs.

Story 2:

A winemaker noticed that the taste and aroma of his wines were subpar. By using demineralised water in the winemaking process, he was able to produce wines with a more refined flavor and higher quality.

Lesson Learned: Demineralised water can enhance the sensory properties of beverages and food products.

Story 3:

A hospital switched to using demineralised water in its medical devices and laboratory equipment. This resulted in reduced contamination and improved device performance, leading to safer and more accurate medical procedures.

Lesson Learned: Demineralised water plays a vital role in maintaining sterility and precision in medical settings.

Tips and Tricks

• Store demineralised water properly: Demineralised water can absorb carbon dioxide from the air, which gradually lowers its pH. Store it in sealed containers to prevent contamination and maintain its purity.
• Consider mixed-bed ion exchange systems: These systems use a combination of cation and anion exchange resins to produce ultra-pure Type I demineralised water.
• Regular maintenance: Ion exchange resins and electrodialysis membranes need regular maintenance to ensure optimal performance. Follow the manufacturer's recommendations for cleaning and regeneration.
• Use demineralised water sparingly: Demineralised water can be costly to produce, so use it only for applications where its purity is essential.

Common Mistakes to Avoid

• Using demineralised water for drinking purposes: While demineralised water is safe to drink, it is not recommended for long-term consumption due to its lack of minerals.
• Mixing demineralised water with mineral-rich water: Mixing demineralised water with untreated water can compromise its purity and increase the risk of contamination.
• Overreliance on ion exchange systems: Ion exchange resins can become exhausted over time, so it is crucial to monitor their capacity and regenerate them when necessary.
• Neglecting maintenance: Regular cleaning and regeneration of ion exchange systems and electrodialysis membranes are essential for maintaining their effectiveness.
• Storing demineralised water in unsealed containers: Exposing demineralised water to air can lead to absorption of carbon dioxide and a decrease in its pH.

Step-by-Step Approach to Demineralization

1. Pretreatment:

• Filter water to remove suspended solids and impurities.
• Use activated carbon filters to remove chlorine and organic contaminants.

2. Demineralization:

• Select an ion exchange system or electrodialysis unit based on the required water quality.
• Pass water through the system to remove mineral ions.

3. Post-treatment:

• Monitor the conductivity of the demineralised water to ensure purity.
• Use ultraviolet (UV) or ozone disinfection to kill bacteria and microorganisms.

4. Storage:

• Store demineralised water in sealed containers to prevent recontamination.
• Regularly monitor pH and conductivity to ensure purity is maintained.

Conclusion

Demineralised water is an essential resource in various industries and applications, offering high purity and specific properties that make it ideal for use in boilers, cooling systems, semiconductors, medical devices, and many more. By understanding the benefits, applications, production methods, and key considerations related to demineralised water, you can leverage its advantages and optimize its use in your own setting.

Tables

Table 1: Conductivity Ranges for Demineralised Water Types

Table 2: Applications of Demineralised Water

Table 3: Common Mistakes to Avoid When Using Demineralised Water