At a Glance

This blog contrasts sodium hypochlorite and calcium hypochlorite to assist you in selecting the most suitable disinfectant for your industrial applications. It delves into their chemical state, uses, benefits, and factors such as stability, expense, mode of handling, and safety. Sodium hypochlorite is perfect for high-flow, quick-action situations, whereas calcium hypochlorite is appropriate for long-term storage and remote or emergency uses. The blog also provides examples based on real-life and technical advice for procurement teams to make a knowledgeable decision based on infrastructure, usage frequency, and budget.

Introduction

In water treatment, food processing, sanitation, bleaching in textile, and chemical production industries, disinfectants play a central role. Among the extensive collection of industrial biocides, sodium hypochlorite vs calcium hypochlorite becomes a common dilemma for purchasing teams and plant engineers.

Both are chlorine-based disinfectants, but their shape, effectiveness, and compatibility vary significantly. So, which one is ideal for your industrial use? Let’s get into the nitty-gritty of the science, uses, advantages, disadvantages, and value for money of each to enable you to make the right buying choice.

What is Sodium Hypochlorite Used For?

Sodium hypochlorite (NaOCl), commonly referred to as liquid bleach, has been traditionally used by both the household user and industrial operator alike. Its considerable oxidative strength will make sodium hypochlorite a potent disinfectant and bleaching agent. But in industrial use, what is sodium hypochlorite used for?

Key Industrial Applications of Sodium Hypochlorite

Water Treatment Plants

Sodium hypochlorite is a common practice in the disinfection of drinking water and wastewater, destroying bacteria, viruses, and fungi. It has been adopted by municipal and industrial plumbing systems for its rapid disinfection while maintaining residual disinfection characteristics in the distribution systems.

Food Processing Industry

Used to sanitise food contact surfaces, machines, and even fresh produce because of its ability to kill harmful pathogens without harmful residues. It does not corrode equipment if used at controlled concentrations and is compatible with Hazard Analysis Critical Control Point (HACCP) requirements.

Pulp and Paper Industry

Acts as a bleaching agent during pulp bleaching to improve whiteness during manufacturing. Sodium hypochlorite is preferred because of its lower cost and very strong oxidising ability, enhancing brightness and reducing microbial load where recycled paper is being used.

Textile Industry

Utilised in the whitening of fabrics and the removal of difficult stains. Key ingredient in a pre-treatment process, especially on cotton and synthetic blends, where it can break down organic contaminants and allow for more uniform dye uptake.

Chemical Manufacturing

An intermediate in the manufacture of other chemical substances, including herbicides and disinfectants. Its reactivity and stability in controlled conditions make it a helpful starting point to synthesise a variety of chemicals in an industrial setting.

Cooling Towers and Industrial Equipment

Contributes to the reduction of bio-fouling and algae formation in aquatic systems. Sodium hypochlorite has a long history of efficient dosing to successfully maintain pipes, pumps, and condensers in a manner that allows for a higher degree of efficiency – and lowers the likelihood of corrosion and biological contamination.

Calcium Hypochlorite Liquid: An Emerging Alternative

Calcium hypochlorite is generally a solid chlorine compound. However, calcium hypochlorite liquid forms are available to support the demand for pre-dissolved formulations typically used for industrial purposes.

What is Calcium Hypochlorite Used For?

Swimming Pools and Spa Sanitization

The most frequently used type—used to kill bacteria and to inhibit algae. High chlorine dosage—generally 65–70%—makes it ideal to clean up water and keep it free from bacteria, and algae thus ensuring water clarity and hygiene, especially in commercial and public swimming pools.

Disinfection in Emergency Situations

Calcium hypochlorite’s longer shelf life and portability make it perfect for disaster zones. Relief organisations often stock it in powdered form for easy distribution in pumps during floods, hurricanes, and any outbreaks where safe water is imperative.

Industrial Sanitization

Used in food, beverage, and dairy facilities to sanitise tanks, lines, and equipment. Both forms of calcium hypochlorite, liquid and calcium hypochlorite powder, and granular, are used to ensure microbial control in clean-in-place (CIP) systems and for surface sanitation.

Drinking Water Treatment in Rural or Remote Areas

Calcium hypochlorite powder or granules is often more favourable because it is easier to transport and has a longer shelf life. It is a reliable disinfectant in case of small or decentralized water treatment systems where liquid chlorine is not practical.

Bleaching Applications

Sodium Hypochlorite has stronger oxidizing properties than chlorine and is great for bleaching due to its capacity to enable a slower, more controllable release of chlorine that allows bleaching to be effective, especially in processes with longer periods of exposure.

Also Read: How Do Chemicals in Industrial Coatings Improve Corrosion Resistance in Harsh Environments?

Sodium Hypochlorite vs Calcium Hypochlorite: In-Depth Comparison

1. Chemical and Physical Form

Sodium Hypochlorite is typically delivered as a liquid (10-15% solution). It is usually produced on-site from chlorine gas and sodium hydroxide, and is easy to apply in larger systems such as water treatment plants, or in larger chemical processes, where a continuous supply is needed.

Calcium Hypochlorite is available in solid form (65-70% available chlorine), but calcium hypochlorite liquid is also available. Solid calcium hypochlorite provides a more concentrated option for chlorine, which may be cost-effective in certain applications. The liquid option allows calcium hypochlorite to be handled more easily on demand, making it best utilized in circumstances requiring quicker dissolution or action. 

Pro: Sodium hypochlorite is immediately usable meaning it is better for continuous or large scale applications, and calcium hypochlorite is easier to handle and store in solid form, and have a greater concentration of available chlorine.

2. Stability and Shelf Life

Sodium hypochlorite is very reactive, it is likely to deteriorate most rapidly with heat or light and will lose potency in a matter of weeks. Sodium hypochlorite has also been shown to be impacted by temperature and sunlight, which ultimately leads to loss of effectiveness through degradation. Thus, it must be replaced regularly.

Calcium Hypochlorite has a longer shelf life and is stable over time. It lasts long, even when conditions for storage were not ideal. These important characteristics make it the first choice for emergency storage where there would need to be a reliable chlorine source.

Advantage: Calcium hypochlorite is better in situations where there is long-term storage. Sodium hypochlorite is better in situations where you need to use it frequently and you want it to act quickly.

3. Ease of Handling and Storage

Sodium Hypochlorite requires substantial storage tanks and is susceptible to temperature and UV light. It should be kept in opaque containers to avoid degradation from UV light and must be reacted at a limited temperature, so controlling the temperature is important. This complicates storage depending on the size of your operations.

Calcium Hypochlorite solid is easier to store but has more of a dust hazard and is more reactive. Calcium Hypochlorite does not need any special storage temperature, but does create dust when being handled or transported, which is hazardous. Additionally, the solid form is more reactive and needs to be stored away from incompatible materials to avoid unsafe reactions.

Advantage: Sodium hypochlorite is easier to handle if you have existing dosing systems, while it is easier to store calcium hypochlorite for a long time but care must be taken to avoid risks while handling.

4. Cost Comparison

Sodium Hypochlorite has a lower cost per unit than calcium hypochlorite, but it also has less available chlorine. Sodium hypochlorite is more economical for consistency and high volume, short-term use, because you will need an abundance of it to achieve the desired disinfecting effect.  

Calcium Hypochlorite may be more expensive, but in its concentration, you need less. Because it has a higher amount of available chlorine, less calcium hypochlorite is needed to achieve similar disinfection results. Due to this aspect of concentration it may be cost-effective long-term, especially in applications where the product is used less often.

Advantage: Sodium hypochlorite is more economical for regular daily high volume disinfectant use, calcium hypochlorite is more efficient since the disinfectant is concentrated with available chlorine to sanitizing doses for long-term lesser frequency of use.

5. Environmental and Safety Considerations

Sodium Hypochlorite can corrode material and release chlorine gas in some conditions. If sodium hypochlorite is exposed to acids or heat, toxic chlorine gas can be released so it can pose a health and safety threat. There is a degree of care that must be taken in the handling and storage of sodium hypochlorite to reduce the risk of an accidental release, especially in small, confined spaces.

Calcium Hypochlorite is more reactive and can ignite easily if you mess up. Although Calcium Hypochlorite has a higher oxidized potential, it is very reactive with organic materials and certain metals. This reactivity can be a significant safety hazard, and precautions should be taken while they are stored and applied.

Advantage: Sodium hypochlorite is usually safer if properly stored and in the right containers; however, calcium hypochlorite typically has stricter procedures with additional handling and safety steps required to limit an accidental release.

Buying Considerations for Procurement Teams

When choosing between sodium hypochlorite vs calcium hypochlorite, consider:

• Required chlorine dosage
  
• Storage capacity and infrastructure
  
• Frequency of use
  
• Application method (manual vs automated)
  
• Logistics and supply chain availability
  
• Wastewater neutralisation requirements
  
• Budget constraints
  

Conclusion

When selecting sodium hypochlorite or calcium hypochlorite, it will ultimately depend on your industrial application. Sodium hypochlorite should be your choice if you know you require rapid action, ease of dosing, a liquid handling system infrastructure, and short-term usage is planned, and that’s not a concern. On the other hand, if your application requires long shelf life, portability, or use at remote and/or emergency sites, choose calcium hypochlorite.

Elchemy can help you to source the right disinfectant for your business. Elchemy can offer solutions tailored to your needs, transparent pricing, and technical knowledge and service provided by chemists. Visit elchemy.com today to get your custom quote and take the stress out of purchasing chemicals.