In the field of water treatment, hypochlorous acid (HClO), as a highly efficient and broad-spectrum disinfectant, is widely used in various water treatment scenarios such as drinking water, swimming pool water, and industrial circulating water. However, many users may not be aware that the disinfection effect of hypochlorous acid is not solely determined by the "chlorine concentration" indicator; the synergistic effect of pH value and concentration is the key factor determining its disinfection efficiency.
The Chemical Nature of Hypochlorous Acid: More Than Just "Chlorine"
Hypochlorous acid exists in a dynamic equilibrium system in aqueous solution:
Hypochlorous acid (HClO) ⇌ Hypochlorite (ClO⁻) + Hydrogen ions (H⁺)
This equilibrium is directly regulated by pH value, and the disinfection capabilities of HClO and ClO⁻ differ significantly—the disinfection efficiency of hypochlorous acid (HClO) is 80-100 times that of hypochlorite (ClO⁻).
pH Value: The "Control Switch" for Disinfectant Forms
The proportion of hypochlorous acid in different forms changes significantly under different pH conditions:
- pH 5.0-6.5 (Optimal Range): Hypochlorous acid (HClO) dominates (>90%), resulting in the strongest disinfection effect.
- pH 7.5: The proportion of hypochlorous acid drops to about 50%, and the disinfection efficiency decreases significantly.
- pH 8.5: The proportion of hypochlorous acid is only about 10%, and the disinfection capacity is greatly reduced.
- pH > 9.0: Hypochlorous acid is almost completely converted to hypochlorite, and the disinfection effect is negligible.
Practical Significance: Maintaining the pH of water bodies between 6.5 and 7.5 ensures both efficient disinfection and water comfort (especially for swimming pool applications).
Concentration: The "Strength Guarantee" of Disinfection Efficacy
While pH determines the proportion of active forms of hypochlorous acid, sufficient concentration is the fundamental guarantee for effective disinfection:
- Insufficient Concentration: Even with an ideal pH, it cannot effectively inactivate all pathogenic microorganisms.
- Excessive Concentration: May lead to increased corrosivity, increased byproducts, and higher operating costs.
- Ideal Balance: Adjust the hypochlorous acid concentration to the optimal range according to the degree of water pollution.
Synergy of Concentration and pH: A Disinfection Effect of 1+1>2
In actual water treatment, concentration and pH must be considered together:
- Case 1: A swimming pool met the chlorine concentration standard but had a high pH (8.2), resulting in poor disinfection and frequent user complaints.
- Solution: Adjust the pH to 7.2 while fine-tuning the chlorine concentration, solving the problem and reducing chlorine consumption by 15%.
- Case 2: A drinking water plant blindly increased the chlorine dosage to enhance disinfection.
- Optimization Solution: Adjust the pH... Adjusting from 7.8 to 7.0, while reducing chlorine usage by 20%, improves disinfection effectiveness by 30%.
With technological advancements, real-time monitoring and automatic adjustment systems have become standard features in efficient water treatment:
Intelligent Monitoring: An Inevitable Choice for Modern Water Treatment
Professional Advice: Four Steps to Optimize Disinfection Effectiveness
- Regular Testing: Establish a daily monitoring system for pH and residual chlorine concentration
- Precise Adjustment: Prioritize adjusting pH to the ideal range before optimizing disinfectant concentration
- System Evaluation: Consider comprehensive factors such as water temperature and organic load
- Professional Consultation: Seek technical support from professional water treatment companies for complex water quality conditions
Conclusion
In water disinfection, simply focusing on "chlorine content" is far from sufficient. Understanding and mastering the synergistic effect of pH and concentration is crucial to maximizing the disinfection potential of hypochlorous acid and achieving efficient, economical, and safe water treatment goals.
As a professional water treatment solutions provider, we are committed to helping our clients scientifically optimize their disinfection processes. Through precise control and intelligent management, we ensure that every drop of water meets the highest hygiene and safety standards. For professional assessment and optimization of your water system, please contact our technical team.