Differences between the use of BTA•Na and BTA

Here’s a clear comparison between BTA•Na (Sodium Benzotriazole) and BTA (Benzotriazole) in terms of their properties, applications, and key differences:

1. Chemical Structure & Solubility

Property BTA (Benzotriazole) BTA•Na (Sodium Benzotriazole)

Chemical Formula C₆H₅N₃ (neutral molecule) C₆H₄N₃Na (sodium salt of BTA)

Solubility Low in water (~2 g/L at 20°C), soluble in organic solvents (e.g., ethanol). High water solubility (~500 g/L at 20°C).

pH Sensitivity Effective in neutral-to-acidic pH (pH 5–9). Stable in alkaline conditions (pH 7–12).

2. Applications & Performance

BTA (Benzotriazole)

Primary Use:

Copper/alloy corrosion inhibitor in cooling water systems, HVAC, and industrial closed loops.

Forms a protective chemisorbed film on metal surfaces (especially Cu, brass).

Advantages:

Excellent long-term stability in neutral/acidic systems.

Low volatility, suitable for high-temperature applications (up to 150°C).

Limitations:

Poor solubility in water requires pre-dissolution in solvents (e.g., alcohols).

Less effective in highly alkaline water (e.g., boiler feedwater).

BTA•Na (Sodium Benzotriazole)

Primary Use:

Water-soluble alternative for alkaline or high-pH systems (e.g., boiler water, oilfield injection).

Used where rapid dissolution is critical (e.g., batch treatment in pipelines).

Advantages:

Immediate solubility in water, no pre-dissolution needed.

Compatible with alkaline treatments (e.g., amine-based corrosion control).

Limitations:

May decompose in acidic conditions (pH <5), releasing free BTA.

Slightly lower thermal stability than BTA (max ~120°C).

3. Key Differences Summary

Aspect BTA BTA•Na

Solubility Low water solubility, needs solvents. Ready-to-use aqueous solution.

pH Range Best in pH 5–9. Best in pH 7–12.

Application Ease Requires pre-mixing. Direct dosing possible.

Cost Lower (but solvent cost adds overhead). Higher (pre-dissolved premium).

Thermal Stability More stable at high temperatures. Slightly less stable above 120°C.

4. When to Choose Which?

Use BTA if:

System pH is neutral/acidic (e.g., cooling water with CO₂ ingress).

High-temperature stability is critical (e.g., steam condensate lines).

Organic solvent carriers are acceptable.

Use BTA•Na if:

Operating in alkaline conditions (e.g., boiler water, alkaline cooling systems).

Rapid dissolution is needed (e.g., emergency corrosion control).

Avoiding organic solvents is preferred (e.g., environmental regulations).

5. Synergistic Blends

BTA + Tolytriazole (TTA): Enhances copper protection in mixed-metal systems.

BTA•Na + Molybdate: Alkaline corrosion inhibition for steel/copper combinations.

6. Environmental & Safety Notes

Both are low-toxicity (LD50 > 500 mg/kg) but require handling precautions (avoid inhalation).

BTA•Na is preferred in systems where wastewater discharge regulations limit solvent use.

Conclusion

BTA is the classic choice for neutral/acidic, high-temperature systems with copper alloys.

BTA•Na simplifies dosing in alkaline, aqueous environments but sacrifices some thermal stability.

For optimal results, match the inhibitor to your system’s pH, temperature, and solubility requirements. Conduct coupon tests to validate performance in your specific water chemistry.