Glycolic acid, formic acid, acetic acid and carbonic acid in a scrubber solution

Importance of the topic

Monitoring organic acids in industrial scrubber solutions is critical for process control, corrosion prevention and environmental compliance. Glycolic, formic and acetic acids are common by-products in amine scrubbing operations, while carbonic acid reflects CO₂ capture efficiency. Reliable quantification helps optimize solvent lifetime and safeguard equipment integrity.

Objectives and overview of the study

This work aims to develop and validate an ion exclusion chromatography method for simultaneous determination of glycolic acid, formic acid, acetic acid and carbonic acid in a di-isopropanolamine-based scrubber solution. The study evaluates selectivity, detection sensitivity and quantitation accuracy under typical operating conditions.

Methodology and Applied Instrumentation

A 1:10 dilution of the scrubber sample with ultrapure water was injected through an H⁺ cartridge to prevent matrix interferences. Chromatographic separation was achieved on a Metrosep Organic Acids column (6.1005.200) using 0.5 mmol/L sulfuric acid with 5% acetone as eluent at a flow rate of 0.5 mL/min. Conductivity detection followed chemical suppression (MSM suppressor with 10 mmol/L lithium chloride). A 20 µL injection volume ensured adequate sensitivity for trace-level acids.

Main results and discussion

The method provided baseline separation of glycolic, formic and acetic acids within 30 minutes. Carbonic acid overlapped partially with the system peak, leading to an estimated value. Sulfide (H₂S) was excluded due to variable peak response. Measured concentrations in the scrubber solution were:

• Glycolic acid: 20.5 mg/L
• Formic acid: 7.98 mg/L
• Acetic acid: 6.87 mg/L
• Carbonic acid: approximately 1.9 g/L (estimation)

Increasing acetone in the eluent to 15% was identified as a strategy to improve carbonic acid resolution.

Benefits and practical applications

The method offers:

• High selectivity for low-molecular-weight organic acids
• Minimal sample preparation and rapid turnaround
• Robust performance in complex amine matrices

This approach supports quality control in gas-treating plants, solvent monitoring and failure diagnosis arising from acid accumulation.

Future trends and potentials

Emerging developments may include coupling ion exclusion chromatography with mass spectrometry for enhanced specificity, adoption of greener suppressor chemistries and automated sample handling systems. Method extensions could target broader acid profiles and real-time process monitoring.

Conclusion

The presented ion exclusion chromatography method reliably quantifies glycolic, formic and acetic acids in amine scrubber solutions, while providing an approximate determination of carbonic acid. Its simplicity and adaptability make it suitable for routine industrial application, contributing to process optimization and environmental compliance.