Six organic acids in a process water of the paper industry

Importance of the topic

The control of organic acid levels in paper industry process water is critical for maintaining equipment integrity, optimizing treatment steps and ensuring regulatory compliance. Accurate quantification of low molecular weight acids supports process optimization and environmental monitoring.

Goals and overview of the application note

This application note describes a method for simultaneous determination of six key organic acids in paper mill process water. The targeted analytes are glycolic acid, formic acid, glutaric acid, acetic acid, propionic acid and butyric acid. The method employs ion exclusion chromatography with suppressed conductivity detection to achieve high sensitivity and selectivity.

Methodology and used instrumentation

The analytical workflow consists of minimal sample preparation and direct injection after cation removal.

• Sample preparation: Injection through H+ cartridge for matrix simplification
• Column: Metrosep Organic Acids 6.1005.200
• Eluent: 0.5 mmol/L perchloric acid
• Flow rate: 0.5 mL/min
• Suppressor: Membrane suppressor module using 10 mmol/L lithium chloride regenerant
• Injection volume: 20 µL
• Detection: Conductivity detection with suppressed background

Main results and discussion

The method delivered baseline separation of all six acids in less than 12 minutes. Quantified concentrations in the process water sample were:

• Glycolic acid 3.35 mg/L
• Formic acid 0.99 mg/L
• Glutaric acid 0.96 mg/L
• Acetic acid 723 mg/L
• Propionic acid 533 mg/L
• Butyric acid 24.5 mg/L

Carbonate and sulfide co-eluted but remained below quantification limits. The high levels of acetic and propionic acids reflect typical fermentation byproducts in pulp processing. Chromatographic resolution and sensitivity were sufficient to detect trace level analytes in a complex matrix.

Benefits and practical application

• Rapid simultaneous analysis of multiple organic acids
• Minimal sample preparation reduces analysis time
• High sensitivity and low detection limits for trace components
• Automated suppression lowers chemical consumption and maintenance
• Applicability for on-site process control and environmental compliance monitoring

Future trends and opportunities

• Integration of ion chromatography with mass spectrometry for enhanced selectivity
• Development of greener eluents and suppressor regenerants
• Miniaturized systems for online and inline monitoring
• Advanced column materials for improved resolution of structurally similar acids
• Artificial intelligence-driven data analysis for real-time process feedback

Conclusion

The described ion exclusion chromatography method provides a robust, sensitive and efficient approach for quantifying key organic acids in paper industry process water. Its ease of use and broad applicability make it an excellent tool for routine quality control and environmental monitoring.

References

No literature references were provided in the original application note.