Comparing PFAS analysis in batch leaching and column leaching tests

Area of Science:

• Environmental Science
• Geochemistry
• Analytical Chemistry

Background:

• Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Assessing PFAS mobility in soils is crucial for environmental risk evaluation.
• Laboratory leaching tests are standard methods for evaluating contaminant mobility.

Purpose of the Study:

• To compare the equivalence of batch and column percolation leaching tests for PFAS-contaminated soils.
• To evaluate the impact of different liquid-to-solid ratios (L/S) on PFAS release.
• To assess the suitability of current analytical standards for PFAS detection in soils and eluates.

Main Methods:

• Comparative laboratory leaching tests using four PFAS-contaminated soils.
• Batch and column percolation tests performed at L/S ratios of 2 L/kg and 10 L/kg.
• Analysis of 10 selected perfluoroalkyl and polyfluoroalkyl substances (PFAS) in soils and eluates.

Main Results:

• Column percolation tests showed smaller replicate differences compared to batch tests, indicating higher reliability.
• Batch tests tend to overestimate the release of shorter-chain PFAS, particularly carboxylic acids.
• Current DIN standard detection limits for soil analysis are insufficient for some perfluorocarboxylic acids (PFCA) and perfluorosulfonic acids (PFSA).

Conclusions:

• Column percolation tests are more representative for assessing PFAS mobility than batch tests.
• Overestimation of shorter-chain PFAS release by batch tests necessitates careful interpretation of results.
• Improved analytical methods and standards are needed for accurate PFAS quantification in contaminated soils and for mass balance calculations.