Saeidi, et al (2024) A FAIR comparison of activated carbonActivated carbon is a form of carbon that has been processed to create a vast network of tiny pores, increasing its surface area significantly. This extensive surface area makes activated carbon exceptionally effective at trapping and holding impurities, like a molecular sponge. It is commonly More, biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More, cyclodextrins, polymers, resins, and metal organic frameworks for the adsorption of per- and polyfluorinated substances. Chemical Engineering Journal. https://doi.org/10.1016/j.cej.2024.155456

Per- and polyfluorinated substances (PFAS) are persistent environmental pollutants that pose significant risks to human health and ecosystems. Due to their unique properties, such as oil and water repellence, and their strong carbon-fluorine bonds, PFAS are difficult to remove from water sources. This study compares the performance of several adsorbents—activated carbon, biochar, cyclodextrins, polymers, resins, and metal-organic frameworks (MOFs)—in adsorbing PFAS.

The research evaluates the adsorption coefficients (Kd) of 44 PFAS across different adsorbents, using data from over 500 studies. The performance of activated carbon (AC) and biochar (BC) stands out, especially for PFAS with more than seven carbon-fluorine (C-F) bonds. For these compounds, Kd values exceeded 10^7 L/kg, indicating high adsorption efficiency. In contrast, cyclodextrins, polymers, and resins were more effective for PFAS with shorter chains (≤ 4 C-F bonds).

The study found that adsorption behavior was influenced by molecular properties such as hydrophobicity and steric factors. Cyclodextrins, though less effective for long-chain PFAS, provided more consistent performance. Meanwhile, the adsorption performance of polymer-based adsorbents, resins, and MOFs was less predictable.

Additionally, the researchers developed a Random Forest Regressor model to predict PFAS adsorption on AC and BC. This model performed well, achieving over 90% accuracy in predicting adsorption, but similar models for other adsorbents were less effective.

The study highlights the complexity of PFAS removal and suggests that combining different adsorbents might be necessary to tackle diverse PFAS types in contaminated water.