Separation of Perfluorooctanoic Acid from Water Using Meso- and Macroporous Syndiotactic Polystyrene Gels

Area of Science:

• Environmental Chemistry
• Materials Science
• Water Treatment

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent, bioaccumulative, and toxic contaminants.
• Perfluorooctanoic acid (PFOA) is frequently detected in ground and surface water.
• Current water treatment methods face challenges in removing PFOA effectively.

Purpose of the Study:

• To develop and evaluate a novel adsorbent for PFOA removal from water.
• To investigate the adsorption mechanism and kinetics of PFOA onto a specific material.
• To assess the efficiency of the adsorbent in meeting regulatory standards.

Main Methods:

• Utilized a high surface area, meso- and macroporous syndiotactic polystyrene (sPS) wet gel.
• Conducted adsorption experiments at environmentally relevant PFOA concentrations (≤1 μg/L).
• Analyzed adsorption isotherms and kinetics, examining the impact of gel porosity and pore size.

Main Results:

• The sPS wet gel successfully removed PFOA to concentrations below the U.S. EPA's 2023 health advisory limit (4 ppt).
• A sigmoidal adsorption isotherm indicated a two-step adsorption mechanism, involving surface affinity and molecular aggregation.
• Adsorption kinetics were significantly influenced by the pore size and pore volume of the sPS wet gel.

Conclusions:

• Syndiotactic polystyrene (sPS) wet gel is a promising adsorbent for PFOA removal from contaminated water.
• The material's porous structure plays a critical role in its adsorption efficiency.
• This adsorbent offers a viable solution for achieving safe drinking water standards concerning PFOA contamination.