Novel carbon-based materials to remove hazardous 'forever chemicals' in water

The use of PFAS has been prohibited by international conventions due to their harmful effects on human health and environment. While recent scientific reports indicate that soils and rivers are contaminated with PFAS, there is a lack of effective and sustainable technologies to remove PFAS. In pursuit of United Nations sustainable development goal 6-clean water and sanitation for all, a team of researchers from Institute of Science Tokyo (Science Tokyo), Japan, led by Associate Professor Toshihiro Isobe from the Department of Materials Science, have turned their attention to carbon-based materials to remove PFAS from water.

The research team, led by Associate Professor Manabu Fujii from the Department of Civil and Environmental Engineering at Science Tokyo, synthesized a novel adsorbent-substance that can trap chemicals on its surface and developed a membrane distillation (MD) method to purify water contaminated with PFAS. Their research findings were presented as an invited lecture at the 23^rd International Symposium on Eco-Materials Processing and Design, held from January 13 to 16, 2025.

Sharing insights on the novelty of the research, Isobe commented, "By utilizing lignin -- a byproduct produced in the pulp and paper industry -- and glucose-a common sugar molecule, as carbon sources, our research group has employed sustainable materials for the development of PFAS-removal technologies. Moreover, the MD method used in our study, combining both distillation and membrane separation, offers an innovative strategy to remove PFAS from water."

The researchers leveraged the difference in the boiling points between water and PFAS to purify water contaminated with PFAS using the MD method. Additionally, the hydrophobic (lacking affinity for water), porous carbon-based separation membrane effectively rejected PFAS, allowing only water vapor to pass through it. In-depth experimental analysis showed that simulated contaminated water, containing perfluorooctanesulfonic acid (PFOS) at a concentration of around 500 ng/L after MD treatment, had a PFOS concentration of around 3 ng/L, which was below the global environmental standards.

Isobe concludes by outlining future plans to improve the MD purification method, "At present, the evaporation of simulated PFAS-contaminated water is achieved using heaters and depends on vacuum pumps to enhance the flow of water vapor. However, in the future, we aim to switch to a solar heating method to develop an electricity-free system that does not rely on heaters."

In addition to developing the novel MD method to purify PFAS-contaminated water, the research team conducted a series of experiments involving lignin-derived adsorbents. They found that minimal amounts of activated carbon (treated with zinc chloride at a 1:3 ratio) could remove up to 99% of PFAS within 10 minutes.

Overall, this study presents novel and sustainable carbon-based materials that could drive the development of future purification technologies to solve critical and persistent environmental issues.