Eliminating PFAS Algae-Based Biochar Breaks Down Toxic PFAS in Water Tests

A new algae-based biochar material could offer a breakthrough in tackling PFAS pollution. Researchers report that a photocatalytic nanoreactor made from marine algae removes more than 97 percent of the toxic “forever chemical” PFOA from water, combining high efficiency, reusability, and easy recovery with a sustainable biomass-based design.

Researchers have developed a new algae-based biochar material that shows remarkable ability to break down perfluorooctanoic acid (PFOA), one of the most persistent and hazardous members of the PFAS chemical family. The new material combines advanced nanotechnology with sustainable biomass resources and may provide a promising strategy for removing difficult contaminants from water.

The study, published in Biochar, introduces a unique photocatalytic nanoreactor constructed from biochar derived from Ulva, a common marine algae. The material forms a cage-like structure that hosts iron oxide and zinc oxide nanoparticles. This design allows the material to both capture and chemically degrade PFOA, a contaminant widely used in industrial and consumer products such as textiles, electronics, and coatings.

PFOA is notoriously difficult to remove from the environment because of the strength of its carbon fluorine bonds, which makes it highly stable and resistant to conventional treatment methods. The chemical has been detected in drinking water, groundwater, sediments, and even remote regions of the planet, raising serious concerns about its toxicity and potential cancer risks. Recent regulatory standards for PFOA in drinking water have become increasingly strict due to these health concerns.

To overcome these challenges, the research team designed a novel nanoconfined structure that improves the efficiency of photocatalytic reactions. When exposed to light, photocatalysts generate highly reactive oxygen species that can attack and break down complex pollutants. However, these reactive species normally have short lifetimes and limited diffusion distances, which reduces treatment efficiency. The new cage-like architecture creates a confined reaction environment that allows these reactive species to form and interact with pollutants more effectively.

The newly developed material demonstrated exceptional performance. Laboratory experiments showed that the optimized composite catalyst removed more than 97 percent of PFOA from water within four hours. The catalyst also exhibited strong stability and could be reused multiple times without losing effectiveness. In addition, its magnetic properties allow it to be easily recovered from treated water using an external magnetic field, improving its practical applicability.

The biochar structure plays a crucial role in enhancing treatment efficiency. The porous material provides an extremely large surface area and helps disperse the nanoparticles, preventing them from clumping together. It also shortens the distance between reactive molecules and pollutants, allowing faster and more efficient degradation. The researchers found that the confined structure promoted the generation of several types of reactive oxygen species, further strengthening pollutant breakdown.

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“This study demonstrates how marine biomass can be transformed into a high-performance material for environmental remediation,” the researchers noted. “By creating a confined nanoreactor environment, we significantly enhanced the efficiency of photocatalytic degradation and opened new possibilities for sustainable water purification technologies.”

Beyond its strong degradation performance, the material also performed well under varying water conditions. The catalyst maintained high removal efficiency across a wide range of pH levels and in the presence of common dissolved ions, suggesting its potential suitability for real-world water treatment systems.

The findings highlight the growing importance of biochar-based materials in environmental engineering. By combining renewable biomass with advanced nanostructure design, researchers are developing cost-effective and environmentally friendly solutions for emerging contaminants.

The team believes that this work not only offers a promising approach for PFAS removal but also provides new insights into designing next-generation photocatalysts for water purification and environmental protection.

Journal Reference: Jing, H., Zheng, D., Du, H. et al. Cage-like ulva biochar confined synthesis of Fe₃O₄/ZnO heterojunction nanoparticles for synergistic adsorption and photocatalytic degradation of PFOA. Biochar 8, 11 (2026). https://doi.org/10.1007/s42773-025-00525-4

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