New filtration system removes 98% of PFAS "forever chemicals" from water

A breakthrough filtration system developed by MIT researchers offers hope for removing harmful “forever chemicals” — dangerous pollutants that have plagued water supplies globally for decades.

These long-lasting pollutants, known as PFAS, persist in the environment and have contaminated water sources worldwide.

A recent study by the U.S. Centers for Disease Control found that 98% of people tested had detectable levels of PFAS in their bloodstream, highlighting the severity of the contamination.

Troublesome scale of PFAS contamination

PFAS chemicals are present in a wide array of products, including cosmetics, food packaging, water-resistant clothing, firefighting foams, and nonstick cookware.

In the U.S. alone, an estimated 57,000 sites are contaminated with these chemicals.

According to the Environmental Protection Agency, the cost of remediation to meet regulations limiting PFAS to less than 7 parts per trillion in drinking water could reach $1.5 billion annually.

Contamination by PFAS and similar compounds “is actually a very big deal, and current solutions may only partially resolve this problem very efficiently or economically,” noted Yilin Zhang, a postdoctoral researcher at MIT. “That’s why we came up with this protein and cellulose-based, fully natural solution.”

An accidental discovery

Researchers at the Massachusetts Institute of Technology, led by Zhang and Professor Benedetto Marelli, have developed a new filtration material made from natural silk and cellulose.

This hybrid material shows great promise in removing persistent PFAS compounds and heavy metals from water while offering antimicrobial properties to reduce filter fouling.

The research is published in ACS Nano and includes contributions from MIT postdocs Hui Sun, Meng Li, graduate student Maxwell Kalinowski, and recent graduate Yunteng Cao, who is now a postdoc at Yale.

“We came to the project by chance,” noted Marelli. Initially, the technology was developed for an unrelated purpose — to create a labeling system to counter the spread of counterfeit seeds.

Hybrid material with distinct properties

The team devised a method of processing silk proteins into uniform nanoscale crystals, known as nanofibrils, using an environmentally friendly water-based method at room temperature.

Zhang hypothesized that these silk nanofibrils might be effective at filtering contaminants, but early attempts with silk alone were unsuccessful.

The team decided to try adding cellulose, a readily available material derived from agricultural wood pulp waste.

By integrating cellulose into the silk-based nanofibrils and tuning the electrical charge, they developed a hybrid material with distinct properties, including remarkable contaminant removal and antimicrobial capabilities.

New water filtration contender

“These materials can really compete with the current standard materials in water filtration when it comes to extracting metal ions and these emerging contaminants, and they can also outperform some of them currently,” noted Marelli.

Lab tests demonstrated that the hybrid materials can remove contaminants more effectively than standard materials like activated carbon.

The team’s findings could serve as a proof of concept for larger-scale applications. As Zhang suggests, the material could first be used as a point-of-use filter, such as an attachment for kitchen faucets.

Eventually, it could be scaled up for municipal water filtration, pending thorough testing to ensure no risks of contamination.

One significant advantage of the material, said Zhang, is that both silk and cellulose are food-grade substances, making harmful contamination highly unlikely.

“Most of the normal materials available today are focusing on one class of contaminants or solving single problems,” noted Zhang. “I think we are among the first to address all of these simultaneously.”

Advanced water filtration systems

While this discovery is a promising first step, the team is already working on improving the material’s durability and exploring alternative protein sources to ensure scalability.

Enhancing the material’s lifespan and resistance to wear will be crucial for its widespread application in real-world water filtration systems, especially in regions with heavily contaminated water sources.

According to Marelli, while silk proteins can be sourced as a byproduct of the silk textile industry, alternatives may offer lower-cost, more abundant solutions for global water filtration needs.

Therefore, alternatives such as plant-based or synthetic proteins are being considered, which could offer lower-cost, more abundant solutions for global water filtration needs without compromising performance or sustainability.

These alternative materials could also help expand the technology’s reach, ensuring that even regions with fewer resources can benefit from advanced filtration systems.

The full study was published in the journal ACS Nano.

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