A groundbreaking advancement in environmental remediation has emerged from the laboratories of the German Federal Institute for Materials Research and Testing (BAM), promising a novel solution to one of the most persistent and concerning pollutants known today: PFAS, commonly referred to as ‘forever chemicals.’ These fluorinated compounds are widely used in everyday products due to their durability, heat resistance, and dirt repellence. Yet, their very stability renders them remarkably resistant to breakdown in the environment, accumulating in water, soil, and living organisms. Tackling the removal of PFAS from wastewater has long been a challenge, involving complex, energy-intensive filtration methods. However, a newly developed filter material, synthesized through an innovative mechanochemical process, offers remarkable potential to address this issue with unprecedented efficiency and environmental friendliness.
The innovative filters are constructed from covalent organic frameworks (COFs), a class of porous materials characterized by nanoscale pores just a few billionths of a meter in diameter. These tiny cavities can effectively trap PFAS molecules, physically capturing them to prevent contamination. What sets this approach apart is not only the filter’s nanostructure but also the groundbreaking mechanochemical synthesis method employed. Unlike traditional chemical manufacturing, which often relies on solvents and heating, this new technique uses a ball mill that grinds powders in the presence of minimal solvent volumes, initiating chemical reactions solely through mechanical energy and frictional heat. This process is notably sustainable, cutting down waste and energy use while producing highly functional materials.
At the core of the mechanochemical synthesis is a compact device roughly the size of a film canister, containing a small quantity of powder, a few drops of solvent, and two steel balls approximately the size of peppercorns. When the mill vibrates at high frequency—up to 36 times per second—the balls grind the powder, generating localized heat and pressure. These conditions trigger reactions that assemble the powders into complex, crystalline framework structures, forming the covalent organic frameworks required for effective filtration. This ancient yet sophisticated method, known as mechanochemistry, bridges a fascinating connection between historical medicinal practices and cutting-edge material science.
Real-time analysis of the synthesis process was made possible through the high-intensity, focused X-ray beams of PETRA III, DESY’s renowned X-ray source. By directing the X-ray beam into the grinding mill while it operated, researchers could monitor the crystalline transformations down to the second. As the ball mill engaged, diffraction patterns revealed diminishing signals from the initial starting materials and the concurrent emergence of the target crystalline frameworks. This direct observation enabled fine-tuning of the synthesis parameters, such as milling frequency and solvent quantity, to optimize the formation of the COF filters.
Through meticulous experimentation, the research group identified optimal synthesis conditions — a milling frequency of 36 Hz, with 266 milligrams of powder and 250 microliters of solvent — that resulted in the highest quality framework structures. Importantly, unlike many prior filtration materials, these new COFs contain no heavy metals, alleviating concerns about toxicity and environmental impact. This characteristic is of significant importance if these materials are to be scaled up for broader commercial use, aligning with global calls for green chemistry and sustainable industrial practices.
The implications of this work extend beyond laboratory success. Though industrial-scale manufacturing protocols have yet to be established, the future applications are tantalizing. Martin Etter, a physicist at DESY and co-leader of the research, envisions deployment in wastewater treatment plants, particularly those serving manufacturing sites producing PFAS chemicals. Such targeted integration could dramatically reduce environmental PFAS loading at the source. Furthermore, the prospect of embedding these filters directly into household water taps points towards a future where consumers might routinely benefit from PFAS-free drinking water, enhancing public health on a wide scale.
This breakthrough is a vivid demonstration of mechanochemistry’s renaissance within modern materials science. While mechanochemical processes undoubtedly have ancient roots—early pharmaceutical compounds were likely formed by grinding plant materials in mortars—their contemporary applications are pushing the boundaries of chemical synthesis. The mechanochemical approach in this research minimizes solvent usage and energy consumption, establishing a paradigm shift towards greener, more sustainable manufacturing methods suitable for a range of pharmaceuticals, catalysts, and functional materials.
Looking forward, the team anticipates further advances enabled by upcoming technological upgrades at DESY, particularly the PETRA IV upgrade. Scheduled as PETRA III’s successor, PETRA IV will produce much sharper, more precisely collimated X-ray beams that vastly increase temporal resolution. This capability will enable researchers to capture rapid, fleeting intermediate structures during mechanochemical reactions, which until now have been elusive. The enhanced temporal resolution—from one scan every ten seconds to potentially ten scans per second—could unlock new fundamental insights, accelerating the optimization of filter fabrication and related materials.
Such rapid, high-precision monitoring will also have broad implications across chemistry and materials science, extending beyond filtration technologies. It opens doors to real-time control of reactions, fine adjustment of parameters on the fly, and better understanding of reaction pathways that can lead to breakthroughs in multiple industrial processes. This synergy between advanced instrumentation, novel synthesis routes, and pressing environmental challenges exemplifies how cutting-edge science can translate into highly impactful solutions.
Ultimately, the successful synthesis of covalent organic frameworks using mechanochemistry as demonstrated in this study is a major milestone in the ongoing battle against environmental pollutants like PFAS. It heralds a future where problematic, persistent chemicals can be effectively captured and removed by materials that are themselves sustainable and non-toxic. This innovation melds centuries-old chemical wisdom with state-of-the-art technology, creating a blueprint for how mechanochemistry might continue to reshape sustainable materials development.
With such promising results published in the journal small, the research group sets a precedent for multidisciplinary collaboration. Scientists, engineers, and environmentalists alike will be watching closely as this technology progresses from bench to potential real-world application. As humanity grapples with persistent organic pollutants and their footprints on ecosystems and health, solutions like these offer hope—and a glimpse of a cleaner, safer tomorrow.
Subject of Research: Mechanochemical synthesis and application of covalent organic frameworks for PFAS filtration
Article Title: Mechanochemically Synthesized Covalent Organic Framework Effectively Captures PFAS Contaminants
News Publication Date: 18-Sep-2025
Web References: 10.1002/smll.202509275
Image Credits: Science Communication Lab for DESY
Keywords
PFAS, covalent organic frameworks, mechanochemistry, ball milling, water filtration, environmental remediation, sustainable materials, DESY, PETRA III, real-time X-ray analysis, green chemistry, environmental pollutants
