TAGS: Sustainability / Natural Solutions
PFAS filters available for industrial waste usually consist of activated carbon (PFAS-Per- and polyfluorinated alkyl compounds). Since this is comparatively expensive, research is looking for alternative filter materials for the so-called “forever poisons”, whose dangerous residues only break down very slowly in the environment.
A team from the TU Bergakademie Freiberg is now proposing a bentonite clay modified with organic substances as a possible PFAS filter.
Using Organic Additives to Capture PFAS
In laboratory tests, the team led by chemistry professor Martin Bertau achieved a filter performance of up to 95 percent of perfluoroheptanoic acid (PFHpA) with the innovative material. PFHpA is a prominent representative of PFAS and is frequently detected in environmental analyses.
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The so-called organoclays are known for their good filter effect. We have newly investigated the modification of the material with the help of organic additives that are specialized in capturing the PFAS,” explains prof. Martin Bertau.
The chemists in the laboratory can introduce organic additives between the split clay layers like a deck of cards. “
The organic components look out from the clay components in such a way that the carbon atoms can interact with the PFAS,” explains Paul Scapan, who is studying the clay filters for his doctoral thesis. “
These carbon atoms have the ability to pick out and bind the PFAS molecules.”
The organoclay with the bound PFAS can then be ashed at at least 1,200 degrees, completely destroying the pollutants. Doctoral student Paul Scapan is now investigating which biodegradable molecules are best able to perform the gripping function for the various PFAS. If the additives are environmentally friendly, the ashed clay filter can be completely reused. “
The material is suitable, for example, for further processing into geopolymers as an environmentally friendly cement alternative,” says prof. Martin Bertau.
Cheapest Substitute to Activated Carbon Filter for PFAS Elimination
With the various additives, the filter effect of the innovative organoclays can be tailored specifically to numerous per- and polyfluorinated alkyl compounds. “
Compared to activated carbon filters currently available on the market, organoclays would cost around a tenth of the cost in terms of PFAS elimination performance, according to our current knowledge,” calculates Paul Scapan.
PFAS stands for per- and polyfluorinated alkyl substances. In industrially produced organic compounds, hydrogen atoms are replaced by fluorine atoms. This makes them extremely resilient. More than 10,000 solid, liquid and gaseous chemicals are PFAS, some of which are carcinogenic and harmful to health. They are used, for example, in waterproofing spray, functional clothing, medical products or non-stick coatings.
Dangerous residues of PFAS have been detected in the environment worldwide, accumulating in water, soil, plants and animals. PFAS are found even in the polar regions - and in the blood of children. Even with a planned future ban on PFAS in the EU, these substances have already entered the environment and only break down very slowly. The first substances in this group of chemicals have already been banned across the EU in recent years. A ban on all PFAS is now being discussed, which is currently being developed by the European Chemicals Agency ECHA.
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Source: Technological University Bergakademie Freiburg