The persistent nature of perfluorinated and polyfluorinated alkyl compounds (PFAS) in aquatic systems, soils and other environmental components has galvanized a quest for quick and economical contaminant removal methods. Researchers in Germany are advancing the use of a clay made of bentonite modified with organic substances as a possible PFAS filter.

The bentonite is subjected to inorganic modification with titanium dioxide to obtain a pillared clay, and organic modification to obtain an organo-pillared-clay. The treated clay offers the possibility of increasing the adsorption capacity for PFAS from wastewater and exploits the catalytic mineralization of these “foreverA filter performance of up to 93% PFAS removal was demonstrated in the laboratory. Source: Andreas Hiekel, TU Bergakademie Freiberg chemicals.”

A filter performance of up to 93% of perfluoroheptanoic acid, a prominent representative of PFAS that is frequently detected in environmental analyses, was demonstrated in laboratory tests. The organoclay with the bound PFAS can then be incinerated at a temperature of at least 1,200° C, destroying the pollutants.

Investigations now focus on which readily biodegradable molecules can best capture various PFAS. If the additives are environmentally friendly, the ashed clay filter can be completely reused. With different additives, the filter effect of the innovative organoclays can be specifically tailored to numerous PFAS compounds with filters produced at considerably lower cost compared with available options.

Researchers from TU Bergakademie Freiberg, Forschungsinstitut für Glas/Keramik and Stephan Schmidt KG contributed to this development, which is described in the journal Chemie Ingenieur Technik.