Iron-clay-cyclodextrin composites were designed to adsorb and oxidize per-fluorinated compounds from water. Seven perfluorinated compounds (PFAS), ranging in chain size from C4 to C10, were chosen to test the efficiency of the novel materials. Clay montmorillonite decorated with nanoparticles of iron oxides served as a heterogenous Fenton catalyst, and the cyclodextrin molecules (α- or βCD) cross-linked with polyfluorinated aromatic molecules were used to accommodate adsorption of the pollutants and accelerate oxidation. The FeOx-clay surface was synthesized and characterized in terms of size, morphology, and activation properties. The nano-sized oxides were amorphous with both di- and tri-valent iron present, and the oxidant activation properties were significantly higher than magnetite and nano-magnetite decorated clays. The resulting iron-clay-β-cyclodextrin-polymer composites exhibited excellent adsorption of the long-chained PFAS (C7-C10). PFOA, for example, was completely adsorbed under the tested conditions - showing affinity to the βCD- polymer, not the iron-clay surface. To accommodate adsorption of the lower chained PFAS, the composites were further optimized in terms of cyclodextrin size and charge. PFAS degradation using H<sub>2</sub>O<sub>2 </sub>was followed by TOC, LC-MS and ICP. Degradation efficiency was inversely correlated to the chain length - meaning high MW PFAS were less prone to degradation at the adsorbed state. Still, PFOA (C8) degradation was highly efficient, reaching over 80% removal after one hour. Moreover, in the presence of other micropollutants (atrazine and bisphenol A) - a selectivity towards the per-fluorinated compounds was observed. In addition, the composites’ activity remained steady for five consecutive cycles with negligible damage to the materials - highlighting their durability and applicability. The ability to remediate a broad range of per-fluorinated pollutants, and the high overall removal exhibited by these novel materials, demonstrates the potential for future application in water remediation technologies.

Iron-montmorillonite-cyclodextrin composites as recyclable sorbent-catalysts for the adsorption and surface oxidation of per-fluorinated compounds

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.