Reductive transformation of perfluorooctanesulfonate by nNiFe0-Activated carbon

Jenny E Zenobio; Mahsa Modiri-Gharehveran; Chloe de Perre; Chad D Vecitis; Linda S Lee

doi:10.1016/j.jhazmat.2020.122782

Reductive transformation of perfluorooctanesulfonate by nNiFe⁰-Activated carbon

J Hazard Mater. 2020 Oct 5:397:122782. doi: 10.1016/j.jhazmat.2020.122782. Epub 2020 Apr 21.

Authors

Jenny E Zenobio¹, Mahsa Modiri-Gharehveran², Chloe de Perre², Chad D Vecitis³, Linda S Lee⁴

Affiliations

¹ Department of Agronomy, Purdue University, West Lafayette, IN, 47907-2054, USA; Interdisciplinary Ecological Sciences & Engineering, Purdue University, West Lafayette, IN, 47907-2054, USA; Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
² Department of Agronomy, Purdue University, West Lafayette, IN, 47907-2054, USA.
³ Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA.
⁴ Department of Agronomy, Purdue University, West Lafayette, IN, 47907-2054, USA; Interdisciplinary Ecological Sciences & Engineering, Purdue University, West Lafayette, IN, 47907-2054, USA. Electronic address: lslee@purdue.edu.

PMID: 32361141
DOI: 10.1016/j.jhazmat.2020.122782

Abstract

Degradation of linear (L) and branched (Br) perfluorooctanesulfonate (PFOS) using nNiFe° particles supported on activated carbon (AC) and heat is demonstrated for the first time and with several lines of evidence. At 60 °C, PFOS degradation plateaued at 50 ± 6%, while at 50 °C, 94 ± 4.1 % PFOS transformed. The accelerated iron corrosion at the higher temperature is attributed to the lower PFOS transformation at 60 °C. However, at both temperatures, ≥ 97 % of the PFOS transformed was accounted for by the moles of fluoride generated. At 60 °C, PFOS degradation rates were estimated at 0.028 ± 0.003 h^-1 and fluoride and sulfite generation rates of 0.70 ± 0.165 h^-1 and 0.62 ± 0.157 h^-1, respectively, with no differences between L-PFOS and total Br-PFOS. Using time-of-flight mass spectrometry, some organic products were identified in the particle extracts from the 60 °C reaction. Products included single-bonded C8 polyfluoroalkyl sulfonates (F₁₆ to F₇) and alkyl acids (PFCAs, C₄-C₈) and one perfluorinated C₈ desulfonated product supporting both defluorination and desulfonation pathways. Most of the organic products were gone after the first 25 h. High PFOS mineralization using nNiFe°-AC technology warrants further investigation for its use in permeable reactive barriers.

Keywords: Defluorination; Degradation products; Desulfonation; PFOS destruction; nNiFe.