Novel remediation of per- and polyfluoroalkyl substances (PFASs) from contaminated groundwater using Cannabis Sativa L. (hemp) protein powder

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a group of environmentally persistent, man-made chemicals used in many industrial products and everyday consumer items. Of the plant proteins trialled, those of hemp (Cannabis sativa L.) were found to be far superior for PFAS removal than the next best protein, soy. The use of hemp plant proteins as a possible pump-and-treat solution to PFAS remediation from groundwater has been successfully demonstrated with very good removals (>98%) of the main contaminants of PFOS and PFHxS in approximately 1 h of contact time, with salinity enhancing removal of short chain PFAS. Changes to the secondary structure of hemp proteins was found using FTIR spectroscopy analysis and calculated based on the integrated areas of the amide I component bands. The amount of beta-turns increased from similar to 9.3% (control) to 44.1% (undiluted groundwater); with a decrease in random coils (25.6-8.6%); alpha-helix (193-8.6%) and beta-sheets (38.8-23.1%). These changes indicate that hemp proteins partially unfold during the reaction with PFAS with other FTIR evidence suggesting sorption at hydrophobic sites of the protein as well as with the side chains of the amino acids aspartic and glutamic acid. The absence of these side chains in soy protein, as evidenced from FTIR and amino acid analysis, being part of the reason why soy removed less (approx. half) of the Sigma(PFHxS + PFOS) load when compared to hemp. The findings reported here will lead to new, environmentally friendly methods for PFAS remediation. Crown Copyright (C) 2019 Published by Elsevier Ltd. All rights reserved.