Nanocellulose-based systems for the removal of perfluoroalkyl compounds from water

Abstract

The contamination of drinking water sources with poly- and perfluoroalkyl substances (PFAS) is a cause for concern. These compounds have been linked to several health problems in humans, and thus there is an urgent need to develop sustainable removal technologies for PFAS remediation. Cellulose nanocrystals (CNCs) are derived from plants and offer a sustainable, green approach for the development of adsorbents due to their ease of modification. The modification of CNCs with glycidyltrimethylammonium chloride (GTMAC) and the lignin-based flocculant, Tanfloc, was used to prepare positively charged CNCs, while beta cyclodextrin (β-CD) was grafted onto CNCs to promote hydrophobic interactions between PFAS and β-CD. TF-CNC was incorporated into sodium alginate hydrogel beads for ease of adsorption and removal. Treatment of an anionic dye, methyl orange (MO), with the adsorbents resulted in a maximum adsorption capacity of 125.7 mg/g for β-CD-CNC, and up to 80% removal of 1000 ppm MO by GTMAC-CNC. TFSH-CNC and TFSG-CNC resulted in qmax values of 917.8 mg/g and 247.5 mg/g, respectively, while the qmax values of ALG beads impregnated with TF-CNC increased from 2.2 mg/g to 4.9 mg/g. Treatment of KPFBS with the adsorbents resulted in removal percentages ranging from 26.1 to 56.5%, indicating that chemical and physical modifications improve the adsorption capacity of CNCs for PFAS. Together, these results indicate that modified CNCs offer a promising template for the development of adsorbents for PFAS remediation from water sources.