(644e) Cellulose Nanocrystals (CNC)-Based Smart Filter Media for PFAS Removal from Contaminated Water

Aqueous per- and polyfluoroalkyl substances (PFAS) contamination is typically remediated by adsorption using granular activated carbon (GAC) or ion exchange (IEX) resins. Although GAC or IEX resins have higher adsorption capacities the adsorption performance is hindered by low intraparticle diffusion and costly regeneration. Therefore, there is an urgent need for high throughput, low-cost and sustainable adsorbents for point-of-use removal of PFAS from contaminated water. Nanocellulose-adsorbents are highly promising due to high surface areas and sustainable sourcing but have not been commercially implemented due to low removal efficiency and poor selectivity. Smart polymer, responsive to external stimuli such as temperature, be coated on nanocellulose adsorbents to increase/control the adsorption and desorption capacity and rate. The objective of the project is to develop high-capacity smart filter media for the treatment of PFAS-contaminated water using cellulose nanocrystals (CNC) derived from forest residue biomass (FRB). Our proposed smart system is based on the thermos-responsive polymer Poly(N-isopropylacrylamide) (PNIPAM) coupled to the CNC surfaces through a polydopamine (PDA) linkage. PNIPAM/PDA/CNC adsorbent surface properties will be characterized. Batch adsorption kinetics and isotherms of long/short-chain PFAS onto PNIPAM/PDA/CNC will be analyzed at above (40 ºC) and below (25 ºC) the lower critical solubility temperature (LCST) of PNIPAM (32 ºC). Thermo-responsive PFAS retention above LCST and desorption below LCST will be quantified. To enable continuous PFAS removal, PNIPAM/PDA/CNC adsorbent will be coated onto filter paper. Thus, stimulus responsive materials provide intriguing possibilities to design smart adsorbents for PFAS removal from complex solutions.