Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic chemicals whose environmental persistence and aqueous mobility have raised significant human health concerns, increasing the demand for effective remediation technologies. Conventional granular activated carbon and ion exchange resin-based adsorbents exhibit PFAS removal capacities but suffer from slow adsorption kinetics, limited effectiveness toward short-chain PFAS, and energy-intensive regeneration requirements. This project proposes the development of a chromophore-functionalized nanoadsorbent based on cellulose nanocrystals (CNCs) derived from low-grade forest residue biomass for controllable PFAS adsorption and regeneration under ultraviolet-visible (UV-Vis) light. Spiropyran-functionalized CNCs are expected to enable tunable adsorption-desorption toward a broad range of PFAS through light-induced reversible modulation of surface wettability. The project will integrate advanced PFAS sensing technologies with adsorption studies to monitor PFAS removal and support optimization of the photoresponsive adsorbent. The project will synthesize and characterize the smart adsorbent, evaluate short- and long-chain PFAS adsorption performance, and assess regeneration efficiency and reusability. This study proposes the first application of photoresponsive CNC-based adsorbents for light-triggered PFAS capture and release, providing a novel strategy for regenerable and energy-efficient PFAS remediation while supporting the development of sustainable adsorbents from renewable and biodegradable CNCs produced from forest residue biomass.