Photocatalyst-loaded Cellulose Paper Strip to Analyze PFAS

<jats:p>Per- and polyfluoroalkyl substances (PFAS)-contaminated water is a widespread problem. Low-cost methods and materials that reduce the need for expensive PFAS analyses are urgently needed. In this article, we demonstrate a photocatalytic paper strip designed for rapid PFAS detection and quantification through in situ defluorination. We embedded titanium dioxide (TiO2) into porous cellulose paper via alkoxide hydrolysis. PFAS-contaminated water is wicked through the embedded TiO2 within the strip and exposed to ultraviolet (UV) light for defluorination. The fluoride ions from defluorination migrate through the strip and interact with a dispensed indicator along the length of the strip. We quantified the interactions by capturing optical images and analyzing them using ImageJ software. Structural analyses, elemental mapping, optical transmittance, and surface-area measurements confirm successful TiO2 incorporation. Using perfluorobutanoic acid (PFBA) and perfluorooctanoic acid (PFOA) as representative short- and long-chain PFAS, we demonstrate parts-per-billion (PPB) detection limits for PFBA, PFOA, and total organic fluorine (TOF). To achieve these sensitivities, we have also optimized precursor concentration, which indicates rapid defluorination within thirty seconds, which we verified via electrical measurements. Our low-cost technology confirms how engineering paper strips can be used for defluorination, detection, and quantification of PFAS for field deployability.</jats:p>