Designing Mesoporous Test Sticks for Measuring PFAS Concentrations in Water

Abstract: Water contamination through substances called per- and polyfluoroalkyl substances (PFAS) is a worldwide problem. Being able to measure the concentrations of PFAS in water is a first step towards beating this contamination. One alternative is to use a field test kit instead of extensive lab equipment to monitor the contaminated areas. This thesis has investigated the possibility of using amine-functionalized mesoporous carbon as adsorbent to develop a detection method based on adsorbing first PFAS and then dye in aqueous solutions. The non-adsorbed dye concentrations are depending on the amount of PFAS, and hence the colour intensity in the remaining solution is proportional to PFAS concentration. Mesoporous carbon with amine functional groups were chosen as specific adsorbents for PFAS because of its large surface area and high adsorption capacity. It has been shown that some colorants would react in a similar way as PFAS on sorbents and thus can be used as an indicator for the user. In the study, the two most common PFAS, PFOA and PFOS, were studied and Rose Bengal was the dye. The adsorbent’s morphology, pore structure and pore size was verified with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen sorption before being tested. Adsorption tests were performed using different PFAS concentrations and a dye solution range in order to find three things: the detection range, the ratio powder/solution in order to see a difference, and the adsorption or saturation time for both PFAS and dye. This thesis concluded that even though the adsorbent was not as efficient as predicted, this method could be used for detecting PFAS concentrations down to at least 0.1 pg/ml and could be a possible approach for quick field tests in the future.