Forever chemicals are in our landfills.

Per- and polyfluoroalkyl substances (PFAS) are highly persistent and toxic pollutants widely found in municipal solid waste (MSW) landfill leachate, often at concentrations orders of magnitude greater than those in wastewater treatment plant effluents, due to the disposal of consumer products in landfills. An estimated 600 kg/year of PFAS is released to landfill leachate in the United States (U.S.). Although the occurrence of PFAS in landfill leachates is well documented, there is a critical lack of simple, rapid, and in situ PFAS screening technologies suitable for routine monitoring at landfill sites. While laboratory-based analytical methods, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), are accurate, they are costly, time-intensive, and not suitable for real-time, on-site monitoring. With growing regulatory attention and proposed discharge thresholds for PFOS and PFOA, there is an urgent need for field-applicable, high-sensitivity detection technologies to support effective site assessment and treatment optimization. The primary objective of this project is to develop a multifunctional electrochemical sensor capable of detecting and quantifying PFAS in landfill leachate with both high sensitivity and selectivity, particularly in the low hundreds of ppt range (~100–400 ppt). The sensor will incorporate nickel oxide (NiO), polyaniline (PANI), and molecularly imprinted polymers (MIPs) to enhance performance. The main hypothesis is that modifying the working electrode (WE) of a commercial screen-printed carbon electrode (SPCE) with NiO, PANI, and MIPs will significantly improve sensitivity and selectivity for PFAS in complex leachate matrices. Specifically, NiO and PANI are expected to enhance electrochemical response to electroactive PFAS, while MIPs will enable selective recognition of non-electroactive PFAS compounds. Our preliminary tests using MIP-AuNP-modified SPCEs have demonstrated promising electrochemical responses to PFOA, achieving detection limits in the low hundreds of ppt, supporting the technical feasibility of the proposed approach. This project will deliver a cost-effective, portable, and field-adaptable sensor platform to improve environmental monitoring and early decision-making at PFAS-contaminated landfill sites.