Multifunctional smart polymers and citizen science for a comprehensive approach to nitrate pollution: Curative and preventive strategies

Abstract

This work presents the development and evaluation of a multifunctional smart polymer (FNO₃) for the extraction and detection of nitrates in drinking water. A total of 250 tap water samples from various localities were analyzed, revealing nitrate concentrations that in some cases doubled the legal limit (up to 100 mg⋅L⁻¹). FNO₃, composed of 49.75 mol% NNZA monomer with high anion-exchange capacity, exhibited a maximum nitrate adsorption capacity (qmax) of 164 ± 5 mg⋅g⁻¹ , which is 3.6 times greater than that of commercial resins. The polymer demonstrated significant swelling in water (~2014 ± 152 %) and incorporated a sensing functionality via a fluorometric monomer, enabling visual detection when saturation occurs. Fluorescence response studies yielded a limit of detection (LOD) of 4.26 mg⋅L⁻¹ and a limit of quantification (LOQ) of 12.92 mg⋅L⁻¹ , values that are below the regulatory thresholds established by European and Spanish legislation for nitrates in drinking water. The material was tested through multiple adsorption-regeneration cycles using domestic saline solutions, maintaining stable efficiency. Interference studies indicated that carbonates present in hard water partially reduce adsorption effectiveness. Life Cycle Assessment (LCA) identified the structural materials and functional monomers as the main contributors to environmental impact, while reuse and polymer application offer environmental benefits due to nitrate recovery. Additionally, in vitro toxicological assays with HepG2 cells confirmed the absence of cytotoxicity, supporting the polymer’s viability for safe water treatment applications.