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.
