Abstract
In this work, hybrid colorimetric sensor membranes based on PET track-etched membranes and the copper-based metal-organic framework HKUST-1 were developed for ammonia detection. PET track-etched membranes with a pore diameter of approximately 300 nm were used as porous supports, while PVC/HKUST-1 nanofibrous layers were deposited onto their surface by electrospinning. The obtained PVC/HKUST-1@PET track-etched membranes exhibited a clear visual response to ammonia, changing color from light blue to dark blue after exposure. This colorimetric effect is attributed to the interaction of ammonia molecules with copper centers in HKUST-1 and possible changes in the coordination environment of copper ions. The sensing response was confirmed by FTIR spectroscopy, which revealed characteristic bands associated with N-H vibrations and ammonium species after ammonia adsorption. UV-Vis spectroscopy showed an increase in absorption intensity in the 576-610 nm region with increasing ammonia concentration. The membranes demonstrated a linear response in the concentration range from 0.001 to 0.8 M, with limit of detection of 0.0064 M. The repeatability of the sensor response was evaluated at an ammonia concentration of 0.01 M, giving a relative standard deviation of 24%. The results indicate that PVC/HKUST-1@PET track-etched membranes are promising materials for simple, visual, and rapid ammonia detection, with potential application in environmental monitoring and smart food packaging.