Chromoionophoric probe decorated porous polymer monolithic scaffold as solid-state colorimetric sensor and concentrator for target specific capturing of ultra-trace copper and cobalt ions

The present work reports on the development of an affordable aqueous-compatible two-in-one solid-state sensor engineered through the systematic suffusion of a chromoionophoric probe onto the porous poly(BTM-co-EGD) monolithic scaffolds for the selective colorimetric sensing of ultra-trace Cu2+ and Co2+ that are of industrial importance and environmental nuisance. The structurally regulated dual pore poly(BTM-co-EGD) template offers a high surface area for voluminous/homogenous imbuement of the probe molecules in a frozen geometrical alignment. The intriguing properties such as surface morphology, pore dimensions, structural network, phase identification, purity/elemental composition and thermal stability of the polymer monolith and probe-inoculated sensor were studied using XPS, BET/BJH, HR-TEM-SAED, FE-SEM-EDAX, XRD, FT-IR and DTG analysis. The ion recognition efficacy of the sensor material is evaluated through naked-eye color transformations and UV-VisDRS-based analysis. The sensor imposes a vibrant color transitional from pale yellow (blank) to intense olive brown and dark reddish brown for Cu2+ and Co2+, respectively, due to stable ligand-to-metal charge transfer complex formation. The sensor imposes high sensitivity with a response linear range of 0-200 and 0-150 ppb, with a detection limit of 0.13 and 0.16 ppb for Cu2+ and Co2+, respectively. The sensor exhibits impressive workability in the pH range of 7.0-8.0, with 0.05 mmol/g probe coating onto the poly(BTM-co-EGD) template, with an enriched response of <= 50 s, using 4 mg of the sensor material. Upon practical testing with natural/ synthetic samples, the sensor executes stable characteristics with reliable and reproducible data (RSD <= 1.98 %). The proposed sensing methodology is simple, cost-effective and can be reused over eight sensing trails for the ultra-trace detection of Cu2+ and Co2+. The portable sensor has the potential for commercialization based on its effortlessness in real-time utility.