Green and sustainable tannin-immobilized cellulose dipstick for metallochromic sensing of ferric cations

Investigation of chromogenic sensor which can selectively estimate ferric cations in aqueous environment with prospect to produce portable platforms is currently proposed. Herein, the chromogenic sensor (Tannic Acid@Filter Paper; TA@FP) was prepared via doping of tannic acid within filter paper to afford the excellent selectivity for ferric cations over various examined metal ions. The designed chromogenic sensor was applied for estimating ferric ions via turn-on detection, while, it could acquire a marked visible color shifting from white to purple hue depending on the total content of Fe (III) ions in the aqueous medium. Complete characterization of the designed sensor before and after its exploitation in estimation of ferric cations was systematically performed via different spectral and microscopic analyses. The functionalized TA@FP was quite sensitive for quantitative estimation of ferric ions with wide scaling linear concentration range of 10–190 ppm. Maximum sensitivity of the exploited platform was observed at very low concentration (10 ppm) rather than the higher concentrations. The correlation coefficient (R² = 0.99) was closer to unity. The prepared chromogenic sensor could be described as a simple and practical sensing tool for real-time quantitative and qualitative assessment of Fe (III) cations.