Metallochromic electrospun nanofibrous membrane of a biopolymer hybrid for chromogenic identification of ferric

Metallochromic nanofibrous membranes for the detection of iron(III) in aqueous solutions were developed from a composite of polycaprolactone and polylactic acid (PCL/PLA) as the hosting material and tannin as an active detection probe. The reported sensor is simple, easy to use, quick, portable, and accurate. The coloration parameters showed that binding the ferric ions to the phenol hydroxyl groups of the tannin probe resulted in an obvious change in colorimetry from 409 nm (colorless) to 580 nm (purple), demonstrating a bathochromic shift. A direct correlation was monitored between the ferric concentration and the visible color change. A coordination complex formed between Fe 3+ and phenolic tannin provided the rationale for the detection of ferric ions. Transmission electron microscopic (TEM) analysis of Tannin/Fe 3+ complex nanoparticles indicated diameters in the range of 6-23 nm. An average diameter of 100-420 nm was revealed for the electrospun nanofibrous film. The detection range was determined as 0.5-125 ppm, with a detection limit of 0.5 ppm. The tannin-encapsulated PCL/PLA has shown high selectivity as compared to other metallic salts. The optimum conditions for identification of Fe 3+ were monitored in the pH range of 4.0-6.5. In comparison to other detection techniques, the present assay is advantageous in terms of environmental safety, simplicity, rapidity, low cost, and ease of operation.