Porphyrin-Grafted Poly(ethylene terephthalate) as a Reusable and Highly Selective Colorimetric Probe for Mercuric Ion...

Heavy metals are the most hazardous water pollutants, with severe health and environmental consequences. Among these, mercuric (Hg²⁺) ions are known to cause detrimental health issues in both humans and aquatic life. Due to this, several analytical techniques have been devised to detect and quantify the amount of this ion. However, most of these require advanced instrumentation, prolonged analysis time, and sample preparation. In this study, a low-cost and highly reusable colorimetric probe was developed by grafting porphyrin to poly(ethylene terephthalate) sheets using an oxazoline polymer as covalent adhesive. Upon exposure to trace amounts of Hg²⁺ in solution, the fabricated material visually transitioned from faint brownish pink to green by the complexation mechanism. Additionally, the transparency of this probe allowed the quantitative spectrophotometric determination of the Hg²⁺ concentration in aqueous samples. It was also shown that the material is highly stable, which can be reused for more than 50 times without significant decline in its performance, hence, making it suitable for the onsite monitoring of mercuric ion contamination in different bodies of water.