Rapid, low-cost determination of Hg2+, Cu2+, and Fe3+ using a cellulose paper-based sensor and UV–vis method with silver nanoparticles synthesized with S. mammosum

As water effluents are often highly contaminated with metals, having a quick and cost-effective method of analysis is crucial. This study used the supernatant derived from the green synthesis of silver nanoparticles (AgNPs) with Solanum mammosum to detect mercury, copper, and iron with a low-cost cellulose paper-based sensor and a rapid colorimetric method applying ultraviolet–visible spectroscopy (UV–Vis). AgNPs in two precursor concentrations using silver nitrate, 1 mM (17.4 ± 9 nm) and 50 mM (and 22 ± 8.1 nm), were utilized to assess the efficacy of the analysis and removal of Hg 2+ , Cu 2+ , and Fe 3+ from contaminated water. Cellulose paper-based sensor showed limits of detection (LODs) for Hg 2+ of 2.46 and 123 μM using AgNPs at concentrations of 1 and 50 mM, respectively. For Cu 2+ , the LODs were 55 and 2750 μM, and for Fe 3+ , the LODs were 49 and 2470 μM using the respective concentrations. To differentiate and detect the cations with the naked eye, a potassium iodide and potassium ferrocyanide (1:1) aqueous solution was used, producing a yellow, pink, and blue color for Hg 2+ , Cu 2+ , and Fe 3+ , respectively. Additionally, the titration curves of Hg 2+ , Fe 3+ , and Cu 2+ were examined by UV–Vis using the supernatant liquid. The LODs for the UV–Vis method using AgNPs at a concentration of 1 mM were 1.50 μM for Hg 2+ , 10.7 μM for Cu 2+ , and 4.33 μM for Fe 3+ , while the LODs for AgNPs at 50 mM were 5.75, 27.6, and 15 μM for Hg 2+ , Cu 2+ , and Fe 3+ , respectively. Furthermore, these nanoparticles were utilized to assess the efficacy of the removal of Hg 2+ , Cu 2+ , and Fe 3+ from contaminated water. Removal efficiency with the solid 50 mM AgNPs was analyzed via flame absorption spectrophotometry; values over 95% were obtained for the three ions. The results underscore the effectiveness of a green synthesis approach to generating AgNPs, enabling efficient and economical cation analysis and water decontamination. The study used S. mammosum plant-derived silver nanoparticles (AgNPs) to detect metals in water using cellulose paper-based sensors and UV–Vis spectroscopy, demonstrating efficiency in the economical detection and removal of contaminants Hg 2+ , Cu 2+ , and Fe 3+ .