Flexible and reusable carbon dot decorated natural microcline membrane: a futuristic probe for multiple heavy metal...

A flexible nano-engineered natural mineral (carbon dot doped natural microcline) based membrane (MCPV) has been developed, which can efficiently detect the presence of hexavalent chromium (Cr⁶⁺) and trivalent iron (Fe³⁺) ions in water by altering its fluorescence emission. Detailed characterization of the membrane was carried out using XRD, FT-IR spectroscopy, FESEM, TEM, and UV-Vis spectroscopy. Mechanical and temperature stabilities were also investigated. This new-generation sensor membrane is designed in such a way that it does not dissolve in water, keeping the water quality unaffected. The fluorescence studies were conducted at 414 nm and "turn-off" response was observed specifically for Fe³⁺ at 489 nm. A prominent red shift (530 nm) of the fluorescence maxima takes place when it comes to Cr⁶⁺. Figures of merit, such as LOD (8.7 μM for Cr⁶⁺ and 18.4 μM for Fe³⁺) and LOQ (29.1 μM for Cr⁶⁺ and 61.6 μM for Fe³⁺), were evaluated from the linear range (0-60 μM for Cr⁶⁺ and 0-30 μM for Fe³⁺) of the calibration curve (Stern-Volmer plots) showing high sensitivity of this sensing probe toward Cr⁶⁺ and Fe³⁺. Recovery and RSD calculations were done in various real-life water samples on intraday-interday basis to determine the accuracy of the sensor. This work validates the fact that the synthesized sensor membrane is capable of detecting these heavy metals in glutathione environment as well, which could be beneficial for early-stage carcinogen detection in living cells.