This work presents the synthesis, characterization, and evaluation of a hybrid fluorescent sensor based on electrospun poly(vinyl alcohol) (PVA) nanofibers functionalized with carbon quantum dots (CQDs) and rhodamine B (RhB) for the detection of Cd +2 . Two methodologies were used, the classic one in aqueous medium and a second methodology forming a nanofiber mat with the pva-rhodamine-CQD mixture to use it as a pre-concentrator and sensor. CQDs were hydrothermal synthesized from rice husk-derived cellulose The CQDs were dispersed in a 8% pva solution with 25 µM rhodamine b to build a nanofiber mat by electrospinning. The resulting solid platform acts as both a pre-concentrator and a fluorometric transducer. In solution, incremental Cd +2 addition (0–300 µM) induces progressive quenching of CQD (500 nm) and RhB (575 nm) emissions, following a Stern-Volmer behavior of tworegimes. Immobilization on the nanofiber mat improves sensitivity, yielding Stern–Volmer constants of Ksv = 1.84 ng −1 (520 nm) and 1.89 ng −1 (575 nm) with r 2 of 0.98. The system achieves detection limits of 0.078 ng −1 and 0.052 ng −1 at different wavelengths, rapid response (¡5 min), and requires minimal sample volume. These results show the basis for the development of a portable system for detecting Cd +2 with high sensitivity.
Castillo et al. (Sat,) studied this question.