Development of Poly (safranine-co-phenosafranine)/GNPs/MWCNTs Nanocomposites for Quartz Crystal Microbalance Sensor Detection of Arsenic (III) Ions

Contamination of drinking water by heavy metals is extremely dangerous to human health. The formation of a quartz crystal microbalance (QCM) sensor for the rapid and portable detection of harmful heavy metals such as arsenic (As) ions in water samples is detailed in this work. Equimolar ratios of safranine (SF) and phenosafranine (Ph) copolymers (PSF-Ph) were synthesized via a chemical oxidative polymerization approach. The copolymer was modified with multi-wall carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) at different percentages (1, 3, 5, and 10%) to form nanocomposites of PSF-Ph/MWCNTs/GNPs. Thermal analysis of the nanocomposites revealed that the final polymer decomposition temperature (PDTfinal) values fell between 619 and 630 °C, and the nanocomposite with 10% loading exhibited the highest decomposition temperatures for T10, T30, and T50. The nanohybrid QCM sensor detected As(III) down to parts-per-billion levels based on the change in the oscillation frequency. The sensor was tested on water samples spiked with different concentrations of As(III) (0–20 ppb). A strong linear correlation (R2 ≈ 0.99) between the frequency shift and concentration with a low detection limit (0.1 ppb) validated the quantitative detection capability of the sensor. This QCM platform with an optimal recognition ligand is a promising field-deployable tool for on-site arsenic analysis in water.