W2O7 decorated polyindole nanocomposites: A dual-function platform for efficient removal and electrochemical sensing of cadmium metal ion

Our research presents a simple approach for synthesizing W2O7 decorated polyindole nanocomposites for electrochemical detection and adsorptive removal of Cd(II) ions from water. In the adsorption experiments, various parameters including temperature (ranging from 303 to 333 K), initial pH levels (ranging from 2 to 10), interaction time, amount of adsorbent (from 0.32 to 3.2 g/L), and initial concentrations (from 20 to 110 mg/L) were examined to identify the optimum conditions. The results of these studies demonstrated that the removal efficiency of Cd(II) were obtained to be 93.02% at the optimum pH of 7. Detailed adsorption isotherm and kinetic studies reveal that Cd(II) removal follows the Langmuir isotherm and pseudo-second-order (P-so) kinetic model. The PI-W2O7 NCs exhibited an estimated maximum adsorption capacity of 41.32 mg/g for Cd(II). Adsorption-desorption cycle of the Cd(II) laden PI-W2O7 NCs was effectively performed using HCl as an eluent. To enable electrochemical sensing of Cd(II) ions by PI-W2O7 NCs, the cyclic voltammetry (CV) method was employed. Intriguingly, distinct electrochemical responses were observed in our experimental observations, which stemmed from the interaction between the target analyte and the surface of PI-W2O7. The optimized conditions for the detection of Cd(II) using PI-W2O7 NCs were determined to be a concentration of 150 ppb and a pH of 7. The sensitivity and limit of detection (LOD) for Cd(II) ions were determined to be 1.719 μA/ppb cm2 and 1.072 ppb, respectively. The exceptional properties exhibited by PI-W2O7 NCs position them as a promising solution for the simultaneous detection and elimination of Cd(II) ions from water sources.