Integration of Artocarpus heterophyllus peduncle adsorption and cyclic voltammetry for efficient detection and removal of Ni 2+ and Cd 2+ ions

Toxic heavy metals like Ni2+ and Cd2+ in water pose serious environmental and health risks due to their persistence and bioaccumulation. This study explores Artocarpus heterophyllus peduncle (AHP), an underutilized plant biomass, as sustainable and cost-effective adsorbent for removing these metals from water. Characterization of AHP using FTIR, SEM, XRD, BET, XPS, TGA/DTA, DSC, and Raman spectroscopy confirmed the presence of functional groups, mesoporous structure, and amorphous morphology. Batch adsorption at pH 6 and 25°C showed rapid equilibrium within 30 minutes, with maximum capacities of 82.99 mg/g (Ni2+) and 92.42 mg/g (Cd2+). Adsorption data fitted the Langmuir model, indicating monolayer adsorption, while pseudo-second-order kinetics suggested chemisorption. Multivalent ions like PO₄3−, CO₃2−, Fe2+, and Zn2+ significantly inhibited Ni2+ and Cd2+ adsorption due to competitive binding, whereas Cl−, SO₄2−, Mg2+, and Ca2+ showed minimal interference. Competitive bi-metal adsorption moderately reduced uptake but maintained overall efficiency. Thermodynamics confirmed that the process is spontaneous and endothermic. Cyclic voltammetry was used to monitor residual metals sensitively, and the adsorbent demonstrated excellent reusability. This work highlights AHP as an efficient and eco-friendly biosorbent, demonstrating the practical integration of cyclic voltammetry as sensitive tool for detecting and monitoring trace metals.