Magnetic multi-walled carbon nanotubes modified with surface-imprinted polymers for ultrasensitive electrochemical detection of trace-level nickel ions in groundwater

Magnetic multi-walled carbon nanotubes (Fe3O4@MWCNTs) were synthesized utilizing a solvothermal technique in this study, followed by the synthesis of Ni(II)-imprinted polymers (IIP) using a surface imprinting technique in this study. The materials' morphologies, structures, and chemical compositions were characterized using several techniques: Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The IIP was loaded onto a carbon-paste electrode using differential pulsed anodic solution voltammetry (DPASV) to form an electrochemical sensor (IIP-CPE) that could effectively identify Ni(II). The effects of the electrode composition, solution pH, deposition potential, and deposition time on the response of the IIP-CPE electrochemical sensor to Ni(II) peak currents were also investigated. The IIP-CPE demonstrated secondary linearity within the concentration ranges of 0.5–20 μg/L and 20–200 μg/L for Ni(II), with a detection limit of 0.27 μg/L under optimized conditions. It also maintained good selectivity, anti-interference, reproducibility, and stability and showed good accuracy in actual water samples. The constructed IIP-CPE has promising applications for the rapid monitoring trace-level Ni(II) in water bodies.