High-Performance ZIF-7@PANI Electrochemical Sensor for Simultaneous Trace Cadmium and Lead Detection in Water Samples: A Box–Behnken Design Optimization Approach

Abstract

This study presents the development of an innovative electrochemical sensor for the simultaneous detection of cadmium (Cd²⁺) and lead (Pb²⁺) ions in environmental samples. The sensor is developed based on a composite material of zeolite imidazolate framework ZIF-7 and polyaniline (PANI), referred to as ZIF-7@PANI, where ZIF-7 is rapidly synthesized at room temperature and polyaniline used to enhance the conductivity of the composite. Characterization via X-ray diffraction (DRX), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) confirmed successful synthesis. The composite was applied to a glassy carbon electrode (GCE) using drop-casting for heavy metal ion detection. Experimental parameters-including pH, incubation time, deposited quantity, and drying time-were optimized using the Box-Behnken design. Under optimal conditions, the ZIF-7@PANI/GCE sensor demonstrated a broad dynamic concentration range (0.002-1 µM for Pb²⁺ and 0.02-30 µM for Cd²⁺), with low detection limits (2.96 nM for Pb²⁺ and 10.6 nM for Cd²⁺). It also exhibited strong anti-interference properties and high recovery rates (85-110%), highlighting its potential for real practical applications.