Epoxy/Graphite Composite Electrode Modified with Recycled Silver Nanoparticles: An Eco-Friendly Strategy to Improve Lead Detection

In this work, silver nanoparticles (AgNPs) obtained from photographic waste were synthesized and electrodeposited via cyclic voltammetry using epoxy-graphite composite as an electrochemical substrate. Both electrodes, unmodified (Epoxy/C) and modified (Epoxy/C/AgNPs), were characterized electrochemically by electrochemical impedance spectroscopy (EIS), charge transfer constant (K0), and electroactive area. The modified electrode provided lower charge transfer resistance (275 omega), more kinetically favored electron transfer (K0 = 1.15 x 10-3 cm s-1), and a 1.7 fold increase in the active area compared to the unmodified electrode. Additional characterizations by scanning electron microscopy (SEM) and Raman spectroscopy confirmed the presence of AgNPs structures on the carbonaceous surface. As a proof of concept, Pb2+ was used as a model analyte, and a square wave anodic stripping voltammetry (SWASV) method was developed to evaluate the analytical performance of both electrodes. A wider linear range (4.0 to 40.0 mu g L-1), the appropriate limit of detection (1.2 mu g L-1), and a 6-fold increase in sensitivity were found using the modified electrode, suggesting that the AgNPs significantly contributed to the performance of the electrode. The proposed method was applied to three real water samples, where the Pb2+ levels varied from 11.3 to 19.5 mu g L-1. The proposed protocol (reuse of silver waste) has proven to be a powerful tool for improving the detection of Pb2+, which can be helpful for other electrochemical sensing applications in locations with minimal infrastructure.

Automated summary

Silver nanoparticles (AgNPs) obtained from photographic waste were synthesized and electrodeposited onto an epoxy-graphite composite substrate. The modified electrode showed improved electrochemical properties compared to the unmodified electrode, with lower charge transfer resistance, more kinetically favored electron transfer, and increased active area. The presence of AgNPs on the carbonaceous surface was confirmed by SEM and Raman spectroscopy. The modified electrode demonstrated enhanced analytical performance for Pb2+ detection, with a wider linear range, lower detection limit, and increased sensitivity compared to the unmodified electrode. The method was successfully applied to real water samples with varying levels of Pb2+. The reuse of silver waste provides an effective and low-infrastructure solution for electrochemical sensing applications.