Biogenic Silver nanoparticles Based Electrochemical Sensor for Selective Detection of Heavy Metal Ions (Pb2+ and Cd2+)

Abstract

Heavy metal ions and other harmful elements currently pollute the environment. Among heavy metals, cadmium and lead ions are two of the most common contaminants that affect the environment in both natural and anthropogenic ways. Protection of the environment requires proper determination and quantification of these metal ions. Thus, developing a proper sensor with less cost is the focus of the present research studies. Electrochemical sensors have attracted great attention for the determination of these hazardous elements. Herein, a sensitive electrochemical sensor modified by using green synthesized silver nanoparticles from Hagenia abyssinica plant extract provided a new opportunity for enhancing the electrocatalytic performance of the fabricated sensor. The synthesized Ag NPs were characterized using UV‒Vis, XRD, FTIR, DLS, and SEM techniques. The peak absorbance of the UV‒Visible spectra was at 423 nm, confirming the formation of Ag NPs. SEM analysis showed the existence of small spherical nanoparticles with a size range of 10 to 20 nm (average 17 nm). XRD analysis showed that the Ag NPs were face-centered cubic (fcc) with crystallite sizes of 14 nm, 12 nm, and 16 nm for metal to plant extract ratios of 1:1, 1:3, and 3:1 NPs, respectively. FTIR analysis was used to confirm the existence of various functional groups responsible for reduction and stabilization during the biosynthesis process. DLS describes the degree of uniformity and homogeneity of the nanoparticles. Cyclic voltammetry and square wave anodic stripping voltammetry techniques were used to evaluate the electrochemical behavior of the two metals at the modified electrode relative to the unmodified electrode. Moreover, experimental variables such as modifier % ratio, pH of the supporting electrolyte, deposition time, and deposition potential have been optimized. Based on an optimal condition, fairly good calibration lines were obtained to detect these two ions with a detection limit (LOD) of 2.7 µg/L for Cd (II) and 1.3 µg/L for Pb (II). Furthermore, the repeatability, reproducibility, and stability of the present sensor were determined with satisfactory results, and the possible effects of inorganic ions were investigated but did not cause any significant interference. In addition, the proposed method was utilized in the simultaneous detection of Cd (II) and Pb (II) metal ions in real matrix samples, which gave recoveries of 96.2 to 103.7% for cadmium and 97.5 to 104.2% for lead.