A new bismuth (Bi)-biopolymer (chitosan) nanocomposite screen-printed carbon electrode was developed using a co-electrodepositing technique for detecting multiple heavy metal ions. This sensor is environmentally friendly and was tested on real wastewater using square wave anodic stripping voltammetry (SWASV). It showed impressive detection limits of 0.1 ppb for Zn2+ and Cd2+, and 0.2 ppb for Pb2+ in stock solutions. The enhanced sensitivity of this sensor, compared to previous Bi nanocomposite sensors, is due to the role of chitosan. In real wastewater samples from mining sites and soil leachate, it detected Cd2+ at 0.4 ppb and Pb2+ at 0.3 ppb with relative standard deviations (RSD) from 1.3% to 5.6% (n = 8). Temperature changes did not affect its performance. Although Zn2+ was well measured in stock solutions, interference from Cu2+ in real samples suggested the presence of Cu-Zn intermetallic species. This sensor effectively monitors heavy metals in contaminated water without complex sample preparation or transportation to a lab.
Keywords: nanocomposite films; environmental sensors; co-electrodeposition; heavy metal ions; mining wastewater; soil leachates
