Abstract
Metal oxides NPs synthesized using orange peels extract (OE) and lemon peels extract (LE) and polyaniline (PANI) were used to modify the surface of screen printed carbon electrode (SPCE). The electrochemical responses of the various working electrode in potassium hexacyanoferrate (III) probe, and HCl electrolyte were evaluated using cyclic voltammetry. Integrating bimetal oxides NPs Cu2O/ZnO NPs with PANI on SPCE surface increased the electron transport properties of the sensors. The analytical performance of the SPCE treated with OE/Cu2O/ZnONPs/PANI composite, (OE/ZnO/Cu(2)ONPs/PANI/SPCE) and their counterpart LE/Cu2O/ZnONPs/PANI composite (LE/ZnO/Cu(2)ONPs/PANI/SPCE), on Cd-2+,Cd- and Hg2+ ions in 0.1 M HCl electrolyte, was investigated using square voltammetry (SWV). The limits of detection at concentration range of 2.2-12.0 mu M, and 0.17-1.5 mu M for Cd2+ were 3.04 ppb, and 1.08 ppb, while for Hg2+ at concentration range of 2.95-11.8 mu M, and 0.12-1.2 mu M, the values were 5.08 ppb, and 2.72 ppb at LE/Cu2O/ZnONPs/PANI/SPC, and OE/Cu2O/ZnONPs/PANI/SPC modified electrodes respectively. The sensitivities of 108 mu A/mu M, and 27 mu A/mu M towards Hg2+, and Cd2+ were realized at OE/Cu2O/ZnONPs/PANI/SPCE, despite the narrow linear range. Relative standard deviations (RSD) at 6.55 mu M concentrations for Cd2+ were 2.54%, and 6.50% for LE/Cu2O/ZnONPs/PANI/SPCE, and OE/Cu2O/ZnONPs/PANI/SPCE respectively, while the RSDs for Hg2+ at 2.94 mu M concentration were 2.92%, and 4.44% using LE/Cu2O/ZnONPs/PANI/SPCE, and OE/Cu2O/ZnONPs/PANI/SPCE respectively. At OE/Cu2O/ZnONPs/PANI/SPCE, there was no significant drop in the anodic peak current for both target trace metals, in the presence of interferences, like Co2+, Mg2+, Fe2+, Ni2+, Zn2+ and Cu2+, except for 11.39% drop of the stripping peak current of Cd2+ in the presence of Zn2+. Hence, the economy of nanotechnology and sensing could profit from the recycling of biomass wastes, which are frequently poorly managed.