Square-wave Anodic Stripping Voltammetric Method for Novelty Detection of Bismuth Extracted by Aqueous Two-phase Systems

In this work, a voltammetric sensor was used to monitor the concentration of bismuth extracted from an eutectic alloy of BiSn by aqueous two-phase system. This strategy is a sustainable and economically viable way of recovering bismuth from secondary sources. In the aqueous two-phase system (ATPS), biodegradable and non-toxic constituents dispersed in water (major constituent) are used. For monitoring the extraction, bismuth was determined in the upper phase of the aqueous two-phase system, which is rich in L35 copolymer, that causes attenuation of the electrochemical signal (anodic peak current). The electrode and operational parameters of the square-wave anodic stripping voltammetry (SWASV) were evaluated according to the deposition and stripping processes of the bismuth on the surface of the carbon paste electrode (CPE). It was observed a similarity between the electrochemical response of the bismuth extracted by ATPS and with the standard solution of bismuth. The proposed method shows a linear range of 1.29–8.94 μmol L⁻¹, limit of detection (1.07 μmol L⁻¹) and limit of quantification (3.57 μmol L⁻¹) and good precision (RSD%=2.27 %). This method was validated by comparing the results with Flame Atomic Absorption Spectroscopy (FAAS), using statistical tests to verify precision and accuracy. In conclusion, using a voltammetric sensor to monitor the concentration of bismuth extracted by ATPS proved to be an efficient method, in agreement with the concentrations of the referenced method.