Polyelectrolyte assemblies for electrochemistry detection of Pb2+

CELESTE MAGALLANES; LUCILA P. MENDEZ DE LEO; GRACIELA A. GONZÁLEZ

York

Congreso; #EnvChem2021; 2021

It is well known that the quality of water bodies all over the world is threatened by contamination with several components. Industrial activity releases a wide range of waste products into the environment, including heavy metals. 1 Of particular concern, lead (II) have been associated with health problems such as cancer, skin lesions, cardiovascular disease, and neurological disorders.2 Its persistence and bioaccumulation, makes it essential to develop functionalized interfaces and methods for its monitoring and retention in natural and industrial matrices. Monitoring industrial processes, such as battery recovery, is the route for effluent re-entry into the production process towards a greener industry. Among all the commonly used techniques for heavy metal detection, electrochemical methods have advantages because they are inexpensive, highly sensitive, easy to use, portable, and applicable for field monitoring of environmental samples.3 This work used electrochemical impedance spectroscopy (EIS) for final characterization of the system after the reaction between Pb (II) in an aqueous matrix and polyelectrolyte assembly constructed by drop casting technique on screen-printed electrodes. Polyallylamine (PAH) and polystyrenesulfonate (PSS) were used as conductive polymers to functionalize the surface with functional groups that would act as chelators for Pb(II). The influence on cation adsorption and the electrochemical signal obtained by metal ion reduction was evaluated. Characterization by attenuated total reflection (ATR) was carried out to evaluate the modification of the surface, its stability against treatment and the changes induced by the adsorption of lead cation. After undergoing various construction conditions, it was found that by performing three successive deposition of polyelectrolytes in a 1: 1 ratio and with 30 minute incubations, a treatment stable 5 µm layer was formed. A marked trend is achieved in the intensity of the reduction signal, since the lead concentration increases in the range of 0.5 - 2.5 mM. For the 0.5 mM solution, this equates to a retention of 4.5 ng / cm2. In addition, using the EIS technique, a linear correlation was found between the resistance to the transfer of charge of the film and the inverse of the concentration of lead ions.