Estudo do eletrodo de vidro para o seu reaproveitamento em medições de íons Pb(II)

Abstract

This project is based on the theoretical aspects of Electrochemistry and Electroanalytics. It is worth noting that during the pandemic this project was developed, including the study of the pH electrode. The combined glass electrode (EVC) when it has its bulb (glass membrane) broken or cracked, or when the sensitive membrane is rendered useless by irreversible physical or chemical effects, completely loses its function, even if its electrical and electronic components are in perfect condition, so its reuse is a well referenced fact. First, the gelatinous membrane of the glass electrode was removed and replaced by a solid membrane for detection of Pb(II) ions, called the modified chemical electrode (MCE). Thus, the general objective of this project is to present an alternative of reuse for damaged glass electrodes to be applied in teaching and research activities. In the construction of the new electrode, the broken bulb (sensitive to H3O+ions) was completely removed and the internal hydrochloric acid solution drained. The procedure to be performed for the preparation of the solid membrane used for the construction of the Pb(II) EIS followed a replication of the work of Silva, Lehmkuhl and Alcanfor (2009) by precipitation of silver sulfide (Ag2S) and lead sulfide (PbS). Calibration curve assays and efficiency tests on the electrodes diagnosed a rapid wear of the EQM but a high sensitivity for Pb(II) ions in ionic strength adjusted medium as for the EVC a the nernstinian slope is within the acceptable standard in the optimum condition - value of 93% but the importance in the preservation mode of both the buffer solutions for calibration verification and the electrode membrane (EVC) is emphasized.