ONLINE ELECTROCHEMICAL MONITORING OF PRODUCTS’ CONCENTRATIONS DURING THE HBr AND KOH ELECTROSYNTHESIS BY ELECTRODIALYSIS

Abstract

In 2022, an estimated 62 billion kg of e-waste was generated, with an approximate value of $91 billion; however, the externalized and process costs of recycling make it economically unattractive. Our previous studies have demonstrated the possibility of electrochemically producing and regenerating the main reagents required for the Br₂/Br^- leaching system used in metals recovery from waste printed circuit boards. To facilitate the optimization of these processes, in this study, mathematical models were developed that enabled us to calculate concentration of KOH, H₂SO₄ and KBr from temperature and conductivity data and to determine the fitting parameters over the required concentration and temperature ranges using MATLAB’s Curve Fitting Toolbox. The developed models were compared against pre-existing ones and literature data and were validated using experimental data gathered using a complex computer-controlled setup. For KOH and KBr, the adapted models provide an almost perfect fit between the obtained calibration surfaces and literature and experimental data. Contrarily, for H₂SO₄, a more complex 10-parameter model was developed to properly fit data in the desired range of temperature and concentration. Using the obtained fitting parameters, the possibility of online and in situ monitoring of target electrolyte concentrations using inexpensive conductivity and temperature sensors was confirmed.