Thermodynamic Simulations for Determining the Recycling Path of a Spent Lead-Acid Battery Electrolyte Sample with Ca(OH)2

By utilizing thermodynamic calculations, the possible removal path of spent lead-acid battery electrolytes was modeled. The process was divided into precipitation and carbonation processes. In the carbonation process, two scenarios were discussed, namely carbonation with and without pre-filtration of the precipitates resulted from the precipitation process. The results showed that in the precipitation process, the theoretical limit for the chemical removal of SO42− was 99.15%, while in the following carbonation process without filtration, only 69.61% of SO42− was removed due to the fact that CO2 reacts with Ca2+ ion in the solution, and thus leads to the production of CaCO3 and SO42− ions in the solution. In the carbonation process without filtration, with the increase of CO2 in the solution the removal ratio of SO42− further decreases. Thermodynamic simulation was effective in predicting the theoretical removal limits and helps in understanding and optimizing the removal process.