| Summary: | 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 SO<sub>4</sub><sup>2−</sup> was 99.15%, while in the following carbonation process without filtration, only 69.61% of SO<sub>4</sub><sup>2−</sup> was removed due to the fact that CO<sub>2</sub> reacts with Ca<sup>2+</sup> ion in the solution, and thus leads to the production of CaCO<sub>3</sub> and SO<sub>4</sub><sup>2−</sup> ions in the solution. In the carbonation process without filtration, with the increase of CO<sub>2</sub> in the solution the removal ratio of SO<sub>4</sub><sup>2−</sup> further decreases. Thermodynamic simulation was effective in predicting the theoretical removal limits and helps in understanding and optimizing the removal process.
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