Self-sustaining carbon capture and mineralization via electrolytic carbonation of coal fly ash

This study presents a new electrolytic carbonation process to synergize the treatment of different waste streams generated by power plants, including fly ash, brine wastewater, and CO₂. The acidity generated by electrolysis of brine electrolyte directly liberates calcium from fly ash. The metal ions balance the OH⁻ produced at the cathode to form hydroxide, which then fixes CO₂ into high purity carbonate precipitates. Results show that electrolysis increased fly ash dissolution by 32.4% compared to the control with spontaneous dissolution of fly ash, and the carbonation process captured 89% more CO₂ and increased capture capacity from 9.75 to 18.42 kg-CO₂/t-fly ash in the NaCl electrolyte. The energy expenditure was 19.4–29.3 kJ/mol-CO₂, lower than that required for sorbent or solvent based post-combustion carbon capture. The process takes advantage of all waste streams generated on site and can consolidate traditionally separated treatment processes to save costs, produce energy and value-added products, as well as generate carbon benefits.