Publication: Optimizing co2 capture and solubility in calcium chloride molten salt for carbonate formation
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Date
2025-08
Authors
Oasis, Khor En Zhe
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Abstract
The increasing global problem of carbon dioxide emissions due to industrial activities and the consumption of fossil fuels brings a significant environmental challenge. Molten salt electrolysis offers a compelling approach for carbon conversion due to its low cost, high ionic conductivity and the ability to produce valuable materials. This review highlights the impact of CO2 bubbling duration and flow rate on the efficacy of carbonate formation within a CaCl2−CaO (95:5 wt%) molten salt electrolyte at a constant temperature of 870 °C. The experimental design involved varying the bubbling duration (1, 2, 3, and 4 hours) at a fixed flow rate of 0.4 slpm, and altering the CO2 flow rate (0.2, 0.4, 0.6, and 0.8 slpm) for a fixed duration of 2 hours. Following the reaction, the extracted salt samples were then cool down in room temperature and were subsequently analyzed to characterize the formation of carbonate within the salt. The results revealed that optimal conditions for maximizing calcium carbonate formation were achieved at a bubbling duration of 2 hours and a flow rate of 0.4 slpm. XRD analysis confirmed the highest carbonate formation of 32 % under these conditions. EDX analysis corroborated this, showing an oxygen-to-carbon (O/C) ratio of 2.92 and a calcium-to-carbon (Ca/C) ratio of 1.65 at 2 hours, closely approaching the theoretical values for pure CaCO3. FESEM imaging showed morphological changes from stable calcite crystals at low flow to needle-like aragonite structures at higher flow.