Precipitation of potassium-based carbonates for carbon dioxide fixation via the carbonation and re-carbonation of KOH dissolved aqueous ethanol solutions

Mineral carbonation is conducted with 3 g KOH dissolved in a 60-100 % ethanol aqueous solution to fix carbon dioxide (CO2) by precipitating potassium-based carbonates. The carbonation performance of the solutions differs according to the ethanol concentration in terms of the amount of absorbed and fixed CO2 because the reactions involved in carbonation are affected by the ethanol concentration. The KHCO3 and/or potassium ethyl carbonate begin to precipitate in higher than 70 % ethanol solution, and the amount is 4.15 g in a maximum in 90 % ethanol solution, with a fixation ratio of 78.4 % of CO2 of that which is chemically absorbed in the solution. Although the composition of the PEC increases according to the ethanol concentration, it increases drastically for carbonation between 90 % and 100 % ethanol solution. Thus, the ethanol concentration in this range strongly affects the selectivity of the reactions. Re-carbonation is repeated with ten times of recycling of the 3 g KOH replenished in the solution in the same manner for carbonation with the 90 % ethanol solution. Amount of 5.16 g of precipitates are generated on average for all re-carbonation. Thus, the CO2 can be fixed with a ratio of 77.0 % to the total amount of CO2 absorbed per re-carbonation. Considering these results, the process might be one or its assistive option to fix CO2 if the KOH can be readily supplied through regeneration within the process or recovery from waste at small scales.