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 (CO 2 ) 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 CO 2 because the reactions involved in carbonation are affected by the ethanol concentration. The KHCO 3 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 CO 2 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 CO 2 can be fixed with a ratio of 77.0 % to the total amount of CO 2 absorbed per re-carbonation. Considering these results, the process might be one or its assistive option to fix CO 2 if the KOH can be readily supplied through regeneration within the process or recovery from waste at small scales.