Re‐carbonation by recycling NaOH‐dissolved ethanol solution for carbon dioxide fixation

Re‐carbonation is investigated using NaOH‐dissolved ethanol. Five hundred mL of recycled filtrates is obtained from a previous carbonation in which 3 g of NaOH has been replenished and dissolved. CO 2 is physically absorbed at each re‐carbonation, and the amount decreases with increasing numbers of re‐carbonation repetitions. However, the amount of CO 2 chemically absorbed that was consumed in the production of precipitates, such as sodium ethyl carbonates (SEC) and NaHCO 3 , slightly increases. This is due to the slight water that accumulates with repeated re‐carbonation, which increases the generation of NaHCO 3 and the reaction time. The amount of precipitates and SEC composition decrease from the initial carbonation to the 22nd re‐carbonation, and the amount of CO 2 fixed in the precipitates is calculated as a maximum of 0.92 g of CO 2 /g of NaOH at the initial carbonation, which then decreases linearly to 0.56 g of CO 2 /g of NaOH at the 22nd re‐carbonation. However, 3.16 g of NaHCO 3 precipitates is repeatedly obtained from the 23rd re‐carbonation, maintaining an ethanol concentration of 90.33 wt.%. Thus, 0.55 g of CO 2 /g of NaOH is fixed in this region. Therefore, CO 2 can be fixed in the SEC and NaHCO 3 precipitates via re‐carbonation using NaOH‐dissolved ethanol.