© 2018 by the authors. Licensee MDPI, Basel, Switzerland A lab-scale bubble-column scrubber is used to capture CO 2 gas and produce ammonia bicarbonate (ABC) using aqueous ammonia as an absorbent under a constant pH and temperature. The CO 2 concentration is adjusted by mixing N 2 and CO 2 in the range of 15–60 vol % at 55 °C. The process variables are the pH of the solution, temperature, gas-flow rate and the concentration of gas. The effects of the process variables on the removal efficiency (E), absorption rate (R A ) and overall mass-transfer coefficient (KGa) were explored. A multiple-tube mass balance model was used to determine RA and KGa, in which R A and K G a were in the range of 2.14 × 10 −4 –1.09 × 10 −3 mol/(s·L) and 0.0136–0.5669 1/s, respectively. Results found that, RA showed an obvious increase with the increase in pH, inlet gas concentration and gas temperature, while K G a decreased with an increase in inlet gas concentration. Using linear regression, an empirical expression for K G a/E was obtained. On the other hand, ammonia bicarbonate crystals could be produced at a pH of 9.5 when the gas concentration was higher than 30% and γ (=F g /F A , the gas-liquid molar flow rate ratio) ≥ 1.5.
Chen, P., & Yu, S. (2018). CO2 Capture and Crystallization of Ammonia Bicarbonate in a Lab-Scale Scrubber. Crystals, 8(1), 39. https://doi.org/10.3390/cryst8010039