The role of zinc(II) in the absorption-desorption of CO2 by aqueous NH3, a potentially cost-effective method for CO2 capture and recycling.
The absorption of CO2 by aqueous NH3 solutions has been investigated at atmospheric pressure and 0 degrees C. The CO2 absorption is fast and occurs with high efficiency (88-99%). The maximum CO2-removal efficiency increases slightly with the NH3 concentration. Addition of zinc(II) salts (as chloride, nitrate or sulfate) to the NH3 absorbent solution increases the overall CO2-absorption capacity without appreciably affecting the removal efficiency. Stripping of pure CO2 from HCO3(-) solutions is achieved by adding the calculated amount of ZnII salts, which under ambient conditions lead to rapid release of about 30-35% of the initially captured CO2. At the same time, about 65-70% of the captured CO2 is transformed into solid basic zinc carbonates. The recovery of these valuable solid products and the release of only 1/3 of free CO2 at room temperature and pressure reduces the cost of the overall process of CO2 capture, making it a potentially attractive method for CO2 capture on a larger scale.
Mani
Fabrizio
F
Department of Chemistry, University of Florence, Firenze, Italy. fabrizio.mani@unifi.it
Peruzzini
Maurizio
M
Barzagli
Francesco
F
D000042:Absorption; D000641:Ammonia / Q000737:chemistry*; D001274:Atmospheric Pressure; D002245:Carbon Dioxide / Q000737:chemistry* / Q000302:isolation & purification*; D002254:Carbonates / Q000737:chemistry*; D011232:Chemical Precipitation; D003247:Conservation of Natural Resources / Q000191:economics* / Q000379:methods*; D003365:Costs and Cost Analysis; D012996:Solutions; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D017967:Zinc Compounds / Q000737:chemistry*
D002254:Carbonates; D012996:Solutions; D017967:Zinc Compounds; D014867:Water; D002245:Carbon Dioxide; D000641:Ammonia; C036650:zinc carbonate