Carbonic anhydrase promoted absorption of CO2 into potassium carbonate solutions

Abstract

AbstractThe effect of adding relatively small quantities of Novozymes NS81239 (NCA) carbonic anhydrase enzyme on the absorption of CO2 into a 30 wt% potassium carbonate solution has been investigated. Results demonstrated that at 40°C the addition of 2 μM NCA enhances the pseudo‐first‐order rate coefficient and thus the overall absorption process of CO2 into potassium carbonate solvents by around 30%. As the enzyme concentration is increased in the range of about 0 to 2 μM the enhancement increases according to a first order relationship, although further increasing the NCA concentration to 9 μM presented no greater catalytic effect than that from 2 μM. The rate coefficient for NCA catalyzed CO2 hydration measured in 30 wt% K2CO3 solution at 40°C in a wetted wall column is similar to that measured in dilute, neutral pH media at room temperature using stopped flow spectrophotometry. This work also demonstrates that, at a constant enzyme concentration, the overall absorption of CO2 into carbonate solvents increases with temperature from 40°C to 60°C, whereas above this range an increase in temperature proves to be counter‐productive.