REGENERATIVE CONTROL OF CO2 IN AIR BY CARBONIC ANHYDRASE

Previous studies in this laboratory proved the feasibility of enzymatically controlled CO2 removal from closed space capsule atmospheres by carbonic anhydrase in Tris solutions. In a follow-up program equilibrium data, capacity data, and mass-transfer coefficients were obtained for CO2 absorption enhanced twenty to thirty fold, to establish the technological feasibility of the process. The equilibrium concentration of 2.0 M Tris solutions with 1% carbonic anhydrase is 0.17 - 0.20 moles CO2 per mole Tris at 7.6 partial pressure of CO2 and at 10 C. The rate of desorption at 40 C and at reduced CO2 pressure is approximately twice as fast as the rate of absorption. Mass-transfer characteristics under dynamic conditions were obtained by the standard-disc method. At a gas/liquid ratio 40:1 and in nonturbulent liquid flow more than 60% CO2 removal was maintained for several hours. Based on these results, scale-up to man-sized system is possible. It is estimated that this system is competitive with the presently suggested more complex CO2 management subsystems. It has the flexibility of either a cycling or a continuous recycling operation, with high degree of safety and reliability, and minimum expenditure of energy. (Author)