CO₂ absorption rate in an algal culture: Effect of pH

In a CO 2 ‐limited algal culture, grown in a tubular loop photobioreactor, the maximum rate of CO 2 absorption increased about 1.5‐fold when the culture pH value was increased from 6.5 to 7.5 with a fixed initial P CO2 . The mean volumetric CO 2 transfer coefficient ( K L a ) increased about 1.8‐fold. The bicarbonate ion concentration would be increased 10‐fold by the pH increase. The effect of pH on the absorption rate is attributed to changes in either the CO 2 diffusivity, the gas bubble size, or the CO 2 reaction kinetics at the gas/liquid boundary.