Effect of Zeta Potential on Collision-Attachment Coefficient and Removal Efficiency for Dissolved Carbon Dioxide Flotation

Many researchers have studied the importance of zeta potential control for algae separation by flotation processes. This study focused on measuring and comparing the zeta potential of bubbles and algae (Anabaena spp.) at varying pH with and without chemicals, and simulating the flotation model to estimate the effect of the zeta potential on the collision-attachment coefficients and removal efficiency at pH ≥9. The findings of this study are as follows: (1) at pH 2-12, the zeta potential of CO₂ bubbles without surfactants ranged from -14.69 to -32.38 mV and the mean zeta potential of algae ranged from -16 to -31 mV. (2) Bubbles showed positive zeta potential values at pH <9 in the presence of a cationic surfactant, while negative zeta potential values increased in the presence of anionic and nonionic surfactants. Nonionic chemicals did not have a significant effect on the zeta potential of the bubbles. (3) Model simulation results at pH >9 showed the sensitivity of zeta potential and size of bubbles and algal particles on the collision-attachment coefficient and removal efficiency. Optimum algae removal was achieved with CO₂ bubble zeta potential between -0.5 and +2.5 mV at pH ≥9.