Considering the influence on the downstream process of microalgae recovery by cell surface characteristics, in this paper , Microelectrophoresis and Hydrocarbon adsorption have been used for researching the surface electrical property and hydrophobicity of microalgae. The influence on surface characteristics of microalgae cell have been studied by the solution chemistry condition of pH and cationic flocculant. The results show that: The surface charge of microalgae cell is negative under the natural condition. The surface electrical property decreases with the declining pH when pH is less than 7 , but the isoelectric point is not observed until pH low to 1, while it changes little with the pH increased when pH is more than 7; Within the value of experimental pH, microalgae cells have strong hydrophobicity, which increases with the decreasing pH when pH is less than 7 and rises with the pH increased when pH is more than 9. It attains to the minimum value when the pH is about 8. The hydrophobicity of microalgae increases with anhydrous ferric chloride(FeCl3) when cationic flocculant (FeCl3) is added , but the trend became weaker. So the hydrophobicity can be improved by cationic flocculant, which can promote the microalgae cohesion.
