The Combined Action of Surfactant Mixture and Flocculants for Black Carbon Removal

<div><p>In this paper, two commercial surfactants with excellent performance nonionic fatty alcohol polyoxyethylene ether (AEO-9), and anionic sodium dodecyl benzene sulfonate (SDBS) were mixed in different mole ratios to enhance the solution's wetting ability and the flocculating efficiency of black carbon (BC). Results showed that when the mole ratio of AEO-9: SDBS was 1:7, and the concentration of the solution was 0.57 mM, and the solution obtained the lowest surface tension. Furthermore, the existence of AEO-9 in the surfactant mixture reduced the influences of temperature and polyelectrolytes with different electrical properties on the solution's surface tension. In the flocculation system, the flocculation behavior of BC suspensions by anionic polyacrylamide (PAM-A) and polyaluminium chloride (PAC) in the presence of a surfactant mixture were investigated. The results suggested that when BC suspensions were pretreated with the surfactant mixture, the existence of SDBS made the surface of BC own more negative charges. The flocculation ability of PAM-A was governed mainly by bridging. Addition of PAM-A could not get a higher flocculating efficiency in two addition way. When PAC was added into AEO-9-SDBS pretreated BC suspension solution, the electrostatic attraction and the charge neutralization between PAC and BC particles were enhanced significantly.</p> </div>