| Surfactant is a ubiquitous substance in aquatic environment owing to its popular usage. Because of the characteristics of enwrapping insoluble substances and forming colloids, it becomes the carrier of insoluble environmental hazardous substances to water body. To control its behaviors in disposal processes, the coagulation characteristics of anionic surfactant sodium dodecyl benzene sulphonate (SDBS) micellar solution with different dosage of Al salt were investigated. Based on several phenomena observed in samples with different pH, combined with the change of Zeta potential and surface tension measurements, the possible mechanism in each case was investigated. With the experimental evidences, the preferable stoichiometric proportion of Al and SDBS was discussed. Results show that, ① The preferable molar ratio of Al to SDBS is about 1∶3 in samples around pH 4, and about 1∶7 in those of pH within 5-9. ② Under the weak-acidic pH condition about 5-6, the equilibrium zeta potential is near zero and the peak value of surface tension is high. ③ When the molar ratio of Al to SDBS is raised to around 3, the coagulation reduce gradually. It can be thought that the stoichiometric relationship maybe exist between surfactant and coagulant to obtain the rational effect. |
