Influences Of Cationic Surfactant DDMBAC On Coagulation

Surfactants are ubiquitous in natural water. Adsorption of surfactants with particles suspended modifies the surface characteristics of solid particles which are very important to coagulation. Hence studies were undertaken to explore the influence imposed by cationic surfactant, dodecyldimethylbenzylammonium chloride (DDMBAC), on coagulation mechanisms of colloidal particles in this paper. There are certain theory and practical application for the conclusion developed in this paper. In the first place, the cognition is deepened about colloid flocculation. In the second place, it can be used to improve the coagulation process for sewage containing cationic surfactants.Firstly, it is necessary to determine the variation of DDMBAC concentration during coagulant sedimentation. According to basic theory of statistical analysis, the analytical method of DDMBAC, which was based on modification, optimization and perfection of spectrophotometric method using acid blue 1#, was developed in this paper. Calibration graph obtained by the modified procedure for DDMBAC showed good linearity and its correlation coefficient was above 0.999. The coefficients of variation and average recovery of added DDMBAC were up to the mustard. The linear concentration ranges for batch determination of DDMBAC were 0.06~3.33mg/L. And the quality control system was developed for DDMBAC.The coagulating property of DDMBAC was discussed and the interaction model between DDMBAC and colloidal particles was developed. The influence of DDMBAC on coagulation using aluminum sulfate (AS) or polyaluminum chloride (PAC) was also investigated based on analytical method and interaction model. The result showed that mechanisms for the removal of turbidity from kaolin suspension by coagulation with DDMBAC were charge neutralization and bridging. The coagulating property of DDMBAC was comparable to AS and PAC. When AS or PAC was used as a coagulant, coagulation removal of turbidity was enhanced at low DDMBAC concentration (≤10mg/L), but hindered at high DDMBAC concentration (350mg/L). However, its effect on PAC was slightly smaller than that on AS. DDMBAC impacted the coagulation primarily through enhancement for charge neutralization and bridging of...