Preliminary Study On Flocculation Decolorization Effect And Mechanism Of Disperse Dye Wastewater

The flocculation decolorization effect of inorganic flocculants (PAC, PFS, AS and FS) and poly quaternary ammonium salt flocculants (PDMDAAC, PDMC, PDAC and P(AM-DAC)) on disperse dyeing wastewater were studied in this paper.The decolorization rate and CODcr removal rate were used as testing index to study there action ships between the decolorization rate of different flocculants on simulated dyeing wastewater and the dosage. And the influence of pH value of wastewater, sedimentation time of flacculat, intrinsic viscosity and cationic degree of poly quaternary ammonium salt flocculants and disperse dye structure on the maximal decolorization rates was also analyzed and comparied.In addition, the Zeta potential of suspended particles was tested as researching techniques to analyze the mechanism of flocculation decolorization.The experimental results showed that the decolorization rate and CODcr removal rate both increased first with the increase of flocculant dosage and then decreased. However the continous increasesing of Zeta potential showed that there was electricity neutralization in the process of flocculation. When the sedimentation time within2h, the order of maximal decolorization rates for selected flocculants was:PAC and PFS>FS, PDMDAAC, PDMC and PDAC>AS and P(AM-DAC).The effective pH ranges of using inorganic flocculants (PAC, PFS, AS and FS) were respectivetly7-12,8-12,6-9and10-12.The influence of intrinsic viscosity of poly quaternary ammonium salt on decolorization rate was:the lower the intrinsic viscosity of PDMDAAC and PDMC, the higher the maximal decolorization rate.However the higher the intrinsic viscosity of PDAC and P(AM-DAC), the highter the maximal decolorization rate. The influence of cationic degree of poly quaternary ammonium salt on decolorization rate was:the higher the cationic degree, the higher the maximal decolorization rate. But when the cationic degree was greater than a certain value, it would make no sense for the enhancement of decolorization rate. The influence of structure of disperse dye on decolorization rate was:both inorganic and quaternary ammonium salt flocculants was employed for the treatment of three kinds of disperse dye wastewater whose molecular mass were different, the larger the molecular mass, the higher the maximal decolorization rate. It made no sense for inorganic flocculant to improve decolorization rate by extending the time of settlement.But different for ploy quaternary ammonium salt flocculant.The maximal decolorization rate of disperse orange increased from50%of2hours to90%of24hours. This paper the influence of dosage of sonts of flocculants, intrinsic viscosity of poly quaternary ammonium salt flocculant and structure of disperse dye on the decolorization ability of flocculants were also obtained, which would lay the foundation for further research for multicomponent simulated dyeing wastewater and actual dyeing wastewater on treatment process and mechanism.