| The study on the flocculation and decolorization of simulated dyeing wastewater composed of single/double component dyes and their mechanism analysis were carried out by using flocculation method.Using 3 kinds of poly quaternary ammonium salt flocculants,i.e.cationic homopolymers with serial intrinsic viscosities,named as PDMC(1.71?6.39dL/g),PDM(0.78-3.47dL/g)and PDAC(2.19?6.39dL/g),the flocculation and decolorization jar tests using 50mg/L simulated dyeing wastewater of the single component dyes prepared separately by eight dyes from three types,i.e.direct red D-BLL and blue DL,disperse orange S-4RL,red S-5BL and blue H-GL,reactive red 3BF,yellow 3RF and brilliant blue KN-R,were completed.Based on the existing work of our research group,using the decolorization rate(color removal rate)and CODMn removal rate as the indexes,and the Zeta potential and floc formation as the analytical means,the flocculation and decolorization of simulated dyeing wastewater of single component dyes were studied.The CODMn removal rate and floc formation were especially focused on.Furthermore,the flocculation and decolorization of simulated dyeing wastewater,composed of double component dyes selected from above 8 kinds of dyes and with a total mass concentration of 50mg/L were preliminary investigated by adopting PDMC and PDM as flocculants and using the decolorization and CODMn removal rate as the indexes.The results were shown as follows.When using PDMC,PDM and PDAC to treat the simulated dyeing wastewater of single component dyes,the decolorization rates increased at first and then gradually decreased after their top points with the increase of flocculant dosages.Zeta potential analysis showed that the electricity neutralization played an important role in the treatment of simulated dyeing wastewater of all single component direct,disperse and reactive dyes.These results were basically consistent with the reports in literatures.Particularly,the experimental results of simulated dyeing wastewater of single component dyes showed that(1)the CODMn removal rates increased at first and then gradually decreased after their top points with the increase of flocculant dosages.The top points of decolorization rates were generally located in the dosages as same as the top points of CODMn removal rates did,although there were some exceptions.But the top CODMn removal rates were always lower than the top decolorization rates.The differences(about 20%)between the two removal rates for the disperse and reactive dyes were evidently greater than the differences(about 10%)between them for the direct dyes.(2)Among 3 kinds of quaternary ammonium salt flocculants,the CODMn removal rate of using PDAC to treat the simulated dyeing wastewater of direct dyes could reach the best,the CODMn removal rate of using PDMC to treat that of reactive dyes could reach the best,and the CODMn removal rate of using PDM to treat that of the disperse dyes could reach the best.(3)The floc formation analysis showed that the higher the intrinsic viscosity of a flocculant,the bigger the relative molecular weight of a kind of dye,or the more the numbers of sulfonic groups in a molecule of dye,the larger the size of flocs formed in ajar test.When using PDMC and PDM to treat the simulated dyeing wastewater composed of double component dyes,the experimental results showed that(1)the maximal decolorization and CODMn removal rates obtained by the treatment of simulated dyeing wastewater of double component dyes were similar to that by the treatment of the simulated dyeing wastewater of single component dye which with the higher mass concentration in the simulated dyeing wastewater of double component dyes.(2)When the mass concentrations of two dyes in the simulated dyeing wastewater of double component dyes were closed to equal,the maximal decolorization and CODMn removal rates of the simulated dyeing wastewater of most double component dyes were lower than that of any one in single component dyes,respectively,or were fallen in the middle of that of the two.There were exceptions only when treating the simulated dyeing wastewater of double component disperse dyes,and the decolorization and CODMn removal rates were slightly higher than that of each of the two disperse dyes.The above experimental results have complemented and improved the researches on flocculation and decolorization of using quaternary ammonium salt homopolymer flocculants to treat simulated dyeing wastewater composed of single component dyes.The effects of using quaternary ammonium salt homopolymer flocculants to treat the simulated dyeing wastewater composed of double component dyes were preliminarily investigated.It laid the beneficial experimental foundation for the study on the treatment of simulated dyeing wastewater of double component dyes and even actual dyeing wastewater. |
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