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Wastewater high concentration of organic matter, color depth, high salt content, water pH changes, is one of intractable industrial wastewater. Bleaching dye wastewater treatment process is difficult. There are many types of bleaching agents, bleaching works best is condensation, but the handling of the high cost. In this paper, dicyandiamide and formaldehyde-based raw materials, under certain conditions, synthesis of dicyandiamide - formaldehyde decolorizing flocculant for dye wastewater treatment, get good results, prove dicyandiamide - formaldehyde Flocculant is a kind of development promising flocculant. Optimized through orthogonal experiment design dicyandiamide - formaldehyde Flocculant synthesis conditions for the processing of anthraquinone, azo dyes wastewater to good effect. Combined with the use of inorganic coagulant flocculant dye wastewater treatment, not only to get good results, but also greatly reduce the cost of processing. Decolorizing flocculant obtained by testing the optimal synthesis conditions are: reaction temperature 70 ℃ ~ 80 ℃, reaction time 3.5h, and the reaction of various raw materials molar ratio of n (DCD): n (formaldehyde): n (chlorine ammonium hydroxide): n (urea): n (sodium nitrite) is 1:2.4:0.7:0.1:0.05 modifier ammonium chloride as batch dosing. Basic properties of the product obtained: solids content 52%, density 1.247g/cm3, viscosity 550mP.s, pH of 6, the appearance of a pale yellow, transparent and viscous liquid better mobility. With DCD - formaldehyde Flocculant studied the effect of four kinds of dye wastewater and found that: a variety of decolorization rate of more than 99%, CODCr removal rate can reach 60% to 90%. Among them, disperse dyes decolorization best, acid dyes, reactive dyes decolorization effect, followed by a larger bromamine for intermediate solubility wastewater decolorization effect is relatively poor. Studied by orthogonal design decolorizing flocculant formulations and synthesis conditions, results showed that: in the synthesis process of adding a certain proportion of inorganic coagulants (mass fraction 10%), control of the reaction temperature is 40 ℃ ~ 50 ℃, reaction time 2 hours under the conditions of the preparation of the T-type composite flocculant has a good bleaching bleaching effect. Inorganic coagulants are ferrous sulfate (T1), ferric chloride (T2), PAC (T3), aluminum sulfate (T4) decolorizing flocculant is prepared to deal with reactive red X-3B and K-2BP dye wastewater decolorization rate of more than 99%, CODCr removal rate of nearly 80%. With T-decolorizing flocculant Ullmann condensation reaction of the actual production process wastewater (chroma absorbance value 25.74, CODCr 11954mg / L), the effect is good. When the dosage of 650mg / L, the decolorization rate of about 90%, CODCr removal rate of about 65%; when the actual wastewater pH lt; 8, the decolorization best results.
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