Dicyandiamide - Formaldehyde Decolorizing Synthesis And Applied Research

Treating the printing and dyeing wastewater is an important task with practical value. On the basis of surveying the resource, character and treatment approaches inside and outside of country of printing and dyeing wastewater, reaction of synthesizing dicyanodiamide-formaldehyde decolourizating flocculant modified by urea was studied systematically in this paper .The synthetic condition was optimized and the application performance of dicyanodiamide-formaldehyde polymer on printing and dyeing wastewater was also studied. Results showed the excellent performance of decolourization and removal of CODcr and operation condition of product easily controlled. It provided a new-type decolourizating flocculant with high efficiency applying in printing and dyeing wastewater treatment. The main contents of experiment were as follows:(1) By the main polymerizing reaction between dicyanodiamide and formaldehyde, the decolourizating flocculant was prepared and modified by urea .The results showed it is feasible to reduce producing cost by using urea and the optimatic dosage of urea and the condition of reaction were studied.(2) By the measurement of molecular weight, ion types and the function analysis of IR spectrum, the product was indicated to be a kind of oligomer with positive electricity function. The product showed the. character of electrolytical polymer and adapt to applying in wastewater treatment with fine physical property.(3) The rules influenced by many factors, such as reaction condition, reactant proportion, reaction temperature and time, was draw out. On the basis of selection of the range of experiment condition, the optimum symthetic condition was determined by the evaluation criterion of the removal of CODcr and decolourization. The optimization was to be: reaction time:3 hours; reaction temperature: 65 ; reactant proportion (dicyanodiamide:urea):ammonium chloride : formaldehyde =(0.714:0.286):0.9:1.4; rate of raising temperature: l~2 /min. In every factor that influenced the performance of product, the usage of formaldehyde and reaction temperature was the most importantfactor.(4) The performance of the removal of CODCr and decolonization of dicyanodiamide-formaldehyde polymer prepared in the optimum condition applying in reactive, acid and disperse dye-containing wastewater treatment was researched and the application character was found out.(5) The feasibility of dicyanodiamide-formaldehyde flocculant applying in practical printing and dyeing wastewater was studied. The rules influenced by technologic conditions such as dosage, pH value of wastewater and the use of composite agent were studied by single factor experiment .The result of treatment showed that the product was a kind of effective decolourizating flocculant applying in printing and dyeing wastewater with the best effect of treatment: CODCr remained 76.1 mg/L and decoloured almost.