Dicyandiamide-formaldehyde Composite Flocculants Synthesis And Its Application Coking Wastewater Treatment

Coking wastewater is not only difficult to degradation of polycyclic aromatic hydrocarbons, and usually is a strong carcinogen, which causing serious pollution of the environment and being a direct threat to human health. Biological treatment technology with activated sludge process is commonly used in coking wastewater, but after the biochemical treatment the COD and ammonia nitrogen of wastewater is higher than the national standard.In this paper, in order to solve the coking wastewater by biochemical treatment is still not up to the national emission standard problems. Firstly, No.1flocculants was synthesized with dicyandiamide and formaldehyde as the main raw materials, ammonium chloride as catalyst, using the synthesis process by two steps, which catalyst is added in batches, the results of experimental show that:the batch addition of catalyst can effectively control the reaction heating rate. By optimizing the synthesis conditions, the optimal synthesis conditions when cast Jiamoerbi of dicyandiamide, formaldehyde,ammonium chloride is1:1.75:0.76and polymerization temperature is80℃and reaction time is3h.Secondly, with adding acrylamide,No.2composite flocculants is syntheticed, and the synthesis conditions were optimized, the optimum conditions flocculants when investment Jiamoerbi of dicyandiamide, formaldehyde, ammonium chloride, acrylamide is1:2:0.75:0.25and polymerization temperature is80℃and reaction time is3h. IR spectra indicate that the composite flocculants have large amounts of amine base, which keep the flocculants with positive charge, which has the function of adsorption and neutralization in the flocculation process and degrade wastewater pollution factor objective.Finally, the optimum process conditions of actual coking wastewater treatment were determined.when the dosage of No.1flocculants being3mL/L, and pH being7, the removal rate of COD is78.9%and the decolorization rate is92.5%which is best effect of wastewater treatment. when the dosage of No.2composite flocculants being2mL/L and pH being7, the removal rate of COD is83.5%and the decolorization rate is96.7%which is best effect of wastewater treatment. No.2composite flocculants flocculants is superior to that of No.1. Treated wastewater can meet the national discharge standards.