Synthesis And Application Of Ether-modified Dicyandiamide-formaldehyde Bleaching Flocculant

Cationized dicyandiamide-formaldehyde resin is a cationic polymer,andhas a good bleaching effect in reactive, acid dyes wastewater, low dosage cansignificantly reduce the raw water CODcr. Dicyandiamide-formaldehyde resin willrelease formaldehyde, the environment and the human body can cause great harm, andcontrary to environmental regulations.Therefore, the critical study of low-formaldehyderesin without affecting its bleaching flocculation became the subject of research.Theissue first with dicyandiamide, formaldehyde as the main raw material, ammoniumchloride synthesized modified dicyandiamide-formaldehyde resin. and then methanolas etherification agent synthesized etherified dicyandiamide-formaldehyderesin.Then further added to the formaldehyde scavenger, minimized formaldehydecontent in etherified dicyandiamide-formaldehyde resin and get the final modifieddicyandiamide-formaldehyde resin, applied to dyeing wastewater.The main contentof the test includes:1.First with dicyandiamide, formaldehyde as raw material, ammoniumchloride as modifier cation of dicyandiamide-formaldehyde resin.The results showedthat:Dicyandiamide and formaldehyde, the amount of material of1:2.2ratio, thereaction temperature is80oC, the reaction time was2h, the hydroxymethyl stagereaction conditions are optimized for the alkaline reaction conditions.The amount ofsubstance ratio of dicyandiamide and ammonium chloride is1:0.75, the reactiontemperature is60oC, the reaction time was1.5h, weak acid cation stage for optimizingthe conditions of the reaction conditions.2.On the basis of the synthesis step, the etherification with methanol, syntheticresins etherified.The results indicated that when the dicyandiamide and methanol was1:3.2, pH was1.8~2.7, at the temperature of50oC for4h, the content of freeformaldehyde in the dicyandiamide-formaldehyde resin was about1.2%,but the content of free formaldehyde in the etherified dicyandiamide-formaldehyde resinwas about0.3%. The decolorization of dicyandiamide-formaldehyde resin andetherified wdicyandiamide-formaldehyde resin ere88.50%and87.72%, respectively.The CODcrremoval rate were72.34%and71.03%, respectively. The content of freeformaldehyde of the etherified dicyandiamide-formaldehyde resin reducedconsiderably, but the flocculation effect decreased slightly.3.etherified Dicyandiamide-formaldehyde resin On the basis of etherifiedDicyandiamide-formaldehyde resin，from the urea, dimethyl acetamide, hydrogenperoxide Scavenger screened relatively good effect formaldehyde scavenger.The resultsshowed that:Using diethylenetriamine and30%H2O2complex as FormaldehydeScavenger，when the amount of diethylenetriamine (Scavenger amount of flocculant)was3%,30%H2O2dosage was2%, the ether Dicyandiamide-Performance andbleaching flocculation formaldehyde resin is relatively better.At this point etherifiedDicyandiamide-formaldehyde resin free formaldehyde content of0.123percent, therate of bleaching and dyeing wastewater, CODcr removal, ammonia removal rates were88.83%,71.02%,63.73%.Compared to etherification Dicyandiamide-formaldehyderesins without formaldehyde catcher, free formaldehyde content was significantlyreduced, bleaching and dyeing wastewater rates increased slightly, CODcr removal andammonia removal efficiency decreased slightly.4.Etherified modified Dicyandiamide-formaldehyde resin used in dyeingwastewater, the dosage of etherified modified Dicyandiamide-formaldehyde resin, pH,printing and dyeing wastewater, temperature and time on the flocculationflocculation.The results showed that: when the dosage of Etherified modifiedDicyandiamide-formaldehyde resin is300mg/L, pH of dyeing wastewater is weaklyacidic or alkaline, temperature dyeing wastewater is35oC, flocculation time is12h,modified Dicyandiamide-formaldehyde resin flocculation is better.