Synthesis of cationic starch flocculant and its performance when treating coal mine wastewater

In view of the characteristics of high turbidity coal mine wastewater,a cationic starch flocculant which can be used for its treatment was synthesized through the following procedures: synthesizing starch(St)acrylic amide(AM) graft copolymer flocculant with St and AM as the material,ammonium persulfate and sodium hydrogen sulfite as the initiator;and then,modifying the St-AM graft copolymer with GTA as the cationic etherifying agent.The optimal synthesis condition for the said flocculant was determined through orthogonal test: the reaction time of graft copolymerization was 4 h,the dosage of St,initiator,GTA and NaOH were 5,1.4,2.6 and 0.24 g respectively,the mass ratio of AM to St was 4 ∶ 1,the reaction time of etherification was 2.5 h,the temperature was 70 ℃.A performance comparison between cationic starch flocculant compound PAC and present flocculation process was carried out,the influence of flocculant dosage,compound effect,temperature and pH value on flocculation effect were analyzed,and the application condition of cationic starch flocculant was finally determined.