Preparation Of Polycarboxylate-modified Cation Starch-based Flocculant And Its Application Performance

The flocculation method is useful for wastewater treatment,but available inorganic or synthetic polymeric organic flocculants have some defects such as secondary contamination and less active sites.Aiming at the disadvantages of traditional flocculant,the paper in order to enhance flocculant and biodegradable properties of adsorption site for the purpose,choose natural polymer material starch(St)as the main chain,and then select bio-based monomers itaconic acid(IA),using two-step compound polycarboxylate-modified cation starch-based flocculant CS-g-P(AM-IA).Otherwise,the physicochemical and structural properties of the products were studied by some characterization methods.At last,the product was applied to kaolin suspension and cationic crystal violet dye.The experimental contents and results show that:(1)Starch-based flocculant CS-g-P(AM-IA)’s synthesis was divided into two steps.Firstly,use corn starch(St)and 3-chlorine-2-hydroxypropyl trimethyl ammonium chloride(CTA)to react by water to synthesize polymerization modified cationic starch(CS),and single factor method was investigated respectively dissolved water,St:CTA quality ratio,reaction temperature and etherification reaction time on the influence of cationic degree and rotary viscometer.The second step is using the best cationic modified starch and the monomer acrylamide(AM)and itaconic acid(IA)to carry on the graft copolymerization reaction,through the target product was prepared by UV irradiation CS-g-P(AM-IA),and using single factor method respectively investigated the CS percentage of incoming material,AM:IA mass ratio,initiator concentration,p H,light time on the influence of grafting efficiency and rotary viscometer of CS-g-P(AM-IA)to determine the optimization of the preparation conditions.The optimal CS-g-P(AM-IA)rotational viscosity and grafting efficiency can be up to 27.76 m Pa·s and 80.9%,respectively.From this,it is determined that the polymerization product optimizes the synthesis conditions.(2)The solubility of St,CS and CS-g-P(AM-IA)was analyzed and compared.The experimental results showed that the solubility of starch based flocculant was improved after chemical modification,and CS-g-P(AM-IA)can dissolve in the range of p H2.0～12.0.FTIR and ~1H NMR were used to analyze the products.The results confirmed the successful preparation of CS and CS-g-P(AM-IA).TG-DSC analysis showed that the modified product CS-g-P(AM-IA)has good thermal stability,conducive to storage and use at room temperature.What’s more,SEM showed CS-g-P(AM-IA)had a rough surface structure and a lot of pore structure,which was beneficial to enhance the performance of its net trapping and scanning.(3)CS-g-P(AM-IA)was used to treat kaolin suspension wastewater.The optimal conditions for turbidity removal were explored by studying dosage,p H and sedimentation time on turbidity removal rate of kaolin suspension,and the flocculation mechanism was analyzed.The results showd that the cationic monomer CTA linked with CS-g-P(AM-IA)molecule enhances its adsorption capacity of electric neutralization.The addition of other monomers lengthens the molecular chain and enhances the performance of net capture and sweep.In addition,the turbidity removal effect of self-made flocculant CS-g-P(AM-IA)on kaolin suspension is significantly improved compared with that of commercially available polyacrylamide(PAM)and polyaluminum chloride(PAC),and it is more environmentally friendly than that of commercially available flocculant.(4)CS-g-P(AM-IA)was used to treat cationic crystalline violet dye wastewater.The optimal conditions for chroma removal were explored by studying dosage,p H value and initial concentration,and the flocculation mechanism was analyzed.The results showed that active groups on the CS-g-P(AM-IA)chain provide more active flocculation sites for dye particles,which enhance the decolorization ability of dye molecules.In addition,the decolorization effect of the self-made flocculant CS-g-P(AM-IA)on cationic crystalline violet dye is significantly better than that of the commercially available anionic polyacrylamide(APAM)and polyaluminum chloride(PAC).The abundant carboxyl groups on the molecular chain of the flocculant enhance the specific adsorption performance of the flocculant.