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A flocculant is the key in application of flocculation technology and it plays an important role in water treatment. The inorganic flocculants and synthetic organic polymer flocculant,that used for a long time, may lead to the problem of secondary pollution easily.An organic high polymer flocculent,as a kind of safe flocculent,is paid more and more attention.Corn cob is a by-product in agriculture and the output is great.Now most of it is burned.The chief components of corn cob are cellulose,hemicellulose and lignin.The hydroxyl in corncob have made it possible to prepare flocculants through graft modifying.In this paper,at first maleic anhydride is used to modify corn cob,and then the graft copolymerization of acrylamide onto modified corn cob is carried out .Finally a kind of flocculants of tricopolymer of corn cob,maleic anhydride and acrylamide is synthesized.The graft copolymer brings corn cob and polyacrylamide together,which both increases the value of corn cob,and improves ther biodegradability of flocculants.The best conditions of preparation of the graft copolymer flocculants is determined in this paper.In experiments of maleic anhydride modification,the factors influencing on the yield of the reaction ,such as the dosage of toluene,steeping temperature,steeping time,reaction time, reaction temperature,the dosage of maleic anhydride were inspected.The optimum conditions were determined by using a homogeneous experiment.It was found that the optimal conditions were:w(toluene):w(corncob)32:1,steeping temperature50℃,steeping time 6h,reaction time 20min, reaction temperature 70℃,w(maleic anhydride):w(corncob) 1:5.In graft-copolymerization experiments,factors affecting the flocculating activity of the product,such as reaction temperature,the dosage of linking agent,the dosage of monomer, the dosage of initiator,pH,were inspected.First single factor experiments were caught out ,then on the basis of single factor experiment,a homogeneous experiment was adopted.The results suggested that the best technical conditions were as follows:reaction temperature 60℃,the dosage of linking agent 1%,the dosage of monomer 600%,the dosage of initiator 0.5%,pH 7.The flocculation capability of products were studied.The influence of agitation conditions the dosage of the flocculant,pH,mineral salt on the flocculating activity ,using the kaolin suspension as a subject,is dicussed.The optimum conditions of treating the kaolin suspension were:the dosage of the flocculant 0.2g/L,pH 6,mineral salt CaCl2(1%) 3mL,the mixing speed 210r/min at the first four minutes,then slow the speed with 50r/min for 8 minutes, and finally placed it for 2 minutes.They were applied to the kaolin suspension,simulative dyes wastewater ,piggery waste water,aboratory waste water.The results suggested that the effect was better when the products were used in the kaolin suspension and piggery waste water.Using the piggery waste as a subject,the influence of agitation conditions,the dosage of the flocculant,pH,mineral salt on the flocculating activity ,is dicussed.The optimum conditions of treating the piggery waste water were the dosage of the flocculant 0.73g/mL,pH 9,mineral salt CaCl2 the mixing speed 172r/min at the first minute,then slow the speed with 93r/min for 9 minutes,and finally placed it for 2 minutes.Correlation of the infrared absorption strength and the flocculating activity of the products were analysed.The results indicated that there was a great correlation between the infrared absorption strength at wave number 1560cm-1 and the flocculating activity.It follows that the carbonyl group was closely related to the flocculating activity.
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