Modification Of Chitosan And Its Application In Papermaking Wastewater Treatment

In the governance of various types of industrial wastewater discharges,papermaking wastewater，large amount of emissions, deep color and high levelsof organic pollutants，is harmful and intractable industrial wastewater to ourcountry, and about half of the raw organic matter is dissolved into the waste inpulping process of paper industry, which have resulted in environmentalpollution and waste of resources. Therefore, the flocculant plays a key role in thewastewater treatment process. Due to chitosan’ special molecular structure,molecular chain with amino, carboxyl and N-acetyl and other active groups,flocculation of papermaking wastewater is very well. However, the weakerdegree of cation, not sufficient adsorption capacity, a narrow range of pH valueetc limit its application in wastewater. This paper studies the synthesis ofmodified chitosan and its application in papermaking wastewater.（1） AM and DMC was grafted onto chitosan macromolecular chain bypolymerization in aqueous solution to modify chitosan of the polymerization.Polymerization temperature, initiator concentration, chitosan de-acetyl degreeand addition order of monomer were researched and the optimum reactionconditions were found by the orthogonal experiment. The best grafting efficiencyare87%under50°C,15min nitrogen,86%of the chitosan deacetylation degreeof, and0.06%of initiator concentration. Analysis of the orthogonal experimentshows that: the impact factor of reaction is the polymerization temperature,followed by the initiator concentration, and finally the degree of deacetylationand the monomer dosage order. IR, XRD and SEM results show that thecopolymerization occurred and generated modification of the CTS-AM-DMCcopolymer. Effluent transmittance of papermaking water and COD_Cr haveimpaved,and the paper strength is greatly improved when the product wasadded.（2） Chitosan and cationic polyacrylamide was cross-linked together by inversesuspension. Crosslinking agent concentration, chitosan dosage and cationicpolyacrylamide was researched, and found out the optimum reaction conditions by the orthogonal experiment. the best cross-linking degree is67%under0.6ml/g cationic polyacrylamide solution （solid content23%） and0.25ml/g crosslinkerformaldehyde dissolved in10mL of aqueous solution, and then cetain stirringspeed, span80solution,1ml, chitosansugar concentration,8%at cetaintemperature. IR, XRD, SEM and TG results show that the copolymerizationoccurred and generated modification of Chitosan derivatives. Effluenttransmittance of papermaking water and COD_Cr have impaved, and the paperstrength is greatly improved when the product is added.（3） Compared wastewater treatment effect of CPAM、 PFS-CPAM andCTS-CPAM flocculant, experiment shows that at pH6.0,1wt%of the PFS and120mg/LCPAM composite flocculant, COD_Cr value was8mg/L. The effectwas best under the same conditions. Effects of the wastewater compositeflocculant effect than a single flocculant.