Synthesis Of A Copolymer Based On β-CD And Its Application In Waste Papermaking Wet-end

With the increased use of recycled fiber as raw material and increased water systems closurein pulp and paper mills, although it is good to water saving and energy saving, but it brings ananother serious problem which is the increased amounts of dissolved and colloidal substances inprocess water. Which are almost comes from lignin, hemicelluloses, lipophilic extracts and thepapermaking additives. Most of DCS is anionic polymer, when present at sufficientconcentrations, DCS negatively affects the cationic additives, the run ability of the papermachine and impair the physical properties of paper. The best ways for removing detrimentalsfrom the process water is fixation of detrimental material (by the help of proper chemicals) andtheir removal with the paper sheet. But to most fixatives, they only had good removal efficiencyto colloidal material, therefore, the fixing agent which can Simultaneous removal of dissolvedand colloidal substances has been a challenging task. Based on this requirement, a polymerwhich contain cyclodextrin polymer and with cationic charge was synthesized. The trait of cavitystructure and lots of hydroxy to β-CD was used, so it can remove colloidal substance anddissolved substance the same time, and fixed them on finers. It will have a better effect toremove DCS.With DMF as solvent, triethylamine as acid binding agent, the monomer β-CD-A was obtainedafter the esterification between acryloyl chloride and β-CD, it was testified that the esterificationhad been successfully occurred through the Characterization of FT-IR spectra and1HNMRspectra, the process conditions of modification also was studied. The polymer C-CDP wassynthesized when copolymerization between β-CD-A and DADMAC with the typical redoxfree-radical polymerization in water. The results showed that the structure was consistent withthe theory of structure through the Characterization of FT-IR spectra and1HNMR spectra, thepolymerization conditions was studied through cationic charge and intrinsic viscosity.The C-CDP as a fixative to control DCS in waste pulp was studied, and had been comparedwith PAC, PEI. To C-CDP, PAC and PEI, the results showed that the drainage property wereimproved17.5%,14.81%,43.21%respectively, it can concluded that the C-CDP had the effect of flocculant. The productivity decreased4.57%when0.2%C-CDP was used. The removalefficiency of turbidity were98.67%,81.51%,97.55%respectively, it was indicated that theC-CDP had a better remove effect to turbidity. The C-CDP can remove dissolved substanceseffectively, because the cationic demand decreased97.10%when1%C-CDP was used, and theremoval efficiency of COD were48.17%,35.07%,36.12%respectively. When the pH of Slurrysystem was varied, the fixative PAC and C-CDP had a better application effect than PEI when inalkaline environment.Finally, the impact of C-CDP/CPAM/MMT system to control DCS in waste pulp was studied.When the dosage of C-CDP, CPAM and MMT were0.2%,0.1%and0.2%, the system had abetter Synergy effect to remove turbidity, cationic demand and COD. The zeta potential of wastepulp decreased with the system from single to ternary, the drainage property was improved45.06%, and the productivity was decreased4.57%. It was testified that the C-CDP/CPAM/MMTsystem had a better effect than C-CDP ana C-CDP/CPAM, so it will be a good choice for theretention and drainage aids in high DCS circumstances.