The Preparation Of Soda Lignin Graft Copolymer And Its Applicaiton Research

Lignin is one of natural organic compounds which is riched in natural resources and it is widely exist in plants. Lignin cellulose and hemicellulose constitute cellulose fibres. Lignin is the main components of the pulp and paper cooking black liquor. To extract lignin in black liquor and take advantage of, not only can solve the problem of black liquor treatment at the same time, it will achieve the goal of saving resource to obtain economic benefits. This research used poplar soda lignin as raw material, using water solution free radical polymerization method, has carried on the alkali lignin-acrylamide copolymer synthesis and it has applied in the research of sheet dry. strengthening agent. And using 2,3-epoxy propyl trimethyl ammonium chloride as cationic modification agent, the soda lignin was modified with it and the graft product was applied in kaolin flocculation of high turbidity wastewater research.Soda lignin-acrylamide copolymer study has showed that using poplar alkali lignin as raw material, acrylamide as monomer, potassium persulfate as initiator, in aqueous solution synthesized lignin-acrylamide graft copolymer (SL-AM) in the method of free radical graft copolymerization. FTIR, HNMR and elemental analysis were used to characterize the graft copolymerization product. TGA was used to characterize the thermal stability of the graft product. The results show that the optimum synthetic process conditions were, AM/SL molar ratio 7.5,3 wt.%(based on lignin) of K2S2O8, 90℃ of reaction temperature and 4h of reaction time. Grafted product yield reached 80%,353.26% of grafting ratio, the copolymer solubility in the aqueous solution of pH 7 was 100% (concentration of 1 g/L).The SL-AM graft copolymer was used as the sheet dry strengthening agent, the optimum technological conditions were as follows:6.5% of the SL-AM graft copolymer, pulp concentration 3%, the processing time of 3 min. When the beating degree was 27°SR, the breaking length, burst index and tear index increased by 31.3%,34.5% and 19.6%, respectively, and when the beating degree was 45°SR the breaking length, burst index and tear index increased by 10.3%,8.3% and 10.3% respectively.Soda lignin of cationic grafting modification research has shown that with the poplar soda lignin as raw material,2,3-epoxy propyl trimethyl ammonium chloride as the monomer, in alkaline conditions synthesized lignin-2,3-epoxy propyl trimethyl ammonium chloride (SL-EPTAC). The optimal process conditions for grafting material: EPTAC/lignin mole ratio 1.19, NaOH/EPTAC mole ratio 1.5,4 h of reaction time, 50℃ reaction temperature. Under this condition the graft ratio of the grafted product was 22.8%, and the grafted polymer solubility in the aqueous solution of pH 7 was 60% (concentration of 10 g/L). The SL-EPTAC product was characterized using elemental analysis, fourier transform infrared spectroscopy (FTIR), proton Nuclear magnetic resonance(’H-NMR) spectroscopy and thermogravimetric analyzer (TGA). SL-EPTAC grafted product used to treated kaolin high turbidity water has a very good flocculation effect. The optimum technological conditions were as follows:0.03 mg/L of the grafted product (1 g/L of kaolin solution), pH 5, incubation time 6 h, in this condition, the solution of turbidity removal ratio reached 90.5%. Microscope analysis showed that the SL-EPTAC making the kaolin particles flocculated gathered.