期刊
RSC ADVANCES
卷 5, 期 58, 页码 47031-47039出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5ra04526f
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资金
- NSERC
- Canadian Foundation for Innovation (CFI)
- Canada Research Chair program
- FPInnovations
Kraft lignin is currently combusted in the kraft pulping process. However, it can be modified to produce value-added products. The modification of kraft lignin using a combination of oxidation and sulfomethylation was studied in this work in order to produce sulfomethylated lignin. Oxidized lignin with a carboxylate group content of 1.95 meq g(-1) was obtained under the optimal oxidation conditions of 100 degrees C and 1 h of treatment with 20 wt% nitric acid concentration. Sulfomethylated lignin with a sulfonation degree of 2.05 meq g(-1) was obtained under the optimal sulfomethylation conditions of 100 degrees C, 3 h treatment, formaldehyde to lignin molar ratio of 1 : 1, sodium metabisulfite to lignin molar ratio of 0.5 : 1, and 4.0 wt% sodium hydroxide concentration. The sulfomethylated lignin with a higher charge density adsorbed more on cement particles and improved the fluidity of a cement paste more effectively than did commercial lignosulfonates. Adding 0.5 wt% of sulfomethylated lignin to the cement paste increased the fluidity of the paste from 65 mm to 200 mm, while the addition of 0.4 wt% of unmodified kraft lignin to the paste resulted in 70 mm fluidity.
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