Synthesis of starch-g-p(DMDAAC) using HRP initiation and the correlation of its structure and sludge dewaterability

• Published in: Carbohydrate polymers 2014-03, Vol.103, p.285-293
• Main Authors: Lv, Shenghua, Sun, Ting, Zhou, Qingfang, Liu, Jingjing, Ding, Huaidong
• Format: Article
• Language: English
• Subjects: Applied sciences; Carbohydrate Conformation; Cationic starch; Exact sciences and technology; Horseradish peroxidase; Horseradish Peroxidase - chemistry; Horseradish Peroxidase - metabolism; Natural polymers; Other industrial wastes. Sewage sludge; Physicochemistry of polymers; Pollution; Polyethylenes - chemistry; Polyethylenes - metabolism; Quaternary Ammonium Compounds - chemistry; Quaternary Ammonium Compounds - metabolism; Sewage sludge; Sludge dewatering; Starch - chemistry; Starch - metabolism; Starch and polysaccharides; Wastes; Water - chemistry
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2013.12.036

•A cationic starch was prepared by copolymerization of starch and DMDAAC with HRP initiation.•The molecular structure was built by grafting DMDAAC oligomer on starch backbone.•There are intramolecular balanced hydrophobic regions and hydrophilic regions.•The cationic starch with the unique structure can reduce sludge moisture content to 50.6%.•The cationic starch can construct a porous structure in sludge as the key for sludge dehydration. A new cationic starch used as a sludge dewatering agent was prepared by grafting copolymerization of degradation starch and dimethyldiallylammonium chloride (DMDAAC) using horseradish peroxidase/H2O2 initiation. Its chemical structure was characterized by FTIR, 1H NMR, 13C NMR, gel permeation chromatography, graft percent, and graft efficiency. The results indicated that its structure was built by grafting the DMDAAC oligomer onto the starch backbone as branched chains, with stronger hydrophobic regions and higher cationic degree. The specific resistance of the filtration and capillary suction time of the sludge conditioned with the cationic starch decreased distinctly, and the sludge water content could be reduced to 50.6% from 97.85%. The dewatering mechanism is proposed based on the surface tension, zeta potential, and microstructure of sludge, which involves stronger hydrophobic regions and cationic groups producing a porous structure within the sludge. The research results may provide valuable ideas for developing high-performance sludge dewatering agents.