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Materials 2017, 10(3), 282; doi:10.3390/ma10030282

Improvement of Sludge Dewaterability by Ultrasound-Initiated Cationic Polyacrylamide with Microblock Structure: The Role of Surface-Active Monomers

1
Key Laboratory of the Three Gorges Reservoir Region’s Eco-Environment, State Ministry of Education, Chongqing University, Chongqing 400045, China
2
National Centre for International Research of Low-carbon and Green Buildings, Chongqing University, Chongqing 400045, China
3
College of Environmental Science and Engineering, Research Center for Water Pollution Source Control and Eco-remediation, Beijing Forestry University, Beijing 100083, China
*
Author to whom correspondence should be addressed.
Academic Editor: Reza Montazami
Received: 13 January 2017 / Revised: 6 March 2017 / Accepted: 7 March 2017 / Published: 13 March 2017
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Abstract

Cationic polyacrylamides have been employed widely to improve sludge dewatering performance, but the cationic units are randomly distributed in the molecular chain, which restricts the further enhancement of dewaterability. Common template technology to prepare block copolymers requiring a huge number of templates reduces the polymer purity and molecular weight. Here, we adopted the surface-active monomer benzyl dimethyl 2-(methacryloyloxy)ethyl ammonium chloride (BDMDAC) to synthesize cationic microblocky polyacrylamide initiated by ultrasound. The reactivity ratio of monomers suggested that novel cationic monomer BDMDAC had higher homopolymerization ability, and was thus more prone to forming a microblock structure. The statistical analysis of sequence-length distribution indicated that the number and length of cationic segments increased in the PAB molecules. In addition, the characteristic results of Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), and thermogravimetric analysis (TGA) provided evidence for the synthesis of copolymer with cationic microblocks. Finally, the results of dewatering tests demonstrated that sludge dewaterability was greatly improved by adding the synthesized novel flocculants, and the sludge-specific resistance to filtration, filter cake moisture content and residual turbidity all reached a minimum (68.7%, 5.4 × 1012 m·kg−1, and 2.6 NTU, respectively) at 40 mg·L−1. The PAB flocs were large, compact, difficult to break, and easy to regrow. Furthermore, PAB was more effective in the removal of protein from soluble extracellular polymeric substances (SEPSs). In summary, this study provides a novel solution to synthesize cationic microblock polyacrylamide for improving sludge dewatering. View Full-Text
Keywords: cationic polyacrylamide; surface-active monomer; sequence distribution; microblock structure; sludge dewatering; floc properties; soluble extracellular polymeric substances cationic polyacrylamide; surface-active monomer; sequence distribution; microblock structure; sludge dewatering; floc properties; soluble extracellular polymeric substances
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MDPI and ACS Style

Zhao, C.; Zheng, H.; Feng, L.; Wang, Y.; Liu, Y.; Liu, B.; Djibrine, B.Z. Improvement of Sludge Dewaterability by Ultrasound-Initiated Cationic Polyacrylamide with Microblock Structure: The Role of Surface-Active Monomers. Materials 2017, 10, 282.

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