Better understanding the polymerization kinetics of ultrasonic-template method and new insight on sludge floc characteristics research.

As one of the core technologies employed in the field of sludge conditioning, flocculation has the ability to improve the sludge dewatering performance and reduce its volume and amount, which can accordingly result in lower costs in sludge transportation as well as subsequent disposal. Therefore, the development of new and high-efficiency flocculants is a hot topic in this field. The template copolymer (TPAD) of acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) was successfully synthesized through ultrasonic-template copolymerization using sodium-polyacrylate (NaPAA) as a template. The analysis of FTIR, 1H (13C) NMR, TG/DSC and SEM revealed that TPAD had a conspicuously significant cationic segmental structure. In addition, the results obtained from the analysis on the association constant (K M) and the kinetics of the template reaction indicated that the ultrasonic-template was a free radical initiated polymerization and the polymerization mechanism was I Zip-up (ZIP), and which once again confirmed the formation of the cationic fragment structure. This novel cationic fragment structure in TPAD greatly enhanced the ability of charge neutralization, electric patching, adsorption and bridging, thus improving the active sludge conditioning and dewatering performance (FCMC: 72.9%, SRF: 4.0 × 1012 m·kg−1, d 50 : 228.604 μm, D f : 2.02 at 400 r/min). The floc breakage and regeneration experiments showed that the cationic fragment structure in TPAD could make great contribution to the formation of large and dense floc structures, and these flocs were able to regenerate rapidly after breakage. Finally, it was also known that these large and compact floc structures were beneficial to the creation of more channels and voids, thereby decreasing sludge resistance (SRF) and improving sludge dewatering performance. Unlabelled Image • A cationic polyacrylamide (CPAM) with the cationic segment structure was successfully synthesized through ultrasonic-initiated template copolymerization method. • The copolymerization was demonstrated to follow (Ι) Zip template polymerization mechanism and free radical termination reaction through the analyses of association constant (M K) and polymerization kinetics. • All of the instrumental analysis results indicated the formation of the cationic segments in CPAM. • The cationic segments in CPAM could extremely enhance the ability of electrostatic patching and charge neutralization. • The cationic segment structure was more favorable for the regeneration of the broken flocs to form large and compact flocs which could withstand higher pressures. • The ultrasonic-initiated template copolymer showed an excellent performance in sludge flocculation. [ABSTRACT FROM AUTHOR]