UV-H2O2 Preparation of Cationic Polyacrylamide (CPAM) and Its Application in Sludge Dewatering

In this study, a new cationic polyacrylamide (CPAM) was successfully synthesized through UV-H2O2-initiated polymerization technique using acryloyloxyethyl trimethyl ammonium chloride (DAC) and acrylamide (AM) as monomers, and applied to sludge dewatering experiments. Parameters affecting the molecular weight and conversion of the polymers, including total monomer concentration, monomer concentration of DAC, H2O2 concentration, pH and illumination time were examined. Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were employed to characterize the properties of the polymers. The results showed that CPAM was successfully synthesized and possessed a coarse and porous surface morphology and inferior thermal stabilities. When the dosage of polymer was 40 mg L–1 and the initial sludge pH value was 7.0, PAD-3 (cationic degree: 40%, molecular weight: 6.89 × 106 Da) showed a more excellent sludge dewatering performance (FCMC: 70.6% SRF: 2.8 × 1012 m · kg –1; d 50: 436.802 μm, Df : 1.59). During the sludge flocculation process, three mechanisms containing charge neutralization, patching and bridging co-contributed to a prominent flocculation performance.