No abstract

PADB was a highly efficient cationic flocculant, which was synthesized through the copolymerization of acrylamide (AM), acryloyloxyethyl trimethyl ammonium chloride (DAC), and butylacrylate (BA) with ultraviolet initiation by micellar polymerization technology. The PADB was the terpolymer of AM, DAC, and BA. In order to observe this flocculant's structural characteristics, nuclear magnetic resonance hydrogen spectroscopy ( 1 H NMR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA) were used. The most important study was to analyze its physicochemical parameters during dewatering of activated sludge. These tested parameters included residual turbidity of supernatant, dry solid content (DS), extracellular polymeric substances (EPS), specific resistance to filtration (SRF), ζ-potential, floc size, and settling rate. Results demonstrated that the PADB have a superiority over both poly(acrylamide-acryloyloxyethyl trimethyl ammonium chloride) (PAD) and commercially available cationic polyacrylamide (CPAM). However, it was dependent on pH and dosage. A favorable pH was in the neutral range while the appropriate dosage (20 mg·L −1 -60 mg·L −1 ) was crucial to the conditioning process. For the PADB at40 mg·L −1 and pH at 7, the residual turbidity of supernatant, DS, SRF, and settling rate could reach 5.5 NTU, 32.2%, 5.51 × 10 12 m·kg −1 , and 3.318 cm·min −1 , respectively. During the sludge flocculation process, the charge neutralization mechanism and bridging flocculation played an important role in floc's formation and settlement.

In this study, a kind of anionic polyacrylamide (P(AM-AA-AMPS)) was synthesized using acrylamide (AM), acrylic acid (AA), and 2-acrylamido-2-methyl propane sulfonic acid (AMPS) under ultraviolet (UV) irradiation. The conditions of the polymerization reaction such as monomer mass ratio, solution pH value, EDTA concentration and urea concentration were investigated by using the single factor approach and an L 16 (4 5 ) orthogonal array. The structure and morphologies of the copolymer were determined by nuclear magnetic resonance spectrometer (NMR), infrared spectrometer (IR) and scanning electron microscope (SEM). The results show P(AM-AA-AMPS) with the intrinsic viscosity of 1.5 Â 10 3 mL g À1 was synthesized at optimal conditions: mass ratio, m(AM) : m(AA) : m(AMPS) of 70 : 10 : 10, pH value of 9.0, EDTA concentration of 0.10% and urea concentration of 0.20%. In addition, P(AM-AA-AMPS) had better flocculation efficiency than commercial PAM in sludge dewatering experiment; the minimum filter cake moisture content could be reduced to 65.1%. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci.

In this study, a cationic block structure with a strong neutralizing ability was formed through template polymerization. Acryloxyethyltrimethyl ammonium chloride (DAC) and acrylamide (AM) were used as monomers, and the ionic homopolymer sodium polyacrylate (NaPAA) was used as the template. The product containing NaPAA after template polymerization is denoted as NTP, whereas the copolymer obtained after removing the NaPAA is denoted as TP. The common polymer (denoted SP) of AM and DAC was copolymerized through solution polymerization. TP and SP were characterized and compared by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy, and thermogravimetric analysis (TGA). The results of 1 H NMR spectroscopy and TGA showed that a cationic block structure was formed in TP. The mechanism of the cationic block polymer used in water treatment was extensively studied through a jar test in which turbidity, zeta potential, and average floc size were used to evaluate the flocculation performance. The results further supported the cationic block structure of TP. TP, with a different structure than SP, resulting in a stronger neutralization ability, showed a better performance in flocculating kaolin suspensions. The dominant mechanisms for TP flocculation behavior at pH 5, 7, and 9 might be patching, charge neutralization, and bridging adsorption. The flocculation performance of NTP was not acceptable, whereas acidic NTP at pH < 2 showed a flocculation effect similar to that of TP.

A new flocculant with cationic microblock structure was prepared by using template polymerization. Acrylamide (AM) and acryloyl­oxyethyl­tri­methyl­ammonium chloride (DAC) were used as monomers, and sodium polyacrylate was used as the template. The reactivity ratio, 1H NMR, 13C NMR, and thermogravimetric analysis were employed to characterize the structural properties of products. Results show that, with the addition of the template, the reactivity ratio of DAC increased, whereas that of AM decreased. Evident microblock structure was synthesized in copolymers when the molar ratio of template to DAC was 1.0. Activated sludge dewatering experiment results reveal that the cationic microblocky flocculant exhibited superior dewatering efficiency, and a low moisture content of 71% and a specific resistance of 1.99 × 1012 m·kg–1 were acquired at pH 7.0 and a 40 mg L–1 dosage. The enhanced charge neutralization and bridging effect of the cationic microblocky flocculant contributed to the formation of floc with a large size and compact structure.