Cationic polyacrylamide emulsions prepared with ultra-high concentration (CPAME-uhc) have the advantages of fast dissolution, convenient operation, and low transportation cost. In order to further improve the molecular weight, solubility, and temperature/salt resistance of CPAME-uhc, in this study the preparation process of CPAME-uhc was optimized, and the effects of solubilizing agents and functional monomers on solubility and temperature/ salt resistance of CPAME-uhc were evaluated. Finally, the flocculation performance of CPAME-uhc on papermaking wastewater was examined. The results showed that the molecular weight of CPAME-uhc can be increased to 14 to 15 million by process optimization, and the solubility of CPAME-uhc can be greatly increased by adding urea and Na2SO4. The temperature/salt resistance of CPAME-uhc can be improved by adding 2 wt% N,N-dimethylacrylamide, 2 wt% N-vinylpyrrolidone, and 5 wt% sodium 2-acrylamide-2-methylpropionate, based on the total monomer weight. When CPAME-uhc was added to papermaking wastewater the removal percentages of chemical oxygen demand (COD) and suspended solid (SS) were 95% and 93%, respectively. This study provides a useful reference for the preparation, optimization and application of CPAME-uhc.

AbstractA novel amphoteric polyacrylamide (PDAA) was prepared by inverse emulsion polymerization. The influence of its cationic degree and molecular weight on retention property was discussed. Then, the chemical structure and micromorphology of the obtained PDAA were characterized by Fourier infrared spectrum (FTIR), NMR hydrogen spectrum (1H NMR), gel permeation chromatography (GPC), and scanning electron microscope (SEM). Finally, the synergistic retention effects of polydimethyldiallylammonium chloride (PDADMAC), cationic starch (CS), cationic guar gum (CHPG), cationic chitosan (CTS), and polyamine (PA) on the novel PDAA were investigated. The results showed that the optimum cationic degree and molecular weight of PDAA were 25% and 4 million, respectively. The chemical structure of PDAA was confirmed by FTIR, 1H NMR, and GPC. SEM showed that the particle size of PDAA was between 150 and 600 nm, and the particles were very stable because no broken particles were found. In addition, most of the five cationic polymers have good synergistic retention effect on PDAA, and the order of synergistic effect was PDAA/PDADMAC > PDAA/CTS > PDAA/CS > PDAA/CHPG > PDAA/PA.

A super high concentration cationic polyacrylamide emulsion (CPAME‐uhc) was prepared by inverse emulsion polymerization. The influence of its cationic degree and molecular weight on flocculation property was discussed. Then, the chemical structure and micromorphology of the obtained CPAME‐uhc were characterized by Fourier infrared spectrum (FT‐IR), NMR hydrogen spectrum (1H NMR), gel permeation chromatography (GPC), and scanning electron microscope (SEM). Finally, the synergistic flocculation effects of CPAME‐uhc respectively with polydimethyldiallylammonium chloride (PDADMAC), poly methacryloyloxyethyl trimethyl ammonium chloride (PDMC), cationic starch (CS), cationic guar gum (CHPG), cationic chitosan (CTS), and polyamine (PA) on the CPAME‐uhc were investigated. The results showed that the optimum cationic degree and molecular weight of CPAME‐uhc were 25% and 12 million, respectively. FT‐IR and 1H NMR analysis showed that the product was a copolymer of acryloxyethyl trimethyl ammonium chloride and acrylamide. GPC analysis confirmed that the molecular weight distribution of CPAME‐uhc product was very narrow. SEM shows that the latex particles of CPAME‐uhc are regular spheres with a diameter of 200 to 500 nm. When CPAME‐uhc is respectively combined with five cationic polymers in a certain proportion, all of them show good synergistic flocculation to papermaking wastewater. The order of synergistic flocculation effect is: CPAME‐uhc/PDADMAC > CPAME‐uhc/PDMC > CPAME‐uhc/CTS > CPAME‐uhc/CS > CPAME‐uhc/CHPG > CPAME‐uhc/PA. Finally, the mechanism of synergistic flocculation was proposed. This study provides a theoretical and research basis for the preparation of CPAME‐uhc and its application in the treatment of papermaking wastewater.