Preparation of super high concentration cationic polyacrylamide emulsion and its flocculation with cationic polymers

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.