Coacervate of Polyacrylamide and Cationic Gemini Surfactant for the Extraction of Methyl Orange from Aqueous Solution

Coacervation in aqueous solution of the mixture of cationic ammonium surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and 10% hydrolyzed polyacrylamide (PAM) has been investigated. It was found that the 12-6-12/PAM mixture forms coacervate with a large network structure over a wide concentration range of surfactant and polyelectrolyte and shows great efficiency in the extraction of Methyl Orange (MO) from water owing to the cooperation of hydrophobic, electrostatic, and π-cation interactions. Meanwhile, the dye joins the coacervate and strengthens the network structure of the coacervate. In particular, benefiting from partial excess of 12-6-12 molecules, the coacervate phase presents selective adsorption behavior toward anionic dye MO in the presence of cationic dye methylene blue (MB). Furthermore, the coacervate phase is utilized to modify quartz sand and melamine foam, and the coacervate-treated adsorbents can adsorb MO efficiently. Moreover, the MO-loaded adsorbents are easily regenerated with hydrochloric acid, making this an inexpensive and environmentally benign process. These findings offer a simple and effective alternative for the treatment of dye contaminated water and the recovery of dyes.