Synthesis of strongly cationic hydrophobic polyquaternium flocculants to enhance removal of water-soluble dyes in wastewater
Tóm tắt
A series of new hydrophobic and strongly cationic poly(dimethyldiallylammonium chloride)s (HC-PDMDAACs) were synthesized and used to enhance the removal of water-soluble dyes in dyeing wastewater. The water-soluble anionic dyes could be removed from the water phase by forming flocculation precipitations with strongly cationic units in the main chains of HC-PDMDAAC through electrostatic interactions, and suitable contents of hydrophobic groups of HC-PDMDAACs further reduced the water solubility of those precipitations, causing a shift in the interaction equilibrium to form more flocculation precipitations, thus achieving the purpose of improving dye removal. Job’s plotting methods were first used to establish the interaction equations of cationic units (C) in HC-PDMDAAC flocculants and anionic dyes (D) and to reveal the flocculation effect mechanisms of those polycationic structures. It was discovered that controlling the 6% molar contents of hydrophobic DADMAC units in the main chains of HC-PDMDAAC flocculants gave the most efficient combinations with anionic dyes, and the hydrophobic groups and high molecular weights of HC-PDMDAACs both played roles in improving the removal of anionic dyes. Moreover, HC-PDMDAAC flocculants had good application universally and could adapt to the different pH values of the application environment in the purification of dyeing wastewater. In addition, SEM analysis of the flocculation precipitations confirmed that they tended further to condense strongly into large clusters so as to remove anionic dyes from the water phase more easily.
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