An Experimental and Computational Evaluation of the Interaction Between Intelligent Ampholyte Acrylamide/Acrylic Acid/2-(Acryloyloxy)ethyl Trimethylammonium Chloride Hydrogel and Dyes

Novel intelligent ampholyte hydrogel (IAH) was prepared by a free radical solution redox polymerization of acrylamide, acrylic acid, 2-(acryloyloxy)ethyl trimethylammonium chloride as monomers, and ethylene glycol dimethacrylate as crosslinker. Spectroscopic, thermal, and surface properties of IAH were performed using ATR/FTIR, molecular electrostatic potential maps, TGA and DSC. Swelling studies were performed at increasing pH and temperature. IAH has been identified as intelligent and ampholyte. Cavity sizes of IAH were calculated from SEM photographs by digital image analysis method. Due to the large cavities of IAH, this hydrogel was used for dye sorption. The binding of carminic acid to IAH was L-type according to the Giles classification system, while crystal violet and methyl violet were S-type. Binding parameters of dyes such as binding constant, monolayer coverage, and maximum fractional occupancy were calculated from the Langmuir model or Saraydin model. It was observed that the binding between the dyes used and the IAH was realized by electrostatic interaction, and the hydrogen bonds in the carminic acid increased this bonding. This study could be a pioneering model for the preparation of potential and effective intelligent ampholyte hydrogels for the removal of both anionic and cationic dyes from aquatic environments by electrostatic interaction/H-bonding.