One-pot Synthesis of IPN Hydrogels with Enhanced Mechanical Strength for Synergistic Adsorption of Basic Dyes

Interpenetrating polymer network (IPN) hydrogels based on chitosan (CS) and poly(acrylic acid) (PAA) were prepared by one-pot strategy. The hydrogels exhibited porous structure and enhanced mechanical strength due to the entrapment of the two polymeric networks in the IPN. The ability of the hydrogels to adsorb basic dye Nil Blue (BB 12) from aqueous solutions was assessed using UV-VIS spectrophotometer. The adsorption amount was pH dependent, and the maximum adsorption capacity was observed at pH 10.0. The adsorption equilibrium was achieved within 45 minutes and the adsorption process could be well described by the pseudo-second-order kinetic model and Langmuir isotherm. Furthermore, the synergistic interactions between dyes and the two polymeric networks in the IPN were found during the adsorption process. Thermodynamic parameters revealed the dye sorption was an endothermic and spontaneous process with increasing randomness at the hydrogel/solution interface. Finally, studies on the reproducibility suggested that the hydrogel could be repeatedly used without any significant loss of the adsorption capacity.