Synthesis, Characterization and Adsorption Study of Methyl Orange on Imidazolium-based Poly (Ionic Liquid) Hydrogels

New monomeric ionic liquid, 1-butyl-3-(2-hydroxy-3-methacryloyloxy) propyl imidazolium salt was successfully synthesized by chemical modification of glycidyl methacrylate with 1-butyl imidazole. Then, ionic liquid copolymer hydrogels were synthesized by radical crosslinking polymerization of monomeric ionic liquid and methacrylic acid with different molar ratios in the presence of ethylene glycol dimethacrylate as a cross-linker. The prepared hydrogels have been characterized by FTIR, SEM, and swelling test. The hydrogel with 1 : 1 molar ratio of monomers displayed its efficiency in methyl orange adsorption from aqueous solution. The impact of effective parameters such as initial dye concentration, pH, and adsorbent dosage on adsorption capacity was studied and modeled using central composite design superimposed with response surface methodology. ANOVA calculations displayed a high value for coefficient of determination and a second-order regression model with satisfactory prediction was achieved. To estimate the combined effects of the independent factors, response surface plots were generated. Besides, kinetics and isotherm experiments were studied on the developed system. The Langmuir isotherm model described best the data with 0.997 consistency and maximum adsorption capacity of 43.1 mg/g. The adsorption kinetics obeyed a first-order kinetic model. The properties of the prepared hydrogel confirmed that it can be exploited as an efficient adsorbent in the wastewater treatment.