Adsorption of Cationic Dye from Aqueous Solutions by Green pH Responsive Hydrogels Based on Poly(2-acrylamido-2-methyl-1-propanesulfonic acid)

Poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-1-vinylimidazole), hydrogels were synthesized via free radical polymerization reaction at different conditions and modified with di-alkyl halide. P(AMPS-Na+-co-VIm)-Ag and p(AMPS-H+-co-VIm)-Ag were prepared by reducing Ag(CH3COO) salts loaded into p(AMPS-Na+-co-VIm) and p(AMPS-H+-co-VIm) hydrogels and then reduced by NaBH4. Metal nanoparticles embedded p(AMPS-Na+-co-VIm)-Ag and p(AMPS-H+-co-VIm)-Ag were visualized by high resolution X-ray photoelectron spectroscopy (HRXPS) and transmission electron microscopy (TEM). The prepared porous hydrogels and related composites were utilized in the adsorption of Rhodamine B from aqueous solutions. Among non-quaternized hydrogels, p(AMPS-Na+-co-VIm) and its composite outperformed p(AMPS-H+-co-VIm) and p(AMPS-H+-co-VIm)-Ag. since high porosity increases absorption capacity, which depends on the size and shape of the pores. In addition, the effect of 1,4-dibromobutane quaternization on the catalytic performance of nano-composites was investigated. Finally, the catalyst was easily recovered from the reaction medium and re-used for a further four runs without significant loss of activity. The durability of the catalyst structure without leaching was confirmed by FT-IR spectra and atomic absorption spectroscopy, respectively.