Highly efficient poly(acrylic acid-co-aniline) grafted itaconic acid hydrogel: Application in water retention and adsorption of rhodamine B dye for a sustainable environment

Abstract

The present study used a free radical co-polymerization approach to synthesize a smart hydrogel of itaconic acid grafted poly(acrylic acid-co-aniline) (ItA-g-poly(AA-co-ANi)). ItA-g-poly(AA-co-ANi) hydrogel was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman, X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscope (FE-SEM), and X-ray photoelectron spectroscopy (XPS) analysis. Rhodamine B (RhB) dye was removed from an aqueous medium using ItA-g-poly(AA-co-ANi) hydrogel. To determine the maximum adsorption, the effect of parameters such as initial dye concentration, contact time, pH, and adsorbent dose were examined. The ItA-g-poly(AA-co-ANi) hydrogel had a high swelling percentage of 1755.3%. The high water penetration of ItA-g-poly(AA-co-ANi) hydrogel with a high swelling rate exposed the internal adsorption sites for RhB dye adsorption. The adsorption performance of ItA-g-poly(AA-co-ANi) hydrogel was explained by the pseudo-first-order and Freundlich adsorption isotherm models. Moreover, after four adsorption-desorption cycles, the ItA-g-poly(AA-co-ANi) hydrogel maintained an adsorption efficiency of 85.2%. The high water retention ability of ItA-g-poly(AA-co-ANi) hydrogel improved the moisture maintenance limit of soil for irrigation up to 23 days. As a result, ItA-g-poly(AA-co-ANi) hydrogel can be used in the elimination of toxic dyes as well as in irrigation systems.

Keywords: Adsorption; Hydrogel; Itaconic acid; Rhodamine B dye; Swelling; Water retention.