Graphene oxide incorporated chitosan/acrylamide/itaconic acid semi-interpenetrating network hydrogel bio-adsorbents for highly efficient and selective removal of cationic dyes

• Published in: International journal of biological macromolecules Vol. 219; pp. 273 - 289
• Main Authors: Tamer, Yasemin, Koşucu, Alper, Berber, Hale
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31.10.2022
• Subjects: Bio-adsorbent; Chitosan; Graphene oxide; Methylene blue; Semi-IPN hydrogel; Bio-adsorbent; Graphene oxide; Semi-IPN hydrogel; Chitosan; Methylene blue
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2022.07.238

In recent years, polymeric bio-adsorbents offers high removal efficiency, superior adsorption capacity and selectivity against various pollutants in aqueous medium. While designing these adsorbents, their environmental friendliness, sustainability, renewability, easy accessibility, and cost-effectiveness should be considered. In this study, GO incorporated semi-interpenetrating network (semi-IPN) nanocomposite hydrogels (CS/AAm/IA/GO) were obtained by free radical copolymerization of acrylamide (AAm) and itaconic acid (IA) in the presence of chitosan (CS) as an environmentally friendly bio-adsorbent. GO significantly improved the thermal stability, compressive strength, and percentage swelling of the hydrogel. The selective adsorption studies demonstrated that methylene blue (MB) was the most efficiently removed dye from both individual and mixed dye systems with 99.8 % removal efficiency. The adsorption capacity was found to be 247.47 mg g−1 using 0.025 g hydrogel adsorbent containing 0.5 wt% of GO and an initial MB concentration of 5 mg L−1 at pH 8 over 90 min at room temperature. The kinetic and isotherm studies revealed that the adsorption process followed the pseudo-second-order kinetic model and Langmuir adsorption isotherm. Thermodynamic studies suggested the spontaneous and endothermic nature of MB adsorption. Also, the MB removal efficiency above 96 % was obtained after 7 consecutive adsorption-desorption cycles while maintaining the structural stability of the bio-adsorbent. •Semi-IPN hydrogels was obtained from chitosan, acrylamide, itaconic acid, GO.•Nanocomposite hydrogel bio-adsorbents were highly selective for all cationic dyes.•The adsorption capacity and removal efficiency of MB was 247.47 mgg−1 and of 99.8 %.•Dye desorption was found to be 97 % after 7 consecutive adsorption-desorption cycles.•Adsorption mechanism of MB mostly proceeds by electrostatic attraction and H bonding.