Removal of fuchsin acid and methylene blue by β-cyclodextrin/Guar gum hydrogel: Response surface methodology optimization, kinetics and thermodynamic analysis

Abstract

The present study explains the optimum synthesis for β-cyclodextrin (β-CD) and guar gum (GG) based hydrogel using the Response Surface Methodology (RSM) containing Central Composite Design (CCD). To increase the swelling percentage and strength, epichlorohydrin (EPI) is used as a crosslinking agent. The factors like temperature (40–70 °C), reaction time (4–7 h), amount of crosslinker (0.6–1 ml), amount of solvent (6–9 ml), ratio of backbones (β-CD: GG) (3:1–1:1) and pH (7–11) were optimized by RSM to get maximum percentage swelling. The synthesized hydrogel was characterized by FTIR, XRD, FE-SEM, and EDS to know about the morphology and functional group integrity. The synthesized hydrogel was investigated for adsorption of Methylene Blue (MB) and Fuchsin Acid (FA) by batch method. Under optimum conditions, the maximum adsorption capacity for MB and FA was determined to be 453 mg/g and 899 mg/g respectively. The adsorbent demonstrated outstanding reusability, maintaining consistent adsorption capacity over five cycles. Even after repeated use, the removal efficiency remained 43.6 % for MB and 39.76 % for FA after the fifth cycle. In conclusion, the β-CD/EPI/GG hydrogel proved to be a highly effective adsorbent, offering significant potential for the removal of both cationic and anionic dyes, showcasing its versatility and efficiency in water purification.