Performance Evaluation of Gum Gellan-Based Hydrogel as a Novel Adsorbent for the Removal of Cationic Dyes: Linear Regression Models

In this work, the suitability and efficacy of the previously reported biodegradable gellan gum (GG)-based hydrogel have been thoroughly investigated with respect to the adsorption mechanisms of malachite green (MG) and methylene blue (MB) dyes. The dyes' removal from aqueous solutions using GG-cl-poly(AA) as an adsorbent material has been studied in a discontinuous system with respect to contact time, dose, pH, and temperature. The synthesized hydrogel was characterized by FT-IR, TGA, XRD, ¹H NMR, and FE-SEM. The adsorption capacity of GG-cl-poly(AA) hydrogel was investigated at different pH solutions (3, 7, and 10), and it was found that neutralized charge plays a crucial role in the enhancement of dye removal. To better understand the behavior of the GG-cl-poly(AA) hydrogel in adsorbing model dyes, adsorption kinetics, isotherms, and thermodynamics were also investigated. The values of qmax for MG and MB were obtained to be 552.48 and 531.9 mg g^-1. In addition, the influence of NaCl concentration on adsorption efficiency was investigated, and it was found that as the ion concentration increased, the effectiveness of the adsorption process dropped. Moreover, the synthesized hydrogel's potential application in the adsorption and separation of dyes from wastewater is enhanced by the reusability investigations conducted in convenient conditions. As a result, it is possible to conclude that reusing GG-cl-poly(AA) hydrogel as a low-cost, easy-to-handle, nontoxic material in an industrial wastewater treatment plant's adsorption process can provide a number of advantages, including high efficiency for MG and MB removal and cost savings on overall treatment plant operations.