Design and DFT-Based Optimization of GO-Containing Guar Gum Hydrogel for Dye Removal

Abstract

The development of a superabsorbent hydrogel composed of Graphene oxide (GO), Guar Gum (GG), and Resorcinol (Res), cross-linked by La3+ ions, presents a significant advancement in addressing water contamination from dyes. The careful synthesis procedure and the subsequent analysis of the hydrogel beads for dye removal capabilities highlight the potential of the present material in environmental remediation. First the complex of GO, GG, Res and La3+ was optimized at the DFT level of theory using involving Stuttgart-Dresden (SDD) basis set along with WB97XD as functional. Moreover, molecular orbital analysis, followed by the calculation of electronegativity in terms of MO energies, ionization energy (IE), electron affinity (EA), and the related parameters absolute electronegativity (χabs), absolute hardness (η), electrophilicity index (ω), global softness (S) was done. Experimentally, with impressive % swelling dispositions of 2920 and 2850 in water, 2650 and 2070 in NaCl, 2510 and 1750 in CaCl2, 810 and 840 in AlCl3 and 2230 and 1980 at pH 7 and 1880 and 1390 at pH 9 for GO and without GO based beads respectively and increased thermal stability with the inclusion of GO. The study showed a substantial increase in equilibrium removal capacity of Crystal violet dye from 134.88 mg/g to 234.32 mg/g in deionised water and 226.66 to 241.09 at pH 9 from with and without GO. The enhanced dye removal efficiency of beads for crystal violet, demonstrates its promising nature towards wastewater treatment.