Mechanistic Insights of the Adsorption of Eriochrome Black T by the Formulated Mg–Al LDH-Graphene Oxide Composite

Abstract

Adsorption is one of the best techniques to mitigate industrial dye pollution. In this study, surface of the Mg–Al layered double hydroxide (LDH) was modified with graphene oxide (GO) to improve its adsorption efficacy of Eriochrome Black T (EBT) dye molecules. A higher correlation coefficient value of the Langmuir adsorption model indicated monolayer adsorption of EBT at the active sites of Mg–Al LDH. The optimum adsorption potential was obtained around 0.4 and 1.4 mmol of EBT per g of the LDH and the modified LDH, respectively, and both adsorbents followed pseudo-second-order kinetics. Molecular dynamics study revealed that both GO and LDH contribute to adsorb EBT. Hydrogen bonds, such as C-H…O, O–H…N, O–H…O = S, O–H…N, and N = O…H–O-Al are the major contributing forces behind the adsorption. Besides, π…alkyl, Mg…O = S, π…cation, π…anion, π…donor, π…sigma, and π…lone pair of interactions are the additional contributing forces behind the enhancement of the efficacy of the modified composite.