The formation and adsorption mechanism studies of three-dimensional (3D flower-like) layered double hydroxide

Abstract

In this work, a layered double hydroxide with three-dimensional structure (3D-MgAl-LDH) was synthesized by the template-assisted method, the growth mechanism of the three-dimensional structure was investigated through a structure-modulation process, and the adsorption properties were tested. Adsorption experiments revealed that, compared to the conventional 2D inorganic LDHs, the 3D organic LDHs intercalated with SDS exhibited superior adsorption performance for dyes under all conditions. Specifically, the maximum removal capacity of MO reached 1282.5 mg·L^-1, which was almost six times higher than 2D inorganic LDHs, this enhancement was attributed to the pore space formed by the aggregation of 2D lamellae, which provided additional adsorption sites. Adsorption kinetics and isotherm modeling indicated that the removal behavior closely followed the Tempkin isotherm model, and the adsorption process was better described by the Elovich kinetic model. Analysis using XPS and FT-IR indicated that anion exchange was the primary mechanism driving the removal of MO. The interaction energy between 3D-MgAl-LDH and MO was calculated by using density functional theory (DFT), which further confirmed the adsorption mechanism. Moreover, 3D-MgAl-LDH maintained stable adsorption performance after five cycling experiments. This work introduces a novel structural material for industrial wastewater treatment and broadens the dimensional options for LDHs.