2D to 3D controllable synthesis of three Zn-Co-LDHs for rapid adsorption of MO by TEA-assisted hydrothermal method

Layered double hydroxides (LDHs) nanomaterials show their excellent potential for removing organic dyes from waste water by anions or water molecules exchange process. In this work, three novel layered Zn-Co-LDHs adsorbent for rapid adsorption of MO were synthesized for the first time by hydro-thermal synthesis using triethanolamine (TEA) as a alkali source and a structural controlling reagent, and characterized by the SEM, XRD, XPS, FTIR, BET, solid-state UV/vis spectra and TG. Results showed that the size and morphology of Zn-Co-LDHs from 2D to 3D can be controlled by adjusting the volume ratio between TEA and H2O. The maximum adsorption capability of three layered Zn-Co-LDHs adsorbent were 1114.1 mg/g, 1261.97 mg/g, and 1051.78 mg/g, respectively. The adsorption process reached equilibrium rapidly only ten minutes. The pseudo-second-order kinetic equation fitted the adsorption process. The equilibrium adsorption isotherm data followed the Langmuir model. A possible adsorption mechanism will be proposed. The regeneration ability was achieved using 0.5% NaOH solution. The results showed that Zn-Co-LDH could be employed as an efficient adsorbent for the removal of MO from dye waste water.