Removal of Cu 2+ metal ions from water using Mg-Fe layered double hydroxide and Mg-Fe LDH/5-(3-nitrophenyllazo)-6-aminouracil nanocomposite for enhancing adsorption properties

Herein, a new adsorbent was prepared by modifying Mg-Fe LDH for the removal of Cu2+ metal ions from wastewater. Mg-Fe LDH with 5-(3-nitrophenyllazo)-6-aminouracil ligand has been successfully prepared using direct co-precipitation methods and was fully characterized using FTIR analysis, X-ray diffraction, BET surface area theory, zeta potential, partial size, TGA/DTA, CHN, EDX, FESEM, and HRTEM. The surface areas of Mg-Fe LDH and Mg-Fe LDH/ligand were 73.9 m2/g and 34.7 m2/g respectively. Moreover, Cu2+ adsorption on LDH surfaces was intensively examined by adjusting different parameters like time, adsorbent dosage, pH, and Cu2+ metal ion concentration. Several isotherm and kinetic models were investigated to understand the mechanism of adsorption towards Cu2+ metal ions. Adsorption capacity values of LDH and ligand-LDH rounded about 165 and 425 mg/g respectively, applying nonlinear fitting of Freundlich and Langmuir isotherm equations showing that the ligand-LDH can be considered a potential material to produce efficient adsorbent for removal of heavy metal from polluted water. The adsorption of Cu2+ metal ions followed a mixed 1,2-order mechanism. The isoelectric point (PZC) of the prepared sample was investigated and discussed. The effect of coexisting cations on the removal efficiency of Cu2+ ions shows a minor decrease in the adsorption efficiency. Recyclability and chemical stability of these adsorbents show that using Mg-Fe LDH/ligand has an efficiency removal for Cu2+ ions higher than Mg-Fe LDH through seven adsorption/desorption cycles. Moreover, the recycling of the Cu2+ ions was tested using cyclic voltammetry technique from a neutral medium, and the Cu2+ ion recovery was 68%.