MgAl-Layered Double Hydroxide: An Efficient Material for Adsorptive Removal of Methyl Orange from Aqueous Solutions

There is an ever-growing global concern of water pollution and water scarcity. Numerous strategies are investigated within a holistic approach that includes water treatment using inorganic and composite adsorbents. In this context, MgAlCO3-layered double hydroxide (LDH) was synthesized by co-precipitation at pH 10 and characterized by XRD, FTIR, TGA, N2-adsorption–desorption and XPS. MgAlCO3-LDH was evaluated as an adsorbent to remove methyl orange (MO), a model organic pollutant, from aqueous solutions. The effects of initial dye concentration, contact time and pH on the adsorption process were investigated. For 150 ppm MO initial concentration, a maximum adsorption capacity of 120 mg g−1 was obtained at 25 °C and pH 6 after 120 min contact time. The equilibrium adsorption data were found to fit the Freundlich rather than the Langmuir adsorption model (R2 = 0.9971). The adsorption process was found to be chemisorption that most likely involves the anion exchange mechanism. Kinetically, the experimental data fitted very well the pseudo-second order and gave a good representation for the pseudo-first-order, with adsorption rate constants K2 = 4 × 10−6 g mg−1 min−1 and K1 = 0.0082 min−1.