Investigating adsorption behaviour of methyl orange dye onto nano MgAl layered double hydroxide using Box-Behnken Design model

Nano sized nitrate and carbonate intercalated magnesium, aluminium-based layer double hydroxide (LDH-NO3 and LDH-CO3), are considered as promising materials for removal of contaminants from wastewater. In the present work, LDH-NO3 in the size range between 40–120 nm and LDH-CO3 possessing size distribution between 60–200 nm were synthesised via traditional co-precipitation method under reflux condition. The adsorption behaviour of the methyl orange (MO) dye at different temperatures, times, and pHs of the LDH-NO3 containing suspension was optimised using the Box Behnken Design (BBD) and response surface methodology (RSM). The adsorption kinetic and isotherm study were performed at optimised values of three independent variables such as the incubation time of 59 min, the temperature of 30°C, and the pH of 6, under which the maximum MO adsorption capacity of 539.09 mg/g by LDH-NO3 nanoadsorbents was observed. After the adsorption of the MO dye, the LDH-NO3 nanoadsorbents was regenerated using acid-base treatment and revealed significant reusability throughout five adsorption cycles. The nano-sized LDH-NO3 powder exhibited a preferential anion exchange mechanism for the removal of the anionic MO dye from its aqueous solution.