Effect of time, pH, and temperature on kinetics for adsorption of methyl orange dye into the modified nitrate intercalated MgAl LDH adsorbent

The present work evaluated the potential of nitrate intercalated pristine MgAl layered double hydroxide (MA LDH) powder, for adsorption of methyl orange (MO) dye from an aqueous solution for reducing health hazards. Nitrate intercalated pristine MA LDH was synthesized in the particle size range between 60 and 120 nm by co precipitation method in nitrogen atmosphere using reflux process. MO dye was adsorbed into MA LDH by the process of anion exchange to promote formation of MO intercalated MA LDH (MAMO LDH). Both MA LDH and MAMO LDH powders were characterized using XRD, FTIR, FESEM, and TGA analysis. In the adsorption process, all effective parameters such as adsorbent dose, adsorption time, temperature, pH, and MO dye concentration were studied in the batch process using UV visible spectroscopy. It was observed that the pH and temperature of the dye solution exerted a major impact on the kinetics of adsorption of MO dye into 10 mg of MA LDH. The adsorption kinetics at different temperatures such as 25, 40, and 50 degrees C were investigated, and found that pseudo second order kinetic fitted well with the kinetic data. Maximum adsorption percentage of MO dye into MA LDH nanoparticles hardly varied with an increase in temperature as suggested by 98.22% of MO adsorption at 25 degrees C as opposed to 98.66% adsorption at 40 and 50 degrees C within a maximum of 1-hour incubation time from 50 ml of aqueous solution containing 0.03 mg/ml of MO dye. Upto three regeneration cycles, nitrate intercalated MA LDH dye showed no significant decrease in adsorption capacity of MO dye from its aqueous solution. The adsorption isotherm was measured at a temperature of 40 C and indicated that the Langmuir isotherm model fitted well with experimental data with a maximum adsorption capacity of 583 mg/g. Thermodynamic parameters, such as high negative value of triangle G and positive value of triangle H suggested that the adsorption process was spontaneous and endothermic in nature.