Adsorption of Reactive Orange 16 from aqueous solutions by MgAlNO3-LDH: Kinetic and equilibrium studies

An anionic MgAlNO3 layered double hydroxides (MgAlNO3-LDH) with Mg/Al molar ratio 4∶1, was investigated for its ability to adsorb an anionic dye, Reactive Orange 16 (RO16), with the objective of evaluating its suitability as an adsorbent. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Equilibrium data fitted well with Langmuir model for the concentration range of 5–100 mg/L. The equilibrium adsorption capacity of MgAlNO3-LDH was determined with the Langmuir equation and found to be 111 mg dye per gram adsorbent at 25 °C. Adsorption kinetics showed that the rates of adsorption were found to conform to the pseudo-second-order rather than first order kinetics. The results also indicate that MgAlNO3-LDH was a promising adsorbent for reactive dye removal from effluents, and with the potential to be used as an alternative adsorbent to other costly materials such as activated carbon.