MgO nano-sheets for adsorption of anionic dyes from aqueous solution: Equilibrium and kinetics studies

Abstract

MgO nano-sheets with a thickness of 26 nm and reticular structure were synthesized and characterized using FE-SEM, XRD, EDX and N2 adsorption/desorption. The synthesized MgO nano-sheets were used to remove two anionic dye pollutants (reactive orange and reactive yellow) from aqueous solution. The equilibrium and kinetics data were obtained, and fitted very well with Langmuir-Freundlich and Redlich-Peterson isotherms, and fractal like-pseudo second order kinetics model. The effect of solution pH and temperature on the removal efficiency of the synthesized adsorbent was studied in details. The maximum adsorption capacity of MgO nano-sheets to remove reactive orange is more than 30 times higher than reactive yellow. The difference in the adsorption mechanisms is proposed to explain such a noticeable difference in adsorption capacities of these dyes by MgO nano-sheets. The used MgO adsorbent can be regenerated completely using heat treatment in a furnace.