Equilibrium and kinetic studies of the adsorption of acid blue 9 and Safranin O from aqueous solutions by MgO decked FLG coated Fuller's earth

Abstract MgO decked few layer Graphene Coated Fullers' Earth (MgO-FLG-FE) is prepared by microwave irradiation and tested as adsorbent to remove Acid Blue 9 (AB9) and Safranin O (SO) dye from aqueous solutions. MgO-FLG-FE was characterized by FTIR, XRD, FESEM, HRTEM, RAMAN, and BET. The adsorbent dose required for the maximum removal of AB9 and SO dyes are 1.0 g and 0.08 g which is in very low quantity compared with FE. The contact time to achieve equilibrium is 120 min in both the dyes. Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms are applied to understand the adsorption mechanism for both the dyes in aqueous solutions. The uptake of AB9 and SO dye by MgO-FLG-FE is best explained by Langmuir adsorption isotherm. The adsorption capacities of MgO-FLG-FE for AB9 and SO are 37.7 mg/g and 201.1 mg/g respectively when compared with Fuller's Earth (36.7 mg/g and 131.19 mg/g). The adsorbent capacity of FE was enhanced by coating with very small amount of MgO decked FLG. The Pseudo-second order equation is best explained through the adsorption kinetics in this study.