Studies of the kinetics and mechanism of the removal process of proflavine dye through adsorption by graphene oxide

Proflavine, a nitrogen-containing dye is used for DNA staining and as an efficient marker, however, it is harmful to body cells, and its efficient removal is essential. In this work, graphene oxide (GO) has been used as an adsorbent for the removal of the dye through the process of adsorption. Though GO is now being used as an adsorbent for the removal of industrial dyes, very few experiments have been done on biologically useful dyes. GO is synthesized from graphite powder by the modified Hummer's method and is characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Raman and ultra-violet spectroscopies, etc. These characterization techniques indicate the presence of oxygen containing functional groups, e.g., carbonyl, carboxyl and hydroxyl groups on the graphene sheets. These sheets are held well apart by these groups. Parameters like concentration of the adsorbent, pH and temperature have been varied to find the optimum conditions for the most efficient removal of the dye molecules from the solution. Then, for the optimum external conditions, the time dependence of the adsorption was analyzed using pseudo-first and pseudo-second orders kinetics. The adsorption isotherms were also obtaining throws light on the mechanism of the adsorption process which we investigated further by using FTIR characterization. (C) 2017 Elsevier B.V. All rights reserved.