Removal of acridine orange from water by graphene oxide

Dyes are usually used in textile manufacturing and are one of the major contaminations in water. Thus, from an environmental point of view, the removal of dyes is of great concern, and recent applications using carbon-based materials showed high adsorption ability. In this work we use graphene oxide (GO) produced by improved Hummer's method, for adsorption of acridine orange dye (AO) in water. GO is a material containing functional groups such as carboxyl, epoxy, ketone, and hydroxyl, that can adsorb cationic dyes. Factors such as initial concentration of dye, the amount of GO, temperature and contact time were evaluated. Results show that the adsorption equilibrium, with the removal of 40% of the dye, is reached in approximately 1 hour, and that the adsorption capacity increases at higher initial concentrations. The highest value of AO adsorbed was 229.8 mg/g equivalent to 92% removal percentage by using AO initial concentration 0.10 mg/mL. FT-IR analysis of GO with adsorbed AO shows changes in the stretching vibrational bands, which corroborate the AO/GO interaction due to the functional groups present in GO. Furthermore, AO adsorbed on GO does not desorb back into water. Our results show that GO is an effective adsorbent and could be used to treat effluents contaminated with dyes.