Dyes disposal from the industrial sector into the environment greatly affects the quality of the water. Among various technologies of removing dye pollutants from wastewater, adsorption is one of the most effective and favorable methods. Graphene oxides (GO) has been applied to remove dye pollutants in solution since it has a lot of oxygen-containing groups that can attract and bind pollutants. We study the effect of stirring time on MB adsorption onto GO surfaces. We mixed MB solution with GO dispersion and stirred at varied stirring times. The mixture was kept at room temperature to allow precipitation of the GO-MB mixture and then filtered to separate the precipitate from the residual MB solution. A reduction of MB concentration in the solution was measured using spectroscopy. The experimental results show that MB was adsorbed very fast onto GO surfaces in the first minutes and then the rate of the reduction of MB concentration becomes slower. After the stirring for 60 minutes, almost there is no significant change of the MB concentration that indicated a limit of adsorption capacity of GO.

Aminated graphene oxide (AGO) is one of graphene oxide (GO) derivatives that contained amine group (NH2). GO has a lot of oxygen-containing groups, such as hydroxyl, carboxyl, carbonyl, and epoxide functional groups, therefore it is hydrophilic and readily dispersed in water forming a stable colloidal suspension. This property was used to study decolorize of dye pollutant in water contamination. The presence of amine side chain in the molecule might contribute on improving hydrophilic properties of AGO compared to GO. Waste water containing harmful dyes such as methylene blue (MB) is one of the main problems in water contamination. In this work we study MB adsorption onto AGO surface. The experiments were carried out by mixing 50 mL of the MB solution in water (5 ppm; 0.25 mg) with 0.5 mL of dispersed AGO (0.5 mg / ml; 0.25 mg) in dimethylformamide (DMF), and then stirring at 1000 rpm at varied stirring times. The initial and final concentration of MB solutions after AGO adsorption were analyzed using spectroscopy. We obtained that AGO can adsorb MB in water, which the adsorption happened very fast until stirring time of 20 minutes. Addition of stirring time does not have significant change on MB concentration, which indicates that AGO adsorption capacity has saturated.