Removal of Acid Orange 7 Dye from Synthetic Textile Wastewater by Single-Walled Carbon Nanotubes: Adsorption Studies, Isotherms and Kinetics

Colors can cause major environmental pollutions and are responsible for the carcinogenic and mutagenic risks. In this study, single-walled carbon nanotubes have been carried out to determine the efficiency of removal of Acid Orange 7 (AO7) dye from synthetic textile wastewater. In the laboratory study, the color was determined in 484 nm using spectrophotometer. Batch flow laboratory study was designed to investigate the effects of the different parameters including adsorbent dose (0.05 to 0.4 g/ l), contact time (30 to 180 minutes), the initial concentration of the dye (25, 50, 75 and 100 mg/l), pH (3 to 11) and mixing intensity (40, 60, 80, 100 and 120 rpm) on the dye removal efficiency by single-walled carbon nanotubes. All sample test s were repeated three times and then, in order to compare the effect of different parameters, the collected data was analyzed by one-way ANOVA test. The results showed that the dye removal efficiency could be increased when the different parameters including adsorbent dose, contact time and mixing intensity are increased in this process. The results also showed that the decolourization of dye solution is inversely related to the initial dye concentration and the pH solution. The maximum dye removal efficiency was obtained while the adsorbent dose and pH were found to be 0.3 g and 3, respectively. Time of color removal was obtained by 180 min in equilibrium. AO7 adsorption isotherm follows Langmuir model (R2= 99.4%), and the pseudo second-order kinetics. The results showed that the single-walled carbon nanotubes are effective adsorbents for the dye removal from textile wastewater, especially AO7 dye.