Application of a Taguchi L 16 orthogonal array for optimizing the removal of Acid Orange 8 using carbon with a low specific surface area

Abstract

The conditions for the adsorption of the dye Acid Orange 8 onto carbon were optimized using the Taguchi method. Four samples of activated carbon were obtained from guava seeds, and their textures were characterized by nitrogen adsorption isotherms. The equilibrium adsorption isotherm on mesoporous carbon (114 m 2 g −1) showed multilayer adsorption behavior with a kinetic curve that could be described by the Ho equation. To achieve maximum dye removal, the effects of temperature (10–40 °C), specific surface area (67–143 m 2 g −1), initial concentration (250–1500 mg L −1), pH (2–13), and the mass–volume ratio (10–150 g L −1) were studied using an L 16 orthogonal array. The percent dye removal was transformed into an accurate S/N ratio for a “high is better” response. pH was found to be the most effective factor for promoting dye removal, followed by the mass–volume ratio. A temperature of 10 °C, a specific surface area of 114 m 2 g −1, an initial concentration of 500 mg L −1, pH 2, and a mass/volume ratio of 150 g L −1 were the best conditions determined by the Taguchi method. Finally, the carbon was tested using samples of real and simulated wastewater solutions under the optimal conditions, and color removal efficiencies of 60% and 40%, respectively, were obtained.