Abstract In this study, the adsorption of Astrazon Blue and Astrazon Red, which are cationic dyes commonly used in the textile industry, from aqueous solution onto commercial activated carbon has been investigated. The effect of various parameters, including initial dye concentration, temperature, stirring speed, contact time, adsorbent dosage, and pH, on the adsorbed dye amount has been investigated using a Taguchi experimental design. For both dyes, the maximum amount of dye adsorbed and the highest calculated signal-to-noise ratio were found to be obtained in adsorption experiments with the following conditions: initial dye concentration of 300 mg/L, contact time of 180 min, initial pH of 9, temperature of 313 K, stirring speed of 170 rpm, and adsorbent dosage of 0.05 g/100 mL. In the determined optimum experimental conditions, the means of adsorbed dye amounts for Astrazon Blue and Astrazon Red were found to be 586.0 and 583.3 mg/g, respectively. It was determined that the equilibrium adsorption data showed a good fit to the Langmuir and Redlich-Peterson adsorption isotherm models. On the other hand, thermodynamic analysis revealed that the adsorption of both dyes on the activated carbon surface occurs with negative Gibbs free energy changes and positive adsorption enthalpy and entropy changes.
Açıkyıldız et al. (Wed,) studied this question.