Optimization of the adsorption of a textile dye onto nanoclay using a central composite design

The main aim of this study was to evaluate the efficacy of montmorillonite clay for the adsorption of C.I. Basic Yellow 2 (BY2) dye from aqueous media. The experimental results were processed by response surface methodology based on a central composite design (CCD). The effect of four main variables, including initial BY2 concentration, adsorbent dosage, reaction time, and temperature on the removal of BY2 was evaluated by the model. The accuracy of the model and regression coefficients was appraised by employing analysis of variance. The results demonstrated a good agreement between the predicted values obtained by the model and the experimental values (R² = 0.972). Accordingly, the maximum BY2 removal of 97.32% was achieved with an initial BY2 concentration of 60 mg/L, adsorbent dosage of 0.6 g/L, reaction time of 10 min, and initial temperature of 25°C. The results demonstrated the high efficiency of montmorillonite clay for the adsorption of BY2 dye from aqueous solution based on the data processed by CCD approach. The adsorbent dosage was found to be the key factor that controlled dye adsorption. The adsorption kinetic and isotherm were also investigated. The rate of adsorption showed the best fit with the pseudo-second order model (R² = 1). The results of the isotherm study fit the Freundlich model (R² > 0.9). The physicochemical properties of the sample were determined by XRF, XRD, FT-IR, and N₂ adsorption-desorption.