Optimization of Reactive Turquoise blue 15 Removal from Aqueous Solutions by Kaolin- Tetrabutylammonium Iodide Using Response Surface Methodology

Dyes are organic compounds and are resistant against common removal methods and presence of dye wastes in environment causes extensive pollution [1]. Membrane filtration, adsorption, biological methods and advanced oxidation processes have been used to remove of days [2]. Among these methods, adsorption is mostly used due to cost-effectiveness and simplicity [3]. Turquoise blue 15 (AT15) is a reactive dye widely used in the textile industry to color natural fibers [4]. In this research modified Kaolin by Cetyl trimethylammonium bromide is used as an adsorbent for the removal of Turquoise blue 15 from aqueous solutions. The modified Kaolin was characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). Response Surface Methodology was used to study the effect of independent variables such as modified Kaolin dosage, Turquoise blue 15 dye concentration, time and initial pH on dye removal efficiency from aqueous solutions. Analysis of variance (ANOVA) suggested that the predicted values were in good agreement with experimental data. Maximum removal was attained as 92.79% at initial pH 4, dye concentration of 60 mg/L, temperature 30 °C with an adsorbent dosage of 3 g/L. At the optimum conditions, experimental and predicted removal of Reactive Blue 21 by modified Kaolin was 93.76% and 91.31%, respectively. Thus, the statistical approach enabled us to predict Turquoise blue 15 removal by modified Kaolin. Also, study of kinetics and adsorption isotherm models of Turquoise blue 15 adsorption onto modified Kaolin showed that the adsorption of study dye onto modified Kaolin was obeyed pseudo-second-order kinetic and Fundlich isotherm models.