Response surface methodology for optimizing adsorption process parameters of reactive blue 21 onto modified Kaolin

In this research, Kaolin modified by Cetyltrimethylammonium bromide is used as an adsorbent for the removal of Reactive Blue 21 from aqueous solutions. Response surface methodology was used to study the effect of independent variables, such as Reactive Blue 21 dye concentration (20, 40, 60, 80 and 100 mg/L), time (10, 20, 30, 40 and 50 min), initial pH (2, 4, 6, 8 and 10) and modified Kaolin dosage (0.05, 0.1, 0.15, 0.2 and 0.25 g/50 mL) on dye removal efficiency from aqueous solutions. At the optimum conditions, predicted removal of Reactive Blue 21 by modified Kaolin was 98.26%. The confirmatory experiment was conducted, which confirmed the results by 94.42 % dye removal. Thus, the experimental investigation and statistical approach enabled us to predict Reactive Blue 21 removal by modified Kaolin. Also, the kinetics and isotherm adsorption of Reactive Blue 21 onto modified Kaolin was obeyed pseudo-second order kinetics and Langmuir isotherm