Optimisation of crystal violet removal onto raw kaolin using response surface methodology

This work aimed to investigate the removal of crystal violet (CV) dye from coloured wastewater using natural kaolin as an adsorbent. In order to investigate the effects of independent variables and to determine the optimum conditions on the dye removal, a 23 central composite design combined with a response surface methodology was employed. Experiments were carried out as a function of agitation rate (80 to 150 rpm), initial dye concentration (50 to 150 mg L-1) and adsorbent dosage (0.5 to 1.0 g L-1). The accuracy of the model was evaluated by employing the analysis of variance (ANOVA). The results revealed a good agreement between the model predicted and the experimental values. Under the optimal experimental conditions, the CV removal efficiency was 71% and the maximum adsorption capacity was 48.8 mg g-1. These results indicated that the kaolin can be successfully applied as a potential low-cost adsorbent for the removal of dyes from coloured wastewaters.