Process optimization studies of Congo red dye adsorption onto cashew nut shell using response surface methodology

Adsorption of Congo red dye from an aqueous solution with a low-cost adsorbent prepared from an agricultural waste was studied to determine the potential use of this adsorbent for complete removal of the dye. Batch studies were performed to address the influence of various parameters such as pH, adsorbent dose, initial dye concentration, time, and temperature. Response surface central composite design methodology was used to find the interaction among the variables and to determine the optimum conditions towards the adsorption of dye from the aqueous solution. The optimum values of pH, adsorbent dose, initial dye concentration, time, and temperature were found to be 3.2, 24.76 g/L, 20 mg/L, 67 min, and 30°C for complete removal of Congo red dye, respectively. The experimental values were in good agreement with predicted values.