Development of kinetic models for removing Congo red dye from an aqueous solution using natural clay composites

Abstract This study examined the adsorption potential of Montmorillonite, a natural clay, for the removal of Congo red dye. A continuous sorption technique was implemented to represent industrial conditions. The evolution of breakthrough curves was evaluated as a function of key process variables, including flow rate, adsorbent bed height, and initial adsorbent concentration. A device consisting of a fixed-bed glass column with an internal diameter of 1.5 cm and a height of 30 cm was used to perform various measurements. Different bed heights ranging from 5 cm to 20 cm, inlet flow rates from 1.6 mL min −1 to 8 mL min −1 , and inlet CR concentrations from 10 mg L −1 to 50 mg L 1 were tested. Increasing the bed depth resulted in a decrease in concentration and inlet flow rate, which increased the contact time required for depletion. The influence of the pH of the initial solution and the contact time on the adsorption process was evaluated in order to determine their impact. Based on the observations, the pseudo-second-order kinetic model seems to be the most appropriate for describing the adsorption of RC dyes over time.