Adsorption of 2,4‐Dichlorophenoxyacetic Acid by Iron‐Modified and PEI‐Coated Peanut Shells: Batch and Column Performances

Abstract This study investigates the adsorption of 2,4‐Dichlorophenoxyacetic acid (2,4‐D) using Fe‐modified polyethyleneimine‐coated peanut shells (Fe‐PEI‐PS). The property of Fe‐PEI‐PS toward 2,4‐D was performed through static and column modes. The Fe content in the Fe‐modified adsorbent reached 8.67% and Fe‐PEI‐PS exhibited a stable adsorption capacity for 2,4‐D in the pH range of 3–8. The maximum experimental adsorption capacity of Fe‐PEI‐PS can reach 61.6 mg∙g −1 at 293 K. The equilibrium data was found to conform to the Langmuir model while pseudo‐second‐order kinetic model is suitable to predict the kinetic process. This indicates a monolayer adsorption with stronger forces of attraction occurring between the Fe‐PEI‐PS and 2,4‐D. Thermodynamic analysis shows the adsorption process to be exothermic and spontaneous nature. For the dynamic studies, the Thomas model and Yan model were both suitable in describing the column breakthrough curves at various conditions. Using 0.1 mol∙L −1 sodium chloride solution as the elution enables the desorption rate to reach 98.5% and the regeneration rate is to reach 81.3%. Furthermore, the used Fe‐PEI‐PS can be reused multiple times. This research highlights the potential of Fe‐PEI‐PS as cost‐effective adsorbent for the removal of 2,4‐D from contaminated water.