Removal of 2,4-Dichlorophenoxyacetic Acid Using Activated Dates Seed Biochar: Adsorption Characteristics and Optimization

The contamination of water bodies with 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide has raised serious environmental concerns. In this study, date seed biochar was chemically activated using sodium hydroxide (NaOH) to enhance its adsorption performance. The adsorbent was characterized using BET, FTIR, SEM, XRD, and EDS analyses to investigate its surface area, functional groups, morphology, crystallinity, and elemental composition. Batch adsorption experiments were conducted under varying initial concentrations, contact times, and pH conditions to evaluate the removal efficiency of 2,4-D. The optimal pH was determined to be 4. The maximum adsorption capacity was found to be 62.11 mg/g based on the Langmuir model, which showed a better fit (R² = 0.95) than the Freundlich model. Kinetic studies revealed that the pseudo-second-order model best described the adsorption behavior (R² = 0.997), indicating chemisorption as the dominant mechanism. These findings highlight the effectiveness of NaOH-activated date seed biochar as a low-cost and sustainable adsorbent for the removal of 2,4-D from aqueous solutions.