Biochar derived from olive kernels: a promising adsorbent for diclofenac uptake in wastewater

This study explores the potential of biochar, derived from the sustainable and cost-effective source of olive kernels, as an efficient adsorbent for the removal of diclofenac from water. The research details the production and comprehensive characterization of olive kernel biochar, specifically examining its efficacy in capturing diclofenac from aqueous solutions. The biochar's structural and chemical properties were analyzed using advanced techniques, including X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller surface area analysis, and scanning electron microscopy. The study systematically investigated the impact pH, biochar dosage, diclofenac concentration, temperature, and time on diclofenac adsorption performance. Under optimized conditions (40 mg/L diclofenac, 1 g/L biochar, 35 °C, and 60 min), the biochar achieved a high removal efficiency of approximately 96%, demonstrating strong adsorption capability. Kinetic modeling suggests that the adsorption process is primarily governed by a pseudo-second-order mechanism, with an excellent correlation coefficient (R²=0.9995). Isotherm analysis indicates that the Temkin model best represents the adsorption behavior, highlighting the energetic heterogeneity of the biochar surface. Thermodynamic parameters reveal the adsorption to be both exothermic (ΔH°=-11.71 kJ/mol) and spontaneous (ΔG°=-6.06 kJ/mol). These findings underscore the promising applicability of olive kernel-derived biochar for sustainable pharmaceutical pollutant removal.