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This research focuses on optimizing the carbonization parameters of Exhausted Kahwa Coffee (EKC) for enhanced biosorption of Cu(II) from aqueous solutions. Utilizing the Box-Behnken design (BBD), the study systematically investigates the combined effects of carbonization temperature, time, and gradient on EKC biochar (EKC-BC) formation, maintaining a constant initial copper concentration. The BBD demonstrates statistical significance through ANOVA testing. The optimized carbonization conditions obtained are at 575.42 °C, 2.59 hours, and a gradient of 19.52 °C/min, yielding a maximum predicted biosorption capacity of 6.62 mg/g. Experimental values for Cu2+ removal rate and adsorption capacity confirm the model's accuracy, with a 2% deviation from predictions. Response surface methodology effectively enhances the preparation conditions of EKC-BC, leading to improved biosorption capacity. Copper biosorption aligns well with a linearly transformed Langmuir isotherm model, while the pseudo-second-order kinetic model accurately forecasts the rate constant. Instrumental analyses, including scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), provide insights into the surface structural modification of EKC-BC after adsorption of Cu2+. |
