چكيده به لاتين
The presence of various pollutants, including heavy metals, pesticides, chemical fertilizers, and particularly dyes, in the effluents of textile industries has created hazardous environmental conditions for human society. The increasing population, coupled with the corresponding rise in pollutant production, has amplified the need for research and development of scientific and effective methods to mitigate adverse environmental and health impacts. Several techniques are employed to prevent the release of dye-contaminated wastewater, with surface adsorption being one of the most efficient methods. Carbon-based adsorbents, such as biochar and carbon nanotubes, have garnered significant attention from researchers due to their high specific surface area, porosity, and low toxicity, among other attributes, making them promising candidates for modification and use as adsorbents. In this study, the biochar/mixed metal oxides composite adsorbent was investigated to examine factors influencing its synthesis, including the molar ratio of metal salts, the type and volume percentage of solvent, and the weight percentage of biochar in the composite. The experimental design was conducted using Taguchi's L9 orthogonal array, with these factors considered at three levels each, and their impact on the adsorption capacity response was analyzed using Minitab software. The results indicated that the molar ratio was the most significant factor, followed by the ethanol percentage and the biochar percentage in the composite. The optimal sample, as suggested by the synthesis software, exhibited a 3.1% deviation from the predicted value. Characterization tests, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), and others, were conducted to elucidate the physical and chemical properties of the biochar/Zinc ferrite composite. The nitrogen adsorption-desorption test revealed that the synthesized composite possessed a specific surface area that was 6.23 times greater than that of the raw biochar. Additional experiments were performed to determine factors such as contact time, optimal pH, point of zero charge (pHpzc), optimal adsorbent dosage, and the number of adsorption and reuse cycles. The thermodynamics of adsorption for the optimal sample were also investigated, demonstrating that the adsorption process on this composite is endothermic and spontaneous. Furthermore, the enthalpy of adsorption suggested that physical adsorption dominates the process. The best-fitting kinetic model, with a correlation coefficient of 0.9923, was the pseudo-second-order kinetic model. Among the various adsorption isotherm models evaluated, the Langmuir model showed the highest conformity, predicting a maximum adsorption capacity of 322/15 mg/g, indicating monolayer adsorption on a homogeneous surface.
