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چکیده
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In this study, biochar-derived rice husk (RHB) was modified with Co-Al layered double hydroxide (LDH) derived from Co-based metal-organic framework (ZIF-67) through hydrothermal method to prepare RHB/ZIF-67-derived Co-Al LDH nanohybrid as adsorbent for efficient removal of copper (II) ions from aqueous medium. The nanohybrid was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, and N2 adorption-desorption. Atomic absorption spectroscopy (AAS) was employed to analyze the concentration of Cu (II) in aqueous solution. In order to investigate the effect of contact time, pH of solution, and adsorbent dose on the removal performance of RHB/ZIF-67-derived Co-Al LDH nanohybrid, batch experimental studies were conducted. The surface adsorption isotherm is well fitted to Langmuir model, and the adsorption mechanism follows the pseudo-second-order kinetic model. In addition, based on the central composite design in the response surface method, the optimal conditions for adsorbent dose, time, pH and initial concentration of Cu (II) are obtained as 2 mg, 3 min, 7 and 50 ppm respectively. In optimal conditions, the nanohybrid shows many advantages including the high removal percent (99.71 %) for Cu (II) ions, excellent adsorption capacity of 1377.94 mg g−1, the ability to reuse for five times, low cost, and compatibility with the environment. The combined properties of RHB and ZIF-67-derived Co-Al LDH provide a large surface area of 849.44 m2 g−1, which increases the contact surface of adsorbent with Cu (II) ions and endows great adsorption performance even in complex environments.
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