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Description
The current study investigates for the first time the potential of using solid residues collected from the hydrodistillation of R. officinalis, after their modification with Fe, as low-cost adsorbents to alleviate the heavy metals in aqueous solutions. Physicochemical properties and adsorptive performances of R. officinalis solid residue (RO-SR) and Fe-modified R. officinalis solid residue (Fe-RO-SR) were investigated. The Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that the iron was successfully fixed to the surface of RO-SR. Furthermore, after iron modification, the specific surface area of ROSR was increased from 36.2 to 50.4 m2/g. Kinetics and isotherms of adsorption of Co onto RO-SR and Fe-RO-SR were fitted by applying different models, though the pseudo-second-order (Adj. R2 > 0.9985) and Langmuir (Adj. R2 > 0.9532) models fitted the experimental results better, respectively. The adsorption performances of RO-SR and Fe-RO-SR for Co were 37.31 and 50.25 mg.g-1, respectively. The equilibrium adsorption capacity was reduced from 22.56 g/L to 10.67 g/L when the temperature was raised from 25°C to 45°C.
