Magnetically modified activated carbon prepared from pine cones for treatment of wastewater containing heavy metals

In this study, activated carbon was prepared from pine cones and then was modified using Fe 3 O 4 nanoparticles. Afterwards, the characterization of the nano-adsorbent surface was completely investigated using different analyses such as scanning electron microscopy (SEM), X-ray diffraction, dynamic light scattering, Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) analyses. BET analysis showed that the specific surface area and the average pore diameter of the adsorbent were 665.27 m 2 /g and 2.52 nm, respectively, which shows the aforementioned adsorbent has a mesoporous structure. Also, SEM and TEM analyses showed that the adsorbent size is smaller than 100 nm. The nano-adsorbent was then used as a novel and efficient adsorbent to remove nickel (Ni(II)) and cobalt (Co(II)) ions from aqueous media. The maximum sorption capacities for Ni(II) and Co(II) were also obtained 169.5 and 196.1 mg/g, respectively, which showed significant adsorption capacities for both heavy metal ions. Moreover, the reusability of the adsorbent showed that the AC/Fe 3 O 4 nano-composite can be used after five cycles of reuse without a significant reduction in the removal efficiency. Furthermore, the Freundlich isotherm model could better be fitted with the experimental data compared to the Langmuir model. Besides, the thermodynamic study demonstrated that the sorption process was irreversible, physical, exothermic, and spontaneous.