Comparison of chemical, morphological and adsorptive properties of physically-activated carbons produced from walnut shell and peach core

Agricultural wastes are appropriate precursors for producing activated carbon due to their accessibility and affordability. Therefore, walnut hard shell and peach hard core were selected to produce activated carbon via physical activation method. Methyene blue was used to study the batch equilibrium adsorption. The equilibrium data was fitted to four isotherm models including Langmuir, Freundlich, Temkin and Dubinin-Radushkevich. Adsorption capacity of the walnut shell-based activated carbon was around 16 mg/g lower than that of the peach hard core. In addition, SEM and image processing technique were applied to compare the morphology of the two adsorbents. Results indicated that the peach core activated carbon has higher disordered structure, more homogeneous pore size distribution, higher pore density and better mechanical hardness reflecting superiority of this activated carbon for adsorption.