Characterization of Microwave and Conventional Heating on the Pyrolysis of Pistachio Shells for the Adsorption of Methylene Blue and Iodine

The production of activated carbon was investigated using the sequential combination of microwave and conventional heating of pistachio shells as the raw precursor with zinc chloride. Several techniques such as thermogravimetric and differential thermal analyses, infrared spectroscopy, scanning electron microscopy, and specific surface area analyses were performed to characterize the samples. The highest specific surface area value for the activated carbon prepared at a microwave power of 200 W with microwave time of 20 min, and flow rate of 50 mL min⁻¹ was 1468 m² g⁻¹. The methylene blue and iodine adsorption capacities were 331 and 1276 mg g⁻¹, respectively. The results were compared to those obtained using physical and chemical activation methods and showed that the sequential combination of microwave and conventional heating reasonably influenced the micropore surface area of the samples as well as the specific surface area.