Preparation and properties of buckwheat shell-based activated carbon

Abstract

In order to realize the utilization of solid waste resource.A novel adsorbent, buckwheat shell-based activated carbon has been developed by chemical activation when applying waste buckwheat hull as thraw material.The authors optimized the activation temperature, activation time, type of activator, mass ratio of buckwheat hull and activator in the preparation process through single factor method.The adsorption efficiency of the optimized buckwheat-shell activated carbon was investigated by iodine value and methylene blue value.Pore structure, microcrystalline structure and micro-surface morphology of activated carbon were characterized by gas adsorption instrument, X-ray diffraction and scanning electron microscopy.The results showed that the optimized buckwheat shell-based activated carbon exhibited the highest adsorption capacity when applying phosphoric acid as the activator, the activation time of 90 min, activation temperature of 500℃, mass ratio of buckwheat shell and activator is 1:3.The iodine value and methylene blue value of the optimized buckwheat shell-based activated carbon were 765.8 mg/g and 222.2 mg/g respectively, and the methylene blue value of the optimized buckwheat shell-based activated carbon was higher than that of the three commercial activated carbons.Moreover, the optimized buckwheat shell-based activated carbon hosted the highest mesopore percentage (96.8%) and higher total pore volume (0.666 cm3/g) than that of the coal-based and coconut shell activated carbons, and the BET surface area (785.3 m2/g) was similar to the commercial activated carbons, indicating that a novel buckwheat shell-based activated carbon with strong mesopore, high adsorption capacity has been developed when applying waste buckwheat hull as raw material and phosphate as the activator.

Keywords

• buckwheat shell
• activated carbon
• iodine value
• methylene blue value
• adsorbent