Preparation and characteristics of medicinal activated carbon powders by CO2 activation of peanut shells

Peanut shells were used as a precursor to prepare activated carbon for medical use via CO2 activation in a high-temperature fluidised bed reactor. The influence of the activation time and activation temperature on the yield and adsorption capacity of the activated carbon, which were estimated using methylene blue (MB) and phenazone adsorption, was studied. The activated carbon microstructure was assessed based on N2 adsorption, scanning electron microscopy, and Fourier transform infrared spectroscopy while the adsorption kinetics was evaluated using MB dye. In this study, the optimised conditions, activation temperature of 900 °C and activation time of 5 h, produced 225.8 mg g− 1 MB, 421.5 mg g− 1 phenazone uptake and 26.15% yield. At the optimised conditions, a 1060 m2 g− 1 Brunauer–Emmett–Teller specific surface area and 0.8021 cm3 g− 1 total pore volume were obtained for the activated carbon samples, and the presence of carboxyl, hydroxyl and alkyl functional groups was detected. The investigation of MB adsorption on the prepared activated carbon indicated that the adsorption kinetics process closely follows a pseudo-second-order chemisorption model. Compared with the quality index of British Pharmacopoeia and the United States Pharmacopoeia standards for activated carbon, this peanut shell-based activated carbon preparation was suitable for medicinal use.