Benefits of microwave heating method in production of activated carbon

This work investigates the chemical activation of a biochar sample using microwaves with KOH and NaOH. The activation of char samples was carried out in a microwave oven operating at 2.45GHz with a power input of 1200W. The specific surface area (SSA), yield (%), and pore size distribution were studied for microwave activation with KOH and NaOH. In microwave-assisted activation, the activation yields for NaOH and KOH activation were in the ranges of 40-70% and 60-80%, respectively. The NaOH-activation takes 1.5h in a furnace to fabricate an activated carbon with a SSA of 2600m(2)center dot g(-1). However, in microwave activation, a 5min activation with a power of 1200W results in activated carbon with a SSA of 1900m(2) g(-1). The activation yield and SSA are mainly controlled by impregnation ratio in microwave-assisted activation because KOH and NaOH were the sources of heat for the activation reaction. In this work, the microwave activation increased the reaction rate by 15 times compared to the furnace activation. Microwaves have a non-thermal effect on the kinetic parameters of chemical activation reactions. This effect was more evident in the case of NaOH microwave activation, probably because it is a more reactive compound compared to KOH.