Preparation of superior humidity-control materials from kenaf

Charcoals were prepared by carbonizing kenaf at temperature between 400 °C and 1,000 °C and their specific surface areas, pore volumes, iodine adsorption capacities and amounts of water vapor absorbed were measured. By comparing the properties of the core charcoal and the bark charcoal, it was found that specific surface areas, pore volumes and iodine adsorption capacities of the former were larger than those of the latter. Most of the obtained values were roughly similar to those of common wood charcoals, while humidity-control capacities (Whc) of charcoals were much larger than those of common wood charcoals. The reason for this is believed to be the presence of potassium in kenaf charcoals. The extraction of potassium by water washing gave Whc values similar to those of common wood charcoals, and the larger the Whc values of original charcoals were, the larger amounts of potassium removed were. Moreover, it was indicated that carbonization at higher temperature helped expose potassium on the pore wall surfaces that had been covered and thus enhanced Whc values.