Adsorption and Preliminary Safety Evaluation of Activated Carbons Refined from Charcoals

The objectives of this study were to investigate the absorption and preliminary safety of activated carbon(AC) refined from Makino bamboo, Moso bamboo and Japanese cedar charcoals with carbon dioxide(CO2) at an 800 and 900°C activation temperature with 90, 120 and 150 min of activation time. The yield ofAC was from 47.5 to 90.4%. The benzene absorption (10.8–37.4%) of AC was also higher than that (1.3–9.4%)of charcoals. The iodine value (562–1088 mg/g) of AC was higher than that (141–628 mg/g) of charcoals.The true density (2.11–2.17 g/cm^3) and BET surface area (791.22–829.78m^2/g) of AC were obviously higher than those (1.68–1.86 g/cm^3 and 58.95–356.62m^2/g) of charcoals. The AC belongs to a mesopore structure because the results of average pore diameters were from 2.22 to 2.69 nm. No matter what the relative humidity (RH) was in high/low RH at either 90 or 40% with a constant temperature of 25˚C, the hygroscopic ability of AC was better than that for charcoals, and the water activity of AC was from 0.45 to 0.46. The heavy metal content as the Pb (Plumbum) ppm base of AC was below 40 ppm and met the Sanitation Standard of Edible Natural Colorants from the announcement by the Department of Health’s Executive Yuan, in Taiwan. The preliminary safety evaluation using the Ames test for the charcoals and AC had no cytotoxicity and mutagenicity toward Salmonella typhimurium TA98 and TA100. It is suggested that the AC, refined from the charcoals, can be expected to be a natural moisture–proof material