2009 年 30 巻 2 号 p. 111-116
Activated carbons (ACs) oxidized and out-gassed were prepared by introducing acidic functional groups in the warming nitric acid and eliminating them in He flow at 1000oC, respectively. Adsorption time course of 4-chlorophenol (4CP) on the carbons was examined in aqueous solutions. Though any significant pH variation could not be observed for the oxidized AC, the pH for the out-gassed AC obviously decreased as a result of concurrently releasing chloride ions from the carbon surface into the aqueous solution. Measuring surface functional groups on the 4CP adsorbed carbon rinsed with methanol to thoroughly remove physically adsorbed 4CP indicated that the hydroxyl groups increased by 2.5 times as many as the released chloride ions, and the basic sites decreased in contrast. 4CP is estimated to degrade on the out-gassed carbon, releasing chloride ions in the aqueous solution and forming chemical bonding between decomposed phenolic compound and some basic sites on the surface.