SORPTION AND DESORPTION OF WATER VAPOR ON CALCIUM CHLORIDE-ANODIZED ALUMINA COMPOSITE SORBENTS

摘要

In the present study, we prepared several calcium chloride (CaCl_2)-anodized alumina composites, and examined them for the water sorption and desorption behaviors. Experimental results showed that most CaCl_2 was deposited into pores of the anodic oxide film and that the amount of CaCl_2 depended on the pore volume and the CaCl_2 concentration in impregnation solution regardless of the pore diameter. The water uptake for the composite prepared using anodized alumina with a mean pore diameter of 115 nm increased in a stepwise fashion in the similar way as bulk CaCl_2. When smaller amount of CaCl_2 deposited in the film, the sorption capacity decreased and the sorption isotherms changed gradually from the stepwise shape to the linear shape. The sorption and desorption isotherms for the composites with large amount of CaCl_2 showed that the water uptake was varied from n = 2 to 7 in the relative pressure range of 0.09-0.29.