1Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo, Kyoto 606-8502, 2Kyoto Kacho University, Faculty of Contemporary Home Economics, Higashiyama, Kyoto 606-0062, 3EARTH Corporation, Sendai, Miyagi 981-3180, Japan
With the aim of utilizing the shell of Unio douglasiae biwae Kobelt which is usually discarded, we attempted to develop an efficient metal adsorbent endowed with precipitation ability using the shell. On measuring the adsorption capacity of the shell powder for Pb(II), Cr(VI) and As(III), it showed significantly high adsorption capacity for Pb(II). The adsorption capacity of the shells of Pinctada fucata martensii, Crassostrea gigas, and Mizuhopecten yessoensis for Pb(II) was also measured, and all shells showed adsorption capacity for Pb(II). After baking the shell of Unio douglasiae biwae Kobelt at temperatures of over 400℃, the surface of the shell became porous and the crystalline structure of CaCO3 changed from aragonite to calcite, thereby increasing the adsorption capacity for Pb(II). By adding a small amount of acrylamide polymer, we succeeded in giving precipitation ability to the shell powder adsorbent.