Cement based solidification/stabilization technology has been widely practiced for the treatment of inorganic hazardous wastes, especially metal-bearing wastes. The advantage of using the solidification/stabilization process is that the mobility of the hazardous materials is greatly retarded in the final disposal sites. The purpose of this study is to assess the stability of a synthetic solid waste through the renewable leaching test. A major cement constituent, dicalcium silicate (C 2 S), was used as a model binder to react with copper oxide to form a solid waste matrix. The semi-dynamic leaching test using 1 N acetic acid was employed to investigate the leaching characteristics of the C 2 S/CuO system. The results show that the dissolution of Ca(OH) 2 is the primary mechanism for the destruction of the matrix, and the subsequent leaching of copper ion. The surfacecontrolled dissolution reaction increases the pore size and porosity of the matrix, thus increasing the diffusion rate of copper ion transport. The C 2 S hydration product, silicate hydrate, might play a role in adsorbing the copper ion in the leaching system.

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