EARTH

[2901-14-12] Engineering aspect of removal and immobilization for toxic anions using adsorbent synthesized from steelmaking slag

○Yuya Okuda¹, Mitsuaki Matsuoka¹, Norihiro Murayama¹ (1. Kansai University)

司会（Chairman）：Jaeheon Lee （University of Arizona）, Mitsuaki　Matsuoka (Kansai University)

キーワード：Layered double hydroxides, Steelmaking slag, Toxic anions

Steelmaking slag is known as by-products discharged from a steel-manufacturing process. It is mainly reused as civil engineering materials, but reusing steelmaking slag due to its chemical composition is limited actually, compared with blast furnace slag. Development of effective usage is required for steelmaking slag. Layered double hydroxide (LDH) is well-known as a functional material having anion exchange ability. Synthesis method of LDH has been investigated using steelmaking slag as a raw material. Fundamental removal properties of slag-LDHs have been also found for toxic anions. However, many engineering problems to be solved are still remained. For example, immobilization of slag-LDHs containing toxic anionic species are important from an engineering aspect.
For the purpose of immobilization properties of As(III), Cr(VI) and Se(IV), the slag-LDHs containing toxic anionic species were heated at various temperatures. The dissolution tests were conducted for the heated slag-LDHs containing anionic species. In order to apply the slag-LDHs to a treatment of contaminated soil, As(III) elution behavior from contaminated soil were carried out by a column operation.
Dissolution properties of Cr(VI) and Se(IV) from heated slag-LDHs are different from the regent-LDH, and it is a little easy to dissolve them from the heated slag-LDHs. This tendency may be caused by an impurity component in the slag-LDH. About 20% of Si are contained in the slag-LDH. When Si component is removed from the slag-LDH, it is found that the dissolution properties are similar to those of regent-LDH. It is possible to improve the immobilization ability of toxic anions from the slag-LDH by the heat treatment and the removal of Si component. On the other hand, As(III) elution behavior from contaminated soil is clarified by a column operation using the slag-LDH. It is possible from these results to estimate the required amount of slag-LDH for the immobilization.