[A-GE41] エネルギ・環境・水ネクサスと持続的発展

[AGE41-P05] Effects of Silicic Acid on Arsenite Leaching from Spent Calcium-Based Arsenic Adsorbents

*杉田 創¹、小熊 輝美¹、張 銘¹、原 淳子¹、川辺 能成¹ (1.国立研究開発法人　産業技術総合研究所)

キーワード：亜ヒ酸溶出、使用済吸着材、酸化カルシウム、水酸化カルシウム、ケイ酸

The spent adsorbents after arsenic removal in arsenic contaminated water itself contain a large amount of arsenic. If they are discarded without appropriate treatment, there is a concern that secondary arsenic pollution may occur due to arsenic leaching from them. In our previous studies, it was suggested silicic acid greatly affects leaching behavior of arsenate from the spent adsorbents. In this study, in order to examine the effects of silicic acid on arsenite leaching from the spent adsorbents, leaching tests with silicic acid solution and 2 kinds of spent calcium-based adsorbent (CaO and Ca(OH)₂) were carried out. This study revealed that when the initial silicic acid concentration in solution is high, the leaching of arsenite is also inhibited as in the case of arsenate. This was inferred that when the silicic acid component in the solution reacted with the calcium component eluted from the spent adsorbents to form the calcium silicate species, the arsenite component leached from the spent adsorbents was taken into the products.