Poster (EARTH)

[PE1-058] Role of dissolved oxygen and ferrous/ferric ion concentrations on arsenic release by oxidative dissolution of arsenopyrite

○Tasuma Suzuki¹, Kentaro Sue¹, Masakazu Niinae¹ (1. Graduate School of Sciences and Technology for Innovation, Yamaguchi University)

Keywords:Arsenopyrite, Oxidative dissolution, Oxygen, Iron ion, Iron(III) hydr(oxide)

Arsenic release by oxidative dissolution of minerals such as arsenopyrite (FeAsS) is an important process that controls the behavior and fate of As in the environment. The objective of this study is to investigate the influence of various factors, including pH and concentration of dissolved oxygen (DO), Fe²⁺, and Fe³⁺ species, on the release of arsenic by oxidative dissolution of FeAsS. The results showed that As leaching was more pronounced at pH 4.0 than at pH 7.0. Moreover, the As leaching levels increased with increasing DO, Fe²⁺, and Fe³⁺ concentrations at pH 4.0, whereas the opposite trend was observed at pH 7.0. The enhanced release of As promoted by DO and Fe³⁺ at pH 4.0 was attributed to the ability of these species to oxidize FeAsS. On the other hand, the enhanced As leaching promoted by Fe²⁺ at the same pH is probably due to its ability to catalyze the phase transformation of Fe(III) (hydr)oxides, resulting in a more effective exposure of the FeAsS surface to the aqueous solution containing DO.