| Summary: | Sulfide precipitation has been widely applied to remove arsenic from acidic wastewater containing As(III) and As(V), due to its simple process and high efficiency. However, the characteristics and composition of the precipitates are also of importance for its further treatment and disposal. To explore the characteristics of elemental S formed by reduction and the combined form of the generated S and As<sub>2</sub>S<sub>3</sub>, the characteristics of precipitates sulfurized from As(III) and As(V) and the effects of temperature, the S(-II) to As ratio (S/As), Cl<sup>−</sup> concentration (c<sub>Cl−</sub>), and the volume fraction of H<sub>2</sub>SO<sub>4</sub> (φ<sub>H2SO4(v)</sub>) on the sulfurization of As(III) and As(V) were investigated in detail. The results showed that the contents of As and S were 60.37% and 39.73% in precipitate-As(III), while they accounted for 47.46% and 52.64% in precipitate-As(V); both precipitate-As(III) and precipitate-As(V) were mainly composed of amorphous As<sub>2</sub>S<sub>3</sub>, while the latter contained elemental S. Temperature and S(-II)/As(III) slightly affected the sulfurization process of As(III), while for As(V), as the temperature increased, the content of As<sub>2</sub>S<sub>3</sub> in precipitate-As(V) increased significantly. Additionally, with the S(-II)/As(V) increasing, the content of A<sub>2</sub>S<sub>3</sub> increased continuously. This study provides a further clarification of the specific composition and structure of the complex precipitates of arsenic sulfide, which will benefit the efficient stabilization of the arsenic sulfide sludge.
|
|---|