Graduate School of Environmental Studies, Tohoku University, Aoba-ku, Sendai, Japan.
J Hazard Mater. 2010 Sep 15;181(1-3):419-25. doi: 10.1016/j.jhazmat.2010.05.027. Epub 2010 May 12.
Coal fly ash emitted from coal thermal power plants generally contains tens ppm of arsenic, one of the hazardous elements in coal, during combustion and their elution to soil or water has become a public concern. In this study, the acid washing process developed by the authors was applied to the removal of arsenic from coal fly ash. Laboratory- and bench-scale investigations on the dissolution behavior of arsenic from various coal fly ash samples into dilute H(2)SO(4) were conducted. Arsenic in the coal fly ash samples were dissolved into H(2)SO(4) solutions rapidly. However, its concentrations decreased with an increase in the pH of H(2)SO(4) solution in some cases. The species of arsenic in the dilute H(2)SO(4) was estimated as H(3)AsO(4), and its anionic species was considered to adsorb with the elevation of pH under the presence of ash particle. Such adsorption behavior was enhanced under the presence of Fe ion in the solution. The sufficient removal of arsenic was achieved by controlling pH and avoiding the adsorption of arsenic on the surface of coal fly ash particles, and the elution of arsenic from coal fly ash sample was successfully below the regulation limit.
燃煤电厂排放的粉煤灰在燃烧过程中通常含有数十ppm 的砷，砷是煤中的有害元素之一，其向土壤或水中的浸出已引起公众关注。在本研究中，作者开发的酸浸工艺被应用于从粉煤灰中去除砷。对不同粉煤灰样品中砷在稀 H 2 SO 4 中的溶解行为进行了实验室和台架规模的研究。粉煤灰样品中的砷迅速溶解在 H 2 SO 4 溶液中。然而，在某些情况下，随着 H 2 SO 4 溶液 pH 值的增加，其浓度会降低。在稀 H 2 SO 4 中，砷的形态估计为 H 3 AsO 4 ，在存在灰分颗粒的情况下，其阴离子形态被认为会随着 pH 值的升高而吸附。在溶液中存在 Fe 离子时，这种吸附行为会增强。通过控制 pH 值并避免砷在粉煤灰颗粒表面的吸附，可以实现砷的充分去除，并且成功地将砷从粉煤灰样品中的浸出量控制在规定限值以下。
