Arsenic, selenium, and chromium speciation in fly ash

Arsenic (As), selenium (Se), and chromium (Cr) are harmful to humans at certain concentrations, and can possibly be eluted from coal ash (fly ash) discharged from coal-fired power plants. Insolubilization can be employed to treat As, Se, and Cr eluted from fly ash. Arsenic, selenium, and chromium are known to have different environmental toxicities and susceptibilities to insolubilization depending on their chemical forms. Therefore, the speciation analysis of these elements eluted from fly ash is crucial from the viewpoint of environmental science and waste management. Thus, As, Se, and Cr in different fly ash samples were analyzed using X-ray absorption near-edge structure (XANES) spectroscopy and liquid chromatography combined with inductively coupled plasma mass spectrometry (LC–ICP-MS). Compared with As(III) and Se(VI), As and Se were eluted in the form of As(V) and Se(IV), which could be readily insolubilized, and Cr was eluted in the form of carcinogenic Cr(VI). The results confirmed that As, Se, and Cr can be eluted, and insolubilization should be recommended as a treatment method for these elements that elute from fly ash.