The characteristics of arsenic in Chinese coal-fired power plant flue gas desulphurisation gypsum

摘要

Flue gas desulphurization (FGD) gypsum had broad application prospects in soil, but the trace heavy metals in FGD gypsum directly determine the severity of secondary pollution. In this work, we focused on arsenic in FGD gypsum for 70 samples from Chinese 20 provinces, investigating the characteristics of distribution and leaching by total contents, fractions, leaching tests, and species, and identifying arsenic mode of occurrence and possible risk for FGD gypsum applications. The result showed arsenic was generally approximately 15 mg/kg in Chinese FGD gypsum, and had an obvious geographical distribution by samples from different areas. Leaching tests showed a lower ability of arsenic release in short-term leaching as well as a large potential leaching risk by the sustained release of arsenic in long-term leaching for high-level arsenic FGD gypsum. X-ray photoelectron spectroscopy showed arsenic in FGD gypsum was mainly present as As(III), which has a higher toxicity. Based on our results, with regard of arsenic, most FGD gypsum is a safe material for soil application, but we did notice the potential risk of arsenic release due to long-term leaching and the content of arsenite.