Arsenic Transformation and Volatilization during Incineration of the Hyperaccumulator Pteris vittata L.

Abstract

Safe incineration of harvested hyperaccumulators containing high content of heavy metals to avoid secondary environmental pollution is a problem for popularizing phytoremediation technology. The As volatilization behavior and its mechanism during incineration of Pteris vittata, an As-hyperaccumulator, was investigated. Incineration results reveal that 24% of total As accumulated by P. vittata (H-As) containing high As content (1170 mg/kg) is emitted at 800°C, of which 62.5% of the total emitted As is volatilized below 400°C. A study of the extended X-ray absorption fine structure (EXAFS) shows that part of As(III) was identified in the thermal decomposition residue of dried P. vittata (H-As), As 2 O 5 + P. vittata (L-As) containing low As content (14.7 mg/kg), and As 2 O 5 + charcoal (C) at 200°C, suggesting that carbon originating from biomass incineration might catalyze As(V) reduction. This speculation was tested through thermogravimetric experiments, in which either C or P. vittata (L-As) markedly catalyzed the volatilization of pure As 2 O 5 at low temperature. Therefore, the reduction of As(V) to As(III) is responsible for As volatilization during incineration of P. vittata below 400°C. This study provides important insights into As behavior during incineration of As-hyperaccumulators, which is helpful to safely dispose harvested biomass with high As content.

Thermal characteristics and fate of heavy metals during thermal treatment of Sedum plumbizincicola, a zinc and cadmium hyperaccumulator

“…Wu et al [17] investigated the control of HM emissions from incineration and found that kaolin and activated carbon removed most of the Cd from the flow gas. Yan et al [12] investigated the volatilization behaviour of arsenic (As) and its mechanism during incineration of Pteris vittata. Lu et al [13] reported that incineration favours the volatilization of Cd in contrast to pyrolysis and the contents of HMs in ashes and flow gas were studied in S. plumbizincicola.…”

Biomass reduction and arsenic transformation during composting of arsenic-rich hyperaccumulator Pteris vittata L.

“…Mg 3 (AsO 4 ) 2 ⋅8H 2 O disappeared after heat-treated leachate solid (see Fig. 2b upper) due to As volatilization (Yan et al 2008). …”

“…2a upper) possibly due to As volatilization. Yan et al (2008) indicated that As in the fern biomass started to volatilize at temperatures higher than 200°C.…”

“…However, disposal of the As-rich fern biomass after harvesting was not addressed in that study. Yan et al (2008) reported transformation and volatilization of As during incineration of As-rich fern biomass. However, as the authors stated, arsenic emission into the atmosphere may cause secondary contamination.…”

Phytoremediation of Soil Trace Elements

“…Yan et al [232] demonstrated that incineration of As-rich biomass caused volatilization of the plant As, but that should have been expected. Copper smelters would emit large amount of As if not required to control all emissions, which is readily achieved using existing technology.…”