Thermal Characteristics of Hyperaccumulator and Fate of Heavy Metals during Thermal Treatment of Sedum plumbizincicola

Thermal treatment is one of the most promising disposal techniques for heavy metal- (HM)-enriched hyperaccumulators. However, the thermal characteristics and fate of HMs during thermal treatment of hyperaccumulator biomass need to be known in detail. A horizontal tube furnace was used to analyze the...

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Bibliographic Details
Published in:International journal of phytoremediation 2015-08, Vol.17 (8), p.766-776
Main Authors: Zhong, Daoxu, Zhong, Zhaoping, Wu, Longhua, Xue, Hui, Song, Zuwei, Luo, Yongming
Format: Article
Language:English
Subjects:
Aluminum Silicates - metabolism
Biodegradation, Environmental
Biomass
Biomass energy
Bioremediation
China
Chlorine - metabolism
Fly ash
Heat treatment
Heavy metals
Hot Temperature
hyperaccumulators
Lead (metal)
Materials recovery
Metals, Heavy - metabolism
Oxides
Process engineering
Recovery
Sedum
Sedum - metabolism
Soil contamination
Soil Pollutants - metabolism
Sulfur - metabolism
thermal disposal
thermodynamic analysis
Thermodynamics
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Summary:Thermal treatment is one of the most promising disposal techniques for heavy metal- (HM)-enriched hyperaccumulators. However, the thermal characteristics and fate of HMs during thermal treatment of hyperaccumulator biomass need to be known in detail. A horizontal tube furnace was used to analyze the disposal process of hyperaccumulator biomass derived from a phyto-extracted field in which the soil was moderately contaminated with heavy metals. Different operational conditions regarding temperature and gas composition were tested. A thermo-dynamic analysis by advanced system for process engineering was performed to predict HM speciation during thermal disposal and SEM-EDS, XRD and sequential chemical extraction were used to characterize the heavy metals. The recovery of Zn, Pb and Cd in bottom ash decreased with increasing temperature but recovery increased in the fly ash. Recovery of Zn, Pb and Cd fluctuated with increasing air flow rate and the metal recovery rates were higher in the fly ash than the bottom ash. Most Cl, S, Fe, Al and SiO 2 were found as alkali oxides, SO 2 , Fe 2 (SO 4 ) 3 , iron oxide, Ca 3 Al 2 O 6 , K 2 SiO 3 and SiO 2 instead of reacting with HMs. Thus, the HMs were found to occur as the pure metals and their oxides during the combustion process and as the sulfides during the reducing process.
ISSN:1522-6514
1549-7879
DOI:10.1080/15226514.2014.987373