Potential mechanisms of cadmium removal from aqueous solution by Canna indica derived biochar

The objective of this study was to investigate the mechanisms of cadmium (Cd) sorption on biochars produced at different temperature (300–600°C) and their quantitative contribution. The sorption isotherms and kinetics of Cd2+ sorption on biochars were determined and fitted to different models. The C...

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Veröffentlicht in:The Science of the total environment Jg. 562; S. 517 - 525
Hauptverfasser: Cui, Xiaoqiang, Fang, Siyu, Yao, Yiqiang, Li, Tingqiang, Ni, Qijun, Yang, Xiaoe, He, Zhenli
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Netherlands Elsevier B.V 15.08.2016
Schlagworte:
aqueous solutions
Biochar
cadmium
Canna indica
electrons
Heavy metal
ion exchange
kinetics
Mechanisms
minerals
pyrolysis
Pyrolysis temperature
sorption
Sorption characteristics
sorption isotherms
temperature
Sorption characteristics
Pyrolysis temperature
Mechanisms
Biochar
Heavy metal
ISSN:0048-9697, 1879-1026, 1879-1026
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Zusammenfassung:The objective of this study was to investigate the mechanisms of cadmium (Cd) sorption on biochars produced at different temperature (300–600°C) and their quantitative contribution. The sorption isotherms and kinetics of Cd2+ sorption on biochars were determined and fitted to different models. The Cd2+ sorption data could be well described by a simple Langmuir model, and the pseudo second order kinetic model best fitted the kinetic data. The maximum sorption capacity (Qm) obtained from the Langmuir model for CIB500 was 188.8mgg−1, which was greater than that of biochars produced at other temperature. Precipitation with minerals, ion exchange, complexation with surface oxygen-containing functional groups, and coordination with π electrons were the possible mechanisms of Cd2+ sorption on the biochars. The contribution of each mechanism varied with the pyrolysis temperature. With increasing pyrolysis temperature, the contribution of surface complexation and metal ion exchange decreased from 24.5% and 43.3% to 0.7% and 4.7%, while the contribution of precipitation and Cd2+-π interaction significantly increased from 29.7% and 2.5% to 89.5% and 5.1%, respectively. Overall, the precipitation with minerals and metal ion exchange dominated Cd2+ sorption on the biochars (accounted for 73.0–94.1%), and precipitation with minerals was the primary mechanism of Cd2+ sorption on the high-temperature biochars (≥500°C) (accounted for 86.1–89.5%). [Display omitted] •Sorption capacity of metal on biochars is affected by pyrolysis temperature.•Biochar derived from Canna indica at 500°C has a high sorption capacity for Cd2+.•Cd2+ sorption on the biochars fits a pseudo second order and Langmuir model.•Precipitation and ion exchange mechanisms dominated Cd2+ sorption on the biochars.
Bibliographie:ObjectType-Article-1
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content type line 23
ISSN:0048-9697
1879-1026
1879-1026
DOI:10.1016/j.scitotenv.2016.03.248