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Sci Total Environ. 2019 Mar 10;655:751-758. doi: 10.1016/j.scitotenv.2018.11.282. Epub 2018 Nov 20.

Effect of production temperature on lead removal mechanisms by rice straw biochars.

Author information

1
National Engineering Laboratory for Site Remediation Technologies, Beijing 100015, China; School of Environment, Tsinghua University, Beijing 100084, China; Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada.
2
National Engineering Laboratory for Site Remediation Technologies, Beijing 100015, China; School of Environment, Tsinghua University, Beijing 100084, China. Electronic address: houdeyi@tsinghua.edu.cn.
3
School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK.
4
School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China.
5
Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
6
Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada.

Abstract

Production temperature significantly affects biochar properties and consequently the removal mechanisms of heavy metals. In this study, rice straw biochars were produced at 300, 500 and 700 °C (RSB300, RSB500 and RSB700). The influence of production temperature on the adsorption characteristics and removal mechanisms of lead on this set of rice straw biochars were investigated by batch adsorption tests, micro-structural analyses and sequential metal extractions. Biochars produced at higher temperatures had significantly higher pH values and surface areas, resulting in higher metal removal capacities and faster uptake kinetics. Precipitation was a key mechanism for lead removal from solution for all biochars: lead oxalate was precipitated on RSB300, and hydrocerussite was precipitated on RSB500 and RSB700. The immobilized lead fraction on the biochars could be divided into exchangeable, acid soluble and non-available fractions. RSB300 had 11.34% of the total immobilized Pb attributed to the exchangeable fraction, whereas for RSB500 and RSB700, it was <1%. Immobilized Pb on RSB500 and RSB700 was almost exclusively attributable to the acid soluble and non-available fractions (>99%). Based on our results, RSB500 and RSB700 are likely much more appropriate for soil remediation of Pb as compared with RSB300.

KEYWORDS:

Adsorption; Biochar; Lead immobilization; Precipitation; Production temperature; Soil remediation

PMID:
30476855
DOI:
10.1016/j.scitotenv.2018.11.282
[Indexed for MEDLINE]

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