title: Salisbury biochar did not affect the mobility or speciation of lead in kaolin in a short-term laboratory study.
abstract: Salisbury biochar (produced from British broadleaf hardwood) with two different particle sizes (≤2mm and ≤0.15mm) was applied on a kaolin with three different lead (Pb(2+)) contamination levels (50mg/kg, 300mg/kg and 1000mg/kg) at the dosage of 1% in w/w. The short-term impact of biochar on the mobility and speciation of Pb(2+) in the kaolin was investigated using attenuation periods of 1, 7 and 28 days. The leachability and extractability of Pb(2+) in carbonic acid leaching and EDTA extraction tests as well as the speciation of Pb(2+) in soils were not significantly affected by biochar treatment during all periods. The insignificant effects of biochar on Pb(2+) immobilisation were most likely attributed to the high adsorption capacity of Pb(2+) on the kaolin and biochar failed to competitively adsorb Pb(2+) against kaolin. The kaolin immobilised Pb(2+) primarily through cation exchange, which represents the readily bioavailable fractions of Pb(2+) in soils and may still pose environmental risks. This paper suggests the inefficiency of biochar treament on heavy-metal contaminated clay-rich soils. Therefore a laboratory treatablity study with respect to the soil type may be crucial when large-scale biochar applications in heavy-metal associated soil remediation are evaluated.
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom. Electronic address: ztshennju@gmail.com.
authors.forename: Zhengtao
authors.initials: Z
authors.lastname: Shen
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: McMillan
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Fei
authors.initials: F
authors.lastname: Jin
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Abir
authors.initials: A
authors.lastname: Al-Tabbaa
mesh_terms: D000327:Adsorption; D002412:Cations; D002606:Charcoal / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry; D052918:Environmental Restoration and Remediation; D006863:Hydrogen-Ion Concentration; D007616:Kaolin / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008670:Metals; D019216:Metals, Heavy / Q000032:analysis*; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D002412:Cations; D008670:Metals; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; D007616:Kaolin; D007854:Lead; D004492:Edetic Acid
keywords: Biochar; Immobilise; Kaolin; Lead; Speciation