Journal
SCIENCE OF THE TOTAL ENVIRONMENT
Volume 730, Issue -, Pages -Publisher
ELSEVIER
DOI: 10.1016/j.scitotenv.2020.139119
Keywords
Phosphorus-modified biochar; Immobilization; Soil; Heavy metal
Categories
Funding
- National Key Research and Development Program of China [2016YFD0800805]
- National Science and Technology Support Program [2015BAD05B02]
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Biochars are widely used in the remediation of soil heavy metals, but there has been no clear understanding to the effects of novel co-pyrolysis biochars derived from biomass and orthophosphate on soil heavy metals. In this study, co-pyrolysis biochars derived from rape straw and orthophosphate (Ca (H2PO4)(2)center dot H2O/KH2PO4) were prepared and used to explore their effects on the speciations and ecological risks of Pb, Cd, and Cu in contaminated agricultural soil. The results showed that the addition of these co-pyrolysis biochars significantly decreased TCLP extracted concentrations (decreased by 5.9-81.7%) and ecological risks of heavy metals (Pb, Cd, and Cu) by transforming the metals from available speciation to stable speciation in soils. Co-pyrolysis biochar derived from rape straw and KH2PO4 showed the highest immobilization capacities, and the immobilization capacities of biochars for threemetals were in the order of Pb > Cu > Cd. Co-pyrolysis biochars could precipitate and complex with heavy metals directly by the phosphate and -OH on their surface, and also could promote immobilization of heavy metals indirectly by increasing soil pH value and available P content. During incubation, the content of carboxyl groups on biochars increased significantly, which was beneficial to the further complexation of heavy metals. In summary, the application of co-pyrolysis biochar derived from rape straw and orthophosphate (especially for KH2PO4) could effectively reduce ecological risks of Pb, Cd, and Cu in contaminated soil. (C) 2020 Elsevier B.V. All rights reserved.
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