Synthesis of MgO-coated corncob biochar and its application in lead stabilization in a soil washing residue

Zhengtao Shen, Jingzhuo Zhang, Deyi Hou, Daniel C.W. Tsang, Yong Sik Ok, Daniel S. Alessi

Research output: Journal article publicationJournal articleAcademic researchpeer-review

134 Citations (Scopus)


In this study, a magnesium oxide (MgO) coated corncob biochar (MCB) was synthesized by pyrolyzing MgCl 2 pretreated corncob, for a better performance in lead immobilization in a contaminated soil compared with corncob biochar (CB). The properties and microstructures of CB and MCB were investigated. It was observed that MgO particles ranging from 1 to 2 μm were well coated on MCB, and the MgO content in MCB was calculated at 29.90% in w/w. The surface area of the biochar was significantly enhanced from 0.07 to 26.56 m 2 /g after the MgO coating. The MgO coating also significantly facilitated the lead removal percentage from 23% to 74% in aqueous solution by biochar. CB failed to immobilize lead in a soil washing residue and could not reduce its environmental risks in a laboratory incubation study. In contrast, MCB was applied to the soil and resulted in a significant reduction in TCLP leached lead from 10.63 to 5.24 mg/L (reduced by 50.71%). The comparison between MCB and other amendments suggests that the biochar component of MCB adsorbed lead onto its surface through cation-π interaction and increased surface adsorption due to higher surface area, and then the MgO coated on MCB's surface further enhanced the adsorption through precipitation. The synergistic roles of biochar-mineral composites make them a promising candidate for soil remediation.

Original languageEnglish
Pages (from-to)357-362
Number of pages6
JournalEnvironment international
Publication statusPublished - Jan 2019


  • Biochar-mineral composite
  • Engineered biochar
  • In situ stabilization
  • Lead immobilization
  • Magnesium oxide (MgO)
  • Soil remediation

ASJC Scopus subject areas

  • Environmental Science(all)


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