Sorption mechanisms of lead on silicon-rich biochar in aqueous solution: Spectroscopic investigation

Jianhong Li, Lirong Zheng, Shan Li Wang, Zhipeng Wu, Weidong Wu, Nabeel Khan Niazi, Sabry M. Shaheen, Jörg Rinklebe, Nanthi Bolan, Yong Sik Ok, Hailong Wang

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Unraveling sorption mechanisms of lead (Pb) to silicon (Si)-rich biochar at molecular scale in aqueous solution are essential for the effective application of the biochars to the remediation of Pb and other metal(loid)s pollution in the environment. Thus, this study investigated the contributions of phytoliths and other compounds to the Pb sorption on Si-rich coconut fiber biochar (CFB500) and the corresponding sorption mechanisms using spectroscopic techniques, including the micro-X-ray fluorescence (μ-XRF), X-ray absorption fine structure (XAFS), scanning electron microscopy combined with energy dispersive X-ray spectroscopy, and X-ray diffraction. The μ-XRF and XAFS results showed that K, Ca, Cu, Mn, and Fe were released and significantly related to Pb in Pb-loaded CFB500; four major Pb species were formed with similar structures to lead carboxylate (e.g., Pb(C 2 H 3 O 2 ) 2 ), Pb 3 (PO 4 ) 2 , PbSiO 3 , and PbCO 3 . On phytoliths in CFB500, Pb 2+ ions were mainly sorbed on the sites of silicate with a structure similar to PbSiO 3 . The contribution of binding sites for Pb 2+ sorption was ascribed to the outer-wall of carbon skeleton of CFB500, which was stronger than that provided by the mineral oxide aggregate and phytoliths on CFB500. Organic carbon functional groups, inorganic carbonates, silicates and phosphates on CFB500 mostly dominated the sorption sites for Pb 2+ . Our results suggest that CFB500 was a promising material for the remediation of Pb-contaminated aqueous environments (e.g., wastewater).

Original languageEnglish
Pages (from-to)572-582
Number of pages11
JournalScience of the Total Environment
Publication statusPublished - 2019 Jul 1


  • Phytoliths skeleton
  • Sorption sites
  • Toxic metal(loid)s
  • XAFS
  • μ-XRF

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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