Enhanced Cr(VI) removal from acidic solutions using biochar modified by Fe3O4@SiO2-NH2 particles

Shunquan Shi, Jiakuan Yang, Sha Liang*, Mingyang Li, Quan Gan, Keke Xiao, Jingping Hu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


Fe3O4@SiO2-NH2 magnetic particles with core-shell structure were attached on carboxylated biochar derived from phoenix tree leaves to synthesize a novel magnetic biochar for removing Cr(VI) ions from acidic solutions. FSEM, FTEM, XRD characterizations of the synthesized magnetic biochar revealed that the Fe3O4@SiO2-NH2 magnetic particles distributed uniformly on the surface or macrospores of carboxylated biochar by strong chemical bonding. The Cr(VI) ions adsorption capacity of magnetic biochar was 27.2 mg·g−1, surpassing original carboxylated biochar (18.2 mg·g−1). VSM and XPS characterizations demonstrated that the attached Fe3O4@SiO2-NH2 magnetic particles not only endowed biochar with perfect magnetic property (23 emu·g−1) but also provided complexing sites for binding Cr(III) cations reduced from Cr(VI) anions. The Cr(VI) ions removal by magnetic biochar contained three steps: (1) adsorption of Cr(VI) anions by protonated functional groups; (2) reduction of Cr(VI) anions to Cr(III) cations by electron-donor groups; and (3) chelation of Cr(III) cations by amine groups. The adsorption recycling test showed that magnetic biochar kept 85% of its initial Cr(VI) adsorption capacity at the sixth cycle, and the Fe leakage under pH 1.0 was smaller than 0.25 mg·L−1. The results indicated that this novel magnetic biochar was applicable for the practical treatment of Cr(VI)-containing wastewater.

Original languageEnglish
Pages (from-to)499-508
Number of pages10
JournalScience of the Total Environment
StatePublished - 1 Jul 2018
Externally publishedYes


  • Cr(III) immobilization
  • Cr(VI) removal
  • FeO@SiO-NH particles
  • Magnetic biochar


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