Efficient arsenate removal by magnetite-modified water hyacinth biochar

Published Date

Available online 2 July 2016, doi:10.1016/j.envpol.2016.06.013

In Press, Corrected Proof — Note to users

Title 

Efficient arsenate removal by magnetite-modified water hyacinth biochar ☆

• Author 

• Feng Zhang ^a,b
• Xin Wang ^a,,
• Ji Xionghui ^b,,
• Lijuan Ma ^a

• aCollege of Resources and Environmental Science, Hunan Normal University, Changsha, Hunan, 410081, China
• bSoil and Fertilizer Institute of Hunan Province/Ministry of Agriculture Key Lab of Agri-Environment in the Midstream of Yangtze River Plain, Changsha, 410125, China

Received 26 December 2015. Revised 29 April 2016. Accepted 6 June 2016. Available online 2 July 2016.

Highlights

• •
  Magnetic biochar (MW) was prepared from invasive water hyacinth biomass.
• •
  MW pyrolyzed at 250 °C(MW250₁) was most efficient in As(V) removal (Q_max7.41 mg g⁻¹).
• •
  As(V) removal efficiency by MW250₁ was unaffected at pH 3–10.
• •
  P exhibited stronger inhibition than Cr and Sb for As(V) sorption onto MW250₁.
• •
  Ligand exchange and Hydrogen bond were mainly responsible for As sorption on MW250₁.

Abstract

Magnetic biochars (MW) prepared by chemical co-precipitation of Fe²⁺/Fe³⁺ on water hyacinth biomass followed by pyrolysis exhibited important potential in aqueous As(V) elimination. In comparison, MW250₁ outperformed other MWs and exhibited the highest As(V) sorption capacity which was estimated to be 7.4 mg g⁻¹ based on Langmuir-Freundlic model. With solution pH ranging from 3 to 10, As(V) removal efficiency by MW250₁ kept stable and consistently higher than 90%. Besides, ∼100% removal of 0.5 mM As(V) can be obtained in the presence of P ≤ 0.1 mM or Cr/Sb ≤ 0.5 mM, indicating a wide applicability of MW250₁ for treatment of As-containing water. The predominance of Fe₃O₄ on MW250₁ surface was evidenced by XRD. Ligand exchange between As(V) anion and the hydroxylated surface of Fe₃O₄as well as H bond was largely responsible for As(V) sorption as suggested by FTIR. XPS analysis further revealed the dominance of As(V) in the sorbed As on MW250₁surface with co-occurrence of a minor proportion of As(III) (11.45%). In parallel, oxidative transformation of Fe₃O₄ to Fe₂O₃ was also suggested by XPS. By a lab-scale column test, the potential and suitability of MW250₁ in As-containing water treatment was further confirmed, which could also provide an alternative way to manage and utilize this highly problematic invasive species.

Graphical abstract

Keywords

• Magnetic biochar
• Arsenic
• Sorption behavior
• Sorption mechanisms
• Invasive species

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• ☆
  This paper has been recommended for acceptance by Baoshan Xing.

• ∗ 
  Corresponding author.
• ∗∗ 
  Corresponding author.

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