Preferential adsorption and surface precipitation of lead(II) ions onto anatase in artificially contaminated Dixie clay

Tasuma Suzuki; Miyu Okita; Satoshi Kakoyama; Masakazu Niinae; Hideki Nakata; Hiroshi Fujii; Yukio Tasaka

doi:10.1016/j.jhazmat.2017.05.061

Preferential adsorption and surface precipitation of lead(II) ions onto anatase in artificially contaminated Dixie clay

J Hazard Mater. 2017 Sep 15:338:482-490. doi: 10.1016/j.jhazmat.2017.05.061. Epub 2017 Jun 1.

Authors

Tasuma Suzuki¹, Miyu Okita², Satoshi Kakoyama³, Masakazu Niinae³, Hideki Nakata⁴, Hiroshi Fujii⁴, Yukio Tasaka⁴

Affiliations

¹ Department of Sustainable Environmental Engineering, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan. Electronic address: tsuzuki@yamaguchi-u.ac.jp.
² Department of Sustainable Environmental Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan.
³ Department of Sustainable Environmental Engineering, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi, 755-8611, Japan.
⁴ Technical Development Center, Cement & Construction Materials Company, Ube Industries, Ltd., 1-6, Okinoyama, Kogushi, Ube, Yamaguchi, 755-8633, Japan.

PMID: 28618370
DOI: 10.1016/j.jhazmat.2017.05.061

Abstract

During TEM-EDS (transmission electron microscopy coupled with an X-ray energy dispersive spectrometer) analysis of Dixie clay artificially contaminated with Pb(II), we observed that Pb(II) was preferentially adsorbed and precipitated on the surface of TiO₂. To deepen the understanding of the mechanism and importance of this phenomenon, batch sorption experiments, XANES (X-ray absorption near edge spectroscopy) analysis, and sequential extraction analysis were performed. The TiO₂ in Dixie clay was found to be anatase, and anatase showed a higher Pb(II) sorption propensity than rutile, α-FeOOH, and one of two MnO₂ investigated in this study. Our experimental results indicated that the Pb precipitates preferentially formed on the surface of anatase was Pb(II) hydroxide or Pb(II) oxide. Additionally, sequential extraction analysis showed that at least 32% and 42% of Pb(II) was sorbed onto anatase in the Dixie clay contaminated with a Pb content of 736mg Pb/kg and 1,958mg Pb/kg, respectively. These results demonstrated that in addition to Fe and Mn oxides that are well-known metal oxides that serve as sinks for Pb(II) in the soil environment, TiO₂ is also a metal oxide that controls the behavior and fate of Pb(II) in soils.

Keywords: Anatase; Dixie clay; Lead(II); Sequential extraction; Soil contamination.