title: Co-adsorption of phosphate and zinc(II) on the surface of ferrihydrite.
abstract: Ferrihydrite (Fh) is of great importance in affecting the migration and transformation of heavy-metal cations and oxyanions. To advance the understanding of co-adsorption reactions on Fh surface, the co-adsorption of phosphate and Zn(II) from aqueous solution to a synthesized Fh was determined. The batch experiments demonstrated a synergistic adsorption of phosphate and Zn(II) on Fh. In the pH range of 3.5-6, the adsorption of the two contaminants showed strong pH dependence in the single solute adsorption systems, but the dependence alleviated in the simultaneous adsorption system. X-ray photoelectron spectroscopy (XPS) revealed that the chemical shifts of Zn 2p1/2 and Zn 2p3/2 binding energies were more significant than that of P 2p in the single and simultaneous adsorption systems. On the other side, in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) observed increased formation of outer- and inner-sphere complexes of phosphate in the simultaneous system. Thus, the synergistic adsorption of the two contaminants could be attributed to the formation of ternary complexes as well as electrostatic interactions, while surface precipitation could not be completely ruled out. On the basis of the results from both the batch adsorption experiments and structural characterization, these two contaminants were likely to form phosphate-bridged ternary complexes (≡Fe-P-Zn) in the simultaneous adsorption system.
authors.affiliation: Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.affiliation: Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: zhurl@gig.ac.cn.
authors.forename: Runliang
authors.initials: R
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Tianyuan
authors.initials: T
authors.lastname: Xu
authors.affiliation: Xiangtan University, Hunan, 411105, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Xiangtan University, Hunan, 411105, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Ge
authors.affiliation: School of Physical and Chemical Sciences, Queensland University of Technology, Australia.
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xi
authors.affiliation: Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Jianxi
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Mineralogy and Metallogeny, Guangdong Provincial Key Laboratory of Mineral Physics and Material Research & Development, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Hongping
authors.initials: H
authors.lastname: He
mesh_terms: D000327:Adsorption; D005290:Ferric Compounds / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D010710:Phosphates; D012996:Solutions; D014874:Water Pollutants, Chemical; C092844:ferric oxyhydroxide; D015032:Zinc
keywords: Co-adsorption; Ferrihydrite; Phosphate; Ternary complexes; Zinc