title: Structure and properties of vanadium(V)-doped hexagonal turbostratic birnessite and its enhanced scavenging of Pb²⁺ from solutions.
abstract: Vanadium(V)-doped hexagonal turbostratic birnessites were synthesized and characterized by multiple techniques and were used to remove Pb(2+) from aqueous solutions. With increasing V content, the V(V)-doped birnessites have significantly decreased crystallinity, i.e., the thickness of crystals in the c axis decreases from 9.8 nm to ∼0.7 nm, and the amount of vacancies slightly increases from 0.063 to 0.089. The specific surface areas of these samples increase after doping while the Mn average oxidation sates are almost constant. V has a valence of +5 and tetrahedral symmetry, and exists as oxyanions, including V₆O₁₆(2-), and VO4(3-) on birnessite edge sites by forming monodentate corning-sharing complexes. Pb LIII-edge extended X-ray absorption fine structure (EXAFS) spectra analysis shows that, at low V contents (V/Mn≤0.07) Pb(2+) mainly binds with birnessite on octahedral vacancy and especially edge sites whereas at higher V contents (V/Mn>0.07) more Pb(2+) associates with V oxyanions and form vanadinite [Pb₅(VO₄)₃Cl]-like precipitates. With increasing V(V) content, the Pb(2+) binding affinity on the V-doped birnessites significantly increases, ascribing to both the formation of the vanadinite precipitates and decreased particle sizes of birnessite. These results are useful to design environmentally benign materials for treatment of metal-polluted water.
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Yin
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Xionghan
authors.initials: X
authors.lastname: Feng
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
authors.forename: Wenfeng
authors.initials: W
authors.lastname: Tan
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China; Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703HB Wageningen, The Netherlands.
authors.forename: Luuk K
authors.initials: LK
authors.lastname: Koopal
authors.affiliation: Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China.
authors.forename: Tiandou
authors.initials: T
authors.lastname: Hu
authors.affiliation: Department of Ecosystem Science and Management, University of Wyoming, 1000 E. University Ave., Laramie, WY 82071, USA. Electronic address: mzhu6@uwyo.edu.
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River), Ministry of Agriculture, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China. Electronic address: liufan@mail.hzau.edu.cn.
authors.forename: Fan
authors.initials: F
authors.lastname: Liu
mesh_terms: D003460:Crystallization; D007854:Lead / Q000737:chemistry* / Q000302:isolation & purification; D008968:Molecular Conformation; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D012996:Solutions; D013816:Thermodynamics; D017968:Vanadium Compounds / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014877:Water Pollution, Chemical / Q000032:analysis
chemical_list: D010087:Oxides; D012996:Solutions; D017968:Vanadium Compounds; D014874:Water Pollutants, Chemical; C505018:birnessite; D007854:Lead
keywords: Birnessite; Oxyanions; Pb(2+) removal; Vanadium; XAFS