title: The structure of the mineral leogangite Cu10(OH)6(SO4)(AsO4)4·8H2O--implications for arsenic accumulation and removal.
abstract: The objective of this research is to determine the molecular structure of the mineral leogangite. The formation of the types of arsenosulphate minerals offers a mechanism for arsenate removal from soils and mine dumps. Raman and infrared spectroscopy have been used to characterise the mineral. Observed bands are assigned to the stretching and bending vibrations of (SO(4))(2-) and (AsO(4))(3-) units, stretching and bending vibrations of hydrogen bonded (OH)(-) ions and Cu(2+)-(O,OH) units. The approximate range of O-H⋯O hydrogen bond lengths is inferred from the Raman spectra. Raman spectra of leogangite from different origins differ in that some spectra are more complex, where bands are sharp and the degenerate bands of (SO(4))(2-) and (AsO(4))(3-) are split and more intense. Lower wavenumbers of δ H(2)O bending vibration in the spectrum may indicate the presence of weaker hydrogen bonds compared with those in different leogangite samples. The formation of leogangite offers a mechanism for the removal of arsenic from the environment.
authors.affiliation: Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. r.frost@qut.edu.au
authors.forename: Ray L
authors.initials: RL
authors.lastname: Frost
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xi
authors.forename: Sara J
authors.initials: SJ
authors.lastname: Palmer
mesh_terms: D001151:Arsenic / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods; D006860:Hydrogen Bonding; D007477:Ions; D008903:Minerals / Q000737:chemistry*; D008956:Models, Chemical; D012987:Soil; D013053:Spectrophotometry / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D013431:Sulfates / Q000737:chemistry; D014732:Vibration; D014867:Water / Q000737:chemistry
chemical_list: D007477:Ions; D008903:Minerals; D012987:Soil; D013431:Sulfates; D014867:Water; D003300:Copper; D001151:Arsenic