The mineral tooeleite Fe6(AsO3)4SO4(OH)4⋅4H2O – An infrared and Raman spectroscopic study-environmental implications for arsenic remediation

Abstract

The mineral tooeleite Fe 6 (AsO 3 ) 4 SO 4 (OH) 4 4H 2 O is secondary ferric arsenite sulphate mineral which has environmental significance for arsenic remediation because of its high stability in the regolith. The mineral has been studied by X-ray diffraction (XRD), infrared (IR) and Raman spectroscopy. The XRD result indicates tooeleite can form more crystalline solids in an acid environment than in an alkaline environment.Infrared spectroscopy identifies moderately intense band at 773 cm -1 assigned to AsO 3 3-symmetric stretching vibration. Raman spectroscopy identifies three bands at 803, 758 and 661 cm -1 assigned to the symmetric and antisymmetric stretching vibrations of AsO 3 3-and As-OH stretching vibration respectively. In addition, the infrared bands observed at 1116, 1040, 1090, 981 and 616 cm -1 , are assigned to the  3 ,  1 and  4 modes of SO 4 2-. The same bands are observed at 1287, 1085, 983 and 604 cm -1 in the Raman spectrum. As 3d band at Binding energy of 44.05 eV in XPS confirms arsenic valence of tooeleite is +3. These characteristic bands in the IR and Raman spectra provide useful basis for identifying the mineral tooeleite.

Hybrid Inorganic‐Organic Frameworks: Synthesis and Crystal Structures of RbFe(SO4)(C2O4)0.5·H2O and CsM(SO4)(C2O4)0.5·H2O (M = Mn, Fe)

“…The infrared spectra of RbFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O, CsMn(SO 4 )(C 2 O 4 ) 0.5 · H 2 O, and CsFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O are shown in Figure . The infrared peaks observed at 620, 1090, 1174, and 1331 cm –1 [RbFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O], 619, 1078, 1168, and 1323 cm –1 [CsMn(SO 4 )(C 2 O 4 ) 0.5 · H 2 O], 625, 1095, 1174, and 1322 cm –1 [CsFe(SO 4 )(C 2 O 4 ) 0.5 · H 2 O] are assigned to the ν 4 , ν 1 , and ν 3 modes of the sulfate tetrahedra . The bands at 455, 445, 458, 508, 511, and 509 cm –1 can be attributed to symmetric SO 4 2– bending modes ν 2 , and the peak positions for the three compounds are very similar.…”