Mineralogical and spectroscopic characterization, and potential environmental use of limestone from the Abiod formation, Tunisia

Abstract

Limestone beds of the Late Cretaceous Abiod formation (Campanian-Maastrichtian system) are fundamentally important for the economic growth of the raw material sector in Tunisia. However, little attention has been paid to the detailed physical and chemical properties of the Abiod limestone. Nine limestone samples collected from the Abiod formation outcropping in the areas of Bizerte, Gafsa and Gabes, Tunisia, as well as their separated clay fractions, were characterized using different techniques, such as XRF, XRD, FTIR and TG/DTA. XRF showed the chemical composition of the limestone in which calcium carbonate was the main constituent, and silica, iron and magnesium were the impurities. XRD also confirmed the presence of small amounts of clay minerals and quartz along with sharp peaks of calcite. FTIR spectra indicated that the limestone was mainly composed of CaCO 3 in the form of calcite, as identified by its main characteristic absorption bands. These data were in agreement with XRD and XRF analysis data. The TG/DTA curves of the limestone samples, showing a close similarity to that of pure calcium carbonate, exhibited an endothermic peak between 600 and 760°C, with the maximum near 750°C. Moreover, FTIR spectra of clay fraction samples indicated high silica content in some samples.Especially the samples SD1 and SD2 collected in the northern area showed higher amounts of silica compared with those of AS1, AS2, CHB, ZNC, SND, MKM and GBS collected from southern districts. However, among the latter seven samples, one could recognize two groups based on the clay mineral investigations: (1) limestone with minor amounts of smectite and mixed layer minerals of smectite/ illite (AS1 and 2, CHB, ZNC, SND and GBS) and (2) limestone with smectite, kaolinite and apatite (SND and MKM). Differences in these mineralogical and chemical characteristics should be considered when limestone from the Abiod formation is utilized as a medium for heavy metal removal from wastewater.

Natural Hematite and Siderite as Heterogeneous Catalysts for an Effective Degradation of 4-Chlorophenol via Photo-Fenton Process

“…Vibration bands at 736 cm -1 , in the range 860-880 cm -1 and 1390-1440 cm -1 are attributed to the CO bond of the carbonates, confirming the results of XRD and chemical analyses (Siderite: FeCO 3 , Calcite: CaCO 3 and Dolomite: MgCa (CO 3 ) 2 ). This latter result is in agreement with the literature [24,25,28,29]. TPR analysis was performed to get detailed information about the nature of the iron oxides.…”

Adsorption of copper and zinc onto natural clay in single and binary systems

“…The other vibration at 1,635.34 cm -1 was attributed to the bending of adsorbed water (Sdiri et al 2011(Sdiri et al , 2012b. The stretching bands near 1,435.34, 871.67, and 711.60 cm -1 , found in the original sample, were assigned to calcite, but disappeared after the removal of carbonate minerals by acid treatment (Sdiri et al 2010(Sdiri et al , 2011. Detailed mineralogical, geological, and spectroscopic characterization of the studied clay samples can be found in Sdiri et al (2011Sdiri et al ( , 2012b.…”

Competitive Removal of Heavy Metals from Aqueous Solutions by Montmorillonitic and Calcareous Clays

“…3). The stretching bands near 1,435.34, 871.67 and 711.60 cm −1 were assigned to calcite (Sdiri et al 2010b;2011a). The removal of carbonate minerals by acid treatment led to the elimination of the abovementioned bands of calcite in TS and TY spectra.…”