Characterisation of Oued Tfal Clay from the Region of Gafsa, Tunisia: Progressive Elimination of Carbonates
M. Mhamdi *
Laboratory for the Application of Materials to the Environment, Water and Energy LAMEEE (LAM3E), Science Faculty of Gafsa, University of Gafsa, 2112 Gafsa, Tunisia, Laboratory of Applications of Chemistry to Natural Resources and Substances and the Environment (LACReSNE), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia and Chemistry Department, Al Baha University, Al Bahah, Saudi Arabia.
N. Gasmi
Laboratory of Applications of Chemistry to Natural Resources and Substances and the Environment (LACReSNE), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia.
E. Elaloui
Laboratory for the Application of Materials to the Environment, Water and Energy LAMEEE (LAM3E), Science Faculty of Gafsa, University of Gafsa, 2112 Gafsa, Tunisia.
N. Kbir-Ariguib
Laboratory of Applications of Chemistry to Natural Resources and Substances and the Environment (LACReSNE), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia.
M. Trabelsi -Ayadi
Laboratory of Applications of Chemistry to Natural Resources and Substances and the Environment (LACReSNE), Faculty of Sciences of Bizerte, University of Carthage, 7021 Zarzouna, Tunisia.
*Author to whom correspondence should be addressed.
Abstract
Elimination of impurities from raw clay is a very important step. Purified clay has the highest adsorption capacity compared to other forms of raw clay. Purified clay is a versatile absorbent material that can be used in various applications to remove contaminants and impurities from liquids and gases. The major element (like silicon, aluminium, iron and sodium) compositions of OT raw and OTNa purified clay were determined by atomic absorption (spectrometry, Specta-SpanIII). The mineralogy was characterised by X-ray diffraction (Philips goniometer, PW1730/10, using the CuKa, 40KV, 40mA). The infrared spectra, obtained after using KBr pellets, were recorded with a Perkin Elmer 783 dispersive spectrometer from 4000 to 400 cm-1.
The existence of calcium carbonate in raw clay is considered an impurity. In this paper, we have developed a new method for eliminating this impurity without affecting the structure of the clay. This work shows the results of various analyses on a representative clay sample from the southern west of Tunisia, particularly from Oued Tfal near the town of Gafsa.
Some carbonate, quartz, chlorite, and anorthite can be found in the raw smectite. The chemical composition and physical characteristics of the carbonate clay changed when it was attacked by a hydrochloric acid solution. These changes depend on several factors, including acid concentration, clay nature, and the acid-to-clay ratio. Although treatment to 0.5 M represents a total removal of carbonates, there are probably altered layers of the clay fraction. The result shows that for a treatment with acid solutions of concentrations below 0.5 M, there is a gradual removal of carbonate without protonation of the clay layers. The characterisation of the clay fraction shows that the sodium clay purified (OTNa) consists of a sodium montmorillonite smectite. The cation exchange capacity and the specific surface of OTNa measured using the method of methylene blue are equal to 82 meq/100g and 667 m2/g, respectively. The findings of this research have practical implications in various industries or sectors such as construction, ceramics, and environmental remediation, making the research very important for the scientific community.
Keywords: Clay Oued Tfal, characterisation, purification, elimination of carbonate