Mounir Medhioub

Adsorption of a textile dye "Indanthrene Blue RS (C.I. Vat Blue 4)" from aqueous solutions onto smectite-rich clayey rock.

The adsorption of a textile dye, namely, Indanthrene Blue RS (C.I. Vat Blue 4) onto smectite-rich clayey rock (AYD) and its sulphuric acid-activated products (AYDS) in aqueous solution was studied in a batch system with respect to contact time, pH, and temperature. The adsorbents employed were characterized by X-ray diffraction, infrared spectroscopy and specific surface area, cation exchange capacity and point of zero charge were also estimated. The effect of contact time on dye adsorption showed that the equilibrium was reached after a contact time of 40 min for the both adsorbents. The optimum pH for dye retention was found 6.0 for AYDS and 7.3 for AYD. The equilibrium adsorption data were analysed using the Langmuir and Freundlich isotherms. The adsorption capacities (Q(m)) for AYD and AYDS were found 13.92 mg/g and 17.85 mg/g, respectively. The effect of temperature on the adsorption was also investigated; adsorption of Indanthrene Blue RS is an endothermic process. This study demonstrates that all the considered adsorbents can be used as an alternative emerging technology for water treatment.

Identification and use of white clayey deposits from the area of Tamra (northern Tunisia) as ceramic raw materials

Abstract White clayey geomaterials were collected from northeast of the Nefza region (northern Tunisia). These deposits belong to the Mio-Pliocene molassic basins (basin of Tamra-Sidi Dris, Boukhchiba) and Oligocene Numidien in the area of El Aouinet. Analysis by X-ray diffraction showed associations of halloysite and kaolinite (Tamra), kaolinite and illite (Aouinet zone) and mixed layers, kaolinite and feldspars (Boukhchiba zone). Semi-industrial processed bricks showed promising characteristics and were visibly free of defects. Ceramic tiles had a bending strength that met the required standards but water absorption was somewhat high. So, to achieve higher quality, optimisation needs to be carried out in the formulation of batches or in the processing conditions. Finally, the incorporation in whitish sanitary-ware glaze formulations generated smooth coating layers that showed the required strong brightness and were free of defects.

Chromium and nickel removal from industrial wastewater using Tunisian clay

AbstractIn this study, illitic Tunisian (MOM R) clay was applied for the removal of Cr(III) and Ni(II), from industrial wastewater. The considered adsorbent (MOM R) was collected from Jebel El Hamma, Lower Cretaceous age. To characterize the adsorbent structures, infrared spectroscopy and X-ray diffraction techniques were used. The effects of agitation time, adsorbent quantity, pH, initial metal ion concentration, and temperature on the removal of these metals were studied. In order to study the adsorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The estimated optimum pH of chromium (III) ion retention for the considered adsorbents was 2.13 and 6.43 for nickel (II). The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The adsorption capacities of Cr(III) were 7.751 mg/g and 62.5 mg/g Ni(II). The effect of temperature on the adsorption phenomenon was also investigated. The results indicated that adsorption is an endothermic process f...

Production of ceramic bodies from Tunisian Cretaceous clays

Abstract The aim of this research was to assess the potential application of the Late Cretaceous levels as raw material for the production of ceramic tiles. Mineralogical, chemical and grain size distribution studies were carried out on four clays sampled at different sites in the Tunisian Central Atlas. Clays are mainly composed of phyllosilicates, usually illite and kaolinite. Quartz, feldspars and dolomite were also detected. Tiles were prepared by pressing clay bodies at 250 bar and then firing at different temperatures following industrial conditions as closely as possible. Thermal analysis showed the influence of mineralogical composition and grain size distribution on the material behaviour during firing. The physical properties of fired tiles were obtained from specific tests in accordance with international standards (ISO), i.e. the firing shrinkage, water absorption, apparent density and flexural strength. The development of physical properties indicates an optimal firing range between 1050–1150ºC. Results demonstrate the potential of Late Cretaceous materials as raw materials for the production of ceramic tiles.

Performance evaluation of an industrial wastewater treatment plant in South-Eastern Tunisia

Heavy metal pollution has become one of the most serious environmental problems today. Heavy metals treatment is of the special concern due to their recalcitrance and persistence in the environment. In this study, four metals (Cr, Cu, Ni, and Zn) found in an industrial wastewater treatment plant in Sfax (South-Eastern Tunisia) were monitored for 10months in 2012. Metal influent and effluent concentrations of wastewater flocculation process measured via 24-h composite samples were used to determine removal efficiencies. Average influent concentrations varied between 16±13.03mg/L (Zn) and 167.21±120.06mg/L (Cr). The flocculation process yielded high removal efficiencies of the studied metals (P93%). Treated wastewaters quality was evaluated according to Tunisian standards for emission into the sewerage system. It was determined that effluent quality in terms of biological oxygen demand, suspending solid, chemical oxygen demand, pH, Cu, and Zn levels were in agreement with standards, but Cr and Ni residual loads were still above the values required by quality criteria.

Effect of Diagenesis on Clay Mineralogy and Organic Matter in the Tunisian Southern Subsurface

This study aims to follow the effect of the diagenetic transformations on the clayey fraction and the organic matter of the Tunisian southern sub-surface. 61 samples from oil well named NWA-1 were recuperated for series of analyses. This study follows a comparative approach between the mineralogical, geochemical and petrographic studies. To discuss results from a statistical viewpoint, the Principal Component Analysis (PCA) was applied in order to find out any correlation between different components. The associated minerals quartz, feldspar, calcite, pyrite, anhydrite, gypsum, dolomite and olivine are also detected. These associated minerals remove by-products by the illitization reaction. The Index of Crystallinity (IC) of illite shows that, except some anomalies, the studied samples are between the epizone and the anchizone. Downward, samples show the effect of diagenetic processes and weak signs of low-grade metamorphism. As regards to the organic matter, values of Tmax range between 333°C and 463°C. On the other hand, potential hydrocarbon compounds (S2) show low values compared to those of (S1); but they maintain a similar variability from 0.63 to 21.12. SEM observations and X-ray microanalyses supported the formation of authigenic micro-quartz. The PCA of clay minerals, chemical components, and the depth shows three different populations. Feldspar, chlorite and quartz make up a population positively correlated with the depth. The second population seems to be indifferent to depth variation; it is made up of two sub-populations: the population of illite, gypsum and anhydrite, which is obtained by a counter clock rotation of depth population; and the population of pyrite, kaolinite, olivine phyllosilicate, which is obtained by an anticlockwise rotation of depth population. Third, the population of smectite, calcite and dolomite is inversely proportional to the depth variation. On the other hand, the PCA of TOC, Tmax, HI, S1, S2 and the depth make up a homogenous statistical population following the depth evolution.

Magnetic Study of the Heated and Unheated Sedimentary Fillings of Sebkha Mhabeul, Southeast Tunisia: A Geophysical Method for Paleoclimatic Investigation and Tephrochronological Dating

This paper is meant to investigate the climatic and volcanic signals within the sedimentary filling of sebkha Mhabeul through a thermomagnetic study of a 37 cm length core. Values of the magnetic susceptibility at ambient temperature show that the core encompasses four climatic stages: the Warming Present (WP), the Little Ice Age (Late LIA), Early Little Ice Age (ELIA), and the Medieval Climate Anomalies (MCA). Added to the subcycles, the spectral analysis shows the individualization of an 888 yr cycle probably related to solar activity. The heating at 250°C is good-for-nothing since it was useful neither for climatic investigation nor for tephras layers detection. Heating at 700°C generated the complete loss of the climatic signal. On the other hand, it allowed the detection of the previously identified tephras layers. Further, it highlighted the presence of other tephras layers. The extraction by the bromoform confirms the presence of these tephras. The use of the same methodology may allow the detection of tephras layers within other sebkhas.

From the Characterization, Geochemical Behavior and Health Risk Assessments of Tunisian Phosphogypsum to a Potential Way of Inerting and Valorization

Phosphogypsum is the by-product of the acid process for producing phosphoric acid from a phosphate rock. In Tunisia, phosphate production generates very large volumes of the phosphogypsum near the city of Sfax, which is stored without a real management.

Former Extractive Activities in Tunisia: Environmental Risk Assessement and Heavy Metals Immobilization

Mining has a very economic importance worldwide and remains an essential part of the economy in different countries (Nansai et al. in Environ Sci Technol 49(4):2022–2031, 2015; Galas and Galas in Resour Policy 49:204–212, 2016).

Interactions Between Cationic Porphyrins and Standards Clays: Spectroscopic and 3D Confocal Investigations

Clay minerals represent natural and interesting host and guest organic chromophores components inducing the formation of dye molecular assemblies.