Publications Scientifiques
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Item Synthesis and characterization of MoO3: application to the photo production of oxygen under visible light(Springer, 2024) Koriche, Nesrine; Abbas, Moussa; Trari, MohamedOne of the most striking features of molybdenum oxide is the versatility of its catalytic properties, which are determined by the valence states of molybdenum and its coordination. It may be anticipated that MoO3 surface must contain catalytic sites which are active in different types of elementary steps. MoO3 was successfully synthesized by hydrothermal route at 400 °C, acquiring n-type conduction, due to oxygen deficiency. The single phase, elucidated by X-ray diffraction, crystallizes in an orthorhombic unit cell (Space Group (SG) Pbnm, N° 62) with a crystallite size of 12 nm. MoO3 is a direct band gap semiconductor with a forbidden band value of 2.93 eV where the electrical conduction occurs by low polaron hopping between mixed valences Mo+6/+5 with an activation energy of 0.14 eV. The thermo-power indicates n-type conduction, and confirmed by the capacitance-potential measurement; the latter gives an electrons density of 1.87 × 1020/cm3and a mobility of 1.77 × 10−6 m2/V.s. The flat band potential Vfb (0.11 VSCE) is determined from the capacitance measurement. The physical and chemical characterizations are correlated for the construction of the potential diagram in order to assess the photo electrochemical properties of MoO3 for the oxygen evolution. The valence band, is located above the O2/H2O potential ( ~ 1.3 VSCE), allowing O2 evolution upon visible light and the oxide is photocathodically protected against corrosion. An evolution rate of 0.13 mL/(mg. h) is obtained within 20 min. at optimal conditions (100 mg of catalyst and 50 °C).Item Adsorption Behavior of Methylene Blue Onto Activated Coconut Shells: Kinetic, Thermodynamic, Mechanism and Regeneration of the Adsorbent(SAGE, 2024) Abbas, Moussa; Trari, MohamedAdsorption techniques are widely used to remove some classes of pollutants from waters, especially those which are not easily biodegradable. The removal of Methylene blue (MB), as a pollutant, from waste waters of textile, paper, printing and other industries has been addressed by the researchers. The aim of this study is to eliminate MB by Activated Coconut Shells (ACS) produced at low cost by adsorption in batch mode. The ACS was characterized by the FTIR spectroscopy and point of zero charge (pHpzc: 5.06). Some examined factors were found to have significant impacts on the MB uptake of ACS like the initial dye concentration Co (40-120 mg/L), solution pH (2-8), ACS dose (1-12 g/L), agitation speed (50-500 r/min), particles size (1.0- 1.2 mm) and temperature (298-333 K). The best capacity was found at pH 6 with an adsorbent dose 8 g/L, an agitation speed 200 r/min and a contact time of 60 min. Modeling Kinetics and Isotherms shows that the pseudo-second-order kinetic model with R2 (0.935 -0.998) and Langmuir adsorption isotherm model provide better fitness to the experimental data with the maximum adsorption capacity of 30.30 mg/g at 25°C. The separation factor R L (0.933-0.541) in the concentration range studied (10-120 mg/L) shows a favorable adsorption. The isotherms at different temperatures have been used for the determination of the free energy ΔG ° (198-9.72 kJ/mol); enthalpy ΔH ° (82.082 kJ/mol) and entropy ΔS o (245.689 J/K mol) to predict the nature of MB adsorption process. The positive values of (ΔG o ) and (ΔHo ) indicate a non-spontaneous and endothermic MB adsorption with a chemisorption. The adsorbent elaborated from Coconut Shells was found to efficient and suitable for the removal of MB dye from aqueous solutions, due to its availability, low cost preparation and good uptake capacity.Item Removal of Amoxicillin From Wastewater Onto Activated Carbon: Optimization of Analytical Parameters by Response Surface Methodology(SAGE Publications Inc., 2024) Abbas, Moussa; Trari, MohamedAntibiotics are widely used in veterinary and human medicine, but these compounds, when released into the aquatic environment, present potential risks to living organisms. In the present study, the activated carbon (AC) used for their removals is characterized by FT-IR spectroscopy, BET analysis and Scanning Electron Microscopy (SEM) to determine the physicochemical characteristics. Response surface methodology (RSM) and Box-Behnken statistical design (BBD) were used to optimize important parameters including pH (2-12), temperature (20-45°C), and AC dose (0.05-0.20 g). The experimental data were analyzed by analysis of variance (ANOVA) and fitted to second-order polynomial using multiple regression analysis. The optimal conditions for maximum elimination of Amoxicillin (Amox) are (Dose: 0.124 g, pH 5.03 and 45°C) by applying the desirability function (df). A confirmation experiment was carried out to evaluate the accuracy of the optimization model and maximum removal efficiency (R = 89.999%) was obtained under the optimized conditions. Several error analysis equations were used to measure goodness of fit. Pareto analysis suggests the importance of the relative order of factors: pH > Temperature > AC dose in optimized situations. The equilibrium adsorption data of Amox on Activated Carbone were analyzed by Freundlich, Elovich, Temkin and Langmuir models. The latter gave the best correlation with qmax capacities of 142.85 mg/g (R2 = 0.999) at 25°C is removed from solution. The adsorption process is dominated by chemisorption and the kinetic model obeys a pseudo-second order model (R2 = 0.999).Item Elaboration of a new Activated Carbon derived from the Crown of Oak (ACOW) to removal the toxic Iodine: Kinetic, Isotherms modelling and Thermodynamics Study(Taylor & Francis, 2024) Aksil, Tounsia; Abbas, Moussa; Trari, MohamedThe current study aims to develop a new adsorbent material using oak crown and explore its effectiveness in removing I2 ions through a series of batch experiments. ACOW was characterised by zero charge (pHpzc) and FTIR spectroscopy. The impact of the initial I2 concentration (20-100 mg/L), temperature (25-55 °C), pH (2-14), adsorbent dosage (2-10 g/L), Stirring speed (100-900 rpm), particle size (100-2000μm) and contact time (0-30 min) on I2 adsorption was examined. The adsorption kinetic obeys the pseudo-second order model with a determination coefficient (R2) equal to 0.999. Adsorption follows the Langmuir equation well, with the best fit to the experimental data at equilibrium. A qmax value (= 103.606 mg/g) at 25°C and 120.773 mg/g at 55°C were eliminated under the optimised conditions, indicating homogeneous adsorption on the surface of the adsorbent. The thermodynamic parameters gave a negative free energy ΔGo (-3.445 to -5.629 kJ/mol), a positive enthalpy ΔHo (18.406 kJ/mol) and an activation energy Ea (= 22.599 kJ/mol), thus confirming the spontaneous and endothermic nature of adsorption of iodine on ACOW. The positive entropy ΔSo (0.0733 kJ/mol K) show increased randomness of the solid-liquid interface during the adsorption.Item Understanding the rate-limiting step adsorption kinetics onto biomaterials for mechanism adsorption control(SAGE Publications Ltd, 2024) Sahmoune, Mohamed Nasser; Abbas, Moussa; Trari, MohamedBiomaterials are a class of porous materials that have been widely exploited over the past two decades. However, the implications of controlling adsorption by rate-limiting steps are still not adequately established. Identifying the rate-limiting step is a promising approach for the design of adsorption systems. In this review, we study in detail the rate-limiting step of the adsorption of dyes in aqueous media on biomaterials to rationalize the factors governing the rate-limiting step involved in the adsorption process using empirical kinetics and mass transfer models. This knowledge is then applied to identify the best fit of these models to study the rate-controlling step involved in the adsorption process, which is crucial for the design of the adsorption system. This review first studies the limiting step of adsorption of dyes in an aqueous medium on biomaterials. Kinetic modeling is used to better understand the rate control step involved in biosorption. Generally, the equations used are empirical models of kinetics and mass transfer and the biomaterials come from the following categories: agricultural and industrial waste, algae, fungi, bacteria, and plants. In most adsorption studies reported in this review, the pseudo second-order model was found to be best suited for fitting the kinetic data of dyes on biomaterials, indicating that chemisorption is the rate-limiting step that controls adsorption. Concerning the diffusion effects of mass transfer, intraparticle diffusion is among the most often used models to examine the rate-limiting step which is controlled by both film diffusion and intraparticle diffusion. The first takes place when the external transfer is greater than the internal transfer while the opposite occurs in the case of porous diffusion. However, the majority of works do not study the real step of controlling the overall adsorption kinetics, namely, film diffusion or intraparticle diffusion.Item Contribution of zeolite to remove malachite green in aqueous solution by adsorption processes : kinetics, isotherms and thermodynamic studies(SAGE, 2023) Abbas, Moussa; Trari, MohamedThe textile industry produces huge amounts of wastewaters containing synthetic dyes. In the textile industry, acid, basic, reactive, dispersed chemicals are widely used for dyeing. The aim of this study was to evaluate the adsorption of malachite green onto zeolite from aqueous solutions was realized in batch system. The adsorbent was characterized by the Fourier transform infrared spectroscopy, X-ray analysis, and zero point charge (pHzpc = 10.42). However, some examined factors were found to have significant impacts on the adsorption capacity of zeolite such as the initial malachite green concentration (Co), solution pH, adsorbent dose, agitation speed, particles size, and temperature. The best capacity was found at pH 8 with an adsorbent dose 0.2 g/l, an agitation speed 200 rpm and a contact time of 40 min. The kinetic adsorptions were found to follow rather a pseudo-second order kinetic model with a determination coefficient (R2) of 0.999. The equilibrium adsorption data for the malachite green adsorption onto the zeolite were analyzed by the Langmuir, Freundlich, Elovich, and Temkin models. The results indicate that the Langmuir model provides the best correlation with a capacity qmax of 83.33 mg/g at 25°C. The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters, namely the free energy (ΔG°); enthalpy (ΔH°) and entropy (ΔS°) to predict the nature of adsorption. The positive values of ΔG° and ΔH° indicate that the overall adsorption is not spontaneous and endothermic with a physisorption process. The adsorbent elaborated from the zeolite was found to be efficient and suitable for the elimination of reactive dyes from aqueous solutions, due to its availability of adsorption sites, low cost preparation, and good uptake capacityItem Synthesis, characterization and application of tetragonal BaTiO3-δ in adsorption and photocatalysis of congo red(Elsevier, 2023) Merrad, S.; Abbas, Moussa; Brahimi, R.; Bellal, B.; Trari, M.The synthesis by a simple approach of the deficient Barium Titanate BaTiO3-δ (BTO) crystallizing in a perovskite structure is reported along with the physicochemical properties. Thermal analysis (TG/DSC) was performed to elucidate the synthesis process. The X-ray diffraction (XRD), BET analysis, scanning electron microscopy (SEM-EDS) and electrochemistry were investigated. The catalyst revealed a single phase with a tetragonal symmetry obtained by treatment at 650 °C. The direct band gap (3.34 eV), obtained from diffuse reflectance spectroscopy (DRS), is assigned to the charge transfer O2-: 2p-Ti4+: 3d. The electrical characterization indicated a non-degenerate conductivity due to oxygen vacancies with an activation energy of 0.33 eV. The capacitance measurements indicated n-type behavior with a flat band potential (Efb) of − 0.43 V and a carrier concentration (ND) of 3.90 1018 cm−3. The photocatalytic process was elucidated by the electrical impedance spectroscopy (EIS). The performance of BTO was assessed by a combination of the adsorption of Congo Red (CR) followed by its degradation under UV light. The photodegradation kinetic was well fitted by a pseudo-first-order model with an abatement of 50% and 91% under UV and solar lights respectively. Different scavengers were used to evaluate the reaction mechanism and the radicals O2•- are the main reactive species of the CR oxidation. Four regeneration cycles demonstrated the catalyst stability. A degradation mechanism was established based on the scavengers effectItem Adsorption of malachite green onto walnut shells : kinetics, thermodynamic, and regeneration of the adsorbent by chemical process(Korean Fiber Society, 2023) Merrad, Samiya; Abbas, Moussa; Trari, MohamedThe textile industry produces huge amounts of wastewaters containing synthetic and toxic dyes. The aim of this study was to evaluate the adsorption of Malachite green (MG) onto Activated Carbon from Walnut Shells (ACWS) realized in a batch system. The effects of contact time, initial pH, stirring speed, particle size, temperature, adsorbent dose, and initial MG concentration on the adsorption capacity were investigated graphically for determining optimum conditions. The experimental isotherm data were analyzed by the Langmuir, Freundlich, Temkin, and Elovich models. The adsorption follows well the Langmuir equation, providing a better fit of the equilibrium adsorption data. Under optimized conditions, up to 154.56 mg/g at 25 °C and 370.37 mg/g at 45 °C were removed from the solution. The adsorption mechanism of MG onto ACWS was studied using the first-pseudo-order, second-pseudo-order, Elovich and Webber–Morris diffusion models. The adsorptions’ kinetic was found to follow rather a pseudo-second-order kinetic with a determination coefficient (R2) of 0.999. The adsorption isotherms at different temperatures have been used for the determination of thermodynamic parameters, i.e., the free energy ΔGo (0.802 to − 2.123 kJ/mol), positive enthalpy change ΔHo(18.547 kJ/mol), entropy (ΔSo = 0.064 kJ/molK), and activation energy (Ea = 14.813 kJ/mol). The negative ΔGo and positive ΔHo values indicate that the overall MG adsorption is spontaneous and endothermicItem Potential of titanium dioxide to remove bromothymol blue (BTB) in aqueous solution by batch mode Adsorption–Kinetic, isotherm and thermodynamic studies(Springer, 2023) Abbas, MoussaThe adsorption is widely used to remove certain classes of pollutants from water, especially those that are hardly biodegradable and dyes represent one of these problematic groups. The removal of bromothymol blue (BTB) from wastewater using TiO2 was studied in batch system. The adsorbent TiO2 has a specific surface area of 400 m2/g, a mean crystallites sizes (5–10 nm), and pHpzc equal to 6.5. TiO2 is stable over the whole pH range and constitutes a good compromise between efficiency and stability (in both acidic and basic media), therefore, the use of other additives is not necessary. Its non-toxicity and low energy required for its activation (E ~ 3 eV) as well as its low cost for most of the applications envisaged make it advantageous. The influence of effective variables such as solution pH (1–10), contact time (0–60 min), initial BTB concentration (5–40 mg/l), adsorbent dose of TiO2 (0.2–2 g/l), and temperature (20–60 °C) on the adsorption efficiency was examined, while the BTB content was determined by UV–Vis spectrophotometry. The optimal pH, adsorbent dose, and contact time for the efficient removal were found to be 10, 0.2 g/l, and 30 min, respectively, and the adsorbent was characterized by the BET analysis and point of zero charge (pHpzc). Among the different kinetic models, the experimental data of the BTB removal are well fitted with the pseudo-first-order kinetic model with a high determination coefficient. The evaluation of the fitness of equilibrium data by various conventional isotherm models, based on the R2 value as criterion, show the successful applicability of the Langmuir model for the interpretation of experimental data with a maximum adsorption capacity (qmax) of 27.02 mg/g at 20 °C and R2 of 0.997. The adsorption isotherms at different temperatures have been used for the determination of the free energy (ΔGo = 2.1808 to—1.0981 kJ/mol), enthalpy (ΔHo = 20.74 kJ/mol), and entropy (ΔSo = 65.58 J/mol/K) indicate that the overall adsorption is spontaneous and endothermic in natureItem Semiconducting and electrochemical properties of the spinel FeCo2O4 synthetized by co-precipitation. Application to H2 production under visible light(Elsevier, 2023) Bouakaz, H.; Abbas, Moussa; Benallal, S.; Brahimi, R.; Trari, M.FeCo2O4 elaborated by co-precipitation was characterized photo-electrochemically for the first time in order to assess its performance for the hydrogen production. The X-ray diffraction revealed a single phase crystallizing in the spinel structure with a lattice constant of 8.1075 Å and a crystallite size of 35 nm. The UV–Visible diffuse reflectance of the black product exhibits an absorption above 650 nm and a direct optical transition at 1.53 eV was determined, assigned to the crystal field splitting of Co3+: 3d orbital hexa-coordinated. The transport properties indicated semi-conducting properties of FeCo2O4, the positive thermo-power (S300k = 666 μV K−1) demonstrated that holes are majority charge carriers. The Electrochemical Impedance Spectroscopy (EIS) realized in Na2SO4 (0.1 M) electrolyte showed two semicircles at high and intermediate frequencies, characteristic of the charge transfer and grain boundaries respectively. The first diameter (1249 Ω cm2) decreases under visible light down to 742 Ω cm2, thus supporting the semiconducting behavior and no inhibiting effect is observed due to the appearance of the photo-effect. The inverse of the square of the capacitance as a function of the potential (C−2 – E) exhibits a line, negatively slopped, characteristic of p-type behavior with a hole concentration of 21.9 × 1020 cm−3. The conduction band (−0.76 VSCE), made up of Co3+: 3d orbital is more cathodic than the H2-level leading to a spontaneous H2 evolution under visible irradiation (29 mW cm−2) with a liberation rate of 0.58 μmol H2/h−1/g. FeCo2O4 an showed excellent chemical stability after its reuse for the H2 production, as evidenced by X-ray diffraction
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