Fadhel Ismail

Stability of the emulsion (W/O): application to the extraction of a Dawson type heteropolyanion complex in aqueous solution.

Dawson type heteropolyanions form complexes with transition metals. These mixed complexes possess some remarkable electrocatalytic properties. Being soluble in aqueous and organic phases, they are used in homogeneous catalysis. In the setting of the recuperation and the regeneration of these complexes, the extraction of a mixed heteropolyanion (alpha 2P2W12Mo5O61Fe)(7-) is the subject of this work. This extraction was carried out by emulsified liquid membrane using (SPAN80) as surfactant and (TIBA) as extractant. Sulfuric acid was used as the internal phase. The stability of the emulsion was studied according to different parameters and the extracting efficiency in optimal conditions was found to be 70%.

Removal of zinc and cadmium from an aqueous solution using sawdust as a low-cost adsorbent: application of Plackett–Burman design

Abstract In this study, the sawdust was used as an abundant and inexpensive material for the removal of two heavy metals simultaneously from an aqueous solution. In order to evaluate the adsorbent potential of the sawdust, the effects of many operating parameters were studied. The metals considered were zinc and cadmium. The experiments were organized according to a well defined window of a statistical design of experiments. Starting from a large number of operating parameters (type, source, size and quantity of sawdust, temperature, pH, contact time, stirring speed, initial concentrations of cadmium, zinc and salt), a Plackett–Burman design was used to identify the most influential factors on the elimination performance of zinc and cadmium simultaneously with a minimum number of experiments. Effects of these factors were deduced from an interesting statistical treatment of experimental responses. For Zn sorption, the most important factors are mass of sawdust, initial concentration of zinc and time; whil...

Effects of operator parameters, anions and cations on the degradation of AY99 in an aqueous solution using Fenton’s reagent. Optimization and kinetics study

In the present work, the decolourization of azo dye Acid Yellow 99 (AY99) in an aqueous solution by Fenton oxidation process was investigated. The results indicated that the initial pH, the nature of the acid to adjust pH, the temperature and the initial concentrations of the Fenton’s reagent FeSO4 of H2O2 and of the AY99 played an important role on the dye decolourization. It was found that under optimum conditions, which have been determined to be pH = 3, [H2O2]0 = 1.8 mmol/L, [Fe2+]0 = 0.09 mmol/L, [AY]0 = 0.06 mmol/L and T = 30°C, efficiency of degradation obtained after 40 min of reaction was about 95%. The decolourization of AY99 by the Fenton process followed the second-order reaction kinetics. The empirical kinetic equation for AY99 decolourization under the conditions of 0.03 to 0.15 mmol/L of Fe2+, 0.9 to 1.8 mmol/L of H2O2, 0.03 to 0.15 mmol/L of Acid Yellow and pH = 3 was found to follow the relation:K = 6.39 × 107 [AY] −2.8[H2O2]2.29[FeSO4]0.837 exp (−7021.3/T).The decolourization efficiency Ef (in percent) was 88.36%, 87.93%, 85.98% and 39.61% in the presence of H2SO4, HNO3, HCl and H3PO4 acids, respectively. We can deduce that H2SO4, HNO3 and HCl acids lead almost to the same efficiency (Ef), but in the presence of H3PO4, it is too low:Ef (H2SO4) ~ Ef (HNO3) > Ef (HCl) > > Ef (H3PO4).Effects of additives such as inorganic salts (sodium chloride, calcium chloride, sodium sulphate and calcium sulphate) and cations (sodium sulphate, calcium sulphate, copper sulphate, manganese sulphate and magnesium sulphate) on the efficiency (Ef) and on the rate constant (k2) of AY99 degradation were also studied under optimum conditions.Ef (Na2SO4) > Ef (CaSO4) > Ef (NaCl) > Ef (CaCl2)k2 (CaCl2) < k2 (NaCl) < k2 (CaSO4) < k2 (Na2SO4)Ef (ZnSO4) > Ef (MgSO4) > Ef (Na2SO4) > Ef (CaSO4) > Ef (CuSO4) > Ef (MnSO4)k2 (Na2SO4) < k2 (MnSO4) < k2 (CuSO4) < k2 (CaSO4) < k2 (ZnSO4) < k2 (MgSO4).The presence of anions and cations in the aqueous solution decreases the decolourization efficiency and the rate constant of the degradation of AY99. This inhibition may be due to a complexation and a radical scavenging.

Recovery of 4-chlorophenol from an aqueous solution by ELM: stability of the membrane, modeling, and optimization of the extraction using experimental designs

AbstractAn emulsified liquid membrane has been developed for the extraction of the 4-chlorophenol (4-CP) from an aqueous effluent. The membrane used was an emulsion of water in oil (W/O), the internal phase was an alkaline solution (NaOH), and the organic phase was a mixture of a surfactant (SPAN 80) and an extractant (TBP) dissolved in an organic solvent (heptane). The only limitation of this technique was the stability of the membrane (swelling, cohesion, and rupture). To optimize the different parameters that have a direct influence on the stability of the membrane, experiments were conducted using a fractional factorial design of Plackett–Burman. The obtained results showed the behavior of the emulsified membrane under different operating conditions. Among the different factors studied, the concentrations of SPAN 80 of TBP and the stirring velocity appeared to be the most important parameters. Indeed, a high yield above 99% almost a total elimination of 4-CP was achieved under optimized operating cond...

Optimization of methylene blue removal by stable emulsified liquid membrane using Plackett–Burman and Box–Behnken designs of experiments

The stability of an emulsified liquid membrane composed of Span80 as a surfactant, D2EHPA as an extractant and sulfuric acid as an internal phase was first studied according to different diluents and many operating parameters using the Plackett–Burman design of experiments. Then the removal of methylene blue from an aqueous solution has been carried out using this emulsified liquid membrane at its stability conditions. The effects of operating parameters were analysed from the Box–Behnken design of experiments. The optimization of the extraction has been realized applying the response surface methodology and the results showed that the dye extraction yielding 98.72% was achieved at optimized conditions.

Comparative study of chemical compositions and antimicrobial effect of different genius of Thymus harvested during two period of development

The essential oils obtained by steam distillation of the aerial parts of Thymus taxa collected before and during the flowering period in different region of eastern Algeria, were analyzed by gas chromatography coupled with mass spectrometry (GC-MS). The extraction yields of essential oils of T. numidicus species are 1.28 % during pre-flowering. This yield is better during the flowering period with 2.85%. T. algeriensis gave extraction yields 1.156 % and 1.79 % in the two periods respectively. T. ciliatus produced oil with yields of 1.002 % before flowering and 1.79 % during flowering. Chromatographic analysis (GC-MS) showed that these essential oils are rich with oxygenated monoterpene compounds with 54.07 % and 80.37% of the composition for T. ciliatis, 61.86 % and 73.02 % for T. algeriensis, 54.48 % and 77.56 % for T. numidicus, corresponding to the two periods mentioned above respectively. The antimicrobial activity was tested against 3 gram positive and gram negative bacterial by the use of the disc diffusion method. The thymus taxa have shown great sensitivity. The three essential oils are effective against Escherichia. coli 22, while essential oil of T. ciliatus obtained before flowering and essential oil of T. numidicus in flowering period are most effective against Staphyllococcus 23.

Investigation of microstructure and mechanical properties of phosphocalcic bone substitute using the chemical wet method

Selection of calcium phosphate base materials in reconstructive bone surgery is justified by the surprising similarities in chemical compositions with human bones. The closest to natural apatite material is the hydroxyapatite (HAp) which has a chemical composition based on calcium and phosphate (Ca10(PO4)6(OH)2). In this study, HAp is synthesized using the wet precipitation method from hydrated calcium chloride (CaCl2,12H2O) and di-sodium hydrogen phosphate di-hydrate (HNa2PO4,2H2O). The powder is calcinated at 900°C and 1200°C in order to compare with sintered condition at 1150°C. Vickers microhardness tests and X-ray diffraction analyzes are used for the characterization of the crystalline material. Mechanical properties (Hv, σe, σr, and KC) and the degree of crystallinity (Xc) are discussed according to heat treatment temperatures. Results indicate that heat treating the powder at 1200°C increased crystallinity up to 72%. At the same time, microhardness increased with temperature and even outmatched the sintered case at 1150°C. Fracture toughness is ameliorated with increasing heat treatment temperature by more than two folds.Selection of calcium phosphate base materials in reconstructive bone surgery is justified by the surprising similarities in chemical compositions with human bones. The closest to natural apatite material is the hydroxyapatite (HAp) which has a chemical composition based on calcium and phosphate (Ca10(PO4)6(OH)2). In this study, HAp is synthesized using the wet precipitation method from hydrated calcium chloride (CaCl2,12H2O) and di-sodium hydrogen phosphate di-hydrate (HNa2PO4,2H2O). The powder is calcinated at 900°C and 1200°C in order to compare with sintered condition at 1150°C. Vickers microhardness tests and X-ray diffraction analyzes are used for the characterization of the crystalline material. Mechanical properties (Hv, σe, σr, and KC) and the degree of crystallinity (Xc) are discussed according to heat treatment temperatures. Results indicate that heat treating the powder at 1200°C increased crystallinity up to 72%. At the same time, microhardness increased with temperature and even outmatched th...

Characterization of diatomite from Sig region (West Algeria) for industrial application

Purpose – Diatomite also known Kieselguhr, is a non-metallic mineral composed of the skeletal remains of microscopic single-celled aquatic algae called diatoms. The purpose of this paper is to test and to evaluate the diatomite of Sig region (West Algeria) to substitute the main mould powder used in continuous casting of steel for thermal insulation and lubrication. Design/methodology/approach – To assess the behavior of diatomite at different temperatures, a combination of simultaneous scanning calorimetric and thermogravimetric testing was used and to evaluate the structure of diatomite, the scanning microscopy method was applied. Findings – The results showed different endothermic and exothermic peaks, mainly at 84.7°C and 783.5°C for endothermic peaks and 894.9°C for exothermic peak. The scanning microscopy method was used and a large porosity was observed. The trial industrial in continuous casting of steel showed a weak loss temperature of steel. Originality/value – This product may be used for ther...