[1] Junior Maimou Nganko, Ekoun Paul Magloire Koffi, Prosper Gbaha, Alpha Ousmane Toure, Moustapha Kane, Babacar Ndiaye, Mamadou Faye, Willy Magloire Nkounga, Claudine Tiogue Tekounegning, Echua Elisabeth Jasmine Bile, Kouassi Benjamin Yao "The importance of parameters such as compaction pressure, binder percentage and retention time and their interaction in the production of carbonized briquettes for domestic or industrial use cannot be overestimated, as they have a considerable impact on the properties of the resulting briquettes. This study used Box-Behnken Response Surface Methodology (RSM) and Analysis Of Variance (ANOVA) to show how the above parameters and their interactions significantly in- fluence the Higher Heating Value (HHV), ash content and Impact Resistance Index (IRI) of the biofuels obtained. The briquettes are characterized in accordance with American Society for Testing and Materials ASTM D-(5865 and 3172). IRI is determined by the drop test. The Niton XLT900s X-ray fluorescence spectrometer is used for mineralogical analysis. The peel starch used as a binder is characterized by the Association of Official Agricultural Chemists standard. This starch has a starch purity of 89.8 %, an HHV of 13974 kJ/kg, a protein content of 4.79 % and a sugar content of 1.3 %. The HHV of the biofuels ranged from 23783 to 26050 kJ/kg, their ash content from 2.86 to 5.24 %, and the IRI from 136.36 to 500 %. The significant effect of binder on these results is confirmed (p < 0.05). The Standard deviations of ± 21.425 kJ/kg, ± 0.021 % and ± 2.121 % were obtained between the experimental values and those of the mathematical models developed to predict HHV, ash content and IRI. The optimum parameters for industrial biofuel production correspond to a binder percentage of 10 %, a compaction pressure of 75 kPa and a retention time of 7.49 min. The experimental results under these conditions are: 25596 kJ/kg" Modeling and optimization of compaction pressure, binder percentage and retention time in the production process of carbonized sawdust-based biofuel briquettes using response surface methodology (RSM). heliyon 2024 Lien...
2023
[2] Kalidou Ba, Fatou Ndiaye, Alpha Ousmane Toure, Mamadou Faye "This study focuses on the optimization and modelling of the green charcoal formulation process using experimental design methodology. The fuel is made from peanut shells, typha, sawdust, charcoal dust and sewage sludge used as a binder. These residues were mixed in the proportions suggested by the plan and underwent a direct densification process. The desirability function used and the physico-chemical analyses carried out revealed that the best results obtained were briquettes made from 50% sludge, 24.29% groundnut shells, 5.71% typha, 10.57% sawdust and 9.43% dust. They therefore have a calorific value of 5619.33 kcal/kg, an ash content of 22.98%, a moisture content of 3.13%, a volatile matter content of 56.75% and a fixed carbon content of 20.27%. Analysis of the elemental composition and calorific values of the fuel briquettes produced shows that they have good combustion properties. However, in order to improve the quality of the briquettes produced, a study on the reduction of smoke content needs to be carried out. " Optimization of the operating conditions for the formulation of a green coal. J. Soc. Ouest-Afr. Chim. (2023), 052; 23 - 31 Lien...
[3] Ndeye Coumba Bousso, Alpha Ousmane Toure, Ndeye Awa SENE, Ndeye Maguette Fall, Dame Keinde, Fallou Mbacke Sambe, Vincent Sambou "In a context of accelerating climate change, it is more necessary than ever to produce building materials that are more ecological than Portland cement. The co-valorization of phosphogypsum and fly ash, industrial by-products, constitutes an ecological interest and an opportunity in the field of building materials. The main problem with the recovery of phosphogypsum lies in the quantity recovered. Thus, the general objective of this study is to valorize in greater quantity the phosphogypsum by the manufacture of a new hydraulic binder. In this study, two parameters remained invariant, namely the mass composition of the dry binder powder which was fixed at 30 % phosphogypsum and 70 % fly ash and the ratio of water to dry binder powder taken equal to 0.5. The work was split into two stages. The first step was to determine the optimal sodium hydroxide concentration and cure condition. The mechanical compressive strength was the optimization evaluation parameter. The second step was to determine other characteristics of the formulated binder with the optimal operating parameters determined following the first step. The chemical composition of the materials was determined by X-ray fluorescence spectrometry. The mechanical strength at maximum compression, at the age of 28 days, is 10.548 MPa and was obtained with the concentration 10 M at ambient cure. The characteristics of the material obtained make it possible to consider its use for construction" Fabrication d’un liant hydraulique par activation alcaline des cendres volantes avec incorporation de phosphogypse. Afrique SCIENCE 23(3) (2023) 78-90. Lien...
[4] Abdoul M. Ba, Seckou Bodian, Ndeye A. Sene, Alpha Ousmane Toure, Ibrahima Niang, Aida Gaye, Gnilane Thiam, Elhadji Dieng, Mactar Faye and Vincent Sambou "The building is an object of concern in terms of health, energy consumption and environmental impacts. With more than 40 % of the world's energy consumption and high CO2 emissions, the building sector is among the most energy-intensive sectors. An in-depth analysis of the building sector shows that Concrete, the material currently most used in Senegal is unsuited to the climatic conditions of Sahelian countries. In addition, cement production consumes a lot of energy and is a source of greenhouse gas emissions. Faced with environmental and energy concerns, the choice of appropriate materials is a key to limiting environmental impact and ensuring a healthy and comfortable indoor environment. This is how a sustainable approach using local clay resources for the production of clay bricks was implemented. However, the use of swelling clays is the source of significant problems in construction. Thus for a good prediction of the mechanical and thermal behavior of a material, it is important to determine its physical properties. This is why our study focuses on the physical characterization of the excavated soils of Diamniadio." Physical Characterization of excaved soils in Diamniadio -Senegal. International Journal of Advanced Research 11(08), 745-750 (2023) Lien...
[5] Kalidou Ba, Alpha Ousmane Toure, El Hadji Moussa Diop, Edouard Mbarick Ndiaye, Mamadou Faye, Falilou Mbacke Sambe "This study investigated the potential of using the mixture of titaniferous sand and attapulgite as adsorbents in a fixed bed adsorption process to remove a synthetic dye such as methylene blue in aqueous media. The different adsorbents were characterised by X-ray fluorescence spectroscopy and infrared spectroscopy. The different physico-chemical parameters such as pH, zero charge potential, bulk and absolute density, porosity and specific surface area were determined. The sizing algorithm used resulted in a number of transfer units (NUT) equal to 20.109, a height of transfer unit (HUT) equal to 0.515, a material transfer coefficient (Kya) equal to 3.159 and a height of the column (Z) equal to 1.05m. The influence of different experimental parameters such as initial dye concentration, adsorbent bed height and feed rate on the breakthrough curve was investigated. Various simple mathematical models such as Adams-Bohart and Thomas were applied in order to study the dynamic behaviour of the column and to estimate some kinetic coefficients through the experimental data obtained from the dynamic studies performed on the fixed bed. The results showed that the Thomas and Adams-Bohart models perfectly describe the behaviour of the breakthrough curves with values of coefficients of determination R2 that are higher than 0.90 except for the concentration of the dye equal to 50mg/L which has a coefficient R2 equal to 0.88" Design of A Fixed Bed Adsorption Column and Modelling of Operating Parameters for The Removal of Methylene Blue in Dynamic Mode. The American Journal of Applied Sciences (2023). Lien...
[6] El Hadji Moussa Diop, Kalidou Ba, Mamadou Faye, Alpha Oumane Toure, Falilou Mbacke Sambe. "This present study comes in addition to overcome the problems of separation of fine particles of TiO2 in heterogeneous photocatalysis after treatment. It aims to show the potential for using titaniferous sand as a new semiconductor under solar irradiation. The photocatalytic efficiency of this titaniferous sand was tested on a pesticide (Azadirachtin). A tubular photocatalytic reactor with recirculation of the polluting solution was designed for the elimination of the pesticide in an aqueous solution. Before its use as a photocatalyst, the titaniferous sand has undergone a specific treatment that consists of calcination at 600 ̊C followed by extraction of the calcined natural organic materials, which can interfere with the measurement of analytical parameters such as COD. The titaniferous sand was also characterized by X-ray fluorescence spectroscopy (XRF). XRF analyses have shown that TiO2 is predominant in the titaniferous sand with a percentage that has been estimated at 46.34%. The influence of various experimental parameters such as the flow rate of the polluting solution, the concentration of titaniferous sand, the presence of oxygen and the intensity of the overall rate of sunshine, was studied to optimize the photocatalytic degradation of the pesticide. The results showed that the highest removal rate (70%) was observed under the following conditions: a pH of 6, a titaniferous sand concentration of 150 g/L, a flow rate of 0.3 mL/min, and a sunshine rate of 354 W/m2 and in the presence of atmospheric oxygen. Under these experimental conditions, the rate of photodegradation of the pesticide follows the pseudo first order kinetic model of Langmuir Hinshelwood with a coefficient of determination R2 of 0.9869 and an apparent rate constant of 0.0029 min−1. The results clearly demonstrated the potential of titaniferous sand as a photocatalyst sensitive to sunlight for the effective removal of pesticides in the aquatic environment. " Solar Photocatalysis of A Pesticide in A Tubular Reactor on Titaniferous Sand as A New Semi-Conductor. Advances in Chemical Engineering and Science, (2023),13, 119-131 Lien...
[7] Kalidou Ba, Alpha Ousmane Toure, Samba Ndiaye and Falilou Mbacke Sambe "Copper is considered a heavy metal that can be toxic at certain concentrations and its presence in water is a potential threat to public health. These heavy metals also contribute to a remarkable degradation of the environment, hence the need for effective treatment methods to remove them. In this study, a mixture of titaniferous sand and calcium silicate was used as adsorbent material to eliminate copper in solution. The calcium silicate was synthesized from fluosilicic acid, which is a by-product of phosphoric acid manufacture. The titaniferous sand is a residue from a mining industry. Both adsorbents were characterized by infrared spectroscopy and X-ray fluorescence to deter- mine their compositions and physicochemical properties. The response sur- faces, through the Box-Behnken model, were used to model and optimise various adsorption parameters, namely initial copper concentration (A: 60 - 200 mg/L), adsorbent dose (B: 0.1 - 0.6 g) and pH (C: 4 - 10). The copper removal efficiency (98.92%), after statistical analysis, was obtained under the following optimal conditions: an adsorbent dose of 0.55 g, an initial copper concentration of 197.25 mg/L and a pH of 9.85. The study of the effects of the operating parameters showed that they had a positive effect on the copper removal efficiency. " Modellimg and Optimisation of Copper Adsorption Solution by the Response Surface Method. Advances in Chemical Engineering and Science (2023) 13(01):36-49 Lien...
2022
[8] Faye Mamadou, Sambe Falilou Mbacke, Toure Alpha Ousmane, Diop El Hadji Moussa, Ndoye Mouhamed and DIOP Codou Mar Gueye "A co-flow pilot filter with a packing support material (coated jujube seeds) was constructed and tested for the biological removal of iron from Senegalese groundwater. Indeed, it is a PVC tube with an internal diameter of 40 mm and a height of 90 cm. The performance of the filter was tested at a constant hydraulic head of 261.67 m3/m2 per day while the iron feed concentrations varied between 0.5-1, 0.5-1.5 and 0.5-2 mg/L, respectively. Coated jujube seeds, covered with a plastic layer and a biofilm containing microorganisms, were used as the filter material. The iron removal was carried out in a single stage, for which a period of two months was required for the maturation of the bed. In optimal working conditions (QL = 8.11 L/h; pH = 9.5; [Fe2+]0 = 2 mg/L; P = 1.013 bar and T = 25±1° C; Redox potential = 300 mV), an operating cycle time of 1 day has proven to be sufficient for the filter bed backwash operation. The results show that the biological treatment gives reduction percentages of 39.3, 48.76 and 67.23%, respectively for the boreholes of Pout Kirène (PK2), Pout Sud (PS5) and Koungheul (KK5). " Biological removal of iron from groundwater in a pilot column on a filter support material with coated jujube seeds. African Journal of Environmental Science and Technology (2022). Lien...
[9] Thiao Yaye Ndew, Faye, Mamadou, Toure Alpha Ousmane, Dieng Modou, Sambe Falilou Mbacke. "This paper discusses the method used to correct the non-compliance with Senegalese discharge standards NS-05-061 of the physical and chemical pollution parameters of water at the treatment outlet of the Keur Saïb Ndoye wastewater treatment plant in Thiès. Keur Saïb Ndoye wastewater treatment plant in Thies (near Medina Fall and North Thies), after eleven (11) years of operation, is facing a drop in treatment efficiency which affects the physical and organic pollution parameters at the lagoon outlet. At the beginning of the experiments, for the year 2017, the station obtained average output values of 102 against 50 mg/L for suspended solids, 135 against 40 mg/L for BOD5 and 180 against 100 mg/L for COD. To observe Senegalese discharge standards again, it was recommended to completely isolate one of the two series of lagoons during the second half of 2018, in order to reduce the residence time. Monitoring of the control parameters was carried out at Thiès and Cambérène laboratories over the period from 2018 to the end of 2019 on samples taken at the entrance to the STEP and at the exit from tertiary treatment before, during and after isolation of one of the series of lagoons. The results for 2019, after a year and a half of operation with a single series of four lagoons, were satisfactory overall with average annual yields all above 90% for suspended solids, BOD5 and COD. Output concentrations of SS, BOD5 and COD in the discharged effluent, respectively around 38 mg/L, 42.8 mg/L and 91.3 mg/L are obtained. These values are significantly lower, with the exception of BOD5, at the thresholds set by the Senegalese standard. " European Scientific Journal (2022), ESJ, 18 (40), 314 Lien...
[10] Kalidou Ba, EL Hadji Moussa Diop, Alpha Ousmane Toure, Falilou Mbacke Sambe "In this study, calcium silicate waste material was used as adsorbent of crystal violet in batch mode. The calcium silicate was synthesised from fluosilicic acid (FSA), which is a by-product of phosphoric acid manufacture. The obtained calcium silicate was char- acterised by X-ray fluorescence spectroscopy. The response surfaces, through the Box- Behnken model were used to model and optimize various adsorption parameters namely, the initial concentration of CV (A: 10–100 mg/L), the contact time (B: 5–50 min), the dose of adsorbent (C: 1–5 g/L) and the pH (D: 3–10). The removal efficiency of CV (97.86%), after statistical analysis, was obtained under the following optimal conditions: an adsor- bent dose of 3.349 g/L, an initial CV concentration of 58 mg/L, a pH of 6.87 and a contact time of 30.49 min. The study of the four factors effects highlighted a positive effect on the removal of crystal violet. The interactions between adsorption time (B) and pH (D) and between adsorbent dose (C) and pH (D) were significantly important. However, an inter- mediate situation was noticed in the case of the interaction between adsorbent dose (C) and crystal violet concentration (A), where the lines cannot be considered parallel but do not cross each other in the analysed area either. The analysis of the residues showed that they are normally distributed and fluctuate in a random pattern. The adsorption kinetics were well described by the pseudo second order model and the equilibrium data were in agreement with the Langmuir isotherm model with a maximum adsorption capacity of 277.78 mg/g. " Optimization of Cristal Violet Adsorption by Calcium Silicate. Scientific African (2022), 18(1): e01417 Lien...
[11] Mamadou Faye, Falilou Mbacke Sambe, Alpha Ousmane Toure, Mouhamed Ndoye, Codou Gueye Mar "Three beakers for removing Fe (II) in reconstituted water (doped with FeSO4) were built and tested. Given the set operating conditions ([O2] > 4 mg·L−1, Patm = 1.013 bar, T = 25 ̊C ± 1 ̊C and [Fe2+]0 = 0.5 to 2 mg·L−1), removal of iron was caused by biological and possibly physical and chemical oxidation because there is a quantity of free oxygen in the medium. The extent of each type of oxidation has not been evaluated as it specifically studies the biologi- cal degradation of iron in these beaker tests by setting the operating condi- tions (pH > 6.5, dissolved oxygen from 0 to 8 mg·L−1, Redox Potential from 100 to 400 mV). The experimental studies focused particularly on the mea- surements of maximum wavelength, conversion efficiencies from Fe (II) to Fe (III), the effect of the Fe (II) concentration, the influence of pH, the action of the temperature of the prepared solutions and the effect of O2 concentration under specified operating conditions. It noticed precipitated amounts of iron deposited at the bottom of the beakers. Thus, the low concentrations of Fe (II) detected in the influent after the biological oxidation operation could be attributed to microorganisms that consume iron as a substrate. " Process for the Biological Removal of Fe(II) from Reconstituted Waters on a Support Filter Material with Coated Jujube Seeds. Journal of Geoscience and Environment Protection (2022) 10(12):65-76 Lien...
[12] Ba Kalidou, Toure Alpha Ousmane, Ndoye Mouhamed and Sambe Falilou Mbacke. "In recent years, the discharge of dye-laden effluents from the textile industries into the aquatic environment has increased considerably. These industries are among the largest consumers of water. They generate huge amounts of pollu- tants from their huge discharge of toxic effluents and pose serious public health problems. So, this study focuses on the use of the mixture of titanifer- ous sand and attapulgite for the removal of methyl violet by adsorption in discontinuous mode. The different adsorbents were characterized by X-ray fluorescence spectroscopy and their different physico-chemical properties such as pH, zero charge potential, bulk and absolute density, porosity and specific surface area were determined. The response surfaces, through the Box-Behnken model, were used to model and optimize the operating condi- tions. The different factors studied were the ratio of titaniferous sand and at- tapulgite, the initial concentration of methyl violet and the pH. These vary between 1.25 and 8, 20 and 100 mg/L, 4 and 10 respectively. The results ob- tained after statistical analysis of the data show that the optimum mixture ra- tio is 2, the optimum concentration is 99.92 mg/L and the optimum pH is 9.88 corresponding to a maximum capacity of 5.52 mg/g and a maximum removal efficiency of 99.56%. The study of the effects of the different factors showed that the initial concentration of methyl violet and the pH significantly influence the adsorption capacity and the removal efficiency of the dye." Modelling and Response Surface Optimisation of methyl Violet Removal by a Mixture of Titaniferous Sand and Non-Actived Attapulgite. Journal of Materials Science and Chemical Engineering (2022), 10,10-26 Lien...
[13] 13. Samba Ndiaye, Alexander Pish, Alpha Ousmane Toure, Severine Camy, Samba Mody Sow, Adrien Chen, Falilou Mbacke Sambe, Laurent Prat and Laurent Cassayre. "This work focuses on the carbonation reaction of calcium silicate hydrates (CaO)(SiO2)(H2O) (CSH) powders synthesized by an aqueous process using fluorosilicic acid waste and lime as main reactants. We investigated whether these CSH could constitute a secondary raw material to produce building materials that harden at low temperature by reaction with CO2, according to a process that is commonly based on the use of minerals such as natural wollastonite (CaSiO3). CSH and wollastonite powders were placed in a gas stream consisting either of pure CO2 or of a 15 vol % CO2−85 vol % air mixture, saturated with water, at atmospheric pressure and 40 °C. Based on thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy of the products, we proved the occurrence of the carbonation reaction and we calculated the carbonation degree α for various reaction times. The structural water contained in the CSH played a beneficial role in the carbonation reaction since their carbonation degree is much higher than that of wollastonite: for a reaction time of 120 min at 40 °C, α = 75% for CSH against 12% for CaSiO3. Furthermore, carbonation promotes the formation of calcite with only 15 vol % CO2, allowing the direct use of cement plant fumes." Carbonation of Calcium Silicate Hydrates as Secondery Raw Material from the Recovery of Hexafluorosilicic acid. ACS Sustainable Chemistry & Engineering (2022). Lien...
2021
[14] Kalidou Ba, Alpha Ousmane Toure, El Hadji Moussa Diop, Falilou Mbacke Sambe and Codou Gueye Mar Diop. "This paper focuses on the removal of methylene blue by adsorption using a mixture of titaniferous sand and attapulgite. The different adsorbents were characterized by X-ray fluorescence spectroscopy and their different parameters such as pH, zero charge potential, and specific surface area were determined. The experiments performed were optimized and modeled by a full 2-level and 4-factor design. The four factors are the ratio of titaniferous sand and attapulgite, the concentration of methylene blue, pH, and time. These vary from 4 to 19, 20 to 100 mg/L, 2 to 9, and 30 to 150 min respectively. The study of the effects of the different factors showed that the effect of methylene blue concentration and pH significantly influence the adsorption capacity and removal efficiency of the dye. The optimum parameters (adsorbent ratio, adsorbate concentration, pH and time) obtained for the adsorption capacity through the desirability function are: 19, 100mg/L, 9 and 150min. Those obtained for the yield are: 4, 100mg/L, 9, 150min. The pseudo second order adsorption kinetics gave an equilibrium adsorption capacity qe (calculated) = 7.6863 mg/g which is almost equal to that obtained experimentally qe (exp) = 7.3562 mg/g. This shows that the pseudo second order kinetic model is the adequate mathematical model to describe the methylene blue adsorption phenomenon on the mixture of titaniferous sand and attapulgite. The thermodynamic study showed that the methylene blue adsorption reaction is exothermic, non-spontaneous, and the degree of disorder of the particles at the adsorbing surface decreases. " Modeling and optimizing the removal of methylene blue by the mixture of attapulgite and titaniferous sand using a complete factorial design. European Scientific Journal (2021) 17(40):88 Lien...
[15] Samba Ndiaye, Alpha Ousmane Toure, Falilou Mb. Sambe, Laurent Prat et Laurent Cassayre. "The production of phosphoric acid for use in fertilizer generates toxic fluorosilicic acid as by-product, which can have, when disposed in ocean, negative effects on the maritime ecosystem. With the objective of developing a process for the treatment and valorization of this industrial waste, we study a route starting with a reaction between fluorosilicic acid and sodium chloride that produces a hydrochloric acid solution and sodium fluorosilicate powder. In the present work, we focused on the conversion step of sodium fluorosilicate, consisting of a caustification reaction in an aqueous solvent, with the purpose of obtaining valuable products. We identified a reaction scheme based on a preliminary thermodynamic study using the PHREEQC geochemical software. Experimental tests were then carried out in a 2 L stirred batch reactor, with various characterization techniques of the products (ICP-OES, XRD, TGA) allowing to establish mass balances. We propose two new steps in the conversion process, consisting of the aqueous reaction of CaO with Na2SiF6 at 50 °C, with an intermediate filtration for a molar ratio (CaO/Na2SiF6) of 2.77. This process generates two solid products: (i) pure CaF2, which can be used as an additive in various pyrometallurgical processes and (ii) a mixture of calcium silicate hydrates with low content of CaF2, which constitutes a promising resource for construction and building materials. " Exploration of a Two-Step Aqueous Process for Valorization of Sodium Fluosilicate (Na2SiF6), an Intermediate Product of the Fluosilicic Acid Conversion. Waste and Biomass Valorization (2021). Lien...
2020
[16] Alpha Ousmane Toure, Nicholas Auyeung, Falilou Mbacke Sambe, Jackson Scott Malace and Fuqiong Lei. "The manufacturing of cement consumes energy and results carbon dioxide emissions. This work focused on producing cement clinker using coal fly ash (CFA), sewage sludge ash (SSA) and an industrial waste with a high content of calcium silicate (CS). Experiments were conducted to assume the use of a process that may consume less energy and raw materials that used in cement clinker manufacturing. The raw mixtures were prepared with lower clay and limestone contents than those used in Portland clinker manufacturing and then burned at lower temperatures, ranged from 1000 to 1200°C. Due to the content of fluxes and mineralizers of the raw mixtures, this method could decrease carbon dioxide emissions from calcination up to 60% and energy consumption up to 350 kcal/kg of clinker. The free lime content of the clinker was found out by volumetric analysis and was consistent with free lime content in Portland cement clinker. Activation energies ranged from 42.7 to 91.1 kJ/mol and the cement clinkers contents of fluorine varied from 0.82 to 3.9%. The main characterizations of the obtained clinker, which were X-ray fluorescence, X-ray diffraction and SEM, highlighted interesting composition as building material." Cement Clinker based on Industrial Waste Materials. Journal of Civil Environmental Engineering Volume 10:3 (2020): 343 Lien...
[17] Alpha Ousmane Toure, Falilou Mbacke Sambe, Codou Mar Gueye Diop, Rita maria Ghantous "The manufacture of sustainable bricks using waste materials is a topic of ongoing research in many countries. Unfired bricks made from industrial waste materials provide one promising approach. This study examined the potential to manufacture bricks for use in housing applications that are made using coal fly ash (CFA), calcium fluoride and calcium silicate (CFS). Moreover, in practice, the CFS comes from the reaction between calcium hydroxide and sodium fluosilicate. The bricks described in this paper were made at atmospheric pressure and room temperature. The materials were characterized using X-Ray Fluorescence, X-Ray Diffraction and Scanning Electron Microscopy. In addition, the bulk density, the compressive strength and the water absorption were measured and compared with common building bricks. The compressive strength of the brick specimen containing 75% of CFA at 28 day was 6.1 MPa and the water absorption was found to be about 23.8%. " Manufacturing unfired bricks using Coal Fly Ash, Calcium Fluoride and Calcium Silicate. International Journal of Civil and Environmental Engineering. IJCEE- IJENS Vol: 20 No: 02 (2020) Lien...
2019
[18] Mamadou Faye, Falilou Mbacke Sambe, Alpha Ousmane Toure, El Hadji Moussa Diop, Aminata Fall Mbaye et Codou Gueye Mar Diop. "The majority of Senegal's groundwater has a surplus concentration of iron and manganese. The diagnosis of drilling water shows that more than 80% of the water collected in different areas of Senegal have high amount of those both elements. Their concentrations are higher than the WHO guideline value of 0.3 mg. L-1 and 0.05 mg. L-1. While iron and manganese do not pose a serious health risk, their presence may indicate that groundwater is of poor quality and may be indicative of other problems that may have adverse effects on human health. The purpose of this study was therefore to characterize the groundwater of some areas in Senegal and to evaluate the representativity of iron and manganese in terms of concentration in order to provide elements of response to high concentrations in the water. To reach this objective, we applied the Principal Component Analysis (PCA) and Variance Analysis (ANNOVA) method of the MinitabR version 17 software on physical and chemical analysis results in order to better interpret the results. Therefore, the characterization of the samples showed globally that the groundwater must be treated before consumption by the populations. The qualitative study made it possible to highlight that the Maastrichtian is the most exploited tablecloth like the other tablecloths. Thus, this present study has also shown that the groundwater collected in these different regions deserve to be purified before consumption by the populations because the following physical and chemical parameters: electrical conductivity, turbidity, sulphates, iron and manganese far exceed the potability standards accepted by WHO" Groundwater physical and chemical characterization of some regions in Senegal: study on the representativeness of iron and manganese concentration in boring water. Research Journal of Chemical Sciences. Vol 9(4) 1-10 (2019) Lien...
[19] Mamadou Faye, Falilou Mbacke Sambe, Modou Dieng, Alpha Ousmane Toure, Mactar Faye et Codou Gueye Mar Diop. "In the present work, the treatment of synthetic waters doped with iron (II) has been studied. The treatment mechanism used in this study is the bio- logical oxidation which consists, in test tubes, of bringing bacteria isolated on Petri dishes into contact with water containing divalent iron (II). These de-ironing bacteria (non-specific bacteria) are used to carry out laboratory biological oxidation experiments on iron (II) under different pH conditions (pH = 3.4 - 3.6, pH = 7.3 - 7.5 and pH = 9.8 - 10) and variable concentration of iron (II). Biological treatment trials included different concentrations of iron during time intervals of a day. Examination of the elimination kinetics of Iron (II) indicates a removal rate of 59.453% for an initial iron concentration in the synthetic solution of 1 mg∙L−1 at basic pH (pH = 9.8 - 10). Therefore, the degradation of divalent iron by this method seems to be quite effective, but it should be noted that biological nitrification is impaired by the presence of high iron concentrations above 5 mg∙L−1. " Isolation of Iron Bacteria from Washing Sludge Filters Kolda (Senegal) Water Treatment Station and Study of the Kinetics of Biological Degradation of the Iron (II). Open Journal of Metal, (2019), 9, 19-32 Lien...
[20] Mamadou Faye, Falilou Mbacke Sambe, Alpha Ousmane Toure, Aboubacry Thiam, El Hadji Moussa Diop and Codou Gueye Mar Diop "To fully understand the mass transfer efficiency in biofilters, hydrodynamics and mass transfer parameters were investigated for two different fillings (monkey bread and jujube) in a three-phase fixed-bed reactor operating at co-flow gas-liquid. As part of this work, after the characterization of seeds a hydrodynamic study and transfer of oxygen mass were made. The experiments were carried out in a cylindrical glass column 0.1 m in diameter and 1.5 m in height. The latter was filled with monkey bread or jujube as filling materials. The results obtained showed that the energy losses or the pressure drop (P) is 3.11875 cmCE against 0.725 cmCE on average respectively for monkey bread and jujube, the dynamic liquid retention (εLD) is 0.223 against 0.348 on average respectively for monkey bread and jujube and the oxygenation capacity (OC) is 70.282 gm-3.h-1 against 163.674 gm-3.h-1 on average respectively for monkey bread and jujube. As a result, jujube nuts have the best characteristics on all levels for use as packing materials for pilot studies. " Study of Two Fillings (Monkey Bread and Jujube Nuts) in a Garnished Column: Hydrodynamic and Mass transfer. European Scientific Journal. (2019). Vol 15 (3). Lien...
2018
[21] Malang Bodian, Dame Keinde, Alpha Ousmane Toure, Prince Momar Gueye and Modou Fall. "The behavior of Fe500-3 iron was studied in the interstitial solution of mortar concrete, formulated from sand, cement, water, admixtures and in the presence of a clay (attapulgite) added as corrosion inhibitor. Indeed, in most cases in Senegal, mixing water and sand used in concrete formulations for buildings are subject to no treatment. The study solution was synthesized from these concretes at the 3rd, 7th and 28th day of wet cure. Fe500-3 iron corrosion tests in the interstitial concrete solution were carried out by monitoring the free corrosion potential, Tafel polarization curves and electrochemical impedance spectroscopy measurement. The protective power of attapulgite was also evaluated by electrochemical methods with different levels of inhibitor (0 to 20%). The measurements reveal a probable attack of Fe500-3 iron at the 3rd and 7th day of cure in the absence of inhibitor and the protective effect of the interstitial solution of the concretes without inhibitor at the 28th day of cure by the formation of a protective layer on the iron surface. The results also showed the corrosion inhibition effect of the clay on the 3rd and 7th day of cure by the formation of a protective film on the surface of the metal. The layer thickness increases with the content of the clay. A maximum average inhibitory efficiency of about 87.8% was obtained at the 7th day of cure at the 20% clay content. " Valorization of Pout Attapulgite as inhibitor for Fe500-3 concrete reinforcing iron in the interstitial solution of concrete. International Journal of Innovation and Applied Studies. 24 (4) (2018). pp. 1603-1613 Lien...
[22] Ibrahima Diouf, Oumar Dia, Moussa Bagha Diedhiou, Patrick Drogui, Alpha Ousmane Toure, Sidy mambaye Lo, Michel Rumeau and Codou Gueye mar Diop "In this work, the study of hydrogen peroxide (H2O2) electro-generation using graphite from exhausted batteries (Gr-Bat) was conducted. Linear sweep voltammetry and electrolysis experiments were carried out in a single compartment electrochemical cell. Study of the possibility to use this electrode revealed that it presents, as vitreous carbon (VC) electrode, a reduction of oxygen with two successive waves (bi-electronic reduction). The first wave corresponds to the reduction of O2 to H2O2, while the second one corresponds to the reduction of H2O2 to H2O. The cathodic potentials for electro-generation of H2O2 appeared at -600 mV and -700 mV Vs Ag/AgCl for Gr-Bat and VC electrodes, respectively. Subsequently, electrolysis experiments were conducted by imposing the potentials required for H2O2 formation. The effect of several operating parameters on H2O2 production, such as the nature and concentration of the electrolyte, the pH, the presence of ferrous ions and O2 injection were studied using Gr-Bat and VC electrodes, respectively. For both electrodes, the acidic medium was more favorable for H2O2 electro-generation. The oxygen injection in solution promoted an increase of H2O2 concentration, but its effect was more pronounced in the case of VC electrode. Application for crystal violet degradation by electro-Fenton revealed that Gr- Bat had the best purification performance. A removal rate of 73.18% was obtained with Gr- Bat electrode against 62.27% with VC electrode for an electrolysis time of 120 min. This study has demonstrated the possibility of recycling Gr-Bat by using them as cathode materials in the electro-Fenton process. " Electro- generation of hydrogen peroxide using a graphite cathode from exhausted batteries : Study of influential parameters on electro-Fento process. Environmental Technology. 2018. Lien...
2017
[23] El hadji Moussa Diop, Falilou Mbacké Sambe, Ibrahima Diouf, Alpha Ousmane Toure et Codou Gueye Mar Diop "The elimination of fluoroquinolone antibiotic, ofloxacine, was carried out by adsorption on titaniferous sand with a 58% content of TiO2. Various parameters such as contact time, sand concentration and initial pH influencing the adsorption of the antibiotic were optimized. Thus, the adsorption equilibrium was obtained after 100 minutes and the kinetics followed the second pseudo order model. The removal of the ofloxacine was better at a pH of 6.5 for a sand concentration of 160 g/L. Among the isothermal models tested, to represent the experimental results, the Langmuir model better described the adsorption process with a maximum adsorption capacity of 1.1383 mg/g and a kinetic constant of 0.0389 L/mg" Removal of fluoroquinolone antibiotic, ofloxacine, by adsorption on titaniferous sand. Research Journal of Chemical Sciences, Vol. 7(11), 8- 14, Novembre (2017) Lien...
[24] El hadji Moussa Diop, Falilou Mbacké Sambe, Alpha Ousmane Toure et Codou Gueye Mar Diop. "Over the last decades, the world production of cigarettes has increased considerably. However, the industrial production generates large quantities of colloidal effluents consisting of toxic and recalcitrant compounds. Thus, taking account the colloidal aspect of the effluent and the persistence of some compounds, this study aims at coupling chemical coagulation and photodegradation on titaniferous sand to treat wastewater from a cigarettes plant in Senegal. The chemical coagulation was handled by aluminium sulfate. The optimal conditions of this chemical process were found at a pH of 7 and a coagulant concentration of 350.4 mg/L. In these conditions, the elimination rate of the chemical oxygen demand (COD) and suspended materials (SM) were respectively 51.32 and 76.92%. Despite its good performances, the chemical coagulation only did not come up with a standard effluent discharge. That is why the photodegradation was conducted to complete the treatment. With a maximum titaniferous sand concentration of 320 g/L, the results highlighted a COD elimination rate of 60% at an initial concentration of 240 mg/L. The COD elimination rate was highly enhanced by increasing the amount of hydrogen peroxide in the system. Indeed, the COD elimination rate was shifted from 61.2 to 72% when the rate of hydrogen peroxide varied from 0.2 to 0.6%. " Coupling chemical coagulation and photodegradation on titaniferous sand for the treatment of tobacco effluents. African Journal of Environmental Science and Technology Vol. 11 (5), pp. 248-254, May C2017) Lien...
[25] Alpha Ousmane Touré, Dame Keinde, Falilou Mbacké Sambe, Maci Joseph and Codou Gueye Mar Diop "This study aims at using a mixture of calcium fluoride and calcium silicate (CFS), which is a by- product from the process of working-up aqueous fluosilicic acid solutions, in the raw mix for clinker manufacturing. The core objective is to lower the temperature of the buring process and to reduce the carbon dioxide emissions. The addition of 12.5% of this industrial waste which acts as a mineralizer reduced the temperature for clinker burning to 1373 K and the carbon dioxide emissions to about 30%. This reduction of temperature improved the clinkering process and conserved energy efficient. The obtained clinker with l.96% of free lime content could lead to an enhancement of the cement quality. Volumetric analysis of free lime content and X-ray fluorescence were used to characterize the synthesized clinker. The kinetic model of the burning processhighlighted an activation energy of 82.347 kJ/mol. " Use of a Fluoride Waste in the Raw Mix for Clinker Manufacturing. American-Eurasian Journal of Scientific Research 12 (1) 01-06, 2017 Lien...
2016
[26] El Hadji Moussa Diop, Falilou Mbacké Sambe, Alpha Ousmane Touré et Codou Gueye Mar Diop. "Over the last decades, the treatment of industrial wastewater has become a main concern in Senegal. Then, manufacturing companies should respect the standards of industrial waste discharges. Nonetheless, some molecules are refractory to conventional methods of treatments. The solar heterogeneous photocatalysis is an efficient technology for the treatment of the refractory pollution. In this study, titaniferous sand with a 46 % of TiO2 content was used for the degradation of technical azadirachtin. The influence of some process parameters (minimum weight of sand, initial pH and concentration of the solution of azadirachtin) on pollutant degradation was studied. The obtained results highlighted an optimum pH of 6 for the azadirachtin degradation. The use of 30 g titaniferous sand lead to a reduction of 78 % of an azadirachtin solution which concentration was 60 mg/L at optimal pH. Elsewhere, the photocatalytic degradation kinetics of azadirachtin followed Langmuir-Hinshelwood model and was a first order. " Photocatalytic degradation of technical azadirachtin by titaniferous sand. Afrique SCIENCE 12 (3) (2016) 43-50 Lien...
2015
[27] Samba Ndiaye, Alpha Ousmane Toure, Falilou Mbacke Sambe, Laurent Prat, et Laurent Cassayre. "Superphosphate plants such as the Chemical Industries of Senegal dump nearly 276,000 m3/year of fluorosilicic acid (H2SiF6) into the sea for a production of 600,000 tons/year of phosphoric acid. These factories must commit to continuously improving their health, safety and environmental performance in order to meet people’s expectations. Therefore, it is absolutely essential to opt for a recycling of industrial waste constituted by fluorosilicic acid, by a system of treatments generating substances usable in other chemical processes. The long-term motivations remain the protection of the environment but also and especially the creation of jobs by the establishment of new industrial units for the manufacture of valuable chemicals. In this context, work carried out at the Ecole Supérieure Polytechnique de Dakar since 2010 has aimed at the development of treatment and recovery processes for fluorosilicic acid. This work has led to the production of a whole range of chemicals. A first reaction between fluosilicic acid and sea salt produces hydrochloric acid and sodium fluosilicate. The latter is then caustified with an excess of lime to form soda and a mixture of calcium fluoride and calcium silicate. The solid effluent obtained by the current process (CaF2+CaSiO3 mixture) could be used as a mineralizer in the portland cement manufacturing process. However, this mixture contains far too much calcium fluoride to be used as is, resulting in clinkers with a fluoride content 50 times the maximum allowable value. Thus the caustification step of sodium fluosilicate has been revisited in the framework of a collaboration with the Laboratory of Chemical Engineering of Toulouse. Based on a thermodynamic study of the aqueous process, supplemented by experimental tests on a model compound (Na2SiF6 pure), this work resulted in the proposal of a new step in the process, to generate two distinct solids flows and open up new options for further product valuation. The three elements of the initial Na2SiF6 effluent are finally recovered as three distinct streams: NaOH(aq), CaF2(s) and Ca-Si-O(s)." Valorization of an effluent from the production of phosphoric acid. Récents Progrès en Génie des Procédés (Numéro 110-2017). Lien...
[28] Abdoulaye Thiam, Alpha Ousmane Toure, Falilou Mbacké Sambe and Codou Gueye Mar Diop "This work concerned the feasibility of working-up an industrial waste for the production of cement. The addition effect of the waste on the clinker was studied. Samples were prepared by using 5%, 20% and 35% of waste content in the cement. The mixtures were hydrated and characterized by X-ray fluorescence. Hardening time of the mortars (445 min) was determined by Vicat apparatus. The hardening times depend on the amounts of waste which were added. Compression resistances of the several were measured by the compression apparatus. Acceptable results were found when a 5% of waste content in the mixture was used. These values at 1 day (2.9MPa), 2 days (15.9MPa) and 28 days (47.5MPa) decreased when the amount of the used waste raised. " Adding a mixture of calcium silicate and calcium fluoride to clinker mortars. Journal de la Société Ouest-Africaine de Chimie (2015) 040 ; 41-44 Lien...
2013
[29] Alpha Ousmane Toure, Falilou Mbacke Sambe, Démo Koïta, Codou Gueye Mar Diop "Fluosilicic acid is the main fluoride waste water on phosphoric acid production. This effluent is simply discharged into the sea from phosphoric acid plant in Senegal. The disposal of this effluent is an ever more serious environmental problem for phosphoric acid manufacturers. In fact large amount of fluosilicic acid is discharged into the sea. Therefore, our attention has been focused on developing process for working-up this fluorine waste by producing hydrochloric acid. Through laboratory research, we have been able to use a water treatment plant containing fluosilicic acid in a 25% solution in order to produce hydrochloride acid in a 33% solution. " Recovery and valorization of fluosilicic acid from phosphoric acid plant for the production of concentrated hydrochloric acid. Journal de la Société Ouest-Africaine de Chimie (2013) 036 ; 21 – 25 Lien...
2012
[30] Alpha Ousmane Touree, Falilou Mbacke Sambe, Démo Koita, Codou Gueye Mar Diop, Oumar Sock. "Aqueous fluosilicic acid solutions were once considered to be only adverse by-products of phosphoric acid production, which required treatment to prevent ecosystem destruction when discharged into the sea. However, a range of chemicals can be generated by the transformation of this industrial waste product. Through experiments undertaken in the laboratory, we have shown the possibility of caustic soda production. Volumetric analysis showed caustic soda to be present as a 6% – 7% solution with yields of about 70% – 80% by weight. Two processes were investigated for the caustification of sodium fluoride, using different precipitates: sodium chloride and ethanol and are described by modelling caustification curves. The activation energies of precipitation determined by semi-empirical correlations showed that precipitation by ethanol (EA = 933.536 J/mol) was more successful than precipitation by sodium chloride (EA = 7452.405 J/mol). Analyses performed on the precipitates highlighted compositions that are essential and useful constituents in the cement industry. " Processes for working-up an aqueous fluosilicic acid solution. South African Journal of Science (2012);108 (11/12) Lien...
2011
[31] Alpha Ousmane Toure, Falilou Mbacke Sambe, Senghane Ndiaye, Codou Gueye Mar Diop, Oumar Sock "Aqueous fluosilicic acid solutions constitute interesting intermediate reagents in the manufacturing of numerous chemicals. However, they are sometime considered as simple by-products which are at the origin of a relatively former environmental preoccupation in phosphoric acid and fertilizer production. Indeed a whole range of chemicals can be generated by the transformation of this industrial waste. Among these chemicals, distinguish itself soda, which is an essential substance in the industrial practice, as well as calcium fluoride and calcium silicate which are frequently used in cement industry. In this work, fluosilicic acid is converted into sodium fluosilicate which is treated by lime to obtain soda and a mixture of calcium fluoride and calcium silicate. Experiments already made in laboratory showed the feasibility of this production of soda. The obtained yields can be about 70% for the reaction of caustification which generate 6% of NaOH aqueous solution. Analyses made on precipitates highlight compositions in essential and useful constituents in cement industry." Utilization of an aqueous fluosilicic acid solution for the production of caustic soda aqueous solution and a mixture of calcium silicate and calcium fluoride, Physical and Chemical News 60 (2011) 105 – 112 Lien...
