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Characterization of Pyroclastic Deposit from Three Different Areas within Foumbot Region (West-Cameroon): Comparative Studies of Their Effects as Pozzolanic Materials in Mortars and Cement Manufacture

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Journal of Geoscience and Environment Protection 2019年第11期7卷 195-209页

作者： Mahomed Aziz Mounjouohou Amidou Moundi benjamin ntieche Daouda Dawai Frédéric Michel Department of Earth Sciences University of Maroua Maroua Cameroon Department of Earth Sciences University of Yaoundé I Yaounde Cameroon Higher Teacher Training College Geology laboratory University of Yaoundé I Yaounde Cameroon Department of Architecture Geology Environment and Construction University of Liege Liege Belgium

Pyroclastics which are known natural pozzolanic materials due to amorphous contents, are present in several areas of the Mbepit Massif in West Cameroon. In this work natural pozzolan from three zones namely Pouoloum, Njimbouot and Nkouonja were characterized. A comparative study was then developed to attest the effect of these pyroclastics as partial substitution in portland cement. The mixtures were made at different pozzolanic proportions (00%, 10%, 15%, 25% and 35%) of substitution of the cement. The compressive and flexibility strength was carried out at 7, 28 and 90 days on mortar specimens (4 × 4 × 16 cm3). The results revealed apozzolanicactivity index of 81.99 %, 83.47% and 74.54% respectively for rock sample from Pouoloum (PCB), sample from Njimbouot (PCC) and sample from Nkouonja (PCN). After 90 days, for a substitution rate of 25% compressive strength are respectively 55.69 MPa, 60.4 MPa, 53.34 MPa for PCB, PCC and PCN. According to the American Society for Testing and Materials (ASTM) C618 classification, the pyroclastics are in accordance with all the criteria to be classified as pozzolan. Independent of the substitution rate, the mechanical performance increases with age in PCB, PCC and PCN. However PCC is most reactive than PCB and PCN. This may be due to the amorphous reactive content in this material and can be linked to the eruptive dynamisms which were more explosive in some areas than in others. The amorphous content is 32.01%, 36.99%, 24.84% for PCB, PCC and PCN respectively. These results also prove that Natural Pozzolan is interesting in the manufacture of composite cement CEM II, CEM IV in accordance with EN197-1 or can be added in mortar for buildings and sustainable environmental management.

关键词： Pyroclastics Pozzolanic Activity Compressive Strength Composite Cement Natural Pozzolan Mbepit Massif

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Geochemistry of Volcanic Rocks of Beka,North East of Ngaoundéré(Adamawa Plateau,Cameroon):Petrogenesis and Geodynamic Context

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Journal of Geological Research 2021年第3期3卷 28-43页

作者： Pauline Wokwenmendam Nguet benjamin ntieche Joseph Legrand Tchop Bouba Christian Mana Eddy Ferdinand Mbossi Research Center for Geophysics and Volcanology Institute of Geological and Mining ResearchPO Box 370 BueaCameroon Geology laboratory Higher Teacher Training CollegeUniversity of YaoundéIPO Box 47 YaoundéCameroon Department of Earth Sciences Faculty of SciencesUniversity of YaoundéIPO Box 812 YaoundéCameroon Research Center for Geology and Mining PO Box 333 GarouaCameroon

Beka area is situated in the Adamaoua Plateau of Cameroon in central *** in this area has not been studied before the present *** volcanism of Beka is characterized by basalt,trachyte and phonolite domes and *** petrographic study shows that basaltic lavas have porphyritic microlitic *** felsic lavas indicate trachytic *** rocks are composed of olivine,clinopyroxene,plagioclase and iron-titanium oxide minerals for the basalts;clinopyroxene,alkali feldspar(including foids),sphene and titanomagnetite for the felsic *** analyses show that basaltic lavas are *** lavas contain modal feldspathoid(nepheline in phonolites).All these lavas belong to the same series,because the felsic lavas are derived from the differentiation of basaltic lavas by fractional *** show an alkaline nature according to their *** elements including Rare Earth Elements characteristics show that rocks emplaced in the Winthin Plate volcanic *** derived from an evolved parent magma showing a low degree of partial melting and characteristics closer to a modified and evolved primitive spinel lherzolite.

关键词： Alkali lavas Fractional crystallization Partial melting Spinel lherzolite Volcanic zone within plate

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Removal of Dyes in Aqueous Media with Hydrochar Base of Solid Tanneries Waste: Optimization Process and Application

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Materials Sciences and Applications 2024年第7期15卷 168-185页

作者： Abdoul ntieche Rahman Gervais Ndongo Kounou Sakué Ngankam Eric Tamafo Fouegue Aymard Didier Kouotou Daouda Abdelaziz Baçaoui Department of Chemistry Higher Teacher Training College Bertoua The University of Bertoua Bertoua Cameroon Department of Fundamental Sciences Institute of Wood Technology of Mbalmayo University of Yaound I Balmayo Cameroon Department of Chemistry Faculty of Science Semlalia University of Cady Ayyad Marrakech Morocco

The Response Surface Methodology (RSM) was used to optimise the conditions of preparation of activated hydrochar from tannery solid waste by hydrothermal carbonisation (HTC). The main factors such as residence time, moisture content and final carbonisation temperature were investigated during the optimisation of hydrochar preparation conditions. The three responses investigated are hydrochar yield, iodine and methylene blue indices. The results of experimental analyses showed that the yield of hydrochar decreases with increasing final temperature, leading to the formation of micropores inside the carbonaceous solid. The optimum conditions for preparing the following hydrochar were obtained: 83.10%, 390.44 mg∙g−1 and 259.63 mg∙g−1 respectively for the hydrochar yield, the iodine and methylene blue indices. The specific surface area of prepared hydrochar is 849.160 m2/g, SEM micrographs showed a porous heterogeneous surface and particularly, the hydrochar surface also revealed external pores on the hydrochar surface which acted as a pathway to the micropores. Fourier transform infrared (FTIR), however, showed a predominance of acid functions on the surface of the carbonaceous solids. Tests were carried out to eliminate indigo carmine in aqueous media. Activated hydrochar showed a high level of activity, with the Langmuir and Freundlich isotherms giving an adsorption quantity of 354.610 mol/g and a KF constant of 468.2489, respectively. The findings of the research revealed that hydrochar produced is well adapted for dyes removal.

关键词： Response Surface Methodology Hydrochar Tannery Hydrothermal Carbonization Adsorption

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New Data on the Genesis and Evolution of the Primitive Magmas of Mount Cameroon: Contribution of Melt Inclusions

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Journal of Geological Research 2020年第4期2卷 46-61页

作者： Legrand Joseph Tchop Pauline Wokwenmendam Nguet benjamin ntieche Victor Metang Jacques Dili Rake Merlin Isidore Teitchou Jacqueline Vander Auwera Georges Emmanuel Ekodeck Charles Nkoumbou Department of Earth Sciences Faculty of SciencesUniversity of YaoundéIPO Box 812 YaoundéCameroon Geophysical and Volcanological Research Unit Institute of Geological and Mining ResearchPO Box 370 BueaCameroon Higher Teacher Training College University of Yaounde1 PO Box 812 YaoundéCameroon Deparement de Geology University of Liège B-4000 Sart-TilmanBelgium

Mount Cameroon is a Plio-Quaternary volcanic massif, without a centralcrater, made up of more than 140 pyroclastic cones. It is one of theactive volcanoes of the Cameroon Volcanic Line. Mount Cameroon meltinclusions are found in microdroplets trapped in the early minerals (olivines)from the pyroclastic products. The analysis of these melt inclusions allowedus to find primitive liquids compared to lavas. Major elements study ofthe magmatic inclusions, trapped in the most magnesian olivines (Mg#84-86) of Mount Cameroon revealed “primitive” liquids of basanite and alkalibasalt type with variable composition compared to the much more uniformbasalts of the magmatic series of Mount Cameroon. The study of thesetrapped liquids shows that: (1) the original primitive lavas did not undergothe process of evolution by FC, but rather underwent fundamentally (orexclusively) the process of partial melting;(2) the emitted lavas, evolvedessentially by FC;(3) the variations in the trace element contents of theprimitive liquids directly reflect a variation in the rate of partial melting ofa homogeneous mantelic source. The very high La/Yb ratios of the MountCameroon melt inclusions (> 20) characterize a garnet lherzolite *** of the melt inclusions show a negative anomaly or depletion in K,Rb and Ba as those of HIMU. The “primitive” liquids and lavas of MountCameroon represent a co-genetic sequence formed by varying degrees ofpartial melting of a source considered as homogeneous.

关键词： Primitive magma Partial melting Fractional crystallization Alkali basalt Mount Cameroon Active volcano

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Adsorption of Indigo Carmine Dye by Composite Activated Carbons Prepared from Plastic Waste (PET) and Banana Pseudo Stem

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Journal of Materials Science and Chemical Engineering 2020年第12期8卷 39-55页

作者： Baissassou Debina Sakué Ngankam Eric Daniel Fotio Kamdem Tamo Arnaud Dai-Yang Lemankreo Abdoul ntieche Rahman Department of Chemistry Faculty of Science University of Maroua Maroua Cameroon Department of Chemistry Faculty of Science Semlalia University of Cady Ayyad Marrakech Morocco Department of Chemistry Higher Teachers’ Training College of Bertoua University of Ngaoundéré Yaounde Cameroon

This study is on the adsorption of indigo carmine dye by composite activated carbons prepared from banana pseudo stems and plastic waste. The activated carbons named TB1P1, TB1P1h and TB2P1 were obtained by pyrolysis at 700°C under steam of raw materials at different ratios (1:1 and 2:1). They were characterized by different techniques such as SEM/EDX, Raman Spectroscopy, FTIR, XRD, TGA/DTA and BET/BJH. Analyses indicate amorphous structures with specific surface areas of 424.37;385.45 and 338.84 m2/g for TB1P1, TB1P1h and TB2P1 respectively. The study of the adsorption of indigo carmine dye by these adsorbents was carried out by varying parameters such as contact time, mass of adsorbent and initial concentration of the dye. The maximum retention is 94.71%, 86.18% and 84.17% for TB1P1, TB1P1h and TB2P1 respectively after 60 min of stirring, for a pH = 4.6 using 0.6 g of adsorbents. The adsorption of indigo carmine follows well, the Langmuir model, with the most suitable kinetics as pseudo second order.

关键词： Adsorption Activated Carbon Composite Plastic Waste Dye

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Preparation and Characterization of Magnetic Banana Peels Biochar for Fenton Degradation of Methylene Blue

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Materials Sciences and Applications 2020年第6期11卷 382-400页

作者： Eric Sakué Ngankam Lemankreo Dai-Yang Baissassou Debina Abdellaziz Baçaoui Abdelrani Yaacoubi Abdoul ntieche Rahman Department of Chemistry Faculty of Science University of Maroua Maroua Cameroon Department of Chemistry Faculty of Science Semlalia University of Cady Ayyad Marrakech Morocco Department of Chemistry Higher Teachers’ Training College of Bertoua University of Ngaoundéré Ngaoundéré Cameroon

Co-precipitation method was used for the synthesis of biochar/Fe3O4 to heterogeneously degrade methylene blue (MB) in an aqueous medium. This catalyst was characterized by different techniques such as Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and Raman Microscopy. The analysis highlighted the presence of iron oxides on the surface of the biochar in the form of magnetite (Fe3O4). Catalytic tests performed on this composite showed significant degradation and simple magnetic separation in the solution for reuse. Maximum degradation was carried out after stirring it for 90 minutes in an MB aqueous solution at different concentrations. The percentages of degradation were 99% and 98.6% 93.3% and 91% for concentrations of MB 40 mg/L and 60 mg/L, 80 mg/L and 120 mg/L respectively. The reactions followed a second-order kinetics with correlation coefficients r2 = 0.9598, 0.9247, 0.9548 and 0.9614 for the same concentrations of MB at pH = 2, 0.2 mL/L H2O2 and 15 mg of biochar/Fe3O4. This work provides a simple and an effective method for the preparation of biochar/Fe3O4 and its use for the oxidation of MB by means of heterogeneous Fenton.

关键词： Co-Precipitation Magnetic Separation Composite Heterogeneous Fenton

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