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Physico-Chemical Characterization and Stability Study in Acidic and Basic Solution of Ceramic Filters from Mouka’s Clay (Cameroon)

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Journal of Materials Science and Chemical Engineering 2019年第11期7卷 42-53页

作者： Ngiongboung Nguiamba Placide Désirée Belibi Belibi Joseph Marie Sieliechi Martin Benoî t ngassoum University of Ngaoundéré Department of Applied Chemistry University of Ngaoundéré Ngaoundéré Cameroon

this paper deals with the characterisation and study of physico-chemical stability of ceramic filters from clays and rice husk obtained from the far north region of Cameroon (Logone Valley) and their application in potable water treatment. Clays from Mouka were characterized by FtIR analysis. the results showed that the filter formulated with a mixture containing 80% clay and 20% rice husk of 100 μm in size each gave the lowest filter shrinkage rate;these formulated filters were chosen for the remaining work. Leaching tests showed that with filters at a sintering temperature of 830°C the leaching was not observed under neutral (pH 6.8) and acidic (pH 5) conditions as compared to 950°C and 1000°C where the leaching was observed. In basic (pH 9) condition, all the filters obtained released ions. Leaching tests revealed that the conductivity of the leachate for the filters sintered at 830°C was lower than those sintered at 950°C and 1000°C. Meanwhile, conductivity decreases with increasing sintering temperature (temperature up to 830°C) due to the fact that ceramization starts as from 850°C that leads to an amorphous state that favours chemical stability, the leaching ions were Fe2+, Ca2+, Mg2+ and Al3+. the ceramic filters sintered at 950°C were applied to the filtration of water and the performance in terms of turbidity reduction was 95% and the flow rate after 50 minutes was 100 × 10−3 L/h.

关键词： Ceramic Filter Chemical Stability Clay Filtration Lixiviation test

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Antioxidant Activity of the Natural Flavonoid 7-Hydroxy-5,6,4’-trimethoxyflavone Isolated from the Leaves of Lippia rugosa A. Chev

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Natural Science 2016年第2期8卷 70-78页

作者： Jean Momeni Jean Paul tsopmejio Francine t. Nkouam Martin B. ngassoum Department of Chemistry Faculty of Science University of Ngaoundere Ngaoundere Cameroon Department of Organic Chemistry Faculty of Science University of Yaounde 1 Yaounde Cameroon National Advanced School of Agro-Industrial Sciences University of Ngaoundere Ngaoundere Cameroon

Phytochemical studies and antioxidant activities were carried out on n-hexane, ethyl acetate, ethanol and methanol extracts of the leaves of Lippia rugosa A. Chev (Verbenaceae), a medicinal plant used traditionally in the Cameroonian savannah’s region to protect foodstuffs and to cure degenerative diseases. Results indicated that theses extracts contain terpenoids, phenolic and flavonoid compounds. Except the n-hexane extract, all of the obtained extracts exhibit antioxidant activities with the ethanol extract being the most effective with an inhibition percentage of 85.668% ± 1.233% and an inhibition concentration (IC50) of 58 μg/ml (R2 = 0.987, P t a concentration of 100 mg/ml. Chromatographic separation on silica gel of the ethanol extract led to the isolation of a pure organic compound which was characterized as 7-hydroxy-5,6,4'-trimethox- yflavone by extensive 1D and 2D NMR spectroscopy, a flavonoid exhibiting antioxidative activity with an inhibitory percentage of 25.506% ± 0.205% and inhibition concentration (IC50) of 221 μg/ml (R2 = 0.966, P this is the first time that 7-hydroxy-5,6,4'-trimethoxyflavone is being isolated from L. rugosa and its antioxidant activity evaluated.

关键词： 7-Hydroxy-5 6 4’-trimethoxyflavone Phenolic Compounds Antioxidant Activity DPPH Assay Lippia rugosa Organic Extracts

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