Analyse et traitement par plasma froid des eaux de rejet de « l’abattoir des Brasseries » à Yaoundé

Des echantillons des eaux usees de á lfabattoir des Brasseries â a Yaounde, preleves ont ete analyses et traites par plasma froid. Les resultats dfanalyse revelent que lesdites eaux sont basiques (pH = 8.65), tres conductrices (conductivite electrique = 1625 ƒÊScm-1), fortement polluees (DBO5 = 1000 mgL-1 dfO2, DCO = 2390 mgL-1 dfO2 et 200 mgL-1 dfammonium) et biodegradables (DBO5/DCO = 0.42). La teneur elevee en chlorures (1347 mgL-1) et lfabsence des metaux lourds ont ete notees. Apres traitement par plasma, on observe une reduction de 50% de la DBO5 en 10 minutes, le debit du gaz plasmagene etant fixe a 1000 Lh-1. Lfefficacite du plasma froid a decharge electrique rampante (glidarc) a ete une fois de plus prouvee pour la reduction de la pollution environnementale.Mots cles: Eaux usees, biodegradables, glidarc, pollution

Elimination of Cu (II) and Zn (II) ions in mono-element and the bi-element aqueous solutions by adsorption on natural clay of Bikougou (Gabon)

This work was undertaken to evaluate the potential of the clay of Bikougou to remove copper (II) and zinc (II) ions (Cu2+ and Zn2+) in  mono-element and binary aqueous solutions. The experiments werecarried out by employing the batch technique through the variations of pH, clay mass, ionic strength, concentration in metal, temperature and contact time. The quantity of ions coppers (II) or zinc (II) adsorbed increases when the pH increases up to pH=5 and beyond, there is precipitation of the metal hydroxides; the quantity of metal ions adsorbed decreases when the clay mass or the ionic force increases. The average adsorption energies of copper (II) and zinc (II) ions are indicative of endothermic reactions. The modeling of the experimental results is better achieved by application ofFreundlich adsorption isotherm and Langmuir adsorption isotherm  concerning the adsorption of Cu (II) ions with correlation coefficients of 0.98 and 0.93, respectively. The Langmuir adsorption isotherm and Freundlich adsorption isotherm are all applicable for describing the experimental result of isotherm adsorption of Zn (II) ions with correlation coefficient respectively, 0.99 and 0.96. The kinetic which shows more clearly the observed phenomenon is that of the pseudo-second order with the coefficients of correlation close to 0.99. In the binary system copper (II) - zinc (II) the adsorption of copper (II) is favoured compared to that of zinc (II). All these results have shown efficiency as adsorbent of theclay from Bikougou to eliminate Cu2+and zinc (II) ions in mono-element or bi-element aqueous solutions. In the mono-element solution, the adsorption rate varied from 98.59 to 94.41% for the Cu(II) ions and from 86.76 to 53.80% for Zn (II) ions.Key words: System of bi-element, copper and zinc, adsorption, technique in batch, natural clay mixture

Chemical and mineralogical characterization and ceramic suitability of raw feldspathic materials from Dschang (Cameroon)

The chemical and mineralogical characterization of raw feldspathic materials from Dschang (Cameroon) was realized by means of X-ray diffraction, differential thermal analyses, optical and scanning electron microscopies, and analytical techniques. It was found that these materials consist of albite (43 ± 3 wt.%), microcline (41 and 26 wt.%), quartz (14.5 ± 1.5 wt.%), plagioclase (oligoclase type) (6 and 12 wt.%) and a minor content of biotite. The amount of fluxing oxides is about 12 wt.% and those of pigments are quasi-null. The ceramic suitability of these materials was assessed in the light of the obtained chemical data and physical characteristics (fusibility, viscosity, colour). The results showed that these raw materials are convenient, as fluxing compounds, for manufacturing white ceramic.KEY WORDS: Raw feldspathic materials, Mineralogy, Chemical composition, Ceramic suitability, Cameroon   Bull. Chem. Soc. Ethiop. 2010, 24(1), 39-46

Acid activation and bleaching capacity of some Cameroonian smectite soil clays

International audienceThree Cameroonian clay materials with high smectite content were used for decolouration of palm oil with a clay / oil ratio of 2%. Particle size distribution, mineralogical and chemical analyses were done. The activation parameters (temperature, acid concentration and activation time) permitting the optimisation of their bleaching capacities have been determined. Their performances were compared to those of a commercial bleaching earth before and after acid activation

Talc based cementitious products: Effect of talc calcination.

AbstractThis study reports the use of calcined talc for cementitious products making. The calcination is used to enhance the availability of magnesium from talc to react with phosphate for cement phase formation. It is shown that previous calcination of talc leads to products having enhanced mechanical performance due to the formation of more cement phase than in products based on raw talc. Talc fired at 900°C was found to be the one in which magnesium release was maximal. Firing at temperature higher than 900°C leads to the stabilization of enstatite, which decreased the magnesium availability. The cement phase is struvite, which was better detected on the X-ray patterns of the products involving fired talc. All the products have very rapid setting time and low shrinkage

Effects of densification and mullitization on the evolution of the elastic properties of a clay-based material during firin

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