In a strong commitment to economic valorisation that began a decade and relevant contribution to the problems of housing and creation of small jobs response, the Cameroonian government has invested heavily in promoting use of local materials through the creation of MIPROMALO (Mission for Promotion of local Materials) in 1991 (economic crisis), and through the signing of government circular from the Prime Minister, thus placing its development policies in prior to any development strategy more distant prospect. It was then that housing through development of local building materials becomes one of major policy priorities of Cameroonian's government. However, there is a low valuation thereof despite availability of local materials and political will expressed in Circular No. 002/CAB/PM of 12 March 2007 on the use of local materials in construction of public buildings. In this study, we analyse the contribution that can play promotion of local materials in construction in the Sahel zone which for a harmonious sustainable development. Specifically, it's to highlight the added value of using local materials, propose strategies for implementation and production of compressed bricks. This scientific work has therefore a double interest, scientific and technological industrial view and contributes to the development, promotion of local materials and the development of soil and/or basement areas. We arrived after analysis of our data to the conclusion that valuation of clay materials from Maroua's town was a factor for economic growth and sustainable development. This inventory allows us to implement and produce prototypes suitable compressed bricks, shapes of housing in Sahel zone. However, physical and geotechnical tests on materials clay (raw materials for production of bricks), allow us to better assess characteristics of clay before production of bricks. Well after we submit our bricks to various mechanical and technological tests to assess their ability to withstand loads in extreme temperature conditions of Sahel zone.
With fluoride-rich groundwater causing a climatic-dependent fluorosis in Mayo-Tsanaga River Basin, the overall objective of this study was to reduce fluoride concentrations in drinking water to acceptable levels thereby improving the resilience of the population to this climate change induced pathology. The specific objectives were to: (1) assess water chemistry in the study area to reaffirm the undesirable fluoride levels; (2) assess the impact of seasons on the concentrations of fluoride; (3) construct and evaluate the performance of a household bone char-based adsorption defluoridation filter. A combination of hydrogeochemical and engineering analyses demonstrated that the groundwater is predominantly Ca+Mg-HCO 3 type, which contains as much as 6.73 mg/l of undesirable concentrations of geogenic fluoride. These concentrations increased with elevated pH, electrical conductivity and in the dry season, and were reduced to less than 0.2 mg/l when the groundwater was subjected to filtration through 300 g of 0.2-0.8 mm faction of charred cow bones in a home-based defluoridation filter. The bone char in the filter can effectively reduce fluoride concentration to less than 0.7 mg/l, which is the local threshold limit, without negative impact on the organoleptic (taste, color and odor) characteristics of drinking water. Compared with the commercially activated carbon, the bone char has an additional capacity of adsorbing fluoride at a rate of 4 mg/liter in 30 minutes, which indicates that with a defined saturation time, the bone char filter can protect the population against climate change-induced fluoride enrichment in drinking water. Mots clés. Groundwater. geogenic fluoride. climate dependent fluorosis. bone char defluoridation. water chemistry.
The objective of this work is to study the elimination of Methyl Orange (MO) contained in wastewater, by adsorption on four different adsorbents, produced from peanut shells. To achieve this, the various adsorbents were first produced. The native biosorbent (BN) was obtained from drying, crushing and sieving the peanut shells. The activated biosorbent (BA) was obtained by chemical activation with ortho-phosphoric acid (H 3 PO 4 ) 10% BN. The activated carbons (CA1 and CA2) were obtained by pyrolysis at 650°C of BN and BA, respectively. The four products were characterized adsorbents and experiments to determine the effects of pH, contact time, of their masses and the concentration of methyl orange in its removal by adsorption was carried out. The results show that the thermal activation of the BN has multiplied its surface area by 11, while chemical activation has multiplied by its specific surface 8. Both treatment (chemical and thermal) have also tripled the micropores of BN. All four adsorbents have a maximum adsorption capacity at pH6. At this pH, the amount of MO adsorbed decreases with increase in its concentration, regardless of the adsorbent used. Likewise, adsorption equilibrium is reached at 3 min on the four adsorbents. The pseudo second order model describes the adsorption kinetics of MO on the four adsorbents. Ultimately, CA1 is found to be the most effective in removing MO from wastewater.
In the present study, a Cameroonian smectite was used as an adsorbent to model the adsorption kinetics of three textile dyes (malachite green, methyl red and acid blue 74) from aqueous solution in a batch system. The effects of pH and temperature were evaluated on the adsorption capacities, the times required to reach adsorption equilibrium and the adsorption mechanisms involved. It can be seen that, although the times required to reach the adsorption equilibrium are independent of the pH of the medium, the adsorption process studied is favourable in acidic media and is globally independent of temperature. Among the pseudo-first and pseudo-second-order kinetic models used to analyse the experimental data, the pseudo-secondorder model was the best suited to describe the adsorption of the three dyes onto the clay. The mechanism involved, independently of the dye, is therefore a two-step process: the transfer of dye molecules from the solution to the clay surface followed by the interaction between the molecules and the surface. The low value of activation energies indicates that the adsorption of Methyl red, Malachite green and Acid blue 74 on the studied clay is a physisorption process.
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