Caractérisation rhéologique de la bentonite de maghnia en suspension aqueuse sans et avec additifs anioniques

L'objectif de ce travail est l’étude de l'effet de l’ajout de deux polymères anioniques sur les caractéristiques rhéologiques d'une suspension aqueuse de bentonite algérienne de forage (de Maghnia, Ouest de l’Algérie). Les additifs sont la gomme de xanthane et le carboxymethylcellulose, CMC, utilisés souvent dans la formulation des boues de forage. Dans cet article, nous présentons et discutons des mesures rhéologiques réalisés sur : 1) une suspension aqueuse de bentonite (3%), 2) des polymères en solution aqueuse (le xanthane et le CMC à trois poids moléculaires différentes) et 3) des mélanges eau-bentonite-(xanthane ou CMC) à différentes concentrations de polymère. Ce travail a permis, notamment, de renforcer la conclusion rapportée dans des travaux conduits antérieurement sur la base d’une bentonite de laboratoire, montrant la dominance du comportement rhéologique du CMC et de xanthane sur celui de la suspension de bentonit

Study And Optimization Of Palm Wood Mechanical Properties By Alkalazition Of The Natural Fiber

Thi

Effect of the Essential Oil of Mentha Piperita and Thymus Numidicus on the Growth of Fusarium Sp

The polluting substances are of industrial or agricultural origin, at the level of the different ecosystems. These are the effects of synthetic products on the fauna and flora we are interested in. So our use of biopesticides based on plant extracts, namely essential oils as a natural insecticide is our concern. These bioactive substances or molecules are of great ecological interest because they are very harmful to the ecosystem. The objective of this study is the use of the essential oil of Mentha peperita harvested from the area of Larabaa (Blida) and Thymus numidicus recovered from the area of Bouira as biofungicides with respect to a fungal strain isolated and identified from the leaves of the zucchini crop in Boudouaou-El Bahri (Boumerdes). The isolated species belongs to the genus Fusarium. The extraction method is the hydraudistilation which allowed us to have yields of essential oil of 2.02%25 for M. peperita and 1.2%25 for T. numidicus. The study of the antifungal activity of these two oils tested was carried out by the direct contact method. The evaluation of the antifungal effect of these two extracts shows that the essential oil of T. numidicus has an inhibitory capacity on mycelial growth. T. numidicus oil is moderately active for concentrations%253B 400 mu%253Bl 700 mu%253Bl is inhibition rates%253B 43.33%25 and 50%25. This natural substance is active with the 1000 mu%253Bl dose, with an inhibition rate of 53.33%25. It appears from this study that M. piperita oil is not very active on Fusarium sp with the following concentrations%253B 400 mu%253Bl 700 mu%253Bl and 1000 mu%253Bl are inhibition rates respectively of 23%25, 21.66%25, and 23%25. The essential oil of Peppermint has a slightly inhibitory activity on Fusarium sp with an inhibition zone diameter of 4.6 cm, 4.7 cm and 4.6 cm respectively for doses 400 mu%253Bl 700 mu%253Bl and 1000 mu%253Bl. So, it is found that the increase in M. piperita oil concentration has no effect on the growth of Fusarium sp. Fusarium sp also shows an allergy to T. numidicus oil, while this plant pathogen is resistant to M. piperita oil

Rheological and electrokinetic properties of carboxymethylcellulose-water dispersions in the presence of salts

The purpose of this work is to investigate the effect of the addition of salts in the form of calcium chloride, sodium chloride and potassium chloride on the rheological and electrokinetic properties of diluted sodium carboxymethylcellulose (Na-CMC) dispersions (0.50%). The rheological data of a water-CMC-salt system were obtained using coaxial cylinder viscometer covering a wide range of shear rate (0 to 600 s-1). Ostwald–de Waele power law was used for fitting flow curves of various samples. The presence of salts in CMC aqueous solutions leads to the reduction of the consistency index and the increase of flow index as salinity increases. When the concentration of salts is greater than 3%, the rheological parameters of CMC solutions in saline medium are quasi stable. The electrokinetic measurements show an increase of the zeta potential of CMC dispersions when the concentration of salts in solution increases. Calcium chloride caused the greatest increase in zeta potential. Excluding the monovalent cations, the divalent cation is able to reverse the sign of the zeta potential from negative to positiv