Variation of Some Physicochemical Parameters to Improve the Properties of Clays of Madagascar: Case of Nitrates in Water

摘要

Clay is a lamellar material made up of elementary layers (phyllosilicates) that pile, aggregate themselves, disaggregate according to the condition of the surrounding environment. This induced arrangement of the internal reactive interfaces, different from external surfaces, and confined spaces which are true nanoreactors. The small size of their layers of which the thickness is on a nanometric scale (millionth mm) confers on clays mineral all the remarkable properties exploited in many application that one daily mixes with since millenia. We applied one of these properties with the process of adsorption to highlight the elimination of certain pollutants in water. The processes of adsorption are the object of this study. They tend to develop quickly and are mainly used for the elimination of polluting compounds. This technique showed great capacities of depollution of waste waters. But, its performance and its effectiveness depend on the nature of the adsorbent. In practice, we will use the adsorbent white clay and green clay. This study makes it possible to determine the effect of the initial nitrate concentration, the effect of the pH and the effect of the load while adsorbing. The best results were got to 76.5% for white clay (WC) and 60% for green clay (GC) with 100mg/L~(-1) of Nitrate. Indeed, the good output of adsorption is obtained with acid pH for the two adsorbents with 200mg/L~(-1) of Nitrate. However, the percentages of retention of thenitrates ion on the adsorbents used vary 35% and 89% for white clay and 28% and 80% for green clay with 100mg/L~(-1) of Nitrate. The analysis is carried out by visible spectrometry U.V of type SHIMADZU U.V- 160A. The experiment shows that the white clay of the I.M.R.A is good adsorbent power that the green clay of Homeopharma.