Propriétés adsorbantes des billes de lignine: application au traitement des eaux usées

This study investigated the adsorption of the heavy metal ions Cd (II) on a lignin isolated from sugar cane bagasse, by alkali treatment. This lignin is converted to beads using another polymer of marine origin, to test its ability to remove heavy metals from wastewater. Factors influencing Cd adsorption such as initial Cd ion concentration (5-50mg/l), pH (1-8), contact times (15min-4h) were investigated. The adsorption process was relatively fast and equilibrium was established about 2h. Maximum adsorption of cadmium ions occurred at around pH 5. The adsorption equilibrium data fitted best with the Freundlich and Dubinin-Radushkevich isotherms, and showed that the adsorption was physical in natureCette étude a eu pour but d’examiner l'adsorption des ions de métaux lourds Cd (II) sur une lignine isolé à partir de la bagasse de canne à sucre, après un traitement alcalin. Cette lignine est convertie en des perles en utilisant un autre polymère d'origine marine, pour tester son aptitude à éliminer les métaux lourds des eaux usées. Les facteurs influant sur l’adsorption du Cd tels que la concentration d'ions de Cd initiale (5-50mg / L), le pH (1-8), les temps de contact (15min-4h) ont été étudiés. Le processus d'adsorption est relativement rapide et l'équilibre a été établi après environ 2h. L’adsorption maximale des ions de cadmium est obtenue à un pH d'environ 5. Les équilibre d'adsorption suivent les isothermes de Freundlich et Dubinin-Radushkevich, et ont montré que l'adsorption était de nature physique

GEOSPATIAL TOOLS FOR PREVENTION OF URBAN FLOODS CASE STUDY: RIVER OF EL MALEH (CITY OF MOHAMMEDIA – MOROCCO)

Today, the prevention and the risk management occupy an important part of public policy activities and are considered as major components in the process of sustainable development of territories. Due to the expansion of IT processes, in particular the geomatics sciences, decision-makers are increasingly requesting for digital tools before, during and after the risks of natural disasters. Both, the geographic information system (GIS) and the remote sensing are considered as geospatial and fundamental tools which help to understand the evolution of risks, to analyze their temporality and to make the right decisions. The historic events (on 1996, 2002 and 2010) which struck the city of Mohammedia and having caused the consequent damage to vital infrastructure and private property, require a thorough and rational analyze to benefit from it and well manage the floods phenomena. This article present i) the contribution of the geospatial tools for the floods simulation of Oued of el Maleh city at various return periods. These tools allow the demarcation of flood-risk areas and so to make floods simulations in several scenarios (decadal flood, 20-year flood, 50-year flood, 100-year flood, 500-year flood & also millennial flood) and besides (ii) present a synthesis map combining the territorial stakes superposed on the flood scenarios at different periods of return

Diastereoselective radical alkylations of alkyl aryl sulfoxides.

1,2-Asymmetric induction in reactions of arylsulfinylated radicals has been examined and compared to the anionic processes. A rule of thumb allowing to predict the stereoselectivity is presented. Copyright (C) 1996 Published by Elsevier Science Lt

Preparation of α-hydroxyphosphonates over phosphate catalysts

Catalysts based on natural phosphate (NP) are able to catalyze the synthesis of α-hydroxyphosphonates by reaction of dimethyl or diethyl phosphite with aldehydes and ketones at room temperature. This eco-friendly method is more efficient with modified phosphate, either impregnated with KF (KF/NP) or modified with sodium (Na/NP). Excellent yields (89–99%) were obtained with Na/NP in very short reaction times, 1–5 min in the case of aldehydes and 1–1.5 h in the case of ketones, a remarkable activity considering the very low surface area of the solid and the absence of solvent during the synthesis process. This catalyst was fully recoverable after calcination in four consecutive runs.This work was made possible by the generous financial support of the Agencia Española de Cooperación Internacional (Project A/3810/05), the C.I.C.Y.T. (Project CTQ2005-08016) and The Research Center for Studies on Mineral Phosphates (CERPHOS), OCP Group, Morocco.Peer reviewe