Etude de l’élimination des polluants émergents par des matériaux composites

Abstract

In this study, two types of adsorbents were prepared: beads of alginate/ nanoparticles of maghemite coated with citrate ions/ multiwalled carbon nanotubes functionalized with carboxylic acid (A/γ-Fe2O3/MWCNTs) and beads of alginate/sepiolite/ nanoparticles of magnetite/nanoparticles of Prussain blue (A/Sep/NP/PB). The beads were characterized by FTIR, XRD, SEM, VSM, TGA-TDA and BET. The results of methylene blue (MB) adsorption onto A/γ-Fe2O3/MWCNTs revealed their efficiency with a maximum adsorption capacity of 905.5 mg.g-1. The adsorption of MB was controlled by intraparticle diffusion. The MB adsorption mechanism onto the beads is based on electrostatic attractions. The beads A/Sep/NP/PB show their efficiency for cesium-137 (Cs) adsorption with a maximum adsorption capacity equal to 130.5 mg.g-1. The reaction of Cs adsorption onto the beads is the controlling step. Cs adsorption is the combined action of the chemisorption and physisorption. The adsorption of MB and Cs increases with increasing in contact time, initial concentration of pollutant and temperature, and decreases with ionic force. The beads presented high stability of adsorption capacity in a large domain of pH (4-10). The beads were used for 5-6 successive cycles of adsorption/desorption without losing their adsorptive performance. Therefore, the two prepared types of beads were considered as high effective and economic adsorbents for MB and Cs adsorption. In addition, the beads present magnetic properties, which facilitate their separation from water to clean up and makes their application in industrial scale more important