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Kinetic and thermodynamic study of adsorption of cationic dyes (methylene blue and safranine) on artificial zeolite

J. Bensalah*1, L. Kadiri1, H. Ouaddari3, A. Habsaoui2, A. Lebkiri1, E. H. Rifi1

The rejections of many industries (plastic, cosmetic, paper, and especially textile) are heavily loaded with dyes that have a toxicological impact dangerous on the environment. Methylen bleu (BM)  is an cationic dye widely used in the laboratory and in the textile industry. Carcinogenic and mutagenic, it is a powerful pollutant of water. And also Safranine is one of the most used synthetic cationic dyes. It is a reddish brown powder soluble in water, which is mainly used as a food coloring in flavoring candies and biscuits. Safranine is also used to dye tannin, cotton, blast fibers, wool, silk, leather and paper. The purpose of this work is the liquid-solid extraction of cationic or anionic dyes from dilute aqueous solutions of 10 mg / l of both dyes with a zeolite material. The effect of several parameters on the adsorption performances were studied (contact time, the mass of the support, pH).The results obtained are as follows: The equilibrium of the adsorption was obtained after 180 min of two cationic dyes (SF and BM) with a low mass of zeolite (0.1g) and at pH = 6.5.

The adsorption capacity of the dye by the zeolite increases slightly with the increase of the temperature from 25 ° to 55 ° C.The evolution of the adsorption capacity over time at different dye concentrations ranging from 10 to 200 mg / l with a maximum capacity of adsorption of the dye by the zeolite to.

ï?¼             Qmax( SF) =7,15mg/g.

ï?¼             Qmax (BM) =7,36mg/g.

The study of the kinetic models confirms, on the one hand, that the adsorption of the two dyes (SF) and (BM) on the zeolite follows the pseudo-first order model, and on the other hand, that the Langmuir isotherm is the appropriate model to explain the safranine adsorption process on the zeolite.