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    Removal of Furfural from Aqueous Solutions by Adsorption Using Organobentonite: Isotherm and Kinetic Studies
    (2015-05-03) Mebrek, Ouassila Rachedi; Derriche, Zoubir
    Lubricant refineries are facing pollution problems associated with the occasional loss of furfural. This constitutes both an economic loss and an environmental hazard, especially for aquatic organisms. Some studies on the removal of furfural by adsorption onto hydrophobic polymeric resins (XAD-4 and XAD-7), activated carbon and the nanoporous material MCM-48 have been published, but none provides information on the adsorption of furfural onto clays. In the present work, we have studied the efficiency of sodium bentonite modified with the cationic surfactant cethyltrimethylammonium bromide (CTAB) in the adsorption of furfural. The structures of both natural and modified bentonites have been examined using XRD and FT-IR analyses. Adsorption studies were performed in a batch system, with the effects of various experimental parameters such as the contact time, the organobentonite concentration, pH, the initial furfural concentration and the temperature being evaluated. Kinetic results showed that furfural could be removed by CTAB–bentonite after contact for 6 h, with the adsorption process being well described by the pseudo-second-order reaction model. Furfural sorption onto CTAB–bentonite was characterized by a linear isotherm, with the adsorption capacity towards furfural being reduced by increasing temperature. A comparison of furfural adsorption capacities revealed that the capacities decreased in the following order: CTAB–bentonite > XAD-4 > XAD-7.
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    Removal of Orange II by Phosphonium-modified Algerian Bentonites
    (University of sciences and technology in Oran, 2015-04-28) Bouzid, Samia
    An Algerian montmorillonite was modified with two organic surfactants, methyltriphenyl phosphonium bromide and n-hexyltriphenyl phosphonium bromide. The solids obtained were used as adsorbents to remove Orange II, an anionic dye from aqueous solutions. Batch experiments were conducted to study the effects of temperature (20–60 C), initial concentration of adsorbate (50–150 mg L_1 ) and pH of solution 6.5 on dye adsorption. Due to their organophilic nature, exchanged montmorillonites were able to adsorb Orange II at a very high level. Adsorption of Orange II for B-NHTPB and B-MTPB at different pH show that the adsorption capacity clearly decreases with an increase in pH of the initial solution from 2 to 8, this decrease being dramatic for pH>8. This may be due to hydrophobic interactions of the organic dye with both phosphonium molecules and the remaining non-covered portion of siloxane surface. The kinetics of the adsorption was discussed on the basis of three kinetic models, i.e., the pseudo-first-order, the pseudo-second-order, and the intraparticle diffusion models. Equilibrium is reached after 30 min and 60 min for B-MTPB and B-NHTPB, respectively; the pseudo-second-order kinetic model described very well the adsorption of Orange II on modified bentonites. The non-linear Langmuir model provided the best correlation of experimental data, maximum adsorption of Orange II is 53.78 mgg_1 for B-NHTPB and 33.79 mg g_1 for B-MTPB. The thermodynamic parameters, such as free energy of adsorption (DG_), enthalpy change (DH_), and entropy change (DS_) were also determined and evaluated. From thermodynamic studies, it was deduced that the adsorption was spontaneous and exothermic.
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    Synthesis and characterization of Mg–Fe layer double hydroxides and its application on adsorption of Orange G from aqueous solution
    (University of sciences and technology in Oran, 2015-03-09) Benselka-Hadj Abdelkader, Naima; A. Bentouami; Z. Derriche; N. Bettahar; L.-C. de Ménorval
    Layered double hydroxide (LDH) with hydrotalcite-like structure containing Mg(II) and Fe(III) in the layers and its calcined form were prepared at different Mg/Fe molar ration by co-precipitation method at fixed pH= 10 and followed by calcination at 500°C (denoted CLDH). The obtained materials were characterized by powder X-ray diffraction (PXRD), FT-IR spectroscopy, and TGA. The prepared LDH and CLDH were used for Orange G (Acid Orange 10) dye removal from aqueous solutions. Batch studies were carried out to address various experimental parameters such as contact time, pH, sorbent dose and temperature. The sorption kinetics data fitted the pseudo-second order model. The isotherms were established and the parameters calculated. The sorption data fitted the Langmuir model with good values of the correlation coefficient. The sorption capacity of CLDH was found to be almost independent on initial pH of solution in the range 3–13 and approximately 5 times higher than that of LDH.