Laurence Reinert

Effect of sonication conditions: solvent, time, temperature and reactor type on the preparation of micron sized vermiculite particles.

The effects of temperature, time, solvent and sonication conditions under air and Argon are described for the preparation of micron and sub-micron sized vermiculite particles in a double-jacketed Rosett-type or cylindrical reactor. The resulting materials were characterized via X-ray powder diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared (FTIR) Spectroscopy, BET surface area analysis, chemical analysis (elemental analysis), Thermogravimetry analysis (TGA) and Laser Granulometry. The sonicated vermiculites displayed modified particle morphologies and reduced sizes (observed by scanning electron microscopy and laser granulometry). Under the conditions used in this work, sub-micron sized particles were obtained after 5h of sonication, whereas longer times promoted aggregation again. Laser granulometry data revealed also that the smallest particles were obtained at high temperature while it is generally accepted that the mechanical effects of ultrasound are optimum at low temperatures according to physical/chemical properties of the used solvent. X-ray diffraction results indicated a reduction of the crystallite size along the basal direction [001]; but structural changes were not observed. Sonication at different conditions also led to surface modifications of the vermiculite particles brought out by BET surface measurements and Infrared Spectroscopy. The results indicated clearly that the efficiency of ultrasound irradiation was significantly affected by different parameters such as temperature, solvent, type of gas and reactor type.

Structural changes of metallic surfaces induced by ultrasound.

The effect of ultrasounds on the surface of metallic plates with cubic faced centered (Al, Ag, Cu) or hexagonal (Zn) structure was studied. Treated surfaces were strongly attacked: a micrometric roughness and a superficial oxidation (characterized by roughness measurements and scanning electron microscopy) were induced. X-ray diffraction analyses showed a preferential reorientation of the maximum density planes for both crystallographic structures.

Binary adsorption isotherms of two ionic liquids and ibuprofen on an activated carbon cloth: simulation and interpretations using statistical and COSMO-RS models

The adsorption equilibriums of binary mixtures of the 4-tert-butyl-1-propylpyridinium bromide (referred to IL1) and 4-tert-butyl-1-(2 carboxyethyl) pyridinium bromide (referred to IL2) ionic liquids and ibuprofen (2-(4-(2-methylpropyl) phenyl) propanoic acid: IBP) on activated carbon cloth were investigated. The binary adsorption isotherms of the studied systems (IL1/IL2, IL1/IBP and IL2/IBP) have been studied in different conditions (different temperatures ranging from 286 to 313 K and at various concentration ratios 0.5, 1 and 2). The experimental isotherms have been simulated by some new statistical physics models established from the grand canonical ensemble. According to the most appropriate model, the adsorbed ILs and IBP molecules are assumed to be parallel to the activated cloth surface. An inhibition effect has been observed between the adsorbed molecules. The determination of the monolayer adsorbed uptake at saturation has shown an endothermic adsorption process of IBP and an exothermic one of IL1 and IL2. The estimated energy values demonstrate a physical adsorption whatever the adsorbate species. The microscopic adsorption process was interpreted from the point of view of molecular stereography and interaction energy. Moreover, a conductor-like screening model for real solvents (COSMO-RS) has been applied to calculate three specific interaction energies between the adsorbate molecules and a graphene layer modeling the activated carbon surface, i.e., the electrostatic misfit energy (EMF), the hydrogen-bonding energy (EHB) and the van der Waals energy (EvdW).

Experimental and theoretical studies of adsorption of ibuprofen on raw and two chemically modified activated carbons: new physicochemical interpretations

Knowledge of the ibuprofen (IBP) adsorption isotherms is important to understand and to improve its depollution process. In this work, the double layer model with two energies was applied to simulate the adsorption isotherms of ibuprofen on raw activated and two chemically modified granular activated carbons, obtained experimentally at pH = 7 and at different temperatures (298, 313 and 323 K). The chemically modified samples were obtained by treatment at 700 °C under nitrogen flow and ultrasonic treatment in H2O2 solution of the raw granulated activated carbon. The establishment of the model is based on a statistical physics approach, particularly on the grand canonical ensemble. The double layer model with two energies for each layer was found to be the best model to describe the adsorption process of ibuprofen. Using this model, the different adsorption isotherms of ibuprofen were described sterically and energetically through these parameters. The different parameters were interpreted as a function of temperature. In addition to this, the entropy, free enthalpy and the internal energy governing the adsorption process were calculated and interpreted.

Characterization and application of three novel biosorbents “Eucalyptus globulus, Cynara cardunculus, and Prunus cerasefera” to dye removal

Abstract Three biosorbents: Eucalyptus globulus, Cynara cardunculus, and Prunus cerasefera leaves were tested to remove Methylene Blue from aqueous solutions. The three biosorbents were characterized by the determination of the Methylene Blue accessible surface, iodine number, BET specific surface area using nitrogen adsorption at 77 K, morphological analysis by scanning electron microscopy, pHPZC, and FTIR analysis. The Methylene Blue adsorption uptakes of the biosorbents were studied as a function of pH, biosorbent dose, stirring speed, ionic strength, and contact time. Optimal conditions for maximum removal of Methylene Blue were found to be: a pH of 10, an adsorbent dose of 8 g L−1, and a contact time of 2 h for E. globulus and C. cardunculus, and a pH of 6.5, an adsorbent dose of 4 g L−1 and a contact time of 2 h for P. cerasefera. The Langmuir models as determined from batch experiments yielded a maximum capacity of adsorption by biosorbent prepared from E. globulus leaves of 250 mg g−1 against 333 ...

THE TRAPPING OF B FROM WATER BY EXFOLIATED AND FUNCTIONALIZED VERMICULITE

Micron-grade natural vermiculite was modified by several physical and chemical treatments in order to increase the adsorption capacity of this material for B. A thermal exfoliation (T = 600°C) of pristine material, a chemical exfoliation through reaction with hydrogen peroxide (H2O2 35%), or grafting of a specific B complexant (i.e. N-methyl-D-glucamine: NMDG) led to an increase in the uptake of B at low initial concentrations of the aqueous solutions ([B] ≈ 5 mg L−1). The more efficient material is the NMDG-grafted clay, for which the adsorption uptake is four times greater than that of raw vermiculite, and reaches 0.04 mmol g−1. For all modified materials, the effect of the pH on B adsorption and the adsorption kinetics were studied and compared to raw vermiculite. Adsorption isotherms were also plotted and fitted well with the Freundlich equation.

Modeling of the sorption of crude oil on a polyurethane foam-powdered activated carbon composite

AbstractIn an adsorption process, spontaneous accumulation of molecules takes place at the surface of solids as compared to the bulk phase. Adsorption is used for the recovery of undesirable components from a liquid mixture by establishing van der Waals bonds between the solid surface and the attracted components. Nowadays, adsorption is recognized as one of the major significant separation processes amid the physical, biological, and chemical processes. Activated carbon adsorption has been widely used for the purification of water and wastewater and for the treatment of numerous environmental problems. In this work, polyurethane (PU) foam-activated carbon composites were synthesized and characterized. The mixing of a number of well-defined ingredients produces flexible foam of alveolar structure after polymerization reactions. The prepared PU-powdered activated carbon composites were used to investigate the sorption of raw crude oil. Multiple experimental manipulations were combined to understand this be...

Adsorptive removal of copper (II) ions from aqueous solution by silane cross-linked chitosan/PVA/TEOS beads: kinetics and isotherms

AbstractIn this study, beads of chitosan (CS) containing polyvinyl alcohol (PVA) were prepared and cross-linked with tetraethoxysilane (TEOS). The cross-linking of CS/PVA beads with TEOS preserved the active adsorption sites of CS and also enhanced its chemical and mechanical stability. The chemical solubility test and swelling behavior of the beads were studied, especially, in acidic media. Adsorbents were characterized by infrared spectroscopy and scanning electron microscopy. The removal of Cu2+ ions from aqueous solution on the prepared beads was investigated in a batch adsorption system as a function of pH, amount of adsorbent, initial concentration of metal ions, and contact time. The adsorption data were analyzed on the basis of Lagergren pseudo-first-order, pseudo-second-order and interparticle diffusion models. Experimental data were fitted with Langmuir and Freundlich isotherm models. The maximum adsorption capacity of cross-linked CS/PVA/TEOS beads for copper ions was of 224.6 mg/g according to...

Characterization of phosphate removal from aqueous solution by manganese oxyhydroxyde

aLaboratory of Pollution and Water Treatment, Chemistry Department, University Mentouri Constantine, Algeria, emails: chahrazed_boukhalfa@yahoo.com (C. Boukhalfa), loubna_bouhouf@yahoo.fr (L. Bouhouf) bLaboratory of Molecular Chemistry and Environment, University Savoie Mont Blanc, F-73000 Chambéry, France, emails: laurence.reinert@univ-savoie.fr (L. Reinert), Laurent.duclaux@univ-savoie.fr (L. Duclaux)

Adsorption of indoor toxic gas by ionic liquid impregnated activated carbons

Butylpyridinium thiocyanate [BuPyr]SCN ionic liquid was synthesized by metathesis and characterized. NMR spectrum has shown the [BuPyr] cation while FTIR has shown the SCN anion peak which confirms the structure of the synthesized ionic liquid. The ionic liquid was impregnated on activated carbon in order to enhance performance of sulfur dioxide adsorption compared to the non-impregnated raw activated carbon. Two types of activated carbons were used; activated carbon cylindrical granules and cloth. Different percentages of ionic liquid loading (1%, 10% and 20%) were applied. The capacity of the adsorbent for treatment of 10 ppm and 50 ppm SO2 was determined by breakthrough curve analysis whereby optimum breakthrough time was obtained. [BuPyr]SCN impregnated on activated carbon cloth have shown higher adsorption performance.