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Muthanna H. Al-dahhan - One of the best experts on this subject based on the ideXlab platform.

  • Activity and stability of iron-containing Pillared Clay catalysts for wet air oxidation of phenol
    Applied Catalysis A-general, 2006
    Co-Authors: Muthanna H. Al-dahhan
    Abstract:

    Abstract Catalytic wet air oxidation of an aqueous phenol solution over Fe–Al Pillared catalyst was conducted in a stirred tank and packed bed reactor. Semi-batch experiments in the stirred tank reactor were designed to investigate the effects of temperature, air pressure, initial phenol concentration, catalyst loading, and catalyst size on the conversion of total organic carbon. The catalyst exhibited an important activity in degrading total organic carbon at mild conditions. Its internal mass transfer resistance was assessed over different catalyst sizes via a chosen criterion. Packed bed runs were conducted under selected temperature and pressure (170 °C, 3.2 MPa) over a long duration (240 h). Various characterization methods were employed for fresh and aged Pillared Clay catalysts. Occurrence of catalyst deactivation by carbonaceous deposits during the packed bed operation was observed through scanning electron microscopy (SEM) and elemental analysis. Insignificant metal leaching was observed because trace amounts of metal elements were detected in the hot acidic liquid solution.

  • Catalytic wet air oxidation of phenol in concurrent downflow and upflow packed-bed reactors over Pillared Clay catalyst
    Chemical Engineering Science, 2005
    Co-Authors: Muthanna H. Al-dahhan
    Abstract:

    Abstract An experimental study is presented for comparing the behavior of a packed bed reactor in the catalytic liquid-phase oxidation of aqueous phenol with two modes of operation, downflow and upflow. The operating parameters investigated included temperature, reactor pressure, gas flowrate, liquid hourly space velocity and feed concentration. Because of the completely wetted catalyst, the upflow reactor generally performs better for high pressures and low feed concentrations when the liquid reactant limitation controls the rate. The interaction between the reactor hydrodynamics, mass transfer, and reaction kinetics is discussed. For both operation modes, complete phenol removal and significant total organic carbon (TOC) reduction can be achieved at rather mild conditions of temperature (150–170 °C) and total pressure (1.5–3.2 MPa). The results show that the phenol and TOC conversion are considerably affected by the temperature, while the air pressure only has minor influence. Total elimination of TOC is difficult since acetic acid, as the main intermediate, is resistant to catalytic wet oxidation. All tests were conducted over extrudates of Fe–Al Pillared Clay catalyst, which is stable and maintains its activity during the long-term experimental process. No significant catalyst deactivation due to metal ion leaching and polymer deposition was detected.

  • Catalytic Wet Oxidation of Phenol by Hydrogen Peroxide over Pillared Clay Catalyst
    Industrial & Engineering Chemistry Research, 2003
    Co-Authors: Muthanna H. Al-dahhan
    Abstract:

    Extrudates of Al−Fe Pillared Clay catalyst suitable for packed-bed operations are evaluated for wastewater treatment via a wet oxidation process employing hydrogen peroxide as the oxidant. The reaction was carried out in a semibatch basket reactor under rather mild conditions. Operational parameters were studied under the following conditions:  temperature from 25 to 90 °C, atmospheric pressure, initial phenol concentration from 100 to 2000 ppm of the liquid phase, catalyst loading from 0 to 10 g/L, and input H2O2 concentration from 0.15 to 0.6 mol/L. Under these conditions, the Al−Fe Pillared Clay catalyst achieves a total elimination of phenol and significant total organic carbon (TOC) removal. This catalyst can be used several times without any change in its catalytic properties, and hence, it would be a promising catalyst for industrial wastewater treatment. The reaction takes place to a significant extent both in the liquid phase and on the catalyst surface. Hence, apparent kinetic models were develo...

M A Vicente - One of the best experts on this subject based on the ideXlab platform.

  • fenton degradation of sulfanilamide in the presence of al fe Pillared Clay catalytic behavior and identification of the intermediates
    Journal of Hazardous Materials, 2015
    Co-Authors: Sesegma Ts Khankhasaeva, Elvira Ts Dashinamzhilova, Darima V Dambueva, A Gil, M A Vicente, M N Timofeeva
    Abstract:

    Abstract Liquid phase catalytic degradation of sulfanilamide with H2O2 was carried out in the presence of Fe,Al/M-Pillared Clay (Fe,Al/M-MM, M = Na+, Ca2+ and Ba2+) as heterogeneous Fenton type catalyst. Fe,Al/M-MMs were prepared by swelling of layered aluminosilicate (90–95 wt.% montmorillonite) from a bed located in Mukhortala (Buryatia, Russia) in Na+, Ca2+ and Ba2+ forms by means of the exchange of these cations with bulky Fe,Al-polyoxocations prepared at Al/Fe = 10/1 and OH/(Al + Fe) = 2.0, and then calcinated at 500 °C. XRD method and chemical analysis demonstrated that the rate of crystalline swelling was dependent on the interlayer cations and decreased in the order: Fe,Al-/Na-MM > Fe,Al/Ca-MM > Fe,Al/Ba-MM. It was found that the catalytic properties of Fe,Al/M-MMs depended on the type of exchangeable cations. The effect of the H2O2/sulfanilamide molar ratio, the catalyst content, the reaction temperature and the reaction pH on the removal rate of sulfanilamide has been studied in the presence of Fe,Al/Na-MM. The catalyst can be applied for degradation of sulfanilamide with H2O2 for at least three successive cycles without loss of activity. HPLC analyses pointed out that the main degradation intermediate products were sulfanilic acid, benzenesulfonic acid, p-benzoquinone and aliphatic carboxylic acids.

  • heterogeneous photo fenton oxidation with Pillared Clay based catalysts for wastewater treatment a review
    Applied Catalysis B-environmental, 2010
    Co-Authors: J Herneyramirez, M A Vicente, Luis M Madeira
    Abstract:

    Due to their excellent properties, Pillared Clays (PILCs) have been widely used in several applications, particularly in catalysis. In this paper, their use in heterogeneous photo-Fenton-like advanced oxidation for wastewater treatment, employing either model/synthetic effluents or real streams, is reviewed. Particular attention is given to the effect that the main operating conditions have on process performance, namely wavelength of the light source and power, initial H2O2 or parent compound concentration, catalyst load, pH and temperature. Emphasis is also given to the type of catalyst used and its synthesis conditions (e.g. thermal aging or acid treatment). Several important technological aspects that should be accounted for in real practice are also discussed in detail, particularly the catalyst stability, the use of continuous-flow fixed-bed reactors, the mode of oxidant addition, the environmental impact/integration with biological processes and the possibility of using visible light instead of UV only. Then, some simple mechanistic studies reported are summarized, as well as modeling works.

  • fe saponite Pillared and impregnated catalysts i preparation and characterisation
    Applied Catalysis B-environmental, 2004
    Co-Authors: Carolina Belver, M A Banaresmunoz, M A Vicente
    Abstract:

    Abstract Several Fe-saponite catalysts have been prepared by different methods, namely, intercalation of the Clay with polymerised Fe solutions, intercalation of the Clay with polymerised mixed Al–Fe solutions, and impregnation of Al-Pillared Clay with Fe precursors. In all cases, Fe is effectively incorporated into the Clay, usually maintaining the layered Clay structure. The basal interlayer spacing of the solids, their specific surface area, their thermal stability against the layer collapse and their reducibility properties strongly depend on the synthesis procedure.

  • platinum catalysts supported on al Pillared Clays application to the catalytic combustion of acetone and methyl ethyl ketone
    Catalysis Today, 2001
    Co-Authors: A Gil, M A Vicente, J F Lambert, L M Gandia
    Abstract:

    Abstract A hectorite, a montmorillonite and a saponite, all of them in their Al-Pillared forms, as well as unPillared saponite were considered as supports of platinum catalysts (2.3 wt.% Pt) for the catalytic combustion of acetone and methyl-ethyl-ketone (MEK). The preparation of the catalysts modified the textural properties of the Al-Pillared Clay supports, giving rise to a significant loss of specific surface area and micropore volume. After hydrogen reduction at 773 K, the presence of poorly dispersed metallic platinum with mean crystallite sizes in the 70–100 A range was detected by X-ray diffraction (XRD). Good activity and stability performances were found under the reaction conditions used. Whatever be the catalyst considered, MEK resulted easier to oxidize than acetone, a fact which has been related to the strength of the weakest C–H bond in these ketones. Remarkable differences in catalytic activity arose depending on the Pillared or unPillared character of the support and the nature of the starting smectite Clay used. Regardless of the ketone molecule, the following order of decreasing catalytic performance was established with respect to the support nature: unPillared saponite > Al - Pillared montmorillonite > Al - Pillared saponite > Al - Pillared hectorite .

Sreenivasan Rijith - One of the best experts on this subject based on the ideXlab platform.

  • removal of uranium vi from aqueous solutions and nuclear industry effluents using humic acid immobilized zirconium Pillared Clay
    Journal of Environmental Radioactivity, 2010
    Co-Authors: T S Anirudhan, C D Bringle, Sreenivasan Rijith
    Abstract:

    Removal of uranium [U(VI)] from aqueous solutions with humic acid-immobilized zirconium-Pillared Clay (HA-Zr-PILC) was investigated using a batch adsorption technique. The adsorbent was characterized using XRD, FTIR, SEM, TG/DTG, surface area analyzer and potentiometric titration. The effects of pH, contact time, initial concentration, adsorbent dose, and adsorption isotherm on the removal process were evaluated. A maximum removal of 97.6+/-2.1 and 94.7+/-3.3% was observed for an initial concentration of 50 and 100 mg L(-1), respectively at pH 6.0 and an adsorbent dose of 2.0 g L(-1). Equilibrium was achieved in approximately 180 min. The mechanism for the removal of U(VI) ions by HA-Zr-PILC was based on an ion exchange reaction. The experimental kinetic and isotherm data were analyzed using a second-order kinetic equation and Langmuir isotherm model, respectively. The monolayer adsorption capacity for U(VI) removal was found to be 132.68+/-5.04 mg g(-1). An increase of temperature of the medium caused an increase in metal adsorption. Complete removal (approximately = 100%) of U(VI) from 1.0 L of a simulated nuclear industry effluent sample containing 10.0 mg U(VI) ions was possible with 1.5 g of HA-Zr-PILC. The adsorbent was suitable for repeated use (over 4 cycles) without any noticeable loss of capacity.

  • removal of uranium vi from aqueous solutions and nuclear industry effluents using humic acid immobilized zirconium Pillared Clay
    Desalination and Water Treatment, 2009
    Co-Authors: T S Anirudhan, C D Bringle, Sreenivasan Rijith
    Abstract:

    Removal of uranium [U(VI)] from aqueous solutions with humic acid-immobilized zirconiumPillared Clay (HA-Zr-PILC) was investigated using batch adsorption technique. Maximum removal of 99.2% was observed for an initial concentration of 25 mg L-1 at pH 6.0 and an adsorbent dose of 2 g L-1. Equilibrium was achieved in approximately 4 h. The adsorbent was characterized using, XRD, FTIR, SEM, TG/DTG surface area analyzer and potentiometric titration. The effects of pH, contact time, initial concentration and adsorbent dose on removal process were evaluated. The experimental kinetic and isotherm data were analyzed using a second-order kinetic equation and Langmuir isotherm model, respectively. The monolayer adsorption capacity for U(VI) removal was found to be 134.65±4.07 mg g–1. Adsorption experiments were also conducted using a commercial cation exchanger, with carboxylate functionality for comparison. Adsorption efficiency was tested using a simulated nuclear industry effluent sample. Experimental results ob...

Joel Barrault - One of the best experts on this subject based on the ideXlab platform.

  • active iron species in the catalytic wet peroxide oxidation of phenol over Pillared Clays containing iron
    Applied Catalysis B-environmental, 2003
    Co-Authors: E Guelou, Joel Barrault, Jeanine Fournier, Jeanmichel Tatibouet
    Abstract:

    Abstract Phenol oxidation by hydrogen peroxide was performed on iron containing Clays, Pillared by Al or mixed Al–Fe complexes. The Al–Fe Pillared Clay has shown good performances towards the total phenol oxidation (80% of TOC abatement at 70 °C). From ESR characterization, it was deduced that on Al Pillared Clay, iron is present as isolated species, probably located on the Clay layer and as oxide clusters, whereas on Al–Fe Pillared Clay, in addition of these preceding species, an other isolated species was detected, probably located on the pillars. From the catalytic results, it can be concluded that this latter species catalyzes more efficiently the total phenol oxidation than the others do. A long time (350 h) catalytic experiment in a continuous flow reactor has shown the high stability of the Al–Fe Pillared Clay, the total amount of dissolved iron by the reaction being less than 5 wt.% of the iron initially contained in the catalyst.

  • catalytic wet peroxide oxidation over mixed al fe Pillared Clays
    Applied Catalysis B-environmental, 2000
    Co-Authors: Joel Barrault
    Abstract:

    Abstract Mixed (Al–Fe) Pillared Clays are very efficient solid catalysts for oxidation of organic compounds in water by hydrogen peroxide. We have shown that in rather mild experimental conditions (atmospheric pressure, T ≤70°C) and with a low excess (20%) of hydrogen peroxide, phenol was rapidly converted, mainly to CO 2 , without significant catalyst leaching. The (Al–Fe) Pillared Clay catalyst (called FAZA) can be used several times without any change of its catalytic properties. According to the low leaching observed and a previous Mossbauer spectroscopy study, the iron species appear to be strongly bonded to the aluminium pillars.

Tadashi Hattori - One of the best experts on this subject based on the ideXlab platform.

  • effect of surface hydrophobicity of tio2 Pillared Clay on adsorption and photocatalysis of gaseous molecules in air
    Applied Catalysis A-general, 2004
    Co-Authors: Chihiro Ooka, Hisao Yoshida, Kenzi Suzuki, Tadashi Hattori
    Abstract:

    Three kinds of TiO2-Pillared Clay were prepared from different raw Clays (montmorillonite, saponite and fluorine mica). Their surface hydrophobicities and performances in adsorption-photocatalytic degradation of toluene, trichloroethylene, ethylene and ethanol in a humid atmosphere, were investigated. The surface hydrophobicity of the Pillared Clay, estimated by adsorption isotherms of nitrogen and water, varied with the kind of the host Clay. It increased in the order of saponitetrichloroethylene on the TiO2-Pillared Clay was consistent with that of the surface hydrophobicity of Pillared Clay. Enrichment of toluene and trichloroethylene by adsorption enhanced the rate of photocatalytic degradation on the Pillared Clay; the order of the catalytic activity also agreed with that of the surface hydrophobicity of Pillared Clay. The surface hydrophobicity of the TiO2-Pillared Clay did not exert much influence on either adsorption or photocatalytic degradation of low hydrophobic substances like ethylene and ethanol.

  • adsorptive and photocatalytic performance of tio2 Pillared montmorillonite in degradation of endocrine disruptors having different hydrophobicity
    Applied Catalysis B-environmental, 2003
    Co-Authors: Chihiro Ooka, Hisao Yoshida, Kenzi Suzuki, Masakazu Horio, Tadashi Hattori
    Abstract:

    Abstract TiO2 Pillared Clay was applied for the adsorption-photocatalytic degradation of the endocrine disruptors with various hydrophobicities (di-n-butyl phthalate, diethyl phthalate, dimethyl phthalate and bisphenol-A). The hydrothermal treatment developed the crystallinity of the TiO2 pillar and the size of the TiO2 crystallites, and enhanced the photocatalytic degradation rate. However, the hydrothermal treatment in hard condition made the specific photocatalytic activity decrease since the size of crystallites increased. The surface hydrophobicity of the Pillared Clay was not affected so much, but reduced slightly, by the hydrothermal treatment. Higher hydrophobic endocrine disruptor was more adsorbed and enriched on the TiO2 Pillared Clay. Enrichment of the reactant enhanced the rate of photocatalytic degradation on the Pillared Clay.