J. Roussy

Ecole des Mines d'Alès, Alais, Languedoc-Roussillon, France

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Publications (33)36.25 Total impact

  • E. Guibal, T. Vincent, J. Roussy
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    ABSTRACT: Chitosan is an emblematic example of biopolymer that can be obtained from renewable resources (fungal biomass, crustacean shells ...) and that can be used for binding a number of metal ions through different mechanisms (complexation, electrostatic attraction, ion pair formation). Chitosan was used for the sorption of various transition metals, from toxic (Hg(II), Cd(II), U(VI), Mo(VI), V(IV) and V(V) ...) to strategic and valuable metals (Pd(II), Pt(IV), Au(III) ...). However, the interactions of chitosan with metal ions are not strictly limited to environmental applications. Hence, the binding of metal ions oil the biopolymer can be used for designing new materials or new applications. Some examples are reported below.
    01/2009: pages 519-526;
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    ABSTRACT: The grafting of thiourea on chitosan backbone allows synthesizing a thiocarbamoyl derivative that was very efficient for mercury sorption in acidic solutions. Though the sorption capacity is not increased compared to raw chitosan in near neutral solutions, this modification allowed maintaining high sorption capacity (close to 2.3 mmol Hg g(-1)) at pH 2. Mercury sorption in acidic solutions is not affected by the presence of competitor metals (such as Zn(II), Pb(II), Cu(II), Cd(II), Ni(II)) or the presence of nitrate anions (even at concentration as high as 0.8M)). The presence of chloride or sulfate anions (0.8M) decreased Hg(II) sorption capacity to 1 mmol Hg g(-1). Kinetics are controlled by a combination of pseudo second-order reaction rate and resistance to intraparticle diffusion. Mercury desorption reached about 75% using thiourea (in HCl solution).
    Journal of hazardous materials 11/2008; 165(1-3):415-26. · 4.33 Impact Factor
  • Source
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    ABSTRACT: A coagulation/flocculation process using a selection of biopolymers (chitosan and tannin) was used to treat an ink-containing effluent generated in the processing of packaging. The efficiency of the process was investigated in terms of the influence of pH, coagulant and flocculant concentrations, as well as chitosan characteristics (especially the molecular weight). The process was particularly efficient under acidic solutions: the amount of coagulant and flocculant to be used were significantly reduced by limiting the pH to 5. Optimum conditions for colour abatement (measured at 528 nm) were obtained at pH 5 using the most viscous chitosan (highest molecular weight) at a concentration close to 20 mg·ℓ -1 and a concentration of tannin close to 70-100 mg·ℓ -1 .
    Water S.A 12/2007; 31(3). · 0.88 Impact Factor
  • E. Guibal, J. Roussy
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    ABSTRACT: Chitosan, dissolved in acetic acid, was used for the coagulation-flocculation of an anionic dye (Reactive Black 5). In acidic solutions protonated amine groups of chitosan attract dye sulfonic groups. Increasing chitosan dosage increases dye removal up to a concentration resulting in complete neutralization of anionic charges; above, the excess of cationic charges leads to suspension re-stabilization. Process efficiency increases with decreasing the initial pH of dye solution: the molar ratio between dye molecules and amine groups ([n]) respects the stoichiometry between sulfonic functions and protonated amine groups at initial pH 5; at initial pH 3 a possible dye aggregation phenomenon results in higher molar ratio [n]. The coefficient [n] depends on both the pH and the molecular weight of chitosan. The main mechanism for dye coagulation with chitosan Sounds to be charge neutralization at acidic pH. (c) 2006 Elsevier B.V. All rights reserved.
    Reactive and Functional Polymers 01/2007; 67(1):33-42. · 2.51 Impact Factor
  • Techniques and Instrumentation in Analytical Chemistry, 01/2007: pages 243-265;
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
    ChemInform 10/2006; 37(43).
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    ABSTRACT: Chitosan has unique properties among biopolymers, especially due to the presence of primary amino groups. Chitosan has been used for the chelation of metal ions in near-neutral solution, the complexation of anions in acidic solution (cationic properties due to amine protonation), the coagulation of negatively charged contaminants under acidic conditions, and for precipitative flocculation at pH above the pKa of chitosan. The coagulation and flocculation properties can be used to treat particulate suspensions (organic or inorganic) and also to treat dissolved organic materials (including dyes and humic acid). This paper will give an overview of the principal results obtained in the treatment of various suspensions and solutions: (a) bentonite suspensions; (b) organic suspensions; (c) anionic dye solutions; and (d) humic acid solutions. Stoichiometry and charge restabilization were determined for the coagulation of humic acid, kaolin, and organic dyes with chitosan, indicating charge neutralization as the dominant mechanism for removal. Charge patch destabilization and bridging mechanisms were inferred in other cases, based on the effects of the apparent molecular weight of the chitosan preparations and effectiveness of sub-stoichiometric doses of chitosan. For dye solutions, results showed that color can be removed either by sorption onto solid-state chitosan or by coagulation-flocculation using dissolved-state chitosan; the reactivity of amine groups was significantly increased when dissolved chitosan was used. For humic materials, chitosan can be used as a primary coagulant or as a flocculant after coagulation with alum or other inexpensive coagulants. The influence of the degree of deacetylation and the molecular weight of chitosan on its performance as coagulant/flocculant is illustrated by several examples.
    Separation Science and Technology 08/2006; 41(11):2487-2514. · 1.16 Impact Factor
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    ABSTRACT: Ten chitosan preparations with different molecular weights (MW) and degrees of deacetylation (DD) were tested for coagulation of 5 g L(-1) bentonite suspensions at pH 5 and 7 in demineralized water (DW) and in tap water (TW). Coagulation was better in TW than in DW for every condition and lower doses of chitosan were required at pH 5 than at pH 7. More than 95% of residual turbidity (after sedimentation in the absence of chitosan) was removed using less than 0.10 mg L(-1) chitosan in either TW or DW at pH 5 or in TW at pH 7. Higher doses were required for removal of turbidity in DW at pH 7, but in all cases the effective concentrations of chitosan were much lower than required for complete neutralization of the negative charge on the bentonite particles. Removal of turbidity was best for the higher MW chitosans in either the B series (89.5% DD) or the C series (95% DD) of chitosans. Overall, the results were consistent with destabilization of bentonite by the combined mechanisms of electrostatic patch and bridging. The improved performance of chitosan in TW could have been due to improved attachment to bentonite due to the presence of sulfate and other counter-ions in TW.
    Water Research 10/2005; 39(14):3247-58. · 4.66 Impact Factor
  • E. Guibal, E. Touraud, J. Roussy
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    ABSTRACT: Chitosan is an amino-polysaccharide with highly efficient properties for the binding of metal ions and anionic dyes. Uptake may occur through chelation on free amino functions (at near-neutral pH) or by electrostatic attraction on protonated amino groups (in acidic solutions). The polymer is soluble in acidic solutions and its binding properties can be used in both solid form (sorption) and liquid form (ultrafiltration coupled with chelation, coagulation–flocculation). These properties have been used for the recovery of mercury from dilute solutions at initial pH 5 (which reveals the most efficient pH in the range pH 4–6) and for the recovery of Reactive Black 5 (RB5, anionic dye) at pH 3. While in the case of mercury binding saturation of the biopolymer is only slightly higher when chitosan is used in the liquid form compared to solid-state adsorption, in the case of the coagulation–flocculation of RB5 (using the liquid-form of chitosan) the saturation of the polymer (calculated on the basis of molar ratio of dye vs. amino groups of the polymer) is reached at a significantly greater value than when the polymer is used for the solid-state binding of the dye. There is a much more efficient use of amino groups when chitosan is used in the liquid-form due to a better availability of amino groups (less hydrogen bonds between the chains of the polymer) and to a better accessibility to internal sorption sites (lower diffusion control).
    World Journal of Microbiology and Biotechnology 09/2005; 21(6):913-920. · 1.35 Impact Factor
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    ABSTRACT: Several samples of chitosan with different degrees of deacetylation and of different molecular weights were tested for the coagulation–flocculation of organic suspensions. Organic suspensions were prepared by mixing mushroom powder with tap water. Experiments were carried out at pH 5, pH 7, and pH 9. Because decreasing the pH reduced the amount of chitosan required to reach the required turbidity, at pH 9, a high concentration of chitosan was required to achieve the required treatment levels, whereas the difference was less significant between pH 7 and pH 5 (the required concentration of chitosan was halved). Though viscosity, correlated to the molecular weight of chitosan, affected treatment performance, its influence on the efficiency of coagulation–flocculation could be substantially reduced by slightly increasing the concentration of the polymer. This is of importance in the processing of industrial effluents: the aging of a chitosan solution, which may cause partial depolymerization, and loss of viscosity, will have a limited impact on process efficiency. The degree of deacetylation also has a limited effect on treatment performance, especially when the degree of deacetylation exceeds 90%. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2070–2079, 2005
    Journal of Applied Polymer Science 09/2005; 98(5):2070 - 2079. · 1.40 Impact Factor
  • E. P. Kuncoro, J. Roussy, E. Guibal
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    ABSTRACT: Chitosan is an aminopolysaccharide that has been widely studied for metal ion recovery. In most cases it is used as a sorbent in solid form, but the polymer can also be used in a dissolved form in the so-called Polymer-Enhanced UltraFiltration (PELTF) process. The present work focuses on the use of dissolved chitosan for the removal of mercury from dilute solutions using an Amicon ultrafiltration unit. Recovery performance is compared to that obtained with poly(ethylenimine) (PEI), a synthetic amine-bearing polymer. The pH, metal concentration, and polymer concentration are the principal pararneters to be taken into account in evaluating the recovery process. The impact of these parameters was tested with respect to metal and polymer retention and the filtration flow rate. In the case of chitosan, the comparison of molar metal/amine group ratios at saturation of the polymer in its solid state (adsorption process) and dissolved state (PEUF process) shows that dissolving the polymer improves the accessibility of sorption sites and enhances the sorption capacity. Although the addition of chloride strongly decreased mercury retention, it hardly influenced PEUF performances when using PEI; this indicates a different binding mechanism or, at least, different contributions on the part of electrostatic attraction and chelating mechanisms at different pHs for these different polymers: linear polymer (chitosan) and branched polymer (PEI).
    Separation Science and Technology 01/2005; 40(1-3):659-684. · 1.16 Impact Factor
  • J. Roussy, M. Van Vooren, E. Guibal
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    ABSTRACT: Chitosan dissolved in acetic or hydrochloric acid was used for the coagulation and the flocculation of bentonite colloids. The influence of pH was investigated and the double effect of the biopolymer was identified. Experiments were performed at different polymer concentrations and at different pHs with simulated suspension (prepared with different amounts of bentonite). At pH 5 (acidic region), the protonation of amine groups led to coagulation effect and very low amounts of polymer were required to achieve a fast and efficient decantation of colloids; at pH close to neutral, a different mechanism was involved in the flocculating effect of the polymer chain (larger amounts of polymer were usually required). The effect of the characteristics of the polymer, i.e., degree of deacetylation, and polymer weight (related to polymer viscosity) was also investigated in order to optimize the selection of the biopolymer for targeted experimental concentrations.
    Journal of Dispersion Science and Technology 01/2004; 25(5):663-677. · 0.60 Impact Factor
  • Source
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    ABSTRACT: Photo-degradation and biodegradability have been studied for three different families of non-biodegradable textile dyes (Intracron reactive dyes, Direct dyes and Nylanthrene acid dyes) and a textile wastewater, using VUV photolysis. Ninety percent of color removal of dye solutions and wastewater is achieved within 7 min of irradiation. Biological oxygen demand (BOD) was found to increase during discoloration process while chemical oxygen demand (COD) decreased. The biodegradability index (BOD5/COD) increases up to 0.40 for most of the dye solutions when total discoloration is obtained. It implies that VUV photolysis tends to enhance the biodegradability of dye containing solutions. Thus, this technique could be used as a pre-treatment step for conventional biological wastewater treatment.
    Journal of Photochemistry and Photobiology A Chemistry 01/2002; · 2.42 Impact Factor
  • E. Guibal, C. Milot, J. Roussy
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    ABSTRACT: Molybdate sorption using chitosan sorbents has proved to be strictly controlled by the pH of the solution. Sorption isotherms exhibit a sigmoid trend, which has been correlated to the appearance of polynuclear hydrolyzed species, the most favorable species for sorption on chitosan. Sorption capacity exceeds 7 mmol.g(-1), which corresponds to a molar ratio between Mo and the amine group significantly higher than 1. The formation of complexes in a pendant fashion and/or the ion-exchange mechanism of polynuclear metal ions are suspected to occur between polynuclear molybdate species and protonated amine groups, though several amine groups can interact with the same polynuclear molybdate group.
    Separation Science and Technology 01/2000; 35(7):1021-1038. · 1.16 Impact Factor
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    ABSTRACT: There are many treatment schemes for industrial wastewater in existence. Generally, the choice of bioprocess is determined with respect to efficiency and ease of operation. This choice is obviously dependent on the possibility for the wastewater to be readily biodegradable. This consideration leads to the use of more adapted process based on chemical operations or even incineration. Starting from the need of non transferring techniques (without production of sludge), UV/H2O2 photooxidation has been studied for the treatment of several chemical process- and waste-water containing dissolved organic carbon concentrations in the range of 5 to 30 g.L-1 were studied. More precisely, the effect of simple steps such as pH adjustment or coagulation have been studied before application of Advanced Oxidation Process schemes. Depending on the initial organic matter concentration (e.g. DOC) conversions higher than 80% can be achieved. Keywords Advanced oxidation process; hydroxyl radicals; industrial wastewater treatment, UV/H2O2
    01/2000;
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    ABSTRACT: Chitosan is effective at removing molybdate from acidic solutions, especially when it is stabilized by crosslinking treatment. The influence of structural and physicochemical properties of chitosan and the glutaraldehyde crosslinking step on molybdate has been studied. This study shows that the maximum sorption capacity mainly depends on the crystallinity and degree of deacetylation. Hydration and accessibility to internal sites are controlled by these parameters, which may explain the intraparticle diffusion control on mass transfer. Chitosan gel beads can be used instead of flaked particles to decrease sorbent crystallinity. These sorbents were used in column systems, and the breakthrough curves obtained under several experimental conditions (flow velocity and column depth) were modelled using numerical analysis. Molybdate-impregnated chitosan beads (MICB) can be used for As(V) removal: sorption isotherms show high sorption levels even at low arsenic concentrations, and at pH 2-3, arsenic removal is optimal and molybdenum release is minimal. The desorption and regeneration of the sorbent was effective using phosphoric acid solutions. (C) 1999 Society of Chemical Industry.
    Polymer International 08/1999; 48(8):671-680. · 2.13 Impact Factor
  • Process Metallurgy 01/1999; 9:577-585.
  • Process Metallurgy 01/1999; 9:587-594.
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    ABSTRACT: A new adsorption process for As(V) ion removal from an aqueous solution was studied using molybdate-based chitosan gel beads. Arsenate ions were strongly absorbed in the pH range from 2.5 to 3.5 with a minimum release of molybdate ions. The sorption mechanism assumed here is a complexation between arsenate ions and molybdate ions. Even at low equilibrium concentration, the sorption capacity is high, and allows the process to the used as a polishing treatment. Phosphates ions significantly depress arsenate collection because of a competing reaction for the active sites. Simultaneously with the arsenate sorption, molybdenum is released to a significant extent (about 15–20%). However this molybdenum release can be reduced using an orthophosphoric pre-treatment of MICB, which allows the weakly bound molybdenum to be removed from the sorbent and therefore its release does not exceed 2%. A binding constant of 1.2 L mg−1 and a capacity constant of, 197.6 mgAs g−1 Mo were obtained, using the Langmuir model. A selective and total elution can be carried out using a 0.1 mol L−1 orthophosphoric acid solution. The spent sorbent can be re-used for further sorption of arsenate ions with the same performance. The process has been successfully carried out with real industrial effluents from Mining and Microelectronics.
    Process Metallurgy 01/1999; 9:277-287.
  • Eric Guibal, Céline Milot, Jean Roussy
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    ABSTRACT: Chitosan, a biopolymer extracted from crustacean shells, exhibits high sorption capacities for metal ion recovery. Sorption efficiency and removal rates are controlled by several diffusion mechanisms. Chitosan gel beads have been prepared and have shown enhanced sorption performance in batch systems. This study shows that, in continuous systems, sorption capacities can reach 700 mg/g, a level close to that obtained in batch studies. The effects of metal concentration, flow velocity, and column size are investigated and demonstrate that, because of diffusion mechanisms, the optimum concentration range is approximately 50 to 100 mg/L. In column systems, the Biot number, though greater than 1, is lower than the Biot number obtained in batch systems, indicating that external mass transfer influences mass transfer at the low superficial velocity investigated in this work (0.5 to 2 m/h).
    Water Environment Research 12/1998; 71(1):10-17. · 1.13 Impact Factor