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A comparative study of the degradation of Direct Red 23 (DR23) dye aqueous solutions by electrooxidation was investigated using different anodes: carbon graphite (CG), dimensionally stable anode (D...

The mineralization of tetracycline by electrochemical advanced oxidation processes (EAOPs) as well as the study of the toxicity of its intermediates and degradation products are presented. Electro-Fenton (EF), anodic oxidation (AO), and electro-Fenton coupled with anodic oxidation (EF/AO) were used to degrade tetracycline on carbon felt (cathode) and a sub-stoichiometric titanium oxide (Ti4O7) layer deposited on Ti (anode). As compared to EF and AO, the coupled EF/AO system resulted in the highest pollutant removal efficiencies: total organic carbon removal was 69 ± 1% and 68 ± 1%, at 20 ppm and 50 ppm of initial concentration of tetracycline, respectively. The effect of electrolysis current on removal efficiency, mineralization current efficiency, energy consumption, and solution toxicity of tetracycline mineralization were investigated for 20 ppm and 50 ppm tetracycline. The EF/AO process using a Ti4O7 anode and CF cathode provides low energy and high removal efficiency of tetracycline caused by the production of hydroxyl radicals both at the surface of the non-active Ti4O7 electrode and in solution by the electro-Fenton process at the cathodic carbon felt. Complete removal of tetracycline was observed from HPLC data after 30 min at optimized conditions of 120 mA and 210 mA for 20 ppm and 50 ppm tetracycline concentrations. Degradation products were elucidated, and the toxicity of the products were measured with luminescence using Microtox® bacteria toxicity test.

International audience; Sub-stoichiometric titanium oxide (TiOx) reactive electrochemical membrane (REM) were integrated for the first time as anode in the electro-Fenton (EF) process. Hydroxyl radicals (•OH) were produced both in the retentate from Fenton's reaction and at the REM from anodic oxidation (AO). Optimal mass transport conditions were implemented because of convection-enhanced mass transport of (i) organic pollutants towards the REM surface during filtration and (ii) dissolved 02 towards cathode active sites owing to the use of a 3D carbon felt cathode in flow-through configuration for H202 generation. The efficiency of the REM/EF process was much higher than EF or REM used as standalone processes. For instance, taking paracetamol as target pollutant, (67 ± 2)% removal of 55 mg L - i of initial TOC was achieved with a high mineralization current efficiency (MCE) of ( 43 ± 1)%. By comparison, standalone REM and EF processes achieved only 47% (MCE = 30%) and 31 % (MCE = 20%) of TOC removal, respectively. By monitoring TOC removal both in retentate and permeate, the effect of homogeneous oxidation in the bulk retentate and heterogeneous oxidation at the REM could be observed separately. It was thus highlighted that the efficiency of AO might be affected by the presence of • OH and Fe2 + in the bulk. It was also emphasized a synergistic effect related to the formation of carboxylic acids in the bulk retentate that are more easily mineralized at the REM where both • OH-mediated oxidation and direct electron transfer occur.

Electro-oxidation of acetaminophen (ACT) in three different doped secondary effluents collected from a conventional Municipal Waste Water Treatment Plant (MWWTP), a MWWTP using a membrane bioreactor (WWTP MBR) and a lab-scale MBR treating source-separated urine (Urine MBR) was investigated by electro-Fenton (EF) coupled with anodic oxidation (AO) using sub-stoichiometric titanium oxide anode (Ti4O7). After 8 h of treatment, 90 ± 15%, 76 ± 3.8% and 46 ± 1.3% of total organic carbon removal was obtained for MWWTP, MWWTP-MBR and Urine-MBR respectively, at a current intensity of 250 mA, pH of 3 and [Fe2+] = 0.2 mM. Faster degradation of ACT was observed in the WWTP MBR because of the lower amount of competitive organic matter, however, >99% degradation of ACT was obtained after 20 min for all effluents. The acute toxicity of the treated effluent was measured using Microtox® tests. Results showed an initial increase in toxicity, which could be assigned to formation of more toxic by-products than parent compounds. From 3D excitation and emission matrix fluorescence (3DEEM), different reactivity was observed according to the nature of the organic matter. Particularly, an increase of low molecular weight organic compounds fluorescence was observed during Urine MBR treatment. This could be linked to the slow decrease of the acute toxicity during Urine MBR treatment and ascribed to the formation and recalcitrance of toxic organic nitrogen and chlorinated organic by-products. By comparison, the acute toxicity of other effluents decreased much more rapidly. Finally, energy consumption was calculated according to the objective to achieve (degradation, absence of toxicity, mineralization).

International audience; Photocatalytic water splitting into hydrogen is considered as one of the key solutions to the current demand for eco-responsible energy. To improve the efficiency and sustainability of this process, the development of a TiO2-based photoanode by adding bio-sourced surfactants to the sol–gel preparation method has been considered. Three different polymeric biosurfactants (GB, GC, and BIO) have been tested, giving rise to three different materials being structurally and morphologically characterized by XRD, Rietveld refinement, BET, SEM, AFM, and XPS, which was completed by light absorption, photocatalytic (Pilkington test), electronic (EIS and C-AFM), and photoelectrochemical (cyclic voltammetry) measurements. Correlations between the structure/morphology of materials and their functional properties have been established. One specific surfactant has been proven as the most suitable to lead to materials with optimized photoelectrochemical performance in direct relation with their photocatalytic properties essentially controlled by their specific surface area.

The presence of pharmaceuticals in water bodies has become a major concern in recent years. An efficient and innovative way of eliminating these pollutants is through photoelectrocatalytic (PEC) degradation owing to its environmental sustainability and its ability to remove recalcitrant pollutants. In this study, palladium loaded zinc oxide/carbon nanofibers (CZnO–Pd) were employed as a novel photoanode for PEC degradation of paracetamol. The CZnO–Pd composite was prepared through electrospinning and atomic layer deposition (ALD). The obtained materials were characterized. Photoelectrochemical studies were carried out with linear sweep voltammetry and chronoamperometry. The removal efficiency was recorded using high-performance liquid chromatography coupled to a mass spectrometer detector (HPLC-MS), while the mineralization was assessed through total organic carbon (TOC) removal. The composite electrode of CZnO–Pd nanofiber showed higher photoelectrochemical activity than ZnO carbon nanofiber, which was evident in the higher photocurrent response recorded. Upon application of the material in photoelectrocatalysis, the total removal of paracetamol was achieved within 3 h with an applied current density of 10 mAcm−2. The percentage of TOC removal was 71.20 ± 0.31% after 4 h, which indicated significant mineralization. The results obtained in the present work reveal that Pd–ZnO/C has great potential for photoelectrocatalytic removal of organic micropollutants.

This study evaluated the feasibility of the electrooxidation process using a sub-stoichiometric titanium oxides (TiOX) reactive electrochemical membrane (REM) as anode for the treatment of a secondary effluent from a wastewater treatment plant. The main objectives were to analyze (i) the degradation of a pharmaceutical pollutant, carbamazepine, added at a concentration of 100 µg L−1, (ii) the mineralization of the residual total organic carbon (TOC = 7 mg L−1), (iii) the formation of toxic by-products and (iv) the energy consumption of the REM process. Two main operating parameters were tested: the current density applied to the REM (74, 149 and 290 A m−2) and the flux of TOC passing through the membrane. The results revealed that the efficiency of the process was maintained above 70% of mineralization and >98% of degradation of carbamazepine until a limiting value of TOC flux was reached. The higher the current density, the higher the limiting value of the TOC flux above which the efficiency decreased. This trend was ascribed to the limitation from the amount of reactive species produced on the REM surface (current limitation instead of mass transport limitation at lower TOC flux). As the energy efficiency strongly increased when applying a higher TOC flux, it is therefore crucial to apply the process around this threshold value. This study also showed that it is possible to control the formation of toxic chlorine-containing by-products (ClO3−, ClO4−, AOCl) by decreasing the current density. This issue is particularly important for such effluents containing a significant amount of Cl− ions. By taking into consideration both advantages and drawbacks, optimal results were obtained with the lowest current density of 73 A m−2 and a TOC flux through the membrane of 4.41 g h−1 m−2 corresponding to 1.34 m3 h−1 m−2. These conditions allowed for >98% degradation of carbamazepine and 70% of mineralization with an energy consumption of 0.15 kWh g−1 of TOC removed (i.e. 0.74 kWh m−3 of treated wastewater).

International audience

The objective of this study was to implement electrochemical advanced oxidation processes (EAOPs) for mineralization and biodegradability enhancement of nanofiltration (NF) concentrate from landfill leachate initially pre-treated in a membrane bioreactor (MBR). Raw carbon felt (CF) or Fe II Fe III layered double hydroxides-modified CF were used for comparing the efficiency of homogeneous and heterogeneous electro-Fenton (EF), respectively. The highest mineralization rate was obtained by heterogeneous EF: 96% removal of dissolved organic carbon (DOC) was achieved after 8 h of electrolysis at circumneutral initial pH (pH 0 = 7.9) and at 8.3 mA cm −2 . However, the most efficient treatment strategy appeared to be heterogeneous EF at 4.2 mA cm −2 combined with anodic oxidation using Ti 4 O 7 anode (energy consumption = 0.11 kWh g −1 of DOC removed). Respirometric analyses under similar conditions than in the real MBR emphasized the possibility to recirculate the NF retentate towards the MBR after partial mineralization by EAOPs in order to remove the residual biodegradable by-products and improve the global cost effectiveness of the process. Further analyses were also performed in order to better understand the fate of organic and inorganic species during the treatment, including acute toxicity tests (Microtox ® ), characterization of dissolved organic matter by three-dimensional fluorescence spectroscopy, evolution of inorganic ions (ClO 3 − , NH 4 + and NO 3 − ) and identification/quantification of degradation by-products such as carboxylic acids. The obtained results emphasized the interdependence between the MBR process and EAOPs in a combined treatment strategy. Improving the retention in the MBR of colloidal proteins would improve the effectiveness of EAOPs because such compounds were identified as the most refractory. Enhanced nitrification would be also required in the MBR because of the release of NH 4 + from mineralization of refractory organic nitrogen during EAOPs.

M-doped TiO2 and mixed oxides MxOy–TiO2 (M = V, Bi, W) were synthesized by the reactive mineralization of ash-free filter paper under anhydrous conditions. Mixtures of metal chlorides (TiCl4 with VOCl3, WCl6, or BiCl3) were reacted directly with cellulose, and three different Ti/M atomic ratios were used (99, 19, and 9). The resulting materials consist of original nanoflower assemblies of needle-shaped primary particles. Their physicochemical characteristics were investigated by various techniques (X-ray diffraction, diffuse-reflectance UV/Vis spectroscopy, electron microscopy, and elemental analysis). The incorporation of the doping metal or the formation of mixture of oxides with TiO2 (WO3, Bi2O3) depends on the metal and the proportions used. The photocatalytic activities of the materials were tested for the degradation of phenol. The vanadium-doped materials exhibit true solid-solution formation and their band gaps shift into the visible range.

International audience; A cathodic electro-Fenton (EF) process consisting of thermally treated carbon felt and anodic photoelectrochemical (PEC) oxidation process consisting of bismuth vanadate – bismuth oxyiodide electrodeposited on fluorine doped tin oxide glass (FTO-BiVO4/BiOI) were coupled into a single electrochemical advanced oxidation system for the mineralisation of paracetamol. EF degradation of paracetamol yielded 71 % total organic carbon (TOC) removal after 4 h with a current density of 20 mA cm−2. With the coupled EF/PEC system, the complete removal of paracetamol was achieved within 2 h and a higher mineralisation of 92 % TOC removal after 4 h was recorded with a 10 mA cm−2 current density. The specific energy consumption of the EF/PEC process was about 64 % lower than the energy consumption of EF process alone. The treated aqueous solution exhibited reduced toxicity in comparison with the untreated solution with about 1% inhibition of Vibrio fisheri. This EF/PEC system showed a synergic improvement in performance over EF and PEC.

International audience; Reactive Electrochemical Membrane (REM) prepared from carbothermal reduction of TiO2 is used for the mineralization of biorefractory pollutants during filtration operation. The mixture of Ti4O7 and Ti5O9 Magnéli phases ensures the high reactivity of the membrane for organic compound oxidation through •OH mediated oxidation and direct electron transfer. In cross-flow filtration mode, convection-enhanced mass transport of pollutants can be achieved from the high membrane permeability (3300 LMH bar-1). Mineralization efficiency of oxalic acid, paracetamol and phenol was assessed as regards to current density, transmembrane pressure and feed concentration. Unprecedented high removal rates of total organic carbon and mineralization current efficiency were achieved after a single passage through the REM, e.g. 47 g m-2 h-1 - 72% and 6.7 g m-2 h-1 - 47% for oxalic acid and paracetamol, respectively, at 15 mA cm-2. However, two mechanisms have to be considered for optimization of the process. When the TOC flux is too high with respect to the current density, aromatic compounds polymerize in the REM layer where only direct electron transfer occurs. This phenomenon decreases the oxidation efficiency and/or increases REM fouling. Besides, O2 bubbles sweeping at high permeate flux promotes O2 gas generation, with adverse effect on oxidation efficiency.

Reactive Electrochemical Membrane (REM) prepared from carbothermal reduction of TiO

International audience; Metal hollow fibre membranes offer excellent chemical and mechanical stability and are promising platforms for the removal of harsh contaminants from solutions. Stainless steel (SS) membranes are however prone to oxidation and advanced decoration routes are required to passivate the surface of such materials. Here, SS membranes were modified with nanoscale coatings of graphene to promote electrochemical reactions and prevent premature corrosion of the bare metal reinforcement upon electro-Fenton (EF) reaction. Samples decorated with graphene oxide or reduced graphene oxide were compared to bare SS membranes to assess the impact of graphitization on the electrochemical performance of the membranes. Membranes properties were characterized using both cyclic and linear scanning voltammetry. The results evidenced that electron transfer kinetics were significantly enhanced on the reduced graphene oxide, compared to raw material. In addition, the removal efficiency of a pharmaceutical pollutant, paracetamol, was evaluated in electro-Fenton batch experiments, on the three membrane electrodes. The best mineralization current efficiency at 37% was found when using reduced graphene oxide membrane cathode at optimal applied potential of -0.5 V vs. SCE (Saturated Calomel Electrode). Finally, the coupling of electro-Fenton and filtration processes was carried out on a pilot-scale unit. Various electrochemical and hydrodynamic parameters that affect mineralization efficiency were studied. By coupling filtration and electrochemical processes, the mineralization current efficiency value was increased remarkably by 165% and remained stable for three consecutive cycles. This strategy opens up opportunities to generate low cost catalytic membrane reactors with high flux and selectivity from the materials reactivity as opposed to sieving, with potential for harsh chemicals mineralization.

In this study, the role of mixing hydrodynamics during the sol–gel synthesis of titania nanoparticles and the consequences on their photocatalytic properties were investigated. For the first time three different T-mixer geometries were tested. Alcoholic solutions of titanium tetra-isopropoxide and water were mixed in three different T-mixers with turbulence promoters and thus different mixing characteristics. The changes of nanoparticle sizes during the induction time of the sol–gel process were followed by dynamic light scattering and velocity and turbulence fields were simulated by Computational Fluid Dynamics (CFD) for the three T-mixer geometries. The results indicated that macro-mixing is crucial during the first step as it determines the nucleation rate and then the primary particle size. The micro-mixing has an influence on particle properties, especially on particle stability. Titanium dioxide nanoparticles synthesized by the sol–gel process were deposited on alumina supports. A homogeneous film of about 200 nm was deposited in all cases. Degradation of Acid Orange 7 (AO7) was used to evaluate the photocatalytic activity of TiO2 coatings. No difference was observed between the photoactivity of synthesized TiO2. Total mineralization of the dye occurred after 24 h irradiation.

This work evidences the interest of coupling advanced oxidation process (Electro-Fenton reaction) to dynamic filtration technology, using a tubular electrochemically reactive carbon graphite membrane, acting as cathode. This original coupling would be ideally adapted to confine organic pollution while achieving the complete degradation of refractory molecules from wastewater (domestic or industrial). The investigation was carried out using Acid Orange 7 (AO7) as a model pollutant. The electrochemical behavior of the membrane was firstly characterized in batch reactor in term of cathodic reactivity, for H2O2 selective production (in situ production from air supply followed by catalyzed ●OH generation). The influence of various parameters was studied to mark out the experimental domain to be investigated in a dynamic cross-flow reactor for AO7 degradation. In the latter case, a 23 full factorial design of experiments was used to screen the effect of operating conditions on two target responses: AO7 degradation efficiency (%) and kinetic constant value. Results showed that interactions effects between pH, current density and catalyst concentration influenced the AO7 degradation efficiency significantly. Moreover, better kinetic performances were obtained under dynamic filtration conditions, compared to a batch reactor. HPLC–MS analyses enabled elucidating at least six by-products formed throughout the process.

Metal oxides and metal oxide/carbon composites are entering the development of new technologies and should therefore to be prepared by sustainable chemistry processes. Therefore, a new aspect of the reactivity of cellulose is presented through its solid/gas reaction with vapour of titanium(IV) chloride in anhydrous conditions at low temperature (80 °C). This reaction leads to two transformations both for cellulose and titanium(IV) chloride. A reductive dehydration of cellulose is seen at the lowest temperature ever reported and results in the formation of a carbonaceous fibrous solid as the only carbon-containing product. Simultaneously, the in situ generation of water leads to the formation of titanium dioxide with an unexpected nanoplate morphology (ca. 50 nm thickness) and a high photocatalytic activity. We present the evidence showing the evolution of the cellulose and the TiO

International audience; M-​doped TiO2 and mixed oxides MxOy-​TiO2 (M = V, Bi, W) were synthesized by the reactive mineralization of ash-​free filter paper under anhyd. conditions. Mixts. of metal chlorides (TiCl4 with VOCl3, WCl6, or BiCl3) were reacted directly with cellulose, and three different Ti​/M at. ratios were used (99, 19, and 9)​. The resulting materials consist of original nanoflower assemblies of needle-​shaped primary particles. Their physicochem. characteristics were investigated by various techniques (x-​ray diffraction, diffuse-​reflectance UV​/visible spectroscopy, electron microscopy, and elemental anal.)​. The incorporation of the doping metal or the formation of mixt. of oxides with TiO2 (WO3, Bi2O3) depends on the metal and the proportions used. The photocatalytic activities of the materials were tested for the degrdn. of phenol. The vanadium-​doped materials exhibit true solid-​soln. formation and their band gaps shift into the visible range.

The bactericidal activity of an Al 2 O 3 -TiO 2 -Ag granular material against an Escherichia coli strain was confirmed by a culture-based method. In particular, 100% of microorganisms were permanently inactivated in 30 to 45 min. The present work aimed to investigate the mechanisms of the bactericidal action of this material and their dynamics on Escherichia coli using different techniques. Observations by transmission electron microscopy (TEM) at different times of disinfection revealed morphological changes in the bacteria as soon as they were put in contact with the material. Notably highlighted were cell membrane damage; cytoplasm detachment; formation of vacuoles, possibly due to DNA condensation, in association with regions exhibiting different levels of electron density; and membrane lysis. PCR and flow cytometry analyses were used to confirm and quantify the observations of cell integrity. The direct exposure of cells to silver, combined with the oxidative stress induced by the reactive oxygen species (ROS) generated, was identified to be responsible for these morphological alterations. From the first 5 min of treatment with the Al 2 O 3 -TiO 2 -Ag material, 98% of E. coli isolates were lysed. From 30 min, cell viability decreased to reach total inactivation, although approximately 1% of permeable E. coli cells and 1% of intact cells (10 5 genomic units · ml −1 ) were evidenced. This study demonstrates that the bactericidal effect of the material results from a synergic action of desorbed and supported silver. Supported silver was shown to generate the ROS evidenced.

The present paper reports the elaboration of porous ceramic membranes from natural and local Cameroonian clay (Wak village). This material has been chosen due to its natural abundance, its non-toxicity and low cost and its valuable properties. In a first stage, we developed and characterized low cost mineral membranes for microfiltration application to produce clear water from high turbidity water. Our second objective is to deposit ultrafiltration and nanofiltration layers on the macroporous clay membranes to achieve high quality and potentially drinkable water. Flat porous ceramic membranes were then prepared by axial-pressing of a plastic paste composed of natural clay and sawdust, largely abundant materials in Cameroon recovered from local industries. After drying at room temperature for 24 h, the obtained green membranes were submitted to a thermal treatment at 1100 °C to ensure consolidation and pores formation. After this treatment, the membranes showed an average porosity of 42% and an average withdrawal of 35%. In addition, clay membranes presented a better chemical resistance in acidic medium than in basic medium. The elaborated membranes were used to clarify aqueous suspensions of clay powder at concentrations of 2 g/L and 1 g/L. Dead-end filtrations of these aqueous suspensions containing suspended matter lead to the removal of feed turbidity up to 97%.

We present a concept of the sol–gel reactor with injection of stock solutions through a T mixer, environmental gas control, thermal control of the reactive medium and in–situ particle size measurement using a monomode optical fibre probe. The rapid injection of the whole amount of reagents leads to short time of nucleation, and the micro-mixer eliminates gradients of concentrations, which results in higher local nucleation and aggregation rates. The reactor is used for production of mono-disperse nanometric titanium oxide sols. With this reactor, induction kinetics are reproducible and agree with a model describing the mean particle size increase by a slow aggregation process. As well as the in–situ size measurement technique, the reactor is a kinetic tool for determination of the sol aggregation rate. As the rules for scale-up of its equipment are already established, it is of interest for the operation and the design of industrial-scale sol–gel reactors.

We report on observations of the temperature dependence ( T = 5–40 °C) of the titanium oxide sols precipitation kinetics in the sol–gel process using Ti(OPr i ) 4 as a metal organic precursor. The nanometric sol particles are produced in the sol–gel reactor with rapid reagent mixing and temperature and atmosphere control. Precipitation kinetics was followed in situ by the light scattering method using an optical fibre probe. From these measurements the activation energy E a = 0.33 ± 0.02 eV has been obtained and assigned to the secondary hydrolysis–condensation reactions between surface Ti–OPr i groups. Careful analysis of experimental data allows concluding about a decrease of the fractal dimension D f of the precipitate with an increase of the temperature, which provides D f = 1 at 35 °C.

The behavior of TiO 2 /Al 2 O 3 composite membranes under different pH conditions was investigated. Filtration and photodegradation were coupled by using these TiO 2 /Al 2 O 3 membranes in a photocatalytic membrane reactor under UV light. Membrane performances were first evaluated by measuring water flux and then by measuring permeate flux and degradation rate during filtration of a model molecule Acid Orange 7 (AO7). Experimental results clearly showed that water permeability of alumina and TiO 2 /Al 2 O 3 composite membranes is influenced by pH conditions. Nonetheless, flux variation with pH is less pronounced for TiO 2 /Al 2 O 3 composite membranes. In addition, UV light enables a stabilization of flux because of hydrophilic properties of TiO 2 . For both membranes, higher permeate flux were obtained at the isoelectric point. It appeared that surface of composite membrane is photoreactive and permits to mitigate membrane fouling with an efficiency which depends on pH of the solution. Initial degradation rate of AO7 also depends on pH as it influences not only the surface properties of TiO 2 but also the dissociation of AO7 and the formation of hydroxyl radicals. Higher initial degradation rate was observed under acidic conditions (pH = 4).

TiO2/Al2O3 composite membranes were prepared using a sol–gel technique. After membrane characterization, six layers as optimal number of coatings was chosen (0.2 μm homogenous thin film). Filtration and photodegradation were coupled by using TiO2/Al2O3 membranes in a photocatalytic membrane reactor under UV light. Experimental results clearly showed that TiO2 thin film under UV irradiation enhanced the wettability of the ceramic membrane, were higher and more stable water flux were reached rapidly. Acid Orange 7 (AO7) were used as model pollutant. Dye was not completely degraded, 25% of degradation was obtained for only one pass corresponding to a contact time of several milliseconds. Photonic efficiency equal to 0.29 was reached. Evolution of the kinetic degradation versus the initial concentration of AO7 were consistent with the Langmuir Hinselwood model. The photodegradation allows to increase significantly composite membrane flux and to strongly prevent flux decrease when AO7 solutions were filtrated. Membrane cleaning was performed without chemicals by irradiating membrane surface under static conditions.

A new kind of metal affinity membrane based on a ceramic support was prepared. It was elaborated in four steps: (i) deposition of a chitosan layer in order to functionalize the ceramic support, (ii) cross-linking with epichlorohydrin to stabilise the polymer layer and to enable the grafting, (iii) iminodiacetic acid grafting, (iv) Cu2+ adsorption. Due to the ceramic support, this membrane is highly resistant and the chitosan layer brings its biocompatibility properties. Each step of the membrane elaboration was studied and the membrane structure was characterized. Both thin coating of the polymer on the alumina grains of the support and the chemical modification of the membrane were proved. Then, bovine serum albumin (BSA) was used as a model protein to test protein retention of the affinity membrane. The protein/membrane interactions were investigated showing that some non-specific ones are involved. Finally, the effect of buffer concentration was checked and it appears that, in the studied range, an increase of the buffer concentration entailed a limitation of the non-specific interactions inducing a better BSA recovering and a higher selectivity.

International audience

National audience; Les matériaux à base d’argent supporté sont une alternative intéressante aux désinfectants chimiquesclassiques car ils permettent une forte activité bactéricide (par action de l’argent) tout en limitant ladésorption d’argent dans l’eau mais aussi la demande en produits chimiques [1-3]. Dans ce contexte,un nouveau matériau Al2O3-TiO2-Ag a été développé pour la désinfection des eaux de spa ; la couchede TiO2 permettant de réduire le relargage en argent [3].De premières études ont démontré l’activité bactéricide de ce matériau en réacteur fermé [3] et ontmis en évidence un mécanisme d’action impliquant aussi bien l’argent supporté que l’argent désorbé[4].Dans ce travail, ce nouveau matériau a été mis en oeuvre dans un réacteur tubulaire continu. Uneapproche systémique, basée sur un plan composite centré, a recherché les effets combinés du débitd’eau à traiter, de la concentration en matériau et de la concentration en sels sur les performancesantibactériennes à 37°C (température des eaux de spa). Des bactéries à Gram négatif (Escherichiacoli) et Gram positif (Staphylococcus epidermidis) ont été utilisées comme modèles de lacontamination microbienne et la désorption en argent a aussi été mesurée. Cette étude multiparamétriquea mis en évidence l’action majoritaire de l’argent supporté, en comparaison à celle del’argent désorbé, ce qui a été confirmé par des expériences en circuit ouvert. De plus, un modèleprédictif ciblant les performances de désinfection a pu être proposé et validé expérimentalement, cequi a permis de déterminer les conditions opératoires optimales du procédé.Références:[1]. Matsumura Y, Yoshikata K, KunisakiS, Tsuchido T. Mode of bactericidal action of silverzeolite anditscomparisonwiththat of silver nitrate. Appliedand EnvironmentalMicrobiology 2003, 69:4278-7281.[2].De la Rosa-Gomez I, OlguínMT, Alcántara D.Bactericides ofcoliformmicroorganismsfromwastewaterusingsilver-clionptiloliterichtuffs. Clay Science 2008, 40:45-53.[3].Tartanson MA, Soussan L, Rivallin M, Chis C, Penaranda D, Lapergue R, CalmelsP, Faur C. A newsilverbased composite material for spa water disinfection. Water Research 2014, 63:135-146.[4].Tartanson MA,Soussan L, Rivallin M, Pecastaings S, Chis C, Roques C, Faur C.Dynamicmechanisms of thebactericidal action of an Al2O3-TiO2-Ag granularmaterial on an Escherichia colistrain. Applied andEnvironmentalMicrobiology 2015, 81(20):7135-7142.