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The use of a photo-electrochemical cell (PEC) to produce hydrogen from wastewater is a promising innovation. In this context, this study investigates the impact of a pollutant on the photo-electrochemical properties of sol-gel synthesized TiO 2 and TiO 2 –Co 3 O 4 thin films for hydrogen production in a polluted electrolyte. Combining the photocatalytic properties of TiO 2 with the electronic properties of Co 3 O 4 offers an effective solution for achieving effective photo-electrochemical properties in polluted environments. Nevertheless, despite the lowest photocatalytic activity, the hybrid thin film TiO 2 –Co 3 O 4 with the highest Ti/Co ratio (1:0.5) shows the most promising performance with simultaneous 11.4 μmol cm−2 h−1 H 2 production and 12% acid orange 7 degradation after 3 h irradiation under xenon light without the use of any sacrificial agent. This indicates that the electronic conductivity provided by the presence of Co 3 O 4 is a critical property for achieving optimal performance in PEC coupling for hydrogen production and wastewater treatment. [Display omitted] • Sol-gel TiO 2 –Co 3 O 4 films enabled coupling of water splitting and remediation. • 11 μmol cm−2 h−1 H 2 was produced after 3h Xe irradiation without sacrificial agent. • Simultaneous 12% acid orange 7 degradation was measured. [ABSTRACT FROM AUTHOR]

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 TiO2 nanostructure formation, along with its photocatalytic activity. This low-temperature process avoids any other reagents and is among the greenest processes for the preparation of anatase and also for TiO2/carbon composites. The anisotropic morphology of TiO2 questions the role of the cellulose on the growing process of these nanoparticles. [ABSTRACT FROM AUTHOR]

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 H 2 O 2 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 2 3 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. [ABSTRACT FROM AUTHOR]

M-doped TiO2 and mixed oxides M xO y-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. [ABSTRACT FROM AUTHOR]

• TiO x REM was used for the first time as anode in EF process. • OH were generated in retentate and at REM with optimal mass transport conditions. • The efficiency of REM/EF integrated process far exceeded that of standalone processes. • High mineralization current efficiency (77%) was obtained with REM/EF process. • Synergy was observed from degradation in the bulk and mineralization at the TiO x REM. Sub-stoichiometric titanium oxide (TiO x) 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 O 2 towards cathode active sites owing to the use of a 3D carbon felt cathode in flow-through configuration for H 2 O 2 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−1 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. [ABSTRACT FROM AUTHOR]

The development of new photoanode materials for hydrogen production and water treatment is in full progress. In this context, hybrid TiO2-Co3O4/Co(OH)2 photoanodes prepared using the sol–gel method using biosurfactants are currently being developed by our group. The combination of TiO2 with a cobalt-based compound significantly enhances the visible absorption and electrochemical performance of thin films, which is mainly due to an increase in the specific surface area and a decrease in the charge transfer resistance on the surface of the thin films. The formation of these composites allows for a 30-fold increase in the current density when compared to cobalt-free materials, with the best TiO2-CoN0.5 sample achieving a current of 1.570 mA.cm−2 and a theoretical H2 production rate of 0.3 µmol.min−1.cm−2 under xenon illumination. [ABSTRACT FROM AUTHOR]

The bactericidal activity of an Al2O3-TiO2-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 Al2O3-TiO2-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 (105 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. [ABSTRACT FROM AUTHOR]

The bactericidal activity of an Al2O3-TiO2-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 Al2O3-TiO2-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 (105 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. [ABSTRACT FROM AUTHOR]

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 (DSA), Magnéli phase Ti4O7, and boron-doped diamond (BDD). Stainless steel (SS) and CG plates were tested as cathodes. The effect of operating parameters on the degradation kinetics of the dye was studied. In this study, NaCl and Na2SO4 were selected as supporting electrolytes; the former was found to be more suitable for the degradation of DR23. The degradation of the dye follows a pseudo-first-order kinetics in both media. Higher total organic carbon (TOC) efficiency was achieved by BDD/CG cells. Thus, the treatment efficiency obtained using a current density of 5 mA cm−2, and DR23 concentration of 60 mg L−1 was about 86% using both NaCl and Na2SO4 electrolyte, at 6 h electrolysis time. The energy consumptions per g TOC removed were found to be 2.05 and 2.6 kWh g−1 TOC in NaCl and Na2SO4 electrolytes, respectively. [ABSTRACT FROM AUTHOR]

Three different graphite powders with different particles sizes were tested to synthesize tubular monochannel carbon supports for micro and ultrafiltration membranes using a new process. Carbon graphite powders and organic additives were mixed with an ethanolic solution of Resol® type phenolic resin. The extruded tubes were firstly consolidated by curing the resin at 150°C then carbonized under nitrogen stream (1mLmin−1) for graphitization and pores opening. Supports with optimal properties were obtained using a mixture of Resol® resin and a 44µm particle size graphite powder, carbonized at 1000°C. They showed a porosity value of 37%, an average pore size diameter of 3µm, high mechanical and chemical resistances and an average conductivity of 190Ω−1 cm−1. The Raman spectroscopy results show that graphitization degree of the material is closely related to the carbonization temperature, which explains the increase of conductivity with temperature. Acid Orange 7 (AO7), a common dye, was finally used as a model molecule to demonstrate the ability of the graphitic membranes to mineralize organic pollutants by electro-Fenton process. Spectrophotometric measurements were conducted on the treated solutions as a function of chemical and electrochemical conditions to determine the degradation kinetic of AO7. Decolorization rate was also measured as a function of time. [ABSTRACT FROM AUTHOR]

Highlights: [•] Performances of TiO2/Al2O3 membranes under different pH conditions were investigated. [•] pH significantly influences water flux performances. [•] Higher flux were obtained at point of zero charge of membranes. [•] A dye solution was used to evaluate the efficiency of photocatalytic membranes. [•] pH of the solution strongly influences initial degradation rate of Acid Orange 7. [Copyright &y& Elsevier]

Highlights: [•] Composite TiO2/Al2O3 membranes were successfully elaborated. [•] They were used in a photocatalytic membrane reactor. [•] TiO2 layer significantly enhances ceramic membrane wettability. [•] A dye solution was used to evaluate the efficiency of photocatalytic membranes. [•] Higher and stable flux were obtained during dye filtration under UV light with composite membranes. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

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 FeIIFeIII 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. Image 1 • NF concentrate of landfill leachate pre-treated in a membrane bioreactor was treated. • Ti 4 O 7 anode and FeII/FeIII LDH-CF cathode was used for the first time for a real effluent. • 96% removal of dissolved organic carbon was achieved by heterogeneous electro-Fenton. • Optimal conditions for biodegradability enhancement were identified. • Optimal conditions for minimization of toxic by-products were identified. [ABSTRACT FROM AUTHOR]

Reactive Electrochemical Membrane (REM) prepared from carbothermal reduction of TiO 2 is used for the mineralization of biorefractory pollutants during filtration operation. The mixture of Ti 4 O 7 and Ti 5 O 9 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, O 2 bubbles sweeping at high permeate flux promotes O 2 gas generation, with adverse effect on oxidation efficiency. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

• Treatment of a WWTP secondary effluent spiked with 100 µg L−1 of carbamazepine. • >98% degradation of carbamazepine and 70% mineralization of organics can be achieved. • Formation of toxic chlorine by-products can be controlled by current density. • Optimal operating conditions resulted in low energy consumption. This study evaluated the feasibility of the electrooxidation process using a sub-stoichiometric titanium oxides (TiO X) 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 (ClO 3 −, ClO 4 −, 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). [ABSTRACT FROM AUTHOR]

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 (Ti 4 O 7). 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). Unlabelled Image • Biorefractory effluents were successfully treated by EF process coupled to AO. • 3DEEM could be a global tool to investigate a domestic effluent along its treatment. • ACT, TOC, acute toxicity and 3DEEM evolution were monitored for different effluents. • Toxic recalcitrant by-products were identified during Urine MBR effluents treatment. [ABSTRACT FROM AUTHOR]

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. Image 1 • The impact of graphitization on the removal efficiency of paracetamol was evaluated in electro-Fenton batch experiments. • The best mineralization current efficiency was found at 37% when using reduced graphene oxide membrane cathode. • By coupling filtration and electrochemical processes, the mineralization current efficiency value was increased remarkably. [ABSTRACT FROM AUTHOR]