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Applied Catalysis B, Environmental (v.104, #3-4)

Editorial Board (pp. co2).

Editorial Board (pp. i).

Contents Continued (pp. i).

Contents (pp. co4).

Catalytic pyrolysis of plastic wastes with two different types of catalysts: ZSM-5 zeolite and Red Mud by A. López; I. de Marco; B.M. Caballero; M.F. Laresgoiti; A. Adrados; A. Aranzabal (pp. 211-219).

Display Omitted► Pyrolysis transforms plastic wastes in valuable liquids and gases useful as fuels or source of chemicals. ► The use of ZSM-5 zeolite in pyrolysis favours the production of gases and of lighter and more aromatic liquids. ► Red Mud, an industrial by-product, exerts a noticeable catalytic effect in pyrolysis, though lower than ZSM-5 zeolite. ► ZSM-5 enables to operate at lower pyrolysis temperatures while Red Mud only modifies the products characteristics. ► Red Mud is a mesoporous material with both strong and weak acid sites.The influence of ZSM-5 zeolite and Red Mud in the pyrolysis of plastic wastes has been studied. Both catalysts have been thoroughly characterized; the zeolite shows weak and strong acid sites and great BET surface area (412.0m²g⁻¹), while Red Mud contains lower acidity, with also weak and strong acid sites, meso-macropores and BET surface area of 27.49m²g⁻¹. Both catalysts have been tested in pyrolysis of a mixture of plastics which resembles municipal plastic wastes, at 440 and 500°C in a 3.5dm³ semi-batch reactor. The results have been compared with those of the thermal process. It has been proved that ZSM-5 zeolite has a strong effect in the characteristics and distribution of pyrolysis products. It generates at both temperatures a greater proportion of gases and liquids with a higher content of aromatics than without catalyst. Red Mud needs higher temperatures than ZSM-5 zeolite to exert a catalytic effect in pyrolysis, since similar results to those obtained without catalyst are obtained at 440°C, while at 500°C a higher yield of gases and a greater proportion of aromatics in the liquids is obtained.

Keywords: Feedstock recycling; Catalytic pyrolysis; Plastic wastes; ZSM-5 zeolite; Red Mud

Mercury removal from aqueous solutions of HgCl₂ by heterogeneous photocatalysis with TiO₂ by M.J. López-Muñoz; J. Aguado; A. Arencibia; R. Pascual (pp. 220-228).

Display Omitted► We studied the scope of heterogeneous photocatalysis for treatment of aqueous Hg(II). ► From 100mgL⁻¹ HgCl₂ solutions Hg values below 100μgL⁻¹ were attained. ► The efficiency of Hg uptake is controlled by pH and nature of organic donors. ► Mercury is deposited mainly as Hg(0) but also as Hg₂Cl₂ on theTiO₂ surface. ► No direct correlation between Hg adsorption and photocatalytic reduction was found.The photocatalytic removal of Hg(II) from aqueous solutions of HgCl₂ using TiO₂ as catalyst was studied. The influence of pH and the addition of methanol, formic acid and oxalic acid as sacrificial additives on the extent of Hg(II) adsorption and photocatalytic reduction was investigated. The results showed that the overall process strongly depended on pH, being enhanced as the pH was increased. At pH 10, an efficient removal of Hg(II) was achieved even in the absence of organic additives, attaining final mercury concentrations in solution at trace levels (μgL⁻¹). In acidic conditions, the addition of sacrificial organic molecules significantly increased the rate and extent of aqueous Hg(II) removal. The nature and distribution of mercury products deposited on the catalyst was dependent on the reaction conditions. In the absence of additives, Hg₂Cl₂ and Hg⁰ were respectively identified in acidic and neutral/alkaline media as main reduced species on the titania surface. The addition of organic additives enhanced the photocatalytic reduction to Hg⁰. Comparison between adsorption and reaction results evidenced that it cannot be established a direct correlation between Hg(II) dark adsorption on the TiO₂ surface and the efficiency of Hg(II) photoreduction achieved.

Keywords: Hg(II) removal; Adsorption; Heterogeneous Photocatalysis; TiO; ₂; Organic donors

A highly loaded and dispersed Ni₂P/SiO₂ catalyst for the hydrotreating reactions by Yu Zhao; Mingwei Xue; Muhan Cao; Jianyi Shen (pp. 229-233).

. A highly loaded and dispersed 60%Ni/SiO₂ was phosphorized with PH₃ at 423K to form a Ni₂P/SiO₂ catalyst (P-Ni₂P/SiO₂). This catalyst exhibited the high surface area (152m²/g) and highly and uniformly dispersed Ni₂P nano-particles (∼4.2nm) on the surface. It thus possessed great amount of surface active sites of Ni₂P as titrated by the adsorption of CO (263μmol/g). Accordingly, the catalyst exhibited the excellent performance for the hydrotreating reactions in a model diesel.Display Omitted► A highly loaded and dispersed Ni/SiO₂ catalyst was phosphorized with PH₃ to form a Ni₂P/SiO₂. ► The Ni₂P/SiO₂ catalyst adsorbed lots of CO and possessed the high density of active sites of Ni₂P. ► The Ni₂P/SiO₂ catalyst exhibited the excellent performance for the hydrotreating reactions.A highly loaded P-Ni/SiO₂ catalyst with the high active nickel surface area was prepared by the co-precipitation method with an n-butanol drying process. Phosphorization of this catalyst with 10%PH₃ in H₂ at 423K resulted in a supported Ni₂P catalyst P-Ni₂P/SiO₂. This catalyst showed the high surface area (152m²/g) with highly and uniformly dispersed Ni₂P nano-particles (∼4.2nm). Thus, it possessed the high density of active sites of Ni₂P as titrated by the adsorption of CO (263μmol/g). Accordingly, it exhibited excellent performance for the hydrodesulfurization of dibenzothiophene, hydrodenitrogenation of quinoline and hydrogenation of tetralin in a model diesel.

Keywords: Supported nickel; Phosphorization; Supported Ni; ₂; P; Microcalorimetric adsorption; Hydrotreating reactions

Facile fabrication of hierarchical porous TiO₂ hollow microspheres with high photocatalytic activity for water purification by Zhaoyang Liu; Hongwei Bai; Darren Sun (pp. 234-238).

Display Omitted► Facile synthesis of hierarchical porous TiO₂ hollow microspheres. ► These TiO₂ microspheres show high photocatalytic activity for wastewater purification. ► These TiO₂ microspheres are easily recovered for reuse.Hierarchical porous TiO₂ hollow microspheres were synthesized by a facile approach from a one-step template method. This novel approach avoids tedious multiple steps from conventional template method for fabricating hierarchical porous and hollow microspheres. The as-prepared microspheres were characterized by XRD, SEM, TEM, nitrogen adsorption, and UV–vis DRS. Its photocatalytic activity was demonstrated in the photocatalytic degradation of Rhodamine B. Structural characterization indicates that the as-prepared microspheres had a hollow interior and a hierarchical porous structure with both large and small mesopores on its surface. The average diameters and BET surface areas of the hierarchical porous TiO₂ hollow microspheres were 1.5μm and 117m²/g, respectively. Optical adsorption investigation shows that the hierarchical porous TiO₂ hollow microspheres possessed the optical band gap of 3.42eV. A possible formation mechanism for the hierarchical porous TiO₂ hollow microspheres was discussed. The hierarchical porous TiO₂ hollow microspheres exhibited much higher photocatalytic activity than the commercial P25 TiO₂. In addition, the as-prepared microspheres can be easily recycling for reuse. All these advantages show a bright future for this microspheric photocatalyst in environmental purification.

Keywords: Hierarchical microspheres; Photocatalytic activity; Water purification; TiO; ₂

Novel photocatalytic applications of sub-nanometer gold particles for environmental liquid and gas phase reactions by Shen Zhao; Girish Ramakrishnan; Dong Su; Robert Rieger; Antonius Koller; Alexander Orlov (pp. 239-244).

Display Omitted► In this study we first ever demonstrate the application of sub-1nm gold particles for both gas and liquid photocatalysis. ► We explore an advanced method of testing based on DRIFTS modified with UV fiber as well as improved method of Au synthesis. ► Our catalysts exhibited a remarkable photocatalytic activity, which was much higher than one of the most active photocatalysts such as P25 TiO₂.Ultra small sub-1nm gold nanoparticles were synthesized, characterized and deposited on TiO₂ support. They exhibited a remarkable photocatalytic activity for both liquid and gas phase oxidation reactions, which have a significant potential for environmental applications. The NO₂ conversion on such catalysts was 6 times higher as compared to that of unmodified catalysts. This is the first ever application of such small clusters for environmental photocatalysis. The presence of sub-1nm clusters was confirmed by TEM, MALDI-TOF MS and UV–vis spectroscopy. This work also included the novel use of modified DRIFT spectroscopy for photocatalytic testing as well improvement of known Au clusters synthesis procedures.

Keywords: TiO; ₂; Photocatalysis; Gold nanoparticles; Phenol degradation; DRIFTS

Hydrogen from ethanol solution under UV–visible light. Photocatalysts produced by nitriding titanium nitride and indium oxide intimate mixtures to form Ti–In nitride composites by Yenting Kuo; Kenneth J. Klabunde (pp. 245-251).

. Schematic representation showing the particle size, different crystal sizes of compounds and the ratio of compounds for the composite.Display Omitted► TiN–In nitride composite of TiN and InN was prepared by nitridation of TiO₂ first, then mixed with In₂O₃ and ammonolysis again under a NH₃ flow of 250mLmin⁻¹. ► The TiN–In nitride composite can stably generate H₂ gas maximum at 1277μmolh⁻¹g⁻¹ (∼13% quantum efficiency) in the ethanol aqueous solution under UV light. ► The XRD and XPS spectra confirmed that the prepared TiN–In nitride composite had nitrogen substituted at some of the oxygen sites in the TiO₂ and In₂O₃.Photocatalytic production of hydrogen gas from 20% ethanol–water was accomplished with Ti–In nitride composites. These materials were produced by nitriding a TiO₂ with ammonia at a high temperature, then adding In₂O₃ and further ammonolysis for different periods of time. The catalysts were very stable and continued to produce H₂ gas at 920μmolh⁻¹g⁻¹ for 50h and accumulated 12.8mmol H₂ gas. The water splitting photocatalytic reaction can be driven by UV–vis light, maximum producing H₂ gas at 1277μmolh⁻¹g⁻¹. It is critical that we understand how having high, stable activity is possible. We used XPS, X-ray (XRD), UV–vis diffuse reflectance spectrometry, and BET surface area and pore size distribution for further characterization.

Keywords: Water splitting; Semiconductor; Ammonolysis; Photocatalysis; TiO; ₂

Strategies for immobilization of manganese on expanded natural clays: Catalytic activity in the CWPO of methyl orange by Luis Alejandro Galeano; Antonio Gil; Miguel Angel Vicente (pp. 252-260).

Display Omitted► A novel procedure for the preparation of Mn-pillared like clays is presented. ► Mn incorporation competitive to wet impregnation is achieved on expanded clay. ► Mn-expanded clay shows interesting catalytic behaviour in CWPO reaction at pH 7.5.The efficiency of the immobilization of manganese on natural bentonite has been studied by the comparison of three methods: (i) pillaring with Al₁₃ followed by wet impregnation with aqueous manganese nitrate, (ii) pillaring with a mixed Al/Mn oligomeric solution and thermal treatment, and (iii) Mn²⁺-homoionization of the starting clay and subsequent in situ generation of MnS clusters by H₂S gas treatment. The resulting solids were characterized by atomic absorption spectroscopy (AAS), cationic exchange capacity (CEC), powder X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray analysis (SEM-EDX), nitrogen adsorption at −196°C and thermal analysis (DSC/TGA). Catalytic assessment of the materials was made in the Wet Peroxide Oxidation (CWPO) of the azo-dye methyl orange in aqueous solution at room temperature and atmospheric pressure. The in situ generation of the intercalated MnS clusters was shown to be the most efficient method for the metal incorporation in the interlayer of the hosting aluminosilicate. The solids obtained by this method resulted to be stable against the chemical leaching of the metal as well as the most active to catalyze the CWPO reaction under very mild conditions of temperature, pressure and pH (18°C, 0.7atm and 7.5).

Keywords: Al/Mn-pillared clay; MnS cluster; Azo-dye methyl orange; CWPO

NOx storage and reduction on a SrTiCuO₃ perovskite catalyst studied by operando DRIFTS by F.E. López-Suárez; M.J. Illán-Gómez; A. Bueno-López; James A. Anderson (pp. 261-267).

Display Omitted► The perovskite SrTiCuO₃ is able to perform both the NO oxidation to NO₂ and the NOx storage. ► Much higher amount of NOx is stored on the perovskite SrTiCuO₃ (41μmol/m² at 300°C) than on noble metal-containing reference catalysts (0.3–23μmol/m²), when compared on surface area basis. ► NOx chemisorption at 300°C is more effective than chemisorption at 350°C, while regeneration at 350°C is more effective than regeneration at 300°C.The behaviour of a perovskite SrTiCuO₃ as NSR catalyst has been studied by simultaneous DRIFTS and activity measurement. The amount of NOx stored on the perovskite SrTiCuO₃ (41μmol/m² at 300°C) is much higher, when compared on a surface area basis, than on noble metal-containing reference catalysts (0.3–23μmol/m²). The perovskite SrTiCuO₃ is able to perform both the NO oxidation to NO₂ and the NOx storage, and copper enhances both the NO oxidation and NOx chemisorption capacities of copper-free SrTiO₃ perovskite. During NOx chemisorption on SrTiCuO₃, the following process have been identified (i) NO chemisorption and nitrite formation or NO oxidation to gas phase NO₂ and further chemisorption of NO₂ with nitrites or nitrates formation, (ii) nitrite oxidation to nitro and/or nitrates, and (iii) nitro and/or nitrate decomposition with release of NO₂. NOx chemisorption at 300°C is more effective than chemisorption at 350°C, while regeneration at 350°C is more effective than regeneration at 300°C because: (i) decreased NOx slip (only for CO regeneration) and (ii) maintains the same chemisorption capacity of the perovskite after regeneration. H₂ is a better reductant than CO, and the differences between both reducing gases are much higher at 300°C than at 350°C.

Keywords: NSR; NOx; Operando; DRIFTS; Perovskite

Visible light active N-doped TiO₂ prepared from different precursors: Origin of the visible light absorption and photoactivity by Yan Wang; Caixia Feng; Min Zhang; Jianjun Yang; Zhijun Zhang (pp. 268-274).

Three kinds of precursors, nanotubular titanic acid (denoted as NTA), raw P25-TiO₂ and novel-TiO₂, were separately used to prepare visible light active N-doped TiO₂ samples by annealing in flowing NH₃, aiming to reveal the determinative factors on visible light response. The physicochemical properties of resultant N-doped TiO₂ samples were investigated by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), diffuse reflectance spectra (DRS), and electron spin resonance (ESR). The visible light photocatalytic activity of the three kinds of N-doped samples was compared by monitoring the photocatalytic oxidation of propylene. It was found that N-doped TiO₂ catalyst obtained by using NTA as the precursor possessed the highest photocatalytic activity. The absorption edge observed in the visible spectral region of 2.34–2.53eV is closely related with single-electron-trapped oxygen vacancy (denoted as SETOV, i.e., F⁺ color centers), while another absorption edge at 2.95–3.10 is assigned to the intrinsic absorption. The visible light sensitization of N-doped TiO₂ was due to the formation of SETOV in NH₃-treatment process, and doped-N played a role in preventing photogenerated electrons and holes from recombination, resulting in visible light photocatalytic activity. N-doped TiO₂ samples made from different precursors had different concentrations of SETOV and hence different visible light photocatalytic performance.

Keywords: Nanotubular titanic acid; P25-TiO; ₂; Nitrogen-doping; Visible light active; Oxygen vacancy

Effect of calcination temperature on morphology and photocatalytic activity of anatase TiO₂ nanosheets with exposed {001} facets by Kangle Lv; Quanjun Xiang; Jiaguo Yu (pp. 275-281).

Anatase TiO₂ nanosheets with exposed (001) facets, fabricated by hydrothermal reaction of tetrabutyl titanate and HF solution, show high thermal stability (up to 1100°C) and photocatalytic activity for photocatalytic oxidation decomposition of acetone in air.Display Omitted► High-energy anatase TiO₂ nanosheets show a remarkable thermal stability against phase transition up to 1100°C. ► Surface adsorbed fluoride ions play important role on the superior thermal stability. ► Heat treatment results in the growth of TiO₂ nanosheets along the [001] direction ( c-axis). ► High crystallization (low impurity) and oxygen vacancy are responsible for the high thermal stability of high-energy TiO₂ nanosheets. ► The high photocatalytic activity is still remained up to 1100°C.Exploring anatase TiO₂ with superior thermal stability and photocatalytic activity is of great importance and challenging. In the present work, surface-fluorinated anatase TiO₂ nanosheets with dominant high reactive {001} facets were fabricated by hydrothermal treatment of tetrabutyl titanate in hydrofluoric acid solution at 200°C for 24h. The as-prepared anatase TiO₂ nanosheets show a remarkable thermal stability against phase transition up to 1100°C, which is associated with the surface fluorination. Calcination treatment accelerates the desorption of surface-bounded fluorine from the {001} facets, which results in the formation of oxygen vacancy first, and then the fusion of neighbor TiO₂ nanosheets along the [001] direction ( c-axis) to minimize the surface energy. High crystallization (low impurity) and oxygen vacancy are responsible for the high thermal stability of the as-prepared TiO₂ nanosheets. On the other hand, heat treatment influences the photocatalytic activity as a result of the change of the textural characteristics, crystallinity degree and surface chemical states. Surprisingly, high photocatalytic activity is still remained up to 1100°C for photocatalytic oxidation decomposition of acetone in air under UV light illumination.

Keywords: Titania; High-energy facets; Fluoride; Photocatalytic oxidation; Thermal stability

TiO₂ nanocrystals grafted on macroporous silica: A novel hybrid organic–inorganic sol–gel approach for the synthesis of highly photoactive composite material by Maurizio Crippa; Emanuela Callone; Massimiliano D’Arienzo; Klaus Müller; Stefano Polizzi; Laura Wahba; Franca Morazzoni; Roberto Scotti (pp. 282-290).

Display Omitted► Meso/macroporous TiO₂–SiO₂ exhibits photoactivity comparable to TiO₂ in slurry. ► TiO₂ nanocrystals were functionalized with organic molecules. ► Functionalized TiO₂ was grafted on macroporous SiO₂ by sol–gel synthesis. ► Grafted TiO₂ was dispersed with mesoporous distribution on SiO₂. ► TiO₂–SiO₂ meso/macroporous structure guarantees high accessibility of the catalyst.TiO₂–SiO₂ composite materials with photocatalytic properties similar to those of slurry powdered TiO₂ is obtained by a novel sol–gel synthetic strategy involving the hydrolysis/condensation of TMOS assisted by PEG as templating agent and the grafting of preformed titania nanocrystals onto the macropore walls of the silica matrix. In order to anchor TiO₂ particles to the surface of SiO₂, avoiding their embedding into silica matrix, functionalization with carboxylic acid or amine derivatives was carried out. The functionalization induces the confinement of titania nanocrystals in PEG, during the silica formation, and allows their dispersion on the silica surface. TiO₂–SiO₂ materials exhibit high thermal and chemical stability and a photocatalytic activity in the phenol mineralization comparable to that of powder TiO₂ in slurry (half degradation time ∼120min). These results suggest that the immobilization procedure here reported provides high accessibility of the catalyst active sites preserving the functional properties of the photoactive catalyst.

Keywords: Photoactivity; Organic–inorganic hybrids; TiO; ₂; –SiO; ₂; composite; Hierarchical porous material

Preparation and photoactivity of samarium loaded anatase, brookite and rutile catalysts by M. Bellardita; A. Di Paola; L. Palmisano; F. Parrino; G. Buscarino; R. Amadelli (pp. 291-299).

Display Omitted► Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl₄. ► The beneficial effect of samarium on the photodegradation of 4-nitrophenol was attributed to an increased separation efficiency of the photogenerated electron–hole pairs. ► The presence of samarium reduced the intensity of the photoluminescence spectra obtained for the bare TiO₂ phases. ► All films revealed low contact angles and in particular, the surface of the Sm-loaded brookite appeared highly hydrophilic.Pure and samarium loaded anatase, brookite and rutile nanopowders were synthesized by thermohydrolysis of TiCl₄. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), specific surface area (SSA) determination, UV–vis diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), contact angle (CA) measurements and photoluminescence (PL) spectroscopy. The photocatalytic activity of pure and Sm-loaded TiO₂ polymorphs was investigated by employing the photodegradation of 4-nitrophenol as probe reaction in a liquid-solid system. Loading with Sm resulted in an improvement of the photoreactivity of the three TiO₂ polymorphs. The beneficial effect was explained by an increased separation efficiency of the photogenerated electron–hole pairs. Thin films were obtained by dip coating from water dispersions of the bare and loaded samples. The addition of samarium caused a reduction of the contact angle of the films. A nearly superhydrophilic property was exhibited by the Sm-loaded brookite film.

Keywords: Titanium dioxide; Photocatalysis; Samarium-loaded TiO; ₂; Superhydrophilicity

A new kinetic model for heterogeneous photocatalysis with titanium dioxide: Case of non-specific adsorption considering back reaction by Sergio Valencia; Francisco Cataño; Luis Rios; Gloria Restrepo; Juan Marín (pp. 300-304).

Display Omitted► The Langmuir–Hinshelwood model cannot fit experimental phenol photo degradation data. ► The “Direct–Indirect” model predicts higher values of the phenol degradation rates. ► The new model predicts the back reaction present in the phenol photo degradation.A new kinetic model for heterogeneous photocatalytic reactions has been developed as an alternative to the Langmuir–Hinshelwood (L–H) and the Direct–Indirect (D–I) models. The L–H model has been widely used to analyze the kinetics of the TiO₂-photocatalytic degradation of water-dissolved organic compounds, assuming the adsorption/desorption equilibrium of the reactants (Langmuir isotherm). Nevertheless, it has been reported by some authors that the experimental data on photocatalytic oxidations are incompatible with the behavior predicted by L–H model. The proposed model, unlike the L–H model, considers all the basic steps involved in heterogeneous photocatalysis with TiO₂, including the back reaction involved in the process, and it is applicable to organic species non-adsorbed on the TiO₂ surface. In the case of phenol photodegradation, the proposed model better describes, mechanistically, the experimental data than L–H and D–I models.

Keywords: Kinetic model; Photocatalysis; Titanium dioxide; Back reaction; Phenol

Modeling the effects of Pt loading on NOx storage on Pt/BaO/Al₂O₃ catalysts by Jin Xu; Michael P. Harold; Vemuri Balakotaiah (pp. 305-315).

Display Omitted► Microkinetic model developed for storage of NO/O₂ and NO₂/O₂ on Pt/BaO/Al₂O₃. ► Spillover chemistry at Pt/BaO interface essential to predict storage enhancement. ► Model captures key transient trends including effect of Pt loading.Platinum plays an important, multi-functional role during NOx storage and reduction (NSR). Understanding and predicting the effect of Pt loading is essential to optimize the lean NOx trap. In this study, a microkinetic model is developed for NOx storage on a series of Pt/BaO/Al₂O₃ catalysts with a range of Pt loadings (0–3.7wt.%). A classification of the Ba sites into two storage site populations, proximal and non-proximal (bulk), is presented. A simple model for estimating the capacities of the two Ba site populations using the Pt loading is used to explain trends in the storage of NO/O₂ and NO₂/O₂. The model integrates existing literature models for NO₂ storage on BaO/Al₂O₃, Pt-catalyzed NO oxidation to NO₂, and spillover chemistry involving NO₂. Wherever possible, simplifications in the model are made based on sensitivity analyses. Literature estimates of kinetic parameters are adjusted if estimates of spillover rate constants are not sufficient to predict the storage data. The dual-site model comprises proximal storage sites that participate in the spillover chemistry and non-proximal sites that involve NO₂ that is generated by the Pt-catalyzed NO oxidation. The model shows reasonable agreement with the measured storage of NO and NO₂ in O₂ at 340°C for a range of storage times and Pt loading. The model helps to elucidate the storage dynamics and the roles of Pt and should be useful for incorporation into a complete NOx storage and reduction model. Some further refinements to the model are discussed.

Keywords: NOx; NOx storage; Diesel emissions; Platinum; Barium; Microkinetic model; Kinetics

Dissolved oxygen concentration: A key parameter in monitoring the photo-Fenton process by L. Santos-Juanes; J.L. García Sánchez; J.L. Casas López; I. Oller; S. Malato; J.A. Sánchez Pérez (pp. 316-323).

Display Omitted► We study dissolved oxygen concentration variations during the photo-Fenton process. ► We study the relationship between DOC reaction, H₂O₂ reaction and oxygen generation. ► A high level of oxygen generation is indicative of inefficient conditions. ► A decrease in dissolved oxygen concentration indicates a lack of hydrogen peroxide. ► Dissolved oxygen monitoring is proposed for studying the photo-Fenton process.Dissolved oxygen concentration variations have been investigated during the photo-Fenton process. Using Paracetamol as a model pollutant and dissolved organic carbon (DOC) removal as the priority objective, we have studied the effects of irradiance intensity (13–87W/m²), iron concentration (0.09–0.45mM), hydrogen peroxide concentration (9–45mM) and finally DOC concentration (4–25mM) on the relationship between the mineralization rate, the H₂O₂ reaction rate and the oxygen generation rate. A high level of oxygen generation is indicative of inefficient conditions whereas a decrease in dissolved oxygen concentration (i.e. generation rates near to zero) indicates a lack of hydrogen peroxide. As a consequence, dissolved oxygen monitoring has been presented as an easy, measurable tool for studying the evolution of the photo-Fenton process and its efficiency.

Keywords: Photo-Fenton; Dissolved oxygen; Paracetamol; Hydrogen peroxide consumption efficiency

Vegetable oil effect on gasoil HDS in their catalytic co-hydroprocessing by Ch. Templis; A. Vonortas; I. Sebos; N. Papayannakos (pp. 324-329).

Display Omitted► The desulphurization rates of the sulphur bearing molecules in gasoil decrease with the addition of the vegetable oil up to 5%. ► The increase of palm oil content from 5% to 10% did not result in any further effect on desulphurization reaction rates. ► The vegetable oil presence in the feed mixture does not affect the rate of the hydrogen consumption reactions of the gasoil molecules. ► The hydrogen consumption for the transformation of the palm oil triglyceride molecules into green diesel was estimated as 210Nl/kg_VO. ► The HDS activation energy decreases with vegetable oil content from 128kJ/mol to 102kJ/mol when the palm oil content increased from 0 to 10wt%.The effect of the presence of triglycerides on the catalytic hydrodesulfurization (HDS) of gasoil and the hydrogen consumption reactions have been studied during catalytic hydroprocessing of gasoil–palm oil mixtures at conventional hydrotreatment conditions over a commercial CoMo/γ-Al₂O₃ catalyst. The experiments were performed at a pressure of 33bar, three temperatures (310°C, 330°C and 350°C), and three values of WHSV (0.7h⁻¹, 1h⁻¹ and 1.4h⁻¹). Desulphurization rates decreased with palm oil content from 0 to 5% but they did not change with a further increase to 10%. Hydrogen consumption rates were not affected by the presence of the vegetable oil molecules. Simple power law formal kinetics has been applied to simulate the desulphurization and hydrogen consumption rates of the gasoil–palm oil mixtures.

Keywords: Co-hydroprocessing; Hydrodeoxygenation; Hydrodesulphurization; Vegetable oil; Gasoil–vegetable oil mixtures

Catalytic activity and stability of multiwalled carbon nanotubes in catalytic wet air oxidation of oxalic acid: The role of the basic nature induced by the surface chemistry by Raquel P. Rocha; Juliana P.S. Sousa; Adrián M.T. Silva; Manuel F.R. Pereira; José L. Figueiredo (pp. 330-336).

Display Omitted► MWCNTs without any impregnated metal are good catalysts for CWAO. ► Oxalic acid can be totally degraded at 140°C in less than 30min. ► The catalytic activity of MWCNTs can be enhanced by increasing their basic sites.Different chemical and thermal treatments (nitric acid at boiling temperature, liquid-phase urea treatment at 200°C, and gas-phase thermal treatment with nitrogen at 600°C) were applied to multiwalled carbon nanotubes (MWCNTs) in order to produce materials with different textural and chemical properties. Nitrogen adsorption isotherms, temperature programmed desorption, pH_pzc (point of zero charge), elemental analysis and X-ray photoelectron spectroscopy were used to characterize these materials. The chemical and thermal treatments have influence on the materials pH_pzc, which decreases upon nitric acid treatment and increases with urea or gas-phase thermal treatments. The original and modified MWCNTs, without any impregnated metal, were investigated as catalysts in the catalytic wet air oxidation (CWAO) process, using oxalic acid as model compound at 140°C and 40bar of total pressure. Oxalic acid is very stable under non-catalytic conditions but can be totally degraded in less than 30min in the presence of MWCNTs. The rate of oxidation of oxalic acid depends on the chemical properties of MWCNTs, the apparent initial first-order rate constants being lower for the MWCNTs with a marked acid character. The textural properties of MWCNTs are stable in cyclic CWAO experiments, but a decrease of their basic character leads to the reduction of their catalytic activity, even if this activity is still high with reused catalysts (nearly total oxalic acid degradation in 45min and complete mineralization in 120min). Therefore, MWCNTs without any impregnated metal, especially those of more basic character, are very active catalysts for CWAO, their activity strongly depending on the stability of their surface chemistry.

Keywords: Catalytic wet air oxidation; Multiwalled carbon nanotubes; Basic character; Surface chemistry; Oxalic acid

One step synthesis of carbon-supported Ag/Mn_yO_x composites for oxygen reduction reaction in alkaline media by Qiwen Tang; Luhua Jiang; Jing Qi; Qian Jiang; Suli Wang; Gongquan Sun (pp. 337-345).

Display Omitted► Ag/Mn_yO_x/C composites were synthesized by one-step pyrolysis of AgMnO₄. ► The Ag/Mn₃O₄/C obtained at 400°C is most active toward the ORR in alkaline media. ► A synergic effect between Ag and Mn₃O₄ is proposed. ► The ORR proceeds via a 4e⁻ pathway on the Ag/Mn₃O₄/C. ► The Ag/Mn₃O₄/C is more stable than Pt/C in alkaline media.Carbon-supported Ag/Mn_yO_x composites were prepared by a one step synthesis method, i.e., silver permanganate pyrolysis at different temperatures. The physical and electrochemical properties of the obtained composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and cyclic voltammetry (CV). The electrochemical activity, selectivity and stability for the Ag/Mn_yO_x/C composites toward oxygen reduction reaction (ORR) in alkaline media were investigated by rotating (ring)-disk electrode (R(R)DE) technique. The XRD results show that the manganese oxides were converted from MnO₂ to Mn₃O₄ and then to MnO gradually with increasing temperature. Among all the Ag/Mn_yO_x/C composites, Ag/Mn₃O₄/C obtained at 400°C exhibits the highest activity toward the ORR. Compared with the Ag/C, Mn₃O₄/C and the physical mixture of Ag/C and Mn₃O₄/C with the same metal loadings, the ORR activity of the Ag/Mn₃O₄/C is improved significantly, suggesting a synergic effect between Ag and Mn₃O₄. At an overpotential of 0.35V, the calculated apparent activation energy for the ORR on the Ag/Mn₃O₄/C catalyst is 56kJmol⁻¹, which is apparently higher than that on a Pt/C catalyst (36kJmol⁻¹). The results from both Koutecky–Levich plots of the ORR and the RRDE measurements suggest that the ORR proceeds via a 4-electron pathway on the Ag/Mn₃O₄/C composite. Moreover, the presence of methanol has little influence on the ORR activity toward the Ag/Mn₃O₄/C catalyst. The accelerated aging tests indicate that the Ag/Mn₃O₄/C is more stable than the Pt/C in 0.1M NaOH solution.

Keywords: Oxygen reduction reaction; Alkaline media; Manganese oxide; Silver; One step synthesis

Tailoring polymer–TiO₂ film properties by presence of metal (Ag, Cu, Zn) species: Optimization of antimicrobial properties by Anna Kubacka; Manuel Ferrer; Marcos Fernández-García; Cristina Serrano; María L. Cerrada; Marta Fernández-García (pp. 346-352).

.Display Omitted► EVOH–TiO₂ films synthesized with Ag, Cu, Zn species at organic–inorganic interface ► These species alter optical but no other film physico-chemical property ► Ag and Zn dramatically enhance both UV and visible disinfection capabilitiesPresence of metallic Ag or oxidic Cu and Zn species on an anatase surface is shown to allow drastic improvement of the disinfection capability of polymer-based TiO₂-containing nanocomposite films against both gram negative ( Escherichia coli) and gram positive ( Staphylococcus aureus) bacteria and upon both ultraviolet and visible light excitations. The inorganic incorporation to the polymer matrix is reached without alteration of the main physico-chemical (structural and thermal) characteristics of the organic component. Irrespective of the excitation wavelength, the disinfection capability improvement is observed for Ag and Zn promoted film materials but not for the Cu-containing composite. A study of the optical properties attempts to interpret the biocidal enhancement observed in presence of such Ag, Cu, and Zn-containing species at inorganic–organic interfaces.

Keywords: Titania; Anatase; Nanocomposites; Thin films; Biocide; Germicide; Disinfection

Study of benzylparaben photocatalytic degradation by TiO₂ by Yixin Lin; Corinne Ferronato; Nansheng Deng; Jean-Marc Chovelon (pp. 353-360).

Display Omitted► We choose benzylparaben, an emerging pharmaceutical and personal care products, as environmental pollutant to research its photocatalysis phenomenon. ► We study effects of several important parameters, such as pH values, TiO₂ loading, dissolved oxygen concentration, initial benzylparaben concentration and light intensity, on benzylparaben photocatalysis. ► The optimal experimental condition for benzylparaben photocatalysis is obtained. ► We identify photocatalytic intermediates using GC–MS and HPLC-DAD, and propose a tentative reaction pathway.The photocatalytic degradation of benzylparaben in TiO₂ suspension under UV irradiation was investigated and different experimental parameters were optimized. The degradation apparently followed a Langmuir–Hinshelwood kinetic relationship and the apparent first order rate constant was found equal to k_app=0.017min⁻¹. It was found that alkaline pH was beneficial for benzylparaben photocatalysis, and the highest degradation efficiency was obtained at pH 9. A TiO₂ loading of 2.5gL⁻¹ was enough to reach an optimal conversion rate while a higher loading (3.0gL⁻¹) had obvious inhibition phenomenon. The pseudo first order kinetic constant increased from 0.0043 to 0.025min⁻¹ while oxygen concentration increased from 0 to 36mgL⁻¹. In addition, the removal efficiency decreased while initial benzylparaben concentrations increased from 5 to 25mgL⁻¹. Light intensity is a quite important parameter influencing benzylparaben photocatalysis since for photonic flux ranging from 1.2 to 5.0×10¹⁵photonss⁻¹cm⁻², the rate constant was directly proportional to the photonic flux, while for higher intensity (from 5.0 to 5.8×10¹⁵photonss⁻¹cm⁻²) the rate of degradation varied as a square root of the photonic flux. Different intermediates of benzylparaben photocatalysis were identified or characterized by GC–MS and HPLC and total organic carbon (TOC) analyses showed an almost total mineralization. These observations suggest that photocatalysis may be envisaged as an efficient method for treatment of diluted waste waters containing emerging paraben pollutants.

Keywords: Photocatalysis; Benzylparaben; TiO; ₂; Kinetic approach; Mineralization

Photocatalytic efficiency and self-cleaning properties under visible light of cotton fabrics coated with sensitized TiO₂ by R. Rahal; T. Pigot; D. Foix; S. Lacombe (pp. 361-372).

Display Omitted► TiO₂ sensitized with anthraquinone-2-carboxylic acid (AQ-COOH) was prepared from a molecular precursor [Ti(OR)3(O2C-AQ)]. ► Coated cotton pieces and modified TiO₂ powders were prepared and characterized. ► Bonding between AQ-COOH and TiO₂ through a carboxylate complex was demonstrated. ► Under visible light, no acetone mineralization but synergy effect leading to significant singlet oxygen production.A simple and reproducible one-pot process for the elaboration of cotton fabrics coated with sensitized TiO₂ was developed. A molecular precursor [Ti(OR)₃(O₂C-AQ)] was prepared starting with anthraquinone-2-carboxylic acid (AQ-COOH) and characterized by FTIR, CPMAS NMR and XPS. Hydrolysis of mixtures of [Ti(OR)₃(O₂C-AQ)] and Ti(OR)₄ at low temperature in an aqueous medium leads to pale yellow cotton fabrics together with the corresponding free P-TiO₂/AQ powders. The diffuse reflectance UV spectra confirmed the shift of absorption towards the visible range. From FTIR, CPMAS NMR and XPS analysis of the samples (cotton pieces and powders), it was shown that AQ-COOH was not only adsorbed on Titania but tightly bond through a carboxylate complex as in the molecular precursor. Anatase polymorph was always characterized by XRD even in the absence of a calcination step. Examination by SEM of treated cotton tissues before and after washing showed stable and homogeneous coating of TiO₂ particles on the cotton fibers.The photocatalytic properties of the samples were investigated, with special care to visible light activation. Under UV light, acetone mineralization was observed, while under filtered visible light, no acetone mineralization occurred. However efficient singlet oxygen addition to di- n-butyl sulfide was evidenced under visible light. Sulfoxide and sulfone were obtained in better yields using sensitized TiO₂ than using un-modified TiO₂ or Anthraquinone alone treated fabrics. Optimum results were obtained with low level of sensitizing AQ-COOH relative to TiO₂ (8%) and no reactivity improvement was noticed with higher AQ-COOH levels. The cotton pieces coated with sensitized TiO₂ also displayed self-cleaning properties towards wine stain, either under solar illumination or even in indoor light.The better efficiency of sensitized TiO₂-coated cotton is accounted for by a synergy effect between TiO₂ and AQ-COOH, enhancing the formation of Reactive Oxygen Species (singlet oxygen and/or superoxide radical-anion). However, under these conditions, the production of hydroxyl radical seems to be ruled out.

Keywords: Sensitized TiO; ₂; Photocatalysis; Coated cotton textiles; Singlet oxygen; Self-cleaning

Impact of induced chlorine-poisoning on the catalytic behaviour of Ce_0.5Zr_0.5O₂ and Ce_0.15Zr_0.85O₂ in the gas-phase oxidation of chlorinated VOCs by Beatriz de Rivas; Rubén López-Fonseca; Miguel A. Gutiérrez-Ortiz; José I. Gutiérrez-Ortiz (pp. 373-381).

Display Omitted► Ce_0.15Zr_0.85O₂ resulted resistant to Cl-poisoning after induced chlorination. ► HCl chlorination led to changes in surface area, and both acid and redox properties. ► Formation of CeOCl and new acid sites were responsible for the stable catalytic behaviour.The main scope of this work is to evaluate the catalytic stability of two Ce/Zr mixed oxides, namely Ce_0.5Zr_0.5O₂ and Ce_0.15Zr_0.85O₂, in the gas-phase oxidation of 1,2-dichloroethane as a model reaction for chlorinated VOC abatement. In order to simulate an accelerated Cl-poisoning of the catalysts the samples were submitted to a chlorination step with an aqueous solution of HCl at room temperature followed by calcination or by reduction and calcination at mild temperature (550°C). For comparative purposes pure CeO₂ and ZrO₂ catalysts were also investigated. It was found that chlorination led to remarkable changes in surface area, acidity and redox properties, as revealed by EDX, N₂-physisorption, XRD, Raman spectroscopy, adsorption of pyridine followed by IR, NH₃-TPD, H₂-TPR and oxygen storage capacity. Interestingly, the balance between negative (significant decrease in surface area, and lower overall acidity and reducibility) and positive (promoted redox properties due to the formation of stable CeOCl patches and generation of new acid sites related to Cl⁻ ions adsorbed on Ce⁴⁺ and Zr⁴⁺ cations) changes introduced by chlorine incorporation appeared to be effectively counterbalanced. As a result the catalytic behaviour of chlorinated samples was not markedly affected when compared with the corresponding parent samples. Hence, a slightly lower activity was found for CeO₂ and Ce_0.5Zr_0.5O₂ while catalytic conversion was somewhat promoted for Ce_0.15Zr_0.85O₂ and ZrO₂. Anyway, after chlorination both Ce_0.5Zr_0.5O₂ and Ce_0.15Zr_0.85O₂ exhibited an adequate catalytic performance not only in terms of low-temperature conversion, but also of stability during extended periods of time on stream.

Keywords: Chlorinated VOCs oxidation; Ceria–zirconia mixed oxides; Chemical stability; Chlorine poisoning; Catalyst deactivation

Electrocatalytic activity of Pt nanoparticles on a karst-like Ni thin film toward methanol oxidation in alkaline solutions by Chung-Shou Chen; Fu-Ming Pan; Hsin-Jung Yu (pp. 382-389).

Display Omitted► Rugged Ni films were prepared as the Pt nanoparticle support for methanol oxidation study in KOH solutions. ► The Pt/Ni electrode demonstrates good methanol electrocatalytic activity and CO tolerance. ► Negative charge transfer occurs from the Ni hydroxides capped support to Pt nanoparticles. ► The great electrocatalytic activity of the electrode is ascribed to the charge transfer.The study prepared rugged Ni thin films for the study on electrocatalytic methanol oxidation reaction (MOR) in alkaline solutions. The rugged Ni thin film has a karst-like morphology, which provides a large surface area for Pt nanoparticle loading by pulse electrodeposition. Cyclic voltammetry measurements showed that the Pt/karst-Ni electrode had a high electrocatalytic activity toward MOR and CO tolerance in the KOH electrolyte. Ni(OH)₂ formed on the Ni support during the potential scan can enhance CO tolerance of Pt nanoparticles via the bi-functional mechanism. The Langmuir–Hinshelwood and the Eley–Rideal mechanisms are used to elucidate the role of OH surface groups on the Ni support and OH⁻ ions in the electrolyte, respectively, in the enhancement of the CO tolerance. XPS analysis indicates that negative charges transfer from the Ni support to Pt nanoparticles. The electronic interaction may modify adsorption properties of CO adspecies on the Pt catalyst; the modification allows easy CO electro-oxidation by OH species surrounding the Pt nanoparticles, either from the Ni support or from the alkaline solution. The synergistic effect of the bifunctional mechanism and the electronic interaction makes the Pt/karst-Ni structure a good catalytic electrode for MOR in the KOH solution.

Keywords: Nickel; Platinum nanoparticles; DMFC; CO tolerance; Alkaline solution

Photocatalysis and disinfection of water: Identification of potential bacterial targets by S. Pigeot-Rémy; F. Simonet; E. Errazuriz-Cerda; J.C. Lazzaroni; D. Atlan; C. Guillard (pp. 390-398).

TEM pictures of E. coli cells in suspension in water exposed to 180min of UV-A in presence of TiO₂ P-25 (0.25g/l) and I_UV-A=3.45mW/cm² illustrating the disruption of the membrane.Display Omitted► TiO₂ particles have deleterious effects on outer membrane permeability in the dark. ► Damages to the bacterial cell envelope precede the total loss of cultivability. ► Some ions and carboxylic acids are released during the photocatalytic treatment. ► TEM illustrates different steps of the bactericidal mechanism of photocatalysis. ► Nucleic acids are potential targets of ROS at in vivo level.In order to identify some of the potential bacterial targets, the effects of TiO₂ nanoparticles on bacteria in aqueous suspension were assessed in the dark and under UV-A ( λ>340nm) radiation exposure, using the microorganism model Escherichia coli K-12. Illumination was produced with a HPK 125W lamp and suspended TiO₂ Degussa P-25 was used as the photocatalyst, absorbing all the incident UV-A radiations.The impact of the photocatalyst on the bacteria was investigated by monitoring cell cultivability, cell wall integrity and nucleic acid stability. The contact of TiO₂ particles with bacteria in the dark increased the bacterial sensitivity to membrane-perturbing agents, suggesting an increase in outer membrane permeability. In contrast, the contact between SiO₂ particles, with an average particle size similar to that of TiO₂ P-25, and bacteria did not induce any alteration of the cell permeability. The TiO₂ deleterious action on the envelope integrity continued during the UV-A radiations exposure. Impacts on bacterial permeability precede the total loss of cultivability. After 2.5h of photocatalytic treatment at 3.45mW/cm², bacteria were no longer cultivable on their standard growth medium. However, some of them could become cultivable again under specific environmental conditions appropriate to their survival. These resilient bacteria exposed again to UV-A photocatalysis were more resistant to the treatment.Some chemical by-products released during photocatalytic inactivation of the bacteria were also monitored. The appearance of oxamic and oxalic acids as well as ammonium cations, sulfate and nitrate anions were observed. Transmission electron microscopy (TEM) was used to study the morphological damages to E. coli structure during the photocatalytic inactivation of the microorganisms. After 1.5h of treatment, bacteria showed disorganized membrane structures, while bacteria were still visible although they were no longer cultivable after a longer exposure time. These results were correlated with damages of nucleic acids at in vivo level. An analysis by electrophoresis revealed that bacterial DNA and RNA molecules completely disappeared after 7h of photocatalytic treatment.

Keywords: Photocatalysis; Nanoparticles; Escherichia coli; Outer membrane; Nucleic acids

PANI/Bi₁₂TiO₂₀ complex architectures: Controllable synthesis and enhanced visible-light photocatalytic activities by Jungang Hou; Rui Cao; Shuqiang Jiao; Hongmin Zhu; R.V. Kumar (pp. 399-406).

Bi₁₂TiO₂₀ and PANI/Bi₁₂TiO₂₀ complex architectures with flower-, spindle- and jujube-like shapes, were prepared through a facile template-free hydrothermal process with assistance of a simple chemisorption approach and the morphologies, growth mechanism and visible-light photocatalytic properties of these architectures were investigated.Display Omitted► Bi₁₂TiO₂₀ complex architectures (BiT) with flower-, spindle- and jujube-like shapes, were prepared through a facile template-free hydrothermal process. ► A possible growth mechanism for BiT architectures is proposed via an Ostwald ripening mechanism followed by self-assembly. ► Much high photocatalytic activities of BiT with 0.5% PANI were obtained for the degradation of RhB under visible-light irradiation. ► An enhanced photocatalytic performance for PANI/BiT architectures was also observed with the assistance of a small amount of H₂O₂.Bi₁₂TiO₂₀ complex architectures (BiT) with flower-, spindle- and jujube-like shapes, were prepared through a facile template-free hydrothermal process, by controlling the reaction parameters, such as temperature, reagent concentration, and reaction time. Within the hydrothermal temperature range from 150 to 200°C, the morphology transformed progressively from microjujube to microflowers consisted with nanospindles. A possible growth mechanism for BiT architectures was proposed to explain the transformation of nanoparticles to microflowers via an Ostwald ripening mechanism followed by self-assembly. Most importantly, much higher photocatalytic activities of BiT spindle-like structures modified with 0.5% polyaniline (PANI) via a simple chemisorption approach in comparison with unmodified BiT were obtained for the degradation of Rhodamine B (RhB) solution under visible-light irradiation ( λ>420nm). Furthermore, an enhanced photocatalytic performance for RhB degradation was also observed with the assistance of a small amount of H₂O₂. The reason could be ascribed to the synergic effect between PANI and BiT, which promoted the migration efficiency of photogenerated electron-hole on the interface of PANI and BiT, demonstrating that PANI/BiT architecture is a promising candidate as a visible light photocatalyst.

Keywords: Photocatalytic activity; Bismuth titanate; Polyaniline; Degradation

Efficiency and recycling capability of montmorillonite supported Fe–Ni bimetallic nanocomposites towards hexavalent chromium remediation by Brijesh S. Kadu; Yogesh D. Sathe; Abhijit B. Ingle; Rajeev C. Chikate; Kashinath R. Patil; Chandrashekhar V. Rode (pp. 407-414).

Display Omitted► Fe–Ni bimetallic nanocomposites for Cr(VI) remediation. ► Intercalation of montmorillonite with Fe–Ni nanoparticles. ► Improved reaction rates for Cr(VI) reduction. ► Reduction of Cr(VI) to Cr(III) and Cr(0). ► Better removal capacity and reusability for nanocomposites.The remediation of Cr(VI) from simulated water streams is investigated using Fe–Ni bimetallic nanoparticles (Fe–Ni NPs) and their nanocomposites prepared with montmorillonite (MMT) clay. These nanocomposites are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyses. XRD analysis revealed proper dispersion as well as intercalation of Fe–Ni NPs in the clay matrix. TEM of nanocomposites showed the presence of spherical particles having a size of 20–40nm. Batch experiments with a 25mgL⁻¹ Cr(VI) solution and 2gL⁻¹ Fe–Ni NPs exhibited complete reduction of Cr(VI) within 10min that follows first order reaction kinetics. Amongst 25%, 50%, 75% in situ and loaded nanocomposites, 75% compositions possess better activity with enhanced reduction capacity below pH 4 due to generation of reactive H species. XPS analysis of nanocomposites after Cr(VI) treatment suggested that reduction process occurs through Cr(III) formation followed by its subsequent reduction to Cr(0). Their potentiality towards reusage is established from the recycling experiments that revealed the order of efficiency as 75% in situ>Fe–Ni NPs>75% loaded nanocomposites.

Keywords: Iron-nickel bimetallics; Nanocomposites; Montmorillonite; Cr(VI) remediation; Recycling

Effect of carbonaceous supports on the Pd-catalyzed aqueous-phase trichloroethylene hydrodechlorination by Eva Díaz; Laura Faba; Salvador Ordóñez (pp. 415-417).

The performance of different palladium catalysts – supported on activated carbon, carbon nanofiber and high surface area graphite – for the abatement of trichloroethylene in synthetic wastewaters (880ppm) has been studied in this manuscript. Experiments were carried out at 303K and 5MPa in a batch reactor. Catalytic activities (expressed as exposed metal-based pseudo-first order kinetic constant) have been correlated to different physico-chemical properties of the catalysts, concluding that Pd dispersion is the main factor affecting catalyst performance. The reaction is strongly structure sensitive, being the largest Pd particles the most active for this reaction under the studied conditions.

Keywords: Carbon functionalization; Water hydrodechlorination; High surface area graphite; Carbon nanofiber

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Applied Catalysis B, Environmental (v.104, #3-4)

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Applied Catalysis B, Environmental (v.104, #3-4)