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A nanocomposite containing zinc oxide and zinc titanate spinel was synthesized from a mixture of layered zinc hydroxide nitrate and titanium (IV) oxysulfate (theoretical Zn 2 TiO 4 :ZnO mass ratio of 10%) by calcination at 700 °C. The resulting material was characterized by XRD, TGA-DSC, FTIR, TEM, SAED, SEM, EDS mapping and Raman spectroscopy, techniques that allowed verifying a heterogeneous material constituted of tubular Zn 2 TiO 4 and granular ZnO particles. The resulting ZnO/Zn 2 TiO 4 nanocomposite was used as a photocatalyst in the advanced oxidative process (AOP) for degradation of Reactive Black 5 dye in aqueous solution. The results indicate excellent photocatalytic performance with significant removal of the integrated spectral area, which suggests significant dye degradation after 60 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • γ-Al 2 O 3 nanowires were successfully synthetized and extensively characterized. • Different amounts of iron were incorporated in order to obtain photoactive catalysts. • Complete decoloration of an azo-dye was achieved after 240 min of irradiation. • Evaluation of different reaction parameters was performed. γ-Al 2 O 3 nanowires (NW) were synthetized and impregnated with different amounts of iron (2, 6 and 10 wt%). Catalysts were further characterized by powder X-ray, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, UV–visible diffuse reflectance, temperature-programmed reduction, thermogravimetric analysis, transmission electron microscopy, X-ray photoelectron spectrometry and atomic absorption. The obtained materials were evaluated as heterogeneous photocatalysts in the degradation of azo dye methyl orange as model compound employing a 125 W high-pressure mercury lamp. After 240 min under irradiation the complete decoloration and 69% of mineralization was obtained when Fe6NW was employed. When commercial γ-Al 2 O 3 was employed as support of 6 wt%. of iron and evaluated in photodegradation the final decoloration reached up to only 46%. Reaction parameters such as iron amount, catalyst amount, pH, effect of support and reuses, were evaluated. The photocatalyst was employed for five consecutive reaction cycles with only a 10% of diminish of activity, resulting in an attractive low-cost and benefit in heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Abstract: To promote bio-based products for the industry, six bio-organic substances (cHALi) isolated from yard trimmings (green) and food (humid) urban residues aged under aerobic digestion for 0–60 days were investigated for their potential to perform as sensitizers for azo-dyes photodegradation. Ethylorange (EO) was used as probe molecule at 5mgL−1 starting concentration and irradiated in a closed Pyrex® cell with a Xenon (1500W) lamp and a cut-off filter for wavelengths below 340nm or in a cylindrical photochemical reactor equipped with a 125W medium pressure Hg lamp. The cHALi/EO ratio in the starting EO solution varied in the 0–200 (w/w) range. The % dye abatement was found a function of the irradiation time, of the type of cHALi substance and of the cHALi/EO ratio. The best results were achieved with cHALi isolated after 7 days biomass aerobic digestion. Total dye abatement was achieved within relatively short few hours. A progressive dye mineralization was observed under the same experimental conditions. On the contrary no significant degradation was evident for the cHALi substances within the same irradiation time. Several hydroxylated azo compounds were identified as likely responsible of residual color after total EO abatement. The results, coupled to the previously reported good performance of the same cHALi substances as auxiliaries for textile dyeing, augur well for the development of both efficient and environmentally friendly textile dyeing processes. [Copyright &y& Elsevier]

Abstract: An efficient solid catalyst, hydroxyl-Fe-pillared bentonite (H-Fe-P-B), was successfully developed for photo-assisted Fenton reaction. The characteristics of the catalyst were detected by N2 adsorption/desorption, X-ray fluorescence spectroscopy (XRF), X-ray powder diffraction (XRD), UV–vis absorption spectra (UV–vis) and atom force microscopy (AFM). The catalytic activity of H-Fe-P-B was evaluated in discolouration and mineralization of Orange II in UV-Fenton system. The effects of pH, Orange II concentration, UV light wavelength and temperature on Orange II degradation were studied in detail. It was found that the catalytic activity of H-Fe-P-B for H2O2 came from Fe-polycations between bentonite sheets rather than Fe3+ or Fe2+ in tetrahedral or octahedral sheets of bentonite. As the leaching of iron from the H-Fe-P-B after treatment was negligible, the H-Fe-P-B exhibited a high catalytic activity and good long-term stability in multiple runs in the discolouration and mineralization of Orange II. Because of the strong surface acidity, the H-Fe-P-B acted as not only catalyst but also solid acid in UV-Fenton system, as a result, almost 100% colour removal and 95% TOC removal of 0.2mM Orange II could be obtained at 40 and 120min even if the initial pH of solution was as high as 9.0. These results implied that the H-Fe-P-B was a promising catalyst for UV-Fenton system. [Copyright &y& Elsevier]

Abstract: Small nanosized clusters of Co3O4 coated on PTFE (polytetrafluoroethylene) flexible film is reported as a novel supported photocatalyst effective in the fast discoloration of the azo-dye Orange II under simulated solar radiation in the presence of oxone (2KHSO5·KHSO4·K2SO4). The photocatalytic discoloration of Orange II on the PTFE/Co3O4 films proceeds within minutes and the process could be repeated many times without a loss in photocatalyst stability. The photodiscoloration proceeds with a photonic efficiency of ∼1. The PTFE seems to act as a structure forming matrix for the colloidal Co3O4 coated on it surface leading to nanosized clusters of Co3O4. Monitoring the amount of Co2+-ions shows the Co2+-ions from the PTFE/Co3O4 during the photocatalysis enter the solution and at a later are stage re-adsorbed the Co3O4 crystallographic network (∼8min). By elemental analysis (EA) the loading of Co-loading per cm2 PTFE film was found to vary between 1% and 2%. Transmission electron microscopy (TEM) shows the size of the Co3O4 clusters to vary between 3 and 10nm. Electron dispersive spectrometry (EDS) confirms the presence of Co on the PTFE. X-ray photoelectron spectroscopy (XPS) of the PTFE/Co3O4 films reveal a partial reduction of the Co3O4 after Orange II discoloration leading to a substantial increase of the amount of Co(II) species in the Co3O4. Physical insight is provided into the catalyst film surface by carrying out Ar-sputtering of the PTFE/Co3O4 surface to remove the catalyst overlayers up to ∼20nm. [Copyright &y& Elsevier]