Sequential biological and photocatalysis based treatments for shipboard slop purification: A pilot plant investigation

This study investigated the treatment of a shipboard slop containing commercial gasoline in a pilot plant scale consisting of a membrane biological reactor (MBR) and photocatalytic reactor (PCR) acting in series. The MBR contributed for approximately 70% to the overall slop purification. More precisely, the biological process was able to remove approximately 40%, on average, of the organic pollution in the slop. Nevertheless, the membrane was capable to retain a large amount of organic molecules within the system, amounting for a further 30% of the influent total organic content removal. However, this affected the membrane fouling, thus resulting in the increase of the pore blocking mechanism that accounted for approximately 20% to the total resistance to filtration (2.85∙10 13 m −1 ), even if a significant restoration of the original membrane permeability was obtained after chemical cleanings. On the other hand, the biological treatment produced a clear solution for the photocatalytic system, thereby optimizing the light penetration and generation of highly oxidizing active oxygen species that enabled the degradation of bio-recalcitrant compounds. Indeed, low total organic carbon (TOC) values (<10 mg L −1 ) were achieved in the output of the photocatalytic reactor by means of only 60 Einstein (E) of cumulative impinging energy after the addition of K 2 S 2 O 8 . Overall, coupling the two processes enabled very high TOC removal (ca. 95%)

Overview on oxidation mechanisms of organic compounds by TiO2 in heterogeneous photocatalysis

This review provides the reader with a general overview on heterogeneous photocatalytic oxidation mechanisms in the presence of TiO2, with a special address to conversion of aliphatic and aromatic organic species. The aim was to clarify the steps of the photo-oxidation of the various classes of compounds and to relate them with the properties of the catalysts and the experimental conditions used. Reactions carried out to perform complete degradation and photocatalytic partial oxidations have been deeply discussed. Recent isotopic studies highlighted new reaction pathways concerning partial oxidation of alcohols to aldehyde and oxidation of benzene while EPR investigations confirmed that not only the photogenerated hole but also the OH radicals are involved in the oxidation of the substrates

Extruded Expanded Polystyrene Sheets Coated by TiO2 as New Photocatalitic Materials for Foodstuffs Packaging

Nanostructured, photoactive anatase TiO2 sol prepared under very mild conditions using titanium tetraisopropoxide as the precursor is used to functionalise extruded expanded polystyrene (XPS) sheets by spray-coating resulting in stable and active materials functionalised by TiO2 nanoparticles. Photocatalytic tests of these sheets performed in a batch reactor in gas–solid system under UV irradiation show their successful activity in degrading probe molecules (2-propanol, trimethylamine and ethene). Raman spectra ensure the deposition of TiO2 as crystalline anatase phase on the polymer surface. The presence of TiO2 with respect to polymer surface can be observed in SEM images coupled to EDAX mapping allowing to monitor the surface morphology and the distribution of TiO2 particles. Finally thermoforming of these sheets in industrial standard equipment leads to useful containers for foodstuffs

Investigating the activity of modified TiO2 photocatalysts used for the photoreforming of biomass derivatives

Different TiO2 modified (with Pt, Cu2O, Nb) photocatalysts have been compared for the photo-reforming of glucose and fructose at ambient conditions with the aim of linking the photoactivity to some structural and surface characteristics. A different degree of conversion, distribution of intermediates and H2 production were observed with the various photocatalysts. Moreover, the results obtained with the same catalysts were slightly different with the two substrates, highlighting the importance of the interaction between the catalyst surface and the organic compound. Bare TiO2 was inactive towards H2 production, Cu2O was effective in replacing Pt for hydrogen generation, and the presence of Pt/Nb was beneficial for both H2 production and selective oxidation. Moreover, Pt not only works as a sink for the photoproduced electrons, as it is well known in the literature, but also modifies the surface acid-base properties of catalysts as revealed by DRIFT and TPD measurements

The combination of heterogeneous photocatalysis with chemical and physical operations: a tool for improving the photoprocess performance

Heterogeneous photocatalysis is a process of great potential for pollutant abatement and waste treatment. In order to improve the overall performance of the photoprocess, heterogeneous photocatalysis is being combined with physical or chemical operations, which affect the chemical kinetics and/or the overall ef\ufb01ciency. This review addresses the various possibilities to couple heterogeneous photocatalysis with other technologies to photodegrade organic and inorganic pollutants dissolved in actual or synthetic aqueous ef\ufb02uents. These combinations increase the photoprocess ef\ufb01ciency by decreasing the reaction time in respect to the separated operations or they decrease the cost in respect of heterogeneous photocatalysis alone, generally in terms of light energy. Depending on the operation coupled with heterogeneous photocatalysis, two categories of combinations exist. When the coupling is with ultrasonic irradiation, photo-Fenton reaction, ozonation, or electrochemical treatment, the combination affects the photocatalytic mechanisms thus improving the ef\ufb01ciency of the photocatalytic process. When the coupling is with biological treatment, membrane reactor, membrane photoreactor, or physical adsorption, the combination does not affect the photocatalytic mechanisms but it improves the ef\ufb01ciency of the overall process. The choice of the coupling is related to the type of wastewater to be treated. A synergistic effect, giving rise to an improvement of the ef\ufb01ciency of the photocatalytic process, has been reported in the literature for many cases

Pt-Nb2O5-TiO2 based semiconductors for photo-reforming of glucose and fructose aqueous solutions

The conversion of biomass derivatives into fuels and valuable compounds under green conditions is increasingly attracting the attention of the scientific community. In this study, the photo-reforming of aqueous glucose and fructose solutions in the presence of 0.5 wt% Pt-loaded homemade bare and Nb2O5-TiO2 catalysts was investigated to maximize the activity of titania for both hydrogen production and valuable chemical production. The most efficient sample was the home-prepared Pt-4 %Nb2O5-HP, for both glucose and fructose conversion, with the highest H2 productivity and the highest selectivity towards partially oxidized compounds. The behaviour of the Pt-4 %Nb2O5-HP derives from a favourable compromise of some surface and intrinsic electronic properties as, for instance, photoluminescence, zeta potential and surface acidity. The presence of Nb2O5 decreased the recombination rate of photoproduced charges. Photo-deposition of Pt was essential for H2 production and, surprisingly, also increased the basicity of the TiO2 surface; an increase in surface acidity was measured when only niobium oxide was added, whereas stronger basic sites were observed in the simultaneous presence of Pt and niobium oxide

High-Fat Feeding Does Not Disrupt Daily Rhythms in Female Mice Because of Protection by Ovarian Hormones

Obesity in women is increased by the loss of circulating estrogen after menopause. Shift work, which disrupts circadian rhythms, also increases the risk for obesity. It is not known whether ovarian hormones interact with the circadian system to protect females from obesity. During high-fat feeding, male C57BL/6J mice develop profound obesity and disruption of daily rhythms. Since C57BL/6J female mice did not develop diet-induced obesity (during 8 weeks of high-fat feeding), we first determined if daily rhythms in female mice were resistant to disruption from high-fat diet. We fed female PERIOD2:LUCIFERASE mice 45% high-fat diet for 1 week and measured daily rhythms. Female mice retained robust rhythms of eating behavior and locomotor activity during high-fat feeding that were similar to chow-fed females. In addition, the phase of the liver molecular timekeeping (PER2:LUC) rhythm was not altered by high-fat feeding in females. To determine if ovarian hormones protected daily rhythms in female mice from high-fat feeding, we analyzed rhythms in ovariectomized mice. During high-fat feeding, the amplitudes of the eating behavior and locomotor activity rhythms were reduced in ovariectomized females. Liver PER2:LUC rhythms were also advanced by ~4 h by high-fat feeding, but not chow, in ovariectomized females. Together these data show circulating ovarian hormones protect the integrity of daily rhythms in female mice during high-fat feeding

Revisiting the Training of Logic Models of Protein Signaling Networks with a Formal Approach based on Answer Set Programming

A fundamental question in systems biology is the construction and training to data of mathematical models. Logic formalisms have become very popular to model signaling networks because their simplicity allows us to model large systems encompassing hundreds of proteins. An approach to train (Boolean) logic models to high-throughput phospho-proteomics data was recently introduced and solved using optimization heuristics based on stochastic methods. Here we demonstrate how this problem can be solved using Answer Set Programming (ASP), a declarative problem solving paradigm, in which a problem is encoded as a logical program such that its answer sets represent solutions to the problem. ASP has significant improvements over heuristic methods in terms of efficiency and scalability, it guarantees global optimality of solutions as well as provides a complete set of solutions. We illustrate the application of ASP with in silico cases based on realistic networks and data

Selective photocatalytic and photoelectrocatalytic synthesis of valuable compounds in aqueous medium

In the past decades, photocatalytic and photoelectrocatalytic methods have been widely employed for the degradation of harmful compounds present both is gaseous and aqueous effluents. In the last years scientists have paid great attention to the synthesis of valuable compounds and hydrogen production. Organic syntheses are generally carried out in organic solvents, under high temperature/pressure, with toxic oxidants such as permanganate. On the other hand, photocatalysis and photoelectrocatalysis using water as solvent, air or water as oxidant, and sunlight as energy source, can be an efficient alternative to the traditional, non-environmentally friendly methods. This review summarizes the photocatalytic and photoelectrocatalytic transformations of organic molecules to commercially valuable products in water, sometimes evaluating also the contemporary H2 production. The reaction conditions, mechanisms and kinetics are presented and discussed. Future perspectives are also given