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Nodularin is a cyanotoxin commonly produced by cyanobacteria in algal blooms. Among Nodularin variants, the most common is Nodularin-R (NOD-R). This toxin is widely detected in water sources worldw...

Made available in DSpace on 2018-12-11T16:54:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-08-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Amoxicillin (AMX) is one of the most commonly prescribed antibiotics around the world to treat and prevent several diseases in both human and veterinary medicine. Incomplete removal of AMX during wastewater treatment contributes to its presence in water bodies and drinking water. AMX is an emerging contaminant since its impact on the environment and human health remains uncertain. This contribution was aimed to evaluate the electrochemical oxidation (EO) of AMX using different anodes in tap water, NaCl or Na2SO4 solutions and to evaluate the potential toxicity of remaining AMX and its by-products on zebrafish early-life stages. Chemical intermediates generated after EO were determined by mass spectrometry and their resulting antimicrobial activity was evaluated. AMX did not induce significant mortality in zebrafish during extended exposure but affected zebrafish development (increased body length) from 6.25 mg/L to 25 mg/L and inhibited enzymatic biomarkers. Carbon modified with titanium oxide (TiO2@C) anode achieved complete AMX removal in just a few minutes and efficiency of the supported electrolytes occurred in the following order: 0.1 M NaCl > 0.1 M Na2SO4 > 0.01 M NaCl > tap water. The order of potential toxicity to zebrafish early life-stages related to lethal and sublethal effects was as follows: 0.1 M Na2SO4 > 0.1 M NaCl >0.01 M NaCl = tap water. Additionally, the EO of AMX using TiO2@C electrode with 0.01 M NaCl was able to inhibit the antimicrobial activity of AMX, reducing the possibility of developing bacterial resistance. Faculty of Pharmacy Federal University of Goiás (UFG) Chemistry Institute Federal University of Goiás Faculty of Pharmaceutical Sciences University of São Paulo USP Department of Organic Chemistry University of Córdoba Biological Sciences Institute University of Brasília (UnB) National Institute for Alternative Technologies of Detection Toxicological Evaluation and Removal of Micropollutants and Radioactives (CNPq: INCT-DATREM) UNESP Institute of Chemistry National Institute for Alternative Technologies of Detection Toxicological Evaluation and Removal of Micropollutants and Radioactives (CNPq: INCT-DATREM) UNESP Institute of Chemistry CNPq: 465571/2014-0

The present work describes two novel magnetic composite catalysts, synthesized by functionalizing the silica/iron oxide composite surface with sulfaguanidine and sulfadiazine. The sulfaguanidine functionalized catalyst was found to be very efficient for multicomponent coupling reactions of phenylacetylene with various aldehydes and amines. The sulfadiazine functionalized catalyst was successfully applied in the synthesis of various 1,8-dioxo-octahydroxanthenes in water. Both the sulfaguanidine and sulfadiazine functionalized catalysts were very active and selective in the alkylation of toluene with benzyl chloride.

The present work demonstrates an efficient continuous flow methodology for the preparation of iron oxide nanoparticles supported on porous silicates. The effect of the iron precursor solution feed rate, the synthesis temperature and time and the support type on the catalyst characteristics were studied, as well on the catalytic activity in the microwave-assisted oxidation of benzyl alcohol with hydrogen peroxide and in the alkylation of toluene with benzyl chloride and with benzyl alcohol. The method appeared to deposit more α-Fe2O3 (hematite) on the support surface compared to similar catalyst materials synthesized using other methods. The catalyst deactivation observed in consecutive reaction cycles was mostly due to the blocking of active sites rather than metal leaching from the catalyst framework.

This work compares the catalytic activity of iron catalysts supported on porous furfuryl alcohol derived resins for the selective conversion of benzyl alcohol to benzaldehyde using hydrogen peroxide as the oxidant and assisted by microwave irradiation. The catalysts were prepared mechanochemically by ball-milling in the dry state. Initial results showed that the pressure in the reaction medium and the oxidant load are essential to achieve significant conversions. An apparent minimum catalyst load of 0.05 mol% Fe was required for significant reactivity at 132 °C.

In this work, we have successfully synthesized a set of titania photocatalytic nanocomposites by the incorporation of different TiO2 content on wheat bran residues. The obtained catalysts were characterized by different techniques including UVeVis spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Transmission Electron Microscopy (TEM) while their photocatalytic activity was investigated in the oxidation of benzyl alcohol under UV light irradiation. Benzaldehyde yields were ca. 20%, with conversion in the systems of ca. 33% of benzyl alcohol by using 10%Ti-Bran catalyst, as compared to 33% yield to the target product (quantitative conversion of benzyl alcohol) using commercial pure TiO2 (P-25). The photocatalytic activity results indicate that designed waste-derived nanomaterials with low TiO2 content can efficiently photocatalyze the conversion of benzyl alcohol with relative high selectivity towards benzaldehyde.

A number of synthesized supported Pd nanomaterials on aluminosilicate supports were investigated in the continuous flow hydroconversion of furfural to a range of furanic derivatives as compared to a commercial Pd/C catalyst. Excellent furfural conversions (>60%) and varying selectivities to products at mild temperatures (90 °C) could be obtained for most catalytic systems, with interesting selectivities to furfuryl alcohol (FOL), 2-methylfuran (MF) and tetrahydrofurfuryl alcohol (THFOL) depending on type of Pd catalyst. A significant deactivation with time on stream was observed for continuous flow synthesized nanomaterials with respect to commercial 5%Pd/C.

In the search for highly active and stable photocatalysts, significant efforts are devoted to find both new materials and innovative synthetic methods. In this study, an environmentally friendly and sustainable approach, dry reactive milling, was employed to synthesize two different semiconducting oxide nanomaterials, namely TiO2 and ZnO using polysaccharides as sacrificial templates. The as synthesized nanomaterials were characterized by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, diffuse reflection UV-vis and Raman spectroscopy, and N2 adsorption tests. Their photocatalytic activity was tested in ethanol degradation, followed by gas chromatographic analysis. Photoelectrochemical measurements were performed to assess the optoelectronic properties and the antimicrobial activity of these photocatalysts was also tested under visible light irradiation. Overall, we found that the performance of the synthesized nanomaterials was comparable to the benchmark P25 EVONIK titania, with ZnO exhibiting a remarkably superior antibacterial activity against E. coli.

The efficient oxidation of alcohols remains a challenge, especially when using solid heterogeneous catalysts. Herein, the catalytic activity of mechanochemically prepared iron and palladium particles on various supports are compared for the oxidation of cinnamyl alcohol to cinnamaldehyde and benzaldehyde in acetonitrile using aqueous hydrogen peroxide as the oxidant assisted by microwave irradiation. Important insights into the mechanism of the reaction towards the differently observed products have been provided.

Organic-inorganic hybrid perovskites have attracted significant attention owing to their extraordinary optoelectronic properties with applications in the fields of solar energy, lighting, photodetectors, and lasers. The rational design of these hybrid materials is a key factor in the optimization of their performance in perovskite-based devices. Herein, a mechanochemical approach is proposed as a highly efficient, simple, and reproducible method for the preparation of four types of hybrid perovskites, which were obtained in large amounts as polycrystalline powders with high purity and excellent optoelectronics properties. Two archetypal three-dimensional (3D) perovskites (MAPbI3 and FAPbI3 ) were synthesized, together with a bidimensional (2D) perovskite (Gua2 PbI4 ) and a "double-chain" one-dimensional (1D) perovskite (GuaPbI3 ), whose structure was elucidated by X-ray diffraction.

Hydrogenation of levulinic acid (LA) towards γ-valerolactone (GVL) is one of the most promising reactions in the field of biomass valorization to fine chemicals and liquid transportation fuels. Bimetallic Ni-Pt and Ni-Ru supported on ZrO 2 and γ-Al 2 O 3 were successfully utilized in this work as highly active and GVL-selective catalysts for the solvent-free hydrogenation of levulinic acid (LA) using formic acid (FA) as a hydrogen source in a microwave reactor, with results further translated into a continues flow system to prove the reaction mechanism. The supported bimetallic catalysts and their corresponding monometallic counterparts were characterized using N 2 -sorption, elemental analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Under microwave irradiation, 100% selectivity to GVL was achieved using both mono- and bimetallic catalysts. Bimetallic Ni-Ru supported on γ-Al 2 O 3 shows the highest LA conversion (71%) among the studied catalysts. This high activity is attributed to a larger Ru° concentration on the surface of γ-Al 2 O 3 in comparison to ZrO 2 as well as to the textural properties of γ-Al 2 O 3 (i.e., surface acidity, specific surface area). In contrast, ZrO 2 ‐based catalysts exhibited a higher stability with respect to γ-Al 2 O 3 -based after four consecutive runs of reaction.

The continuous flow hydroconversion of furfural to a range of furanic derivatives was carried out using a range of metal-containing heterogeneous catalysts in order to provide insights into the reaction pathways for the hydrogenation of furfural. Most of the catalysts used provided excellent furfural conversion (>60%) and varying selectivities to products at mild temperatures (90 °C), including furfuryl alcohol (FA), 2-methylfuran (2-MF), 2-methyltetrahydrofuran (2-MTHF) and furanic intermediates, depending on the flow conditions and the investigated catalyst.

A simple, innovative, and efficient continuous flow methodology for the direct preparation of supported nanoparticles on porous materials by using metal precursor solution flowing through heated packed-bed reactors containing the support material has been developed. The effects of the flow rate of the precursor solution, temperature, and nature of the support material and metal loading have been investigated. Results indicated that optimum conditions comprised short residence times (with typical flow rates of 0.5 mL min−1 and below) under mild heating (100 °C) to achieve optimum materials in terms of nanoparticle size and structure and catalytic activity. The support was found to have a remarkable effect on both loading and distribution and agglomeration of nanoparticles in the system, with a previously reported Fe/Al synergy also observed in the prepared nanomaterials, which led to optimum results.

Catalytically active supported metal nanoparticles on aluminosilicates including Cu and Pd-based systems were investigated in the microwave-assisted conversion to a range of valuable furanic compounds via tandem formic acid-promoted dehydration and subsequent selective hydrogenation processes. Results show that interesting selectivities to reduced products including 5-methylfurfural and 5-methylfurfuryl alcohol as well as hydroxymethylfurfural and furfural could be obtained in various proportions depending on the type of catalyst and the investigated reaction conditions. The investigation of reaction parameters including time of reaction, type of catalyst, quantity of catalyst and formic acid content indicated that reaction conditions can in principle be fine-tuned to maximise selectivity towards individual products.

Microcystin-leucine arginine (MC-LR) is the most abundant and toxic secondary metabolite produced by freshwater cyanobacteria. This toxin has a high potential hazard health due to potential interactions with liver, kidney and the nervous system. The aim of this work was the design of a simple and environmentally friendly electrochemical system based on highly efficient nanostructured electrodes for the removal of MC-LR in tap water. Titania nanoparticles were deposited on carbon (graphite) under a simple and efficient microwave assisted approach for the design of the electrode, further utilized in the electrochemical remediation assays. Parameters including the applied voltage, time of removal and pH (natural tap water or alkaline condition) were investigated in the process, with results pointing to a high removal efficiency for MC-LR (60% in tap water and 90% in alkaline media experiments, under optimized conditions).

Nanoparticle Tracking Analysis (NTA), developed by NanoSight, has been proved to be a highly useful, simple and efficient characterisation tool to differentiate between the capping efficiencies of various biomass-derived stabilising agents (e.g. starch, alginic acid and waste-derived hemicellulosic syrup) of aqueous colloidal silver suspensions. The results indicated that the use of a complex biorefinery-derived hemicellulosic syrup containing a mixture of C5 and C6 sugars, as well as oligomers, provided comparable capping and stabilisation properties to those of the most efficient pure polysaccharides including alginic acid. These findings illustrate the potential of waste-derived feedstocks for the stabilisation of nanoparticles in solution.

Cu nanoparticles have been supported by two types of aluminosilicate materials with and without Zn in their composition in view of their application in the microwave-assisted conversion of glucose to valuable products via tandem formic acid-promoted dehydration (to 5-hydroxymethylfurfural--HMF) and further selective hydrogenation to 5-methylfurfuryl alcohol (MFA). Results show that interesting selectivities (up to 60% to MFA or HMF) could be achieved after short times of reaction (typically 2-30 min) using Cu-containing nanomaterials. Zn was found to play an interesting role in the selectivity to reduced products, even if present in very small quantities (0.2 wt%).

Furfural is an important biorefinery platform chemical, derived from hemicelluloses which represent an import fraction of lignocellulosic biomass feedstocks and waste streams originating from them. Recently, promising results have been reported on the hydrogenation of furfural, although the selectivity still may be improved. Most of these studies dealt with batch hydrogenation, however, hydrogenation in continuous flow is preferable for industrial applications. In this work, we compare the conversion, selectivity and stability on-stream in continuous flow regime of lab-synthesized and commercial palladium and platinum catalysts.