Volume 4, Issue 2 - Special issue: 1st International Conference on Green Chemistry and Sustainable Engineering (GreenChemSE 2014) / Issue editor: Eduardo M. Cuerda-Correa

The catalytic conversion of lignocellulosic biomass to obtain high added value compounds and fuels is a rapidly developing field. Given the abundance of this renewable raw material and its reduced impact on the food chain, it is an attractive source for obtaining chemicals or fuels in the context of a sustainable economy. In this work, bi-functional catalysts were developed that were capable of performing in a single step the hydrolysis and hydrogenation of cellulose to produce compounds that may be used in the production of fine chemicals or easily converted into fuels (e.g., sorbitol). Different activated carbon (AC) supported metal catalysts were examined for the one-pot hydrolytic hydrogenation of cellulose. Among the prepared catalysts, 0.4% Ru/AC was shown to be the most active and selective for the conversion of cellulose into sorbitol. When microcrystalline cellulose was used, a conversion of 32% was reached after 5 h of reaction, with a selectivity to sorbitol of 30%. Moreover, ball-milled cellulose allowed attaining conversions over 50%, with selectivities to sorbitol of 45%. The results obtained showed that Ru/AC is effective for the hydrolytic hydrogenation of cellulose to sugar alcohols and that the conversion can be greatly improved by using the substrate after pre-treatment by ball-milling.

In this work, we present the synthesis details of uniform shape and size-controlled titanium dioxide (TiO 2 ) nanorods followed by the deposition of cadmium sulfide (CdS) quantum dots on their surface. The achieved surfactant-capped-TiO 2 nanorods as well as CdS/TiO 2 nanocomposites were dispersed in nonpolar solvents, which enabled an easy solution blending with poly (2-methoxy, 5-(2-ethyl-hexy-loxy)-p-phenyl vinylene) (MEH-PPV) conjugated polymer to prepare the active layer of bulk heterojunction solar cells (BHJSCs). The properties of the synthesized capped-TiO 2 nanorods, CdS/TiO 2 nanocomposites, as well as those of their corresponding blends with MEH-PPV were characterized using transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-Visible spectroscopy, and photoluminescence (PL) technique. The characterization of the effect of the surfactants (oleic acid, OA, olyamine, OM, and 6-aminohexanoic acid, 6AHA) left on TiO 2 surface and CdS surface modification on BHJSC photovoltaic power conversion efficiency (PCE) showed that: i) for the same surfactants, when CdS was added on the surface of TiO 2 nanorods, the PCE increased due to the higher efficiency of CdS compared to MEH-PPV; and ii) the best PEC was obtained with CdS/OA-6AHA-capped-TiO 2 nanocomposite due to the shortest length of the carbon-chain of 6AHA, leading to higher charge carrier mobility.

The objective of this work was to investigate the possibility of using alkali metal salts of ethylcarbonic acid as a carboxylating reagent in phenol (naphthols) carboxylation and developing a new and simple method for the synthesis of hydroxybenzoic and hydroxynaphthoic acids having broad practical application. It was found that sodium ethyl carbonate and potassium ethyl carbonate can be successfully used as carboxylating agents in carboxylation of phenol and naphthols. For the first time, the effects of the gaseous medium (air, carbon dioxide, argon), pressure, temperature and reaction time on the proceedings of the carboxylation reactions were examined. Simple and convenient procedures for the syntheses of o- and p-hydroxybenzoic, p-aminosalicylic, 1-hydroxy-2-naphthoic, 1-hydroxy-4-naphthoic and 2-hydroxy-3-naphthoic acids were developed. New efficient technologies for preparation of drugs salicylic acid (antiseptic activity), p-aminosalicylic acid (antituberculous activity) and p-hydroxybenzoic acid (bactericide activity) based on carboxylation reactions of phenol and m-aminophenol with sodium and potassium salts of ethyl carbonic acid were worked out.

Biomass from oleaginous microorganisms is an attractive source of materials used for the production of renewable fuels and industrial products due to its high productivity and the fact that it does not compete with human food. To ensure the economic feasibility and environmental sustainability of microbial biomass as feedstock, it is necessary to integrate its production and processing into the biorefinery concept. To achieve this goal, biodiesel production and fractionation of the whole biomass into different types of compounds (lipids, proteins, etc.) and further processing of each fraction must be performed. In the present work, the use of a microbial biomass source, the microalga Nannochloropsis gaditana, has been assessed as potential biorefinery feedstock.

Various silica-supported palladium catalysts were prepared and tested in the carbonylation of aryl iodides in the presence of aliphatic amines and aniline. In the former reaction, the main products are the α-ketoamides, whereas monocarbonylation is favoured with aniline. Small modification of the support, of the palladium precursor, or of the conditions of immobilisation were found to affect considerably the outcome of the reactions and recyclability of the catalysts. Under optimum conditions, the phosphine-free palladium catalysts can be reused six to ten times without considerable loss of activity. By the proper selection of the solvent, the leaching of palladium into the reaction mixtures can be reduced considerably.

In this work, we have investigated the possibility of using low cost ionic liquid analogues, namely deep eutectic solvents (DESs), for the liquid-liquid extraction of ethylbenzene from n -octane. The DESs used in this work were synthesized from ammonium salt with ethylene glycol and sulfolane as complexing agents. Equilibrium data for the ternary system consisting of ethylbenzene, n -octane and the DES were measured at 25°C and atmospheric pressure. The solvent formed by mixing tetraethyl-ammonium p-toluenesulfonate and sulfolane showed the best performance, i.e., the highest distribution ratio and selectivity. The complexing agents were not found in the raffinate phase. This will facilitate the separation process protocol and hence reduce the cost of the process. Finally, the experimental data was satisfactorily correlated using the NRTL model, showing that this classical model can easily be adopted with systems such as DESs.

The antimicrobial activity of nanoparticles (NPs) depends of the surface area in contact with microorganisms. The large surface area of the nanoparticles enhances their interaction with the microbes. In this work, a green, simple, rapid, and efficient ultrasound-assisted reduction method for silver nanoparticles (AgNP) synthesis is presented. For the synthesis, an aqueous solution of silver nitrate, ethanol, and ammonia was used. The adopted method can be easily implemented for any kind of scientific or industrial application due to its cost-effective nature. The effect of sonication time on the nanoparticle formation was investigated. Silver nanoparticles were analyzed through transmission electron microscopy and UV-vis spectroscopy. Antimicrobial additives can be incorporated in mass in different matrixes (polymeric or cellulosic), which is a convenient methodology to achieve antimicrobial activity. In this work, silver nanoparticles were incorporated in cellulose using an ultrasonic bath technique. The most important aspect of cellulose containing silver nanoparticles prepared by this method is its high antimicrobial efficiency. The microbiological study was carried out by a standard agar technique. The analysis showed that cellulose with incorporated silver nanoparticles exhibited strong antimicrobial activity against Escherichia coli bacteria. This makes it a promising antibacterial material for food packaging.

The sea lamprey is an anadromous species that migrates twice during its life cycle between freshwater and seawater. Microphagous larvae generally spend 4–5 years burrowed in the substrate of rivers and streams before undergoing metamorphosis that ends with the beginning of the juvenile trophic migration. Once metamorphosis is complete, sea lamprey juvenile downstream migrants are fully tolerant to seawater salinity. Pollution resulting from industrial effluents may disturb the seawater acclimatization causing oxidative damage, and ultimately may lead to a decrease of sea lamprey population. The aim of this study was to compare salt acclimation of sea lamprey juveniles captured in river basins with different levels of aquatic pollution, using mitochondrial glutathione (GSH) and malondialdehyde (MDA) of gills and liver as markers of physiological stress and cell damage. The results showed that juveniles from the Lima basin exhibited the highest levels of mitochondrial MDA in gills, even though significant changes in the stress markers of mitochondrial gills of all animals subject to salt acclimation were not detected. In addition, an increase in the oxidative damage of hepatic mitochondria of macrophthalmia from the Vouga basin suggests the occurrence of metabolic failures with the potential to disturb the capacity to adaptation to the marine environment.

Triazines and phenylureas, mainly used in agricultural applications for the selective control of germinating grasses and broad-leaved weeds, are often found in contaminated groundwater, surface water and the effluents of wastewater treatment plants. The toxicity of these herbicides in eukaryotic cells is poorly understood. Saccharomyces cerevisiae is a promising unicellular organism for the toxicological evaluation of xenobiotics because its metabolism is similar to that of higher-level organisms. Consequently, the aim of this study was to compare the effects of three herbicides on yeast-cell growth and the glutathione cycle. Saccharomyces cerevisiae grown in the presence of 5 or 50 μ m atrazine, diuron or isoproturon were compared with control cells grown in a rich medium. The results show that the glutathione-dependent buffer capacity decreased significantly in S. cerevisiae grown in the presence of both levels of any of the three herbicides, except in cells exposed to 50 μ m isoproturon. In addition, chlorine herbicides inhibited cell growth, probably due to a decrease in antioxidant power and glutathione reductase activity. Isoproturon at 50 μ m induced yeast-cell growth, increasing the buffer capacity mediated by glutathione as well as glutathione reductase and glutathione peroxidase activities of UE-ME3 strain. This strain may be useful in studies of isoproturon degradation.