Dephosphorization of Iron Ore through Bioleaching

Phosphorus, as phosphate, is frequently found as a constituent of many of the world iron resources. Phosphorus is an extremely harmful element found in iron ore used as a raw material in the steelmaking process because it will affect the quality of iron and steel products. Allowable phosphorus concentration in high quality steel is usually less than 0.08%. Dephosphorization of iron ore has been studied for a long time. Although there are described physical beneficiation and chemical leaching processes, involving inorganic acids, to reduce phosphorus content of iron ores, these processes have several limitations such as poor recovery, require high energy quantity, capital costs and cause environmental pollution. Use of microorganisms in leaching of mineral ores is gaining importance due to the implementation of stricter environmental rules. Microbes convert metal compounds into their water soluble forms and are biocatalysts of leaching processes. Biotechnology is considered as an eco-friendly, promising, and revolutionary solution to these problems. Microorganisms play a critical role in natural phosphorus cycle and the process of phosphate solubilization by microorganisms has been known for many years. This study was performed to analyze the possibility of using bioleaching as a process for the dephosphorization of an iron ore from Northeast of Portugal. For bioleaching, Acidithiobacillus ferrooxidans bacterium were used. For this study two experiments were done with different conditions, which lasts 6 weeks for first experiment and 5 weeks for second experiment. From the result of these preliminary studies, it was observed that for first experiment 6.2 % and for second experiment 3.7 % of phosphorus was removed from iron ore.

Use of inert gas-enriched atmospheres and post-packaging irradiation in shelf-life extension of watercress

Watercress (Nasturtium officinale R. Br.) is a semi-aquatic plant of the Brassicaceae family highly appreciated in the Mediterranean cuisine. It features sharp, peppery and slightly tangy taste and contains health-promoting phytochemicals. Its consumption as a fresh-cut product has increased in recent years, as well as the global market of minimally processed vegetables. This demand is driven by the growing interest in the role of food in promoting the human health and wellbeing and to meet consumer needs for fresh-like and more convenient foods. Due to the reduced shelf-life of this plant, the suitability of inert gas-enriched atmospheres and ionizing irradiation for preserving visual, nutritional and functional quality attributes during cold storage was studied. Watercress samples were gathered in the Northeast region of Portugal, rinsed in tap water and a portion was immediately analyzed (non-stored control). The remaining fresh material was packaged in polyethylene bags under N2- and Ar-enriched atmospheres, conventional atmosphere (air) and vacuum (no atmosphere). Samples under conventional atmosphere were irradiated at 1, 2 and 5 kGy of gamma-rays (predicted doses) in a 60Co experimental chamber. A non-irradiated control followed all the experiment. Then, all packaged samples were stored at 4 ºC for 7 days. The studied quality parameters included the colour that was measured with a Konica Minolta colorimeter, and total soluble solids and pH determined in squeezed juice. The proximate composition (moisture, proteins, fat, ash, carbohydrates and energy) was evaluated using the AOA C procedures. Organic acids, free sugars, fatty acids and tocopherols were analyzed by chromatographic techniques. Samples were also evaluated for its DPPH• scavenging activity, reducing power, and lipid peroxidation inhibition capacity trough the inhibition of the β-carotene bleaching and thiobarbituric acid reactive substances (TBAR S) formation. Differences among treatments were analyzed using the one-way analysis of variance (ANO VA) and a linear discriminant analysis (LDA ) was used to evaluate the effects on the overall postharvest quality. After evaluating the effect on the individual quality parameters, the LDA revealed that the Ar-enriched atmosphere and the irradiation at 2 kGy were suitable processing choices for preserving the integrity of the non-stored control samples during cold storage. Thus, these non-thermal treatments were highlighted for shelf-life extension of fresh-cut watercress.

Why are some cyano-based ionic liquids better glucose solvents than water?

Among different classes of ionic liquids (ILs), those with cyano-based anions have been of special interest due to their low viscosity and enhanced solvation ability for a large variety of compounds. Experimental results from this work reveal that the solubility of glucose in some of these ionic liquids may be higher than in water – a well-known solvent with enhanced capacity to dissolve mono- and disaccharides. This raises questions on the ability of cyano groups to establish strong hydrogen bonds with carbohydrates and on the optimal number of cyano groups at the IL anion that maximizes the solubility of glucose. In addition to experimental solubility data, these questions are addressed in this study using a combination of density functional theory (DFT) and molecular dynamics (MD) simulations. Through the calculation of the number of hydrogen bonds, coordination numbers, energies of interaction and radial and spatial distribution functions, it was possible to explain the experimental results and to show that the ability to favorably interact with glucose is driven by the polarity of each IL anion, with the optimal anion being dicyanamide.