High temperature properties of by-product cold bonded pellets containing blast furnace flue dust

In this investigation, the fundamental reactions occurring during the heat treatment of cold bonded pellets (CBP) comprised of iron and steelmaking by-products have been studied. Blast furnace (BF) flue dust, which contains fractions of coal and coke particles, has been included in the CBP blend as a source of solid reductant. Thermal analysis was performed on CBP samples in inert atmosphere at a heating rate of 10 °C/min in order to observe their high temperature properties, specifically, the mechanisms of self-reduction within CBPs. Both endothermic and exothermic reactions were observed during heating. The gases generated during thermal analysis were analyzed using a quadropole mass spectrometer (QMS). Furthermore, CBP samples heated to several different temperatures and quenched in argon were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results from this investigation demonstrate that the decomposition of hydrates and carbonates in CBP samples contribute, as gaseous intermediates, to an earlier reduction of contained iron oxides. The gaseous intermediates are responsible for an initial gasification of carbon contained in blast furnace flue dust leading to low temperature iron oxide reduction. The step-wise reduction of iron oxides in CBPs at the given conditions begins at ∼500 °C and is nearly completed at 1200 °C. This work can help to provide a fundamental understanding of the reduction characteristics of iron and steelmaking by-product agglomerates.     

Impact of low-frequency ultrasound technology on physical,chemical and technological properties of cereals and pseudocereals

Cereals (CE) and pseudocereals (PSCE) play a pivotal role in nourishing the human population. Low-frequency ultrasound (LFUS) modifies the structure of CE and PSCE macromolecules such as starch and proteins, often improving their technological, functional and bioactive properties. Hence, it is employed for enhancing the traditional processes utilized for the preparation of CE- and PSCE-based foods as well as for the upcycling of their by-products. We report recent advances in LFUS treatments for hydration, germination, extraction of bioactive compounds from by-products, and fortification of CEs and PSCE, including kinetic modelling and underlying action mechanisms. Meta-analyses of LFUS influence on compounds extraction and starch gelatinization are also presented. LFUS enhances hydration rate and time lag phase of CE and PSCE, essential for germination, extraction, fermentation and cooking. The germination is improved by increasing hydration, releasing promoters and eliminating inhibitors. Furthermore, LFUS boosts the extraction of phenolic compounds, polysaccharides and other food components; modifies starch structure, affecting pasting properties; causes partial denaturation of proteins, improving their interfacial properties and their peptides availability. Overall, LFUS has an outstanding potential to improve transformation processes and functionalities of CE and PSCE.     

Identification of by-products in phenylisocyanate pre-column derivatization by thermospray liquid chromatography-mass spectrometry

Summary Thermospray liquid chromatography-mass spectrometry has been applied to the identification of by-products in precolumn derivatization by phenylisocyanate. These byproducts are eluted early in the same chromatographic region as the low molecular weight derivatives and were located by chromatographic analysis of a blank sample. Their identification would offer further qualitative information in the use of phenylisocyanate as a derivatizing agent. Five compounds resulted from the reaction of phenylisocyanate and the reaction medium were identified: two from a reaction between phenylisocyanate and methanol, two from the reaction between phenylisocyanate and water, and one from the polymerisation of phenylisocyanate.     

Nanocrystals of XTiO3 (X = Ba,Sr, Ni,BaxTi1−x) materials obtained through a rapid one-step methodology at 50 °C

Titanate-based perovskite (XTiO₃; Ba, Sr, Ni, Ba_0.6Sr_0.4) nanocrystals were synthesized through a unified sonochemical methodology based on the reaction between XCl₂ and TiCl₄. The effects of the preparation conditions such as ultrasonication time and ultrasonication temperature were studied. XTiO₃ nanocrystals were characterized by field-emission scanning electron microscopy (FE-SEM), X-Ray diffractometry and high-resolution transmission electron microscopy techniques. XTiO₃ nanocrystals were synthesized at a relatively low temperature of 50 °C while were free from any by-product such as XCO₃ (carbonate by-products). Characterization of the morphological characteristics and particle size distribution of the obtained powders indicated that the powder products consist of somewhat regularly shaped and relatively spherical particles with a narrow size distribution. The method described here, is simple, rapid, cost-effective and useful for large-scale production purposes.     

Assessment of benzophenone-4 reactivity with free chlorine by liquid chromatography quadrupole time-of-flight mass spectrometry

The stability of the UV filter benzophenone-4 (BP-4) in free chlorine-containing water was investigated, for the first time, by liquid chromatography quadrupole time-of-flight mass spectrometry (LC–QqTOF-MS). High mass accuracy and resolution capabilities of this hybrid mass spectrometer were used for the reliable assignation of empirical formulae and chemical structures of BP-4 derivatives. Time-course profiles of the parent compound and its by-products were simultaneously recorded by direct injection of sample aliquots, after quenching the excess of chlorine, in the LC–QqTOF-MS system. At neutral pHs, in excess of chlorine, BP-4 showed a limited stability fitting a pseudo-first-order degradation kinetics. A noticeable reduction in the half-lives of BP-4 was observed when increasing the sample pH between 6 and 8 units and also in presence of bromide traces. The reaction pathway of this UV filter involved a first electrophilic substitution of hydrogen per chlorine (or bromide) in the phenolic ring, followed by oxidation of the carbonyl moiety to an ester group, which induced a further electrophilic substitution in the same aromatic ring. Above reactions were also noticed when mixing a BP-4 containing personal care product with chlorinated tap water and in chlorinated swimming pool and sewage water, previously spiked with a BP-4 standard.     

Abatement of volatile organic compounds using an annular photocatalytic reactor: Study of gaseous acetone

Photocatalytic oxidation of organic compounds in gas phase appears to be a promising process for remediation of polluted air. In the present work, the photocatalytic degradation of acetone, which is a typical pollutant of indoor air, was investigated by using an annular photoreactor. After a modelling by a cascade of elementary continuously stirred tank reactor, the annular photoreactor was assimilated to a plug flow reactor (PFR). No transfer limitation (external and internal) has been demonstrated for this reactor with the fibreglass photocatalytic support. The influence of several kinetic parameters has been studied such as pollutant concentration, incident light irradiance, contact time and humidity content. The Langmuir–Hinshelwood model has been verified for acetone. It can be noticed that no by-products have been detected by FID suggesting almost total mineralization. The possible minor gaseous by-products have been accumulated into a mixture of ethanol–liquid nitrogen at −50 °C then a sample of it has been injected into a GC/MS for analysis. A mechanistic pathway is then proposed for the photocatalytic degradation of acetone.     

Supercritical fluid extraction: Recent advances and applications

Among the different extraction techniques used at analytical and preparative scale, supercritical fluid extraction (SFE) is one of the most used. This review covers the most recent developments of SFE in different fields, such as food science, natural products, by-product recovery, pharmaceutical and environmental sciences, during the period 2007–2009. The revision is focused on the most recent advances and applications in the different areas; among them, it is remarkable the strong impact of SFE to extract high value compounds from food and natural products but also its increasing importance in areas such as heavy metals recovery, enantiomeric resolution or drug delivery systems.     

Formations of Active Species and By-Products in Water by Pulsed High-Voltage Discharge

Formations of active species and by-products are different from bubbling different gases in a pulsed high-voltage discharge reactor. The identification of all the products and the formation rate determination of active species are quite important as the process is applied to wastewater disposal. Serials of measurements were conducted to do the identifications and determinations in this paper. Amounts of · OH all increased but that of H₂O₂ all decreased by bubbling gas. The · OH formation rate was 3.49 × 10⁻⁷, 3.56 × 10⁻⁷, 3.21 × 10⁻⁷ and 1.94 × 10⁻⁷ mol l⁻¹ s⁻¹ with bubbling nitrogen, argon, air and oxygen respectively, but it was 1.61 × 10⁻⁷ mol s⁻¹ l⁻¹ without bubbling. Without any bubbling, the H₂O₂ formation rate was up to 6.53 × 10⁻⁶ mol l⁻¹ s⁻¹, while it was 9.97 × 10⁻⁷, 1.663 × 10⁻⁷, 1.73 × 10⁻⁶ and 3.14 × 10⁻⁶ mol l⁻¹ s⁻¹ with bubbling nitrogen, argon, air and oxygen, respectively. NO₂⁻ and NO₃⁻ was detected in discharged water with bubbling nitrogenous gas. Their formation made the pH decreased.     

Aerosol-OT-gamma-alumina admicelles for the concentration of hydrophobic organic compounds in water

A novel admicelle composing of a dialkylated anionic surfactant, di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT) and gamma-alumina was prepared by mixing them in acidic aqueous solution. The amount of the maximum sorption of AOT on 1 g of alumina at pH 2 was ca. 130 mg. By comparing the fluorescence spectra of N-phenyl-1-naphthylamine in different solvents, the solvent property of AOT-gamma-alumina admicelles was corresponding to that of toluene or diethyl ether. Thus, the AOT-gamma-alumina admicelles had greater hydrophobicity than SDS-gamma-alumina admicelles having similar hydrophobicity to 1-octanol or ethyl acetate. Hydrophobic organic compounds, chlorophenols having more than three chloro substituents, octylphenol, nonylphenol, dibutyl phthalate was almost quantitatively (98% or more) collected onto AOT admicelles composing of 1.5 g gamma-alumina and 150 mg AOT. The greater collection yields rather than those in SDS-admicellar system were ascribable to greater hydrophobicity and stability of AOT admicelles. After the 500-fold concentration, traces (nM) of organic contaminants in water samples were successfully detected with an HPLC having a photometric detector.