Equilibrium modified atmosphere packaging of wild strawberries

Wild strawberries (Fragaria vesca L.) are high‐added‐value fruits but their marketing is complex owing to their short postharvest life. In this work, equilibrium modified atmosphere packaging (EMAP) technology was used to maintain their quality and consequently to extend their life. Fresh strawberries were packaged with two continuous and three microperforated films (with different gas permeabilities) with the purpose of obtaining equilibrium atmospheres of diverse compositions. Weight loss, pH and acidity, solid content, colour, firmness, fungal decay and development of off‐flavours were selected to monitor fruit quality during 6 days at 10 °C. Among the five packages tested, microperforated films with one and three perforations provided adequate CO₂ and O₂ equilibrium concentrations in view of the evolution of chemical and physical quality parameters. These results were confirmed by sensory analysis. Copyright © 2007 Society of Chemical Industry     

Determination of As(III) and total inorganic As in water samples using an on-line solid phase extraction and flow injection hydride generation atomic absorption spectrometry

A simple and robust on-line sequential injection system based on solid phase extraction (SPE) coupled to a flow injection hydride generation atomic absorption spectrometer (FI-HGAAS) with a heated quartz tube atomizer (QTA) was developed and optimized for the determination of As(III) in groundwater without any kind of sample pretreatment. The method was based on the selective retention of inorganic As(V) that was carried out by passing the filtered original sample through a cartridge containing a chloride-form strong anion exchanger. Thus the most toxic form, inorganic As(III), was determined fast and directly by AsH(3) generation using 3.5 mol L(-1) HCl as carrier solution and 0.35% (m/v) NaBH(4) in 0.025% NaOH as the reductant. Since the uptake of As(V) should be interfered by several anions of natural occurrence in waters, the effect of Cl(-), SO(4)(2-), NO(3)(-), HPO(4)(2-), HCO(3)(-) on retention was evaluated and discussed. The total soluble inorganic arsenic concentration was determined on aliquots of filtered samples acidified with concentrated HCl and pre-reduced with 5% KI-5% C(6)H(8)O(6) solution. The concentration of As(V) was calculated by difference between the total soluble inorganic arsenic and As(III) concentrations. Detection limits (LODs) of 0.5 μg L(-1) and 0.6 μg L(-1) for As(III) and inorganic total As, respectively, were obtained for a 500 μL sample volume. The obtained limits of detection allowed testing the water quality according to the national and international regulations. The analytical recovery for water samples spiked with As(III) ranged between 98% and 106%. The sampling throughput for As(III) determination was 60 samplesh(-1). The device for groundwater sampling was especially designed for the authors. Metallic components were avoided and the contact between the sample and the atmospheric oxygen was carried to a minimum. On-field arsenic species separation was performed through the employ of a serial connection of membrane filters and anion-exchange cartridges. Advantages derived from this approach were evaluated. HPLC-ICPMS was employed to study the consistency of the analytical results.     

Performance of supported catalysts based on a new copper vanadate-type precursor for catalytic oxidation of toluene

A new copper vanadate precursor with the formula NH(4)[Cu(2.5)V(2)O(7)(OH)(2)] . H(2)O was synthesized and deposited on two different supports, ZSM-5 and amorphous SiO(2), by a hydrothermal method or by mechanical mixture. The catalytic behaviour was evaluated in the total oxidation of toluene and the characterization was performed by H(2)-temperature-programmed reduction (H(2)-TPR), thermogravimetric analysis, elemental analysis, UV-vis diffuse reflectance spectroscopy and X-ray diffraction. It was found that the copper vanadate phase comprises two mixed oxides, one of them crystalline, the Ziesite phase, and the other one amorphous. The supported catalysts presented a content of copper vanadate phase of about 9-11 wt.%. The copper vanadate deposited on ZSM-5 by the hydrothermal method evidences the best performance in the oxidation of toluene. This behaviour can be associated with the smaller size and higher dispersion of the particles on the support, which was confirmed by their better reducibility and higher band gap energy value compared with the other series of studied catalysts.     

Amine‐functionalized mesoporous silica: A material capable of CO2 adsorption and fast regeneration by microwave heating

The surface of ordered mesoporous (MCM‐48) silica has been subjected to covalent grafting with silane molecules containing one to three amino groups. The dielectric properties of the materials were studied in detail, and the functionalized materials were used for CO₂ adsorption at room temperature, followed by regeneration under either conventional heating or microwave irradiation. It has been found that, as the intensity of functionalization with amino groups increases (from mono‐ to tri‐amino silanes) both the CO₂ load and the dielectric response at microwave frequencies increase. In particular, functionalization with a tri‐amino silane derivative gave the highest CO₂ adsorption and the fastest microwave heating, resulting in a fourfold acceleration of adsorbent regeneration. The grafted material was fully stable for at least 20 adsorption‐regeneration cycles, making it an ideal candidate for microwave‐swing adsorption (MWSA) processes. © 2015 American Institute of Chemical Engineers AIChE J, 62: 547–555, 2016     

Thermal and catalytic pyrolysis of vacuum gas oil using HZSM-5: TG and PY-CG/MS study

The zeolite HZSM-5, was synthesized in the absence of an organic template. The characterization of zeolite HZSM-5 was performed by X-ray diffraction, N₂ adsorption/desorption isotherms and scanning electron microscopy. For catalytic tests, applying the free kinetic model, it was observed that the activation energy for the pyrolysis of pure VGO was of 82 kJ mol^?1 and for VGO/HZSM-5, the value decreased to approximately 60 kJ mol^?1, demonstrating the effectiveness of the acid sites effect of zeolite ZSM-5 for the VGO pyrolysis resulting in production of gas, gasoline and diesel.     

Production of biohydrogen from brewery wastewater using Klebsiella pneumoniae isolated from the environment

The use of wastewater for the biological production of H₂ (biohydrogen) by dark fermentation has been studied for a variety of waste substrates and mixed or isolated inocula. However, for brewery wastewater (BW), which is generated in large volumes and has characteristics that are highly suitable for acidogenic fermentation, the available studies describe the use of mixed cultures, especially pretreated methanogenic inocula. The aim of this work was to isolate an enterobacterium from aviary litter that was capable of fermenting BW and generating biogas rich in H₂. The biochemical characterization and species confirmation confirmation revealed the isolation of Klebsiella peneumoniae, which provided efficient production of biogas rich in H₂ (30–40%) in batch assays performed for up to 72 h, with the inoculum in suspension, at a small scale (in serum bottles) and using a mechanically-stirred anaerobic reactor (AnBBR), employing crude BW without any supplementation. The hydrogen yield and molar hydrogen flow rate were 0.80–1.67 mol H₂ mol^?1 glucose and 0.2–2.2 mmol H₂ h^?1, respectively, indicating good performance of the inoculum in metabolizing this substrate and the possibility of optimizing the process by varying the duration of the batch.