Evaluation of oxygen carriers based on manganese-iron mixed oxides prepared from natural ores or industrial waste products for chemical looping processes

Manganese-iron mixed oxides have been identified as promising oxygen carrier materials in chemical looping processes. In this work, low-cost raw materials are considered for the production of this type of oxygen carrier. Four manganese based minerals from deposits of different locations – South Africa, Gabon(x2) and Brazil – and two iron based materials (Fe-ore from Spain and Redmud waste) were used to prepare suitable oxygen carriers through a new two-step production method: a mixing-grinding (about 5 µm) pre-treatment followed by pelletizing, crushing and sieving to produce particles of the desired size (100–300 µm). This method was required in order to form the MnFe mixed oxide and to provide permanent magnetic properties, which were not found when the oxygen carriers were prepared by the classical one-step method, i.e. crushing and sieving of raw materials to the desired particle size (100–300 µm). The oxygen uncoupling capability of the developed materials was extremely low and even completely lost after repeated redox cycles. However, they were reactive under chemical looping conditions with H2, CO and CH4. Reactivity varied with the raw materials used and with the redox cycles, being of crucial importance for its evolution the intensity of the chemical stress during hundreds of redox cycles. © 2022 The Author

Evoking the Mechanoreflex Using Static and Dynamic Approaches: The Influence of Free Radicals and Sex

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Analysis of Fiber optic sensor embedding in metals by automatic and manual TIG welding

In this paper, the embedding of fiber optic sensors in metals, by using both automatic and manual Tungsten Inert Gas welding (TIG) is discussed for nickel- and copper-coated Fiber Bragg Gratings (FBG) written into an optical fiber, as embedding such sensors in metals provides protection against environmental effects. In the investigation and analysis of the performance of a number of such sensors, copper-coated sensors were seen to lose their temperature and strain sensitivity while being embedded due to damage to the coating, while with a nickel coating the sensors in the fiber were found to withstand the process with a lesser effect on the sensor performance. The research has also shown that the Automatic TIG process used is less invasive than the manual TIG approach, although more expensive to implement

Laser Cladding-based metallic embedding technique for fiber optic sensors

IEEE In many applications in industry, securely attaching fiber optic sensors to metallic structures is important for optimum monitoring, overcoming the limitations of glues and adhesives which are known to degrade under certain circumstances. To avoid that problem, creating a metallic bond to attach the sensors securely to the metal surface is important. Commercial fiber optics with metal coatings can be used but it is important not to damage the sensor itself which is written in the thin optical fiber. In this work an alternative laser cladding technology has been studied for embedding metal coated fiber optics into which Fiber Bragg Grating (FBG) sensors have been written. A three-step strategy was selected for embedding the metal coating fibers to create the best conditions to allow high quality measurements to be made. This has been seen to allow good control of the embedding process to be achieved and to minimize the thermal and mechanical stress generated. The research undetaken has shown that it is possible to embed Cu and Ni coated fiber optics containing sensors to over 300 & #x03BC;m with low losses, of between 0-1.5 dB (or 0-30%) and yet still enable satisfactory strain and temperature measurement results to be obtained. The research has shown that both Ni and Cu coated FBG-based fiber optic sensors could be embedded successfully and shown to give good mechanical and thermal response to similar non-embedded sensors and give excellent cross-comparison with the conventional gauge used for calibration. The results are therefore particularly encouraging for the use of sensors of this type when incorporated to create metallic & #x2018;smart structures & #x2019; achieving durability of the sensors through the use of this innovative technique

Nanosheets of MIL-53(Al) applied in membranes with improved CO 2 /N 2 and CO 2 /CH 4 selectivities

MIL-68(Al) and MIL-53(Al) are carboxylate-based metal-organic frameworks (MOFs) with the same chemical composition but different structures (polymorphs). In this study, MIL-53(Al) nanosheets of ca. 150 nm in size with an average thickness of 3.5 ± 0.9 nm were obtained after immersion of a sample composed of MIL-68(Al) and MIL-53(Al) in water under different conditions (ultrasound, stirring, reflux, 60 °C and room temperature). The disaggregated MIL-53(Al) nanosheets produced under more severe conditions were suspended in a PDMS solution and then deposited on asymmetric polyimide P84® supports under vacuum filtration to form supported mixed matrix membranes (MMMs). When applied to the separation of CO 2 /CH 4 and CO 2 /N 2 mixtures, the MMM with MIL-53(Al) nanosheets improved the CO 2 /CH 4 (28.4-28.7 vs. 22.4) and CO 2 /N 2 (19.9-23.2 vs. 17.5) selectivities of the conventional MIL-53(Al) MMM with higher CO 2 permeances (20.8-29.6 GPU vs. 9.5 GPU for CO 2 /CH 4 and 17.7-26.8 GPU vs. 11.2 GPU for CO 2 /N 2 )

Outstanding aspects on the use of spent FCC catalyst in binders

4 pages, 3 fiures, 7 tables.-- En: 1st Spanish National Conference on Advances in Materials Recycling and Eco – Energy Madrid, 12-13 November 2009.-- Editors: F. A. López, F. Puertas, F. J. Alguacil and A. Guerrero.FCC is a waste material from petrochemical plants which has interesting properties for preparing binders. FCC is lightly grey in color, and white FCC-portland cements with L*≥85 can be prepared. FCC reactivity is enhanced by grinding and it is attributed to pozzolanic reaction towards lime. Stratlingite is the main hydrated product from pozzolanic reaction, and CSH and CAH are also formed. Reactivity of FCC is high, and low curing temperature does not affect this contribution to strength in hardened mixtures. Additionally, high strength concrete can be easily prepared, and compressive strength greater 100MPa can be reached. Mixtures with low w/b ratio showed good behaviour in carbonation tests.Authors thank to Ministerio de Ciencia y Tecnología of Spain and FEDER the financial support of MAT 2001-2694 and BIA 2004-0052 projects.Peer reviewe

Interpenetrated polymer networks of Poly(β-cyclodextrin) and Polyvinylpyrrolidone with synergistic and selective sorption capacities

Interpenetrating polymer network (IPN) hydrogels were synthesised using β-cyclodextrin (β-CD) and N-vynil-2-pyrrolidone (NVP) crosslinked with epichlorohydrin and divinylbenzene, respectively, and prepared by four different procedures: simultaneous, sequential, hybrid and a novel one named hybrid-sequential. The IPNs prepared have been characterised by infrared spectroscopy and thermal analysis. The equilibrium swelling in water and the sorption of model substances into the IPNs have also been studied. The model sorbates (1-naphthol, 2-acetylnaphthalene and tannic acid) were selected according to the affinities towards each one of the two constituent polymers. Our studies reveal that these IPNs can be applied for the sorption of substances that can interact with the network by two mechanisms, i.e. inclusion within cyclodextrin cavities and/or via specific interactions with the functional groups present. Besides, due to the complementary character of their constituent polymers, these networks could also serve to retain two substances of different nature such as cetirizine and pseudoephedrine

Caffeine Encapsulation in Metal Organic Framework MIL-53(Al) at Pilot Plant Scale for Preparation of Polyamide Textile Fibers with Cosmetic Properties

Currently in the marketplace, we can find clothing items able to release skin-friendly ingredients while wearing them. These innovative products with high-added value are based on microencapsulation technology. In this work, due to its lightness, flexibility, porosity, chemical affinity and adsorption capacity, metal-organic framework (MOF) MIL-53(Al) was the selected microcapsule to be synthesized at a large scale and subsequent caffeine encapsulation. The synthesis conditions (molar ratio of reactants, solvents used, reaction time, temperature, pressure reached in the reactor and activation treatment to enhance the encapsulation capacity) were optimized by screening various scaling-up reactor volumes (from lab-scale of 40 mL to pilot plant production of 3.75 L). Two types of Al salts (Al(NO3)3·9H2O from the original recipe and Al2(SO4)3 as commercial SUFAL 8.2) were employed. The liporeductor cosmetic caffeine was selected as the active molecule for encapsulation. Caffeine (38 wt %) was incorporated in CAF@MIL-53(Al) microcapsules, as analyzed by TGA and corroborated by GC/MS and UV-vis after additive extraction. CAF@MIL-53(Al) microcapsules showed a controlled release of caffeine during 6 days at 25 °C (up to 22% of the initial caffeine). These capsules were incorporated through an industrial spinning process (with temperatures up to 260 °C) to manufacture PA-6 fibers with cosmetic properties. Up to 0.7 wt % of capsules were successfully incorporated into the fibers hosting 1700 ppm of caffeine. Fabrics were submitted to scouring, staining, and washing processes, detecting the presence of caffeine in the cosmetic fiber. © 2022 The Authors. Published by American Chemical Society