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19 pages, 9914 KiB

Open AccessArticle

Lithium Orthosilicate Solid Porous Membranes for CO₂ Capture Obtained from Silica Microfibers

by Joaquín Penide, Efstratios Stavrakakis, Félix Quintero, Danai Poulidi, Antonio Riveiro, Jesús del Val, Rafael Comesaña, Fernando Lusquiños and Juan Pou

Fibers 2025, 13(5), 59; https://doi.org/10.3390/fib13050059 - 7 May 2025

Viewed by 910

Abstract

Lithium orthosilicate (Li₄SiO₄) has demonstrated a high CO₂ adsorption rate and capacity and its suitability to be implemented in industry as CO₂ capture technology at high temperatures. The optimum solid adsorbent should present a porous structure to maximize surface and enable a high sorption rate. In this work, we present an original approach based on the use of a novel architecture of precursors in the form of very thin free-standing solid silica fibers. An original technique called continuous fiberizing by laser melting (Cobiflas) was used to obtain membranes of pure silica fibers with diameters in the micrometer range, forming a porous membrane which offer a high surface and porous connectivity to be used as precursors without any supporting substrate. Then, we employed a method based on the impregnation of the silica fibers within a lithium-containing aqueous solution and subsequent calcination to obtain a porous solid adsorbent with the maximum proportion of lithium orthosilicate. This method is compared with the results obtained using a sol-gel powder method by analyzing their composition using X-Ray Diffraction (XRD), and their adsorption capacity and adsorption kinetics by Thermogravimetric analyses (TGA). As a result, an outstanding type of solid adsorbent is reported with a 31% adsorption capacity and a total regeneration capacity, which is over 0.8 efficiency with regard to the theoretical maximum adsorption of this material. Full article

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13 pages, 3270 KiB

Open AccessArticle

Mercury Removal from Mining Wastewater by Phytoaccumulation in Autochthonous Aquatic Plant Species

by Franco Hernan Gomez, Maria Cristina Collivignarelli, Ahmed Mohammad Nafea Masoud, Marco Carnevale Miino, Kelly Cristina Torres, Jesus Antonio Quintero, Sabrina Sorlini and Mentore Vaccari

Clean Technol. 2023, 5(3), 839-851; https://doi.org/10.3390/cleantechnol5030041 - 27 Jun 2023

Cited by 6 | Viewed by 3316

Abstract

Mining wastewater (MWW) can contain mercury in high concentrations. In this study, four autochthonous aquatic plant species (Eichhornia Crassipes—EC, Marsilea Quadrifolia—MQ, Ludwigia Helminthorrhiza—LH, and Lemna Minor—LM) were identified and tested for phytoaccumulation of total mercury (THg). To better study the accumulation phenomenon and macrophyte responses, this work has been divided into three phases, and pilot-scale reactors have been used to simulate real conditions. The results highlighted that, in case of 15 µg_THg,fed, the bioconcentration factor (BCF) was significantly higher in EC (19.04) and LH (18.41) with respect to MQ and LM (almost six times and two times higher, respectively). EC granted the best results in terms of THg accumulation (50.90%) and lower evapotranspiration of THg phenomenon with respect to LH. A significant decrease of the BCF (from 23.45 to 21.98) and an increase of the TF (from 0.23 up to 0.73) after 42 d highlighted that a breaking-time in terms of THg accumulation was reached due to the deterioration of the roots. In terms of the kinetics of THg removal by bioaccumulation, an HLT of 69.31 d was found, which is more than the breaking-time of the EC system, proving that a periodic replacement of exhausted macrophytes is required to obtain a higher percentage of THg removal. Full article

(This article belongs to the Collection Water and Wastewater Treatment Technologies)

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11 pages, 3716 KiB

Open AccessArticle

Characterization of Fe₃O₄ Nanoparticles for Applications in Catalytic Activity in the Adsorption/Degradation of Methylene Blue and Esterification

by Juan Sebastian Trujillo Hernandez, Alberto Aragón-Muriel, Willinton Corrales Quintero, Juan Camilo Castro Velásquez, Natalia Andrea Salazar-Camacho, German Antonio Pérez Alcázar and Jesús Anselmo Tabares

Molecules 2022, 27(24), 8976; https://doi.org/10.3390/molecules27248976 - 16 Dec 2022

Cited by 9 | Viewed by 2250

Abstract

The aim of this study is to evaluate the applicability of the catalytic activity (CA) of the Fe₃O₄ magnetic system in the adsorption/degradation of methylene blue and esterification. The thermal decomposition method allowed the preparation of Fe₃O₄ nanoparticles. The crystallites of the Fe₃O₄ structural phase present an acicular form confirmed by X-ray diffraction. Transmission electron microscopy results identified the acicular shape and agglomeration of the nanoparticles. Mössbauer spectroscopy showed that the spectrum is composed of five components at room temperature, a hyperfine magnetic field distribution (HMFD), two sextets, a doublet, and a singlet. The presence of the HMFD means that a particle size distribution is present. Fluorescence spectroscopy studied the CA of the nanoparticles with methylene blue and found adsorption/degradation properties of the dye. The catalytic activity of the nanoparticles was evaluated in the esterification reaction by comparing the results in the presence and absence of catalyst for the reaction with isobutanol and octanol, where it is observed that the selectivity for the products MIBP and MNOP is favored in the first three hours of reaction. Full article

(This article belongs to the Special Issue 2D Nanomaterials and Composites for Energy and Environmental Sustainability)

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11 pages, 8085 KiB

Open AccessArticle

Laser Surface Blasting of Granite Stones Using a Laser Scanning System

by Joaquín Penide, Jesús del Val, Antonio Riveiro, Ramón Soto, Rafael Comesaña, Félix Quintero, Mohamed Boutinguiza, Fernando Lusquiños and Juan Pou

Coatings 2019, 9(2), 131; https://doi.org/10.3390/coatings9020131 - 19 Feb 2019

Cited by 6 | Viewed by 5446

Abstract

Granite stones are the most abundant rock of the crust. Due to their beauty, durability, and virtually zero maintenance, they have been used widely since ancient times in all types of construction, as a structural or decorative element. Commonly, this material is used with a polished finishing, but there has been an increased interest in giving it a rustic aspect, mainly for decorative or functional reasons, e.g., to reduce slipping. Rough surfaces are usually produced by means of bush hammering, but this is an extremely noisy and inefficient process. In this work we have explored the capabilities and limits of a laser blasting process assisted by a scanning system in order to produce precise and controllable roughness on two varieties of granite plates. It was found that laser blasting of thin granite tiles can be accomplished with processing widths up to 250 mm at medium-low laser power, obtaining a rustic aspect suitable for use in façades, paving, or flooring. Moreover, laser scanner systems are capable of enhancing the productivity of this process up to ten times greater than that found in previous works. Full article

(This article belongs to the Special Issue Surface Treatment by Laser-Assisted Techniques)

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12 pages, 4711 KiB

Open AccessArticle

Laser Microdrilling of Slate Tiles

by Joaquín Penide, Antonio Riveiro, Ramón Soto, Mohamed Boutinguiza, Felipe Arias-Gonzalez, Jesús del Val, Rafael Comesaña, Fernando Lusquiños, Félix Quintero and Juan Pou

Materials 2019, 12(3), 398; https://doi.org/10.3390/ma12030398 - 28 Jan 2019

Cited by 5 | Viewed by 3562

Abstract

Slate is a natural rock usually used in roofs, façades, and for tiling. In spite of this broad use, the production process of slate tiles requires substantial improvements. An important quantity of slate from the quarry is wasted during the manufacturing of the final product. Furthermore, processes are not automatized and the production lead times can be considerably shortened. Therefore, new processing methods to increase productivity, reduce costs and to provide added value to the final slate product are required. Drilling is an important part of these manufacturing processes. Conventional drilling processes usually cause the breaking of the slate tiles; then, even a higher quantity of material is wasted. To overcome these problems, lasers emerge as a feasible tool to produce holes in this material, since mechanical stresses are not induced on the workpiece. In this work, we have studied the CO₂ laser microdrilling of slate tiles. We used a Design of Experiments (DOE) methodology to determine the influence of the laser processing parameters on the hole quality. This work demonstrates the capability of a CO₂ laser to produce holes in slate with less than 100 microns in diameter, avoiding any fracture, and with a processing time of less than 50 ms per hole. Finally, this process demonstrates the viability of the production of high-density micron-sized holes in a slate tile for water draining purposes. Full article

(This article belongs to the Special Issue Laser Materials Processing 2019)

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31 pages, 6618 KiB

Open AccessReview

Laser Cutting: A Review on the Influence of Assist Gas

by Antonio Riveiro, Félix Quintero, Mohamed Boutinguiza, Jesús Del Val, Rafael Comesaña, Fernando Lusquiños and Juan Pou

Materials 2019, 12(1), 157; https://doi.org/10.3390/ma12010157 - 6 Jan 2019

Cited by 84 | Viewed by 15133

Abstract

Assist gas plays a central role in laser fusion cutting. In this work, the aerodynamic interactions between the assist gas and the workpiece are reviewed. An insight into those phenomena that hinder the cutting quality and performance is provided. These phenomena include shock waves, choking, boundary layer separation, etc. The most relevant and promising attempts to overcome these common problems related to the gas dynamics are surveyed. The review of the current scientific literature has revealed some gaps in the current knowledge of the role of the assist gas dynamics in laser cutting. The assist gas interactions have been investigated only under static conditions; and the dynamic interaction with the molten material on the cutting front has not been addressed. New nozzle designs with improved efficiency of molten material removal are required to improve cut quality; and cutting speed in current industrial laser cutting machines; especially in those assisted by new high-brightness laser sources. Full article

(This article belongs to the Special Issue Hybrid Additive Manufacturing and Machining Machine-Tools and Processes)

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