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Corrosion behavior of strontium-modified Al-12Si cast alloys in flowing and stagnant chloride-containing media
No full textThe Al-12Si alloy was modified with strontium varied from 0.1% to 0.35% in order to unveil its effect on corrosion resistance in static as well as in flowing solution with and without 3.5% NaCl at pH-11. The Sr contents up to 0.18% changed the eutectic morphology to a fine fibrous network beyond which, the acicular silicon began to emerge. The corrosion resistance of both modified and unmodified Al-12Si alloy during flow reduced to as low as 30% of that observed during static conditions. The 0.25% Sr containing alloy exhibited superior corrosion resistance to other variants including unmodified alloy. The Raman spectroscopy and XRD analyses of corrosion products unveiled the presence of bayerite on both unmodified and modified Al-12Si alloys, irrespective of the presence of Cl- in the solution. The Sr additions, except 0.25%, degrade the corrosion resistance of Al-12Si alloy in both flow and static conditions. The corrosion resistance of 0.25% Sr is correlated to the evolution of thicker and different oxide morphology along with the presence of relatively large silicon on the surface after corrosion
Recent trends in eco-sustainable recycling of energy-critical elements from low-grade and secondary resources
No full textEnergy critical elements (ECEs) are essential for improved generation, transmission, and storage of energy. It is important to note that by 2050 around 3 billion tonnes of minerals and metals will be required to decarbonize the energy system (Akcil et al. 2020). As such, the risk of an adequate supply of these elements could limit their deployment in advanced technologies e.g. in the manufacturing of solar panels, wind turbines, and batteries (Huber and Steininger 2022; IEA 2021a). In contrast to conventional hydrocarbon resources, an energy system driven by clean energy technologies differs quite in terms of the usage of minerals. For example, electric vehicles (EVs) need six times more minerals than conventional fuel-based cars, and building an onshore wind plant would require nine times more inputs of minerals than a conventional gas-fired plant (IEA 2021b). This indicates the importance and the urgent requirement for securing a sustainable supply of ECEs in the current scenario. Since natural resources of such metals are either very less or are depleting, utilization of secondary wastes, for example, electronic wastes has gained rapid momentum. Overall, the management of mineral-metal-containing wastes and the establishment of proper recycling techniques for resource recovery have become highly essential (Fujita et al. 2022; Mishra et al. 2023; Shahabuddin et al. 2023). It will not only serve as a tool for waste management but also contribute to environmental remediation and the circular economy aspects (Marafi and Stanislaus 2008; Panda and Akcil 2021)
Aluminum nanotubes as an efficient catalyst for hydrogen production via thermochemical water splitting: a reactive molecular dynamics simulation
No full textWater splitting is the process of using energy to break down water molecules into hydrogen and oxygen. The use of an aluminum catalyst in the thermochemical process can help to increase the efficiency and rate of the reaction. Furthermore, aluminum is a relatively inexpensive material that can be easily produced, making it an appealing option for use in large-scale water-splitting operations. We investigated the reaction mechanism between aluminum nanotubes and water at various temperatures using reactive molecular dynamic simulations. We found that an aluminum catalyst makes it possible to split water at temperatures higher than T > 600 K. It was also observed that the yield of H2 evolution is dependent on the diameter of the Al nanotube and decreases with increasing size. During the process of splitting water, the inner surfaces of the aluminum nanotubes are seen to be severely eroded, as shown by changes in the aspect ratio and solvent-accessible surface area. In order to compare the H2 evolution efficiency of water with other solvents, we also split a variety of solvents, including methanol, ethanol, and formic acid. We presume that our study will give researchers enough knowledge to create hydrogen through thermochemical process in the presence of an aluminum catalyst by dissociating water and other solvent molecules
A Comprehensive Review on Occurrence and Processing of Phosphate Rock Based Resources- Focus on REEs
No full textIn general, the phosphatic rock contains around 0.05 wt% rare earth elements (REEs). The global commercial phosphatic rock output is anticipated to obtain 250 million tons per year, making phosphate rocks a significant source of REEs. The review discusses the geological aspects of phosphate rocks, their availability, and methodologies to convert them to phosphoric acid and ultimately to phosphogypsum. Phosphogypsum (PG) is a high-volume by-product of phosphate-based chemical industries that produce phosphoric acid. Because of the low radioactivity of radionuclide contaminants, roughly 85% of PG is stored in open fields. These PG stacks require enormous land areas, cause substantial upkeep expenses, and may create major environmental damage. Apart from the detailed analysis of metal worth in phosphogypsum, the efforts put forth by researchers in recovering valuable rare earth elements from PG have been discussed. Additionally, the processes for metal separation and purification are also discussed in vogue
Boron Containing Low Carbon Deep Drawing Continuous Annealed Steel Sheet with Improved Plastic Anisotropy
No full textIn current market scenario, cold-rolled steel sheets need high quality requirements to suit the continuous automated forming process for manufacturing components of diverse end applications. Deep drawability, which is one of the crucial property of steel for forming application, is influenced by factors like alloy chemistry, microstructure, texture evolution and precipitation characteristics. All these microstructural factors are in turn affected directly by the annealing process employed. In the present study, specially designed continuous annealing process has been employed to assess the influence of boron to nitrogen (B/N) ratio (0-0.87)on mechanical and drawing properties of low carbon (0.03-0.035 wt %), low manganese (0.15-0.18 wt%) and low sulphur (0.005-0.008 wt%) steel. Steel with B/N ratio of 0.185resulted into best combination of properties in terms of lowest YS/UTS ratio (0.81),high plastic anisotropy (r(m):1.545) along with 310 MPa yield strength, 380 MPa ultimate tensile strength, 20% uniform elongation and 32% total elongation. It has been found that the B/N ratio, rather than the absolute boron, influences the precipitation characteristics of carbides and favorable texture development during continuous annealing process
Reaction, structure and properties of eco-friendly geopolymer cement derived from mechanically activated pumice
No full textThe suitability of pumice, an altered volcanic rock, for the synthesis of geopolymer cement has been investigated. The reactivity of pumice was improved by mechanical activation (MA) in a stirred media mill for various rotor speeds (3 and 5 m/s) and residence times (ranging from 1 to 10 min), respectively. MA resulted into increase in specific surface area (SSA). The effect of SSA of pumice on reactivity is evident from the increase in lime adsorption capacity, which increased from 70.7 mg CaO/g solid material to 234.7 mg CaO/g solid material and the area under the calorimetric peak which increased from 4 mJ to 16.6 mJ and from 9.3 to 27.2 mJ at 27 and 60 degrees C aging temperatures, respectively. X-ray powder diffraction (XRD) revealed that amorphization increased up to 7% as a result of MA on the particles. Amorphous content has further increased by another 2% after geopolymerization, which can be attributed to consumption of quartz which formed reaction products. A positive correlation has been found between milling time, area under calorimetric peak and compressive strength. Geopolymer with the highest strength (13.8 MPa) was made using pumice with the highest SSA (3838 cm2/g). These results are encouraging and point to the significant potential of the use of pumice as an alternative material to develop an eco-friendly geopolymer cement that contributes toward reducing the carbon dioxide emission associated with the cement production
Na2ZrFe(PO4)(3)-A Rhombohedral NASICON-Structured Material: Synthesis, Structure and Na-Intercalation Behavior
No full textA NASICON-structured earth-abundant mixed transition metal (T-M) containing Na-T-M-phosphate, viz., Na2ZrFe(PO4)(3), has been prepared via a sol-gel route using a low-cost Fe3+-based precursor. The as -prepared material crystallizes in the desired rhombohedral NASICON structure (space group: R (3) over barc) at room temperature. Synchrotron X-ray diffraction (XRD), transmission electron microscopy, X-ray absorption spectroscopy, etc., have been performed to determine the crystal structure, associated details, composition, and electronic structures. In light of the structural features, as one of the possible functionalities of Na2FeZr(PO4)(3), Na-intercalation/deintercalation has been examined, which indicates the occurrence of reversible electrochemical Na-insertion/extraction via Fe2+/ Fe3+ redox at an average potential of similar to 2.5 V. The electrochemical data and direct evidences from operando synchrotron XRD indicate that the rhombohedral structure is preserved during Na-insertion/extraction, albeit within a certain range of Na-content (i.e., similar to 2-3 p.f.u.), beyond which rhombohedral -> monoclinic transformation takes place. Within this range, Na-insertion/extraction takes place via solid-solution pathway, resulting in outstanding cyclic stability, higher Na-diffusivity, and good rate-capability. To the best of the authors' knowledge, this represents the first in-depth structural, compositional, and electrochemical studies with Na2ZrFe(PO4)(3), along with the interplay between those, which provide insights into the design of similar low-cost materials for various applications, including sustainable electrochemical energy storage systems
Mesoporous Fe3O4 nanoparticle: A prospective nano heat generator for thermo-therapeutic cancer treatment modality
No full textIn the present work, we have synthesized Fe3O4 MNPs with a mesoporous feature by the solvothermal process. Through iteration of experiments, we found that the specific solvent helped in stabilizing the mesoporous structure. We have used techniques, such as transmission electron microscopy (TEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) to study the structural features of the sample. The material demonstrated effective heating under an alternating magnetic field (AMF), and the concentration of aqueous ferro-fluid influences the same. The experimental intrinsic loss power (ILP) value of ∼ 5.30 ± 0.25 nHm2kg−1 is suggestively higher than the commercially available ferro-fluids and equivalent to previously reported values for iron oxide MNPs. The material demonstrated an impressive heating performance under near infra-red (NIR) irradiation with a concentration as small as 0.1 mg/mL. The photoluminescence (PL) spectroscopy has allowed corroborating the efficient heating behaviour of the material under NIR irradiation. An effective decrease in SiHa cells viability was observed after NIR exposure with concentration of 250 and 500 μg/mL of MNPs. We believe this work will pave a new pathway in the area of biomaterials thermo-therapeutic cancer treatment with improved efficacy via mesoporous structure, efficient heating under NIR exposure and high ILP value
Mineralogical Characteristics of Hematitic Iron Ore: A Geometallurgical Study on Ore from Eastern India
No full textAfter being subjected to geometallurgical evaluation, the iron ores from Singhbhum Bonai-Keonjhar region, eastern India, have been designated as dense martite microplaty hematite high-strength ore (dM-mH-hs ore), massive dense martite microplaty hematite high-strength ore (mdM-mH-hs ore), schistose microplaty hematite low-strength ore (smH-ls ore), microplaty hematite powdery ore (mH-p ore), vitreous goethitic ore (vG ore), and ochreous goethitic ore (oG ore) end members, with varied strengths attributed to the microporosity levels. The first four variants form typical high-grade run-of-mines (ROMs) (hard, soft and powdery iron ore variants, e.g., ROM-HIO, ROM-SSIO, and ROM-PBD, respectively) with better amenability to beneficiation. In contrast, oG and vG ore end members form ROM lateritic iron ore (ROM-LIO) with poor amenability to beneficiation, having relatively higher concentrates of alumina (similar to 3-6 wt%) due to the complex mineral chemistry of goethite and altered hematite. Banded hematite jasper (BHJ) is a very low-grade siliceous end member. In a mining operation, the ROMs may have the attributes of several combinations of the above-stated end members and ROM variants. The designated end members present in the ROMs determine their liberation, mineralogical processes, geometallurgical characteristics, amenability to beneficiation, product grade and recovery
MnNCN@C nanocomposite as an anode for Li-ion battery
No full textIn order to find other anode materials for lithium-ion batteries, manganese carbodiimide with N-doped C coating (MnNCN@C) has been reported. Initially a gel of precursors was prepared and then calcined for 1.5 h at 700 degrees C in the atmosphere of N2. The MnNCN phase was identified by X-ray diffraction, X-ray Photoelectron Spectroscopy (XPS) and electron diffraction. Further, carbon phase was established by transmission electron microscopy (TEM), FTIR and Raman spectroscopy. The doping of N in carbon phase was confirmed from XPS study. Distribution of pore size as well as specific surface area of MnNCN@C composites were investigated from the BET technique, and their values were 9.19 x 103cm2/g and 7.512 nm, respectively. The cell with this material as anode could be cycled for 100 times. After 100 cycles, the capacity turns out to be around 200 mAh/g. However, the cell was capable to deliver suitable capacity at even higher currents