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Lipophilic EDTA-based ligands in different diluents for the extraction of rare earths: Preliminary results with Nd(III), Dy(III) and Pr(III) in chloride and nitrate media
No full textA separation method for the recovery of neodymium(III) from two different media, chloride and nitrate, by implementing solvent extraction technique with a novel lipophilic diamide derivative of ethylenediamine tetraacetic acid (EDTA), namely 2,2'-N,N '-didecyl-dioxo-N,N ',N '',N '''-tetraazatetratriacontane-N '',N '''-diyl diacetic acid (H2E-4C(10)), has been investigated. Initial screening results demonstrated acceptable solubility (ca. 15 mM) of the diamide in 1,3-diisopropylbenzene (DiPB) and in a 93:7 v:v n-dodecane:n-octanol mixture (DOm) as non-polar diluents. Further investigations aiming at determining operational parameters associated with the befitted extractant systems were conducted at pH ranging from 2 to 4 in chloride and nitrate media. A pH-dependent performance of the proposed systems revealed loading capacity peaking at pH = 3 with the respective values of 1.7 and 2.0 g L-1 in nitrate and chloride media. The extraction efficiency, the distribution coefficients, and the separation factor (E-%,E- D and SF, respectively) were determined for an equimolar mixture of neodymium (Nd) and two other potential competitive lanthanides, namely dysprosium (Dy) and praseodymium (Pr). The best selectivity was observed in the chloride medium at pH = 4 yielding SFNd/Pr = 1.48 and SFNd/Dy = 2.03. Neodymium-to-extractant stoichiometry was evidenced in chloroform to be 1:1 H2E:Nd at pH = 2. Thermodynamic constants related to the considered extraction equilibrium have been determined by using the Van't Hoff relation and the slope analysis method. It appeared within the selected pH-range that the mechanism of the Nd3+ transfer was strongly influenced by the nature of the diluent. This was illustrated by the enthalpy-driven transfer when Nd3+ was extracted with the H2E-4C(10)-Dom system (aliphatic diluent) while the transfer became entropy-driven when the extraction was performed with the H2E-4C(10)-DiPB system (aromatic diluent). The complexation of Nd3+ involved mainly the participation of both the amide and carboxylic functional groups. The transfer of the cation to the organic phase might occur through the formation of the Nd(HE)A(2) complex (where A is either a nitrate or a chloride anion), allowing for the lowest associated standard Gibbs free energy of transfer (-28 < Delta G degrees < -24 kJ mol(-1)) regardless of the aqueous feed
Prediction of creep degradation in Fe-Cr-Ni single-crystal alloys for high-temperature applications: a molecular-dynamics and machine-learning approach
No full textIn this paper, we investigate the creep-deformation behavior of Fe-Cr-Ni single-crystal alloys, a crucial factor in the longevity and safety of materials in high-temperature applications. Using molecular-dynamics (MD) simulations, we generate the creep-strain data on the creep behavior of Fe-Cr-Ni single-crystal alloy. To predict creep curves under various temperatures and stress conditions, we employ random forest (RF) and convolutional neural network (CNN) models. These models are trained, tested, and validated on creep data at 300 K, 750 K, 950 K, and 1150 K, achieving deviations within 20% of simulation values. The RF model demonstrates strong predictive capabilities, with correlation coefficients of 0.96, 0.96, 0.94, and 0.98 at the respective temperatures. In contrast, the CNN model shows correlation coefficients of 0.92, 0.99, 0.99, and 0.99. The results of this investigation show that both models are capable of accurately predicting creep behavior. As compared to the CNN model, which performs better at higher temperatures and with larger datasets, the RF model works better at lower temperatures and with smaller datasets. These results enhance our understanding of creep properties and improve predictive modeling under varying conditions
Recycling strategies for renewable graphite and other carbon nanomaterials from used batteries: A review
No full textRecycling spent/used batteries can solve economic and environmental issues regarding the availability of
graphite and resource depletion since the demand for graphite is growing with exponential technologies. Various
batteries, including primary (manganese, alkaline) and secondary (lithium-ion, nickel-based batteries, vanadium
redox flow batteries, sodium-sulfur batteries, lead acid batteries, electrochemical batteries, and supercapacitors),
have been taken into consideration as a source of graphite. The graphite recovered must be converted to useable
form like graphite oxide/graphene oxide or further as reduced graphene oxide for its high electrochemical
property imparted to lithium-ion batteries (LIBs) via thermal, chemical and mechanical routes. The generated
forms of graphite or carbon nanomaterials or carbon nanotubes (CNTs) have multiple merits viz., productivity,
electrical conductivity and higher capacitance, over pristine, natural and synthetic graphite. These methods have
shown high potential to prepare graphene oxide making it useful in photocatalysis, electronics, energy storage
and sensors. Apart from the processing methods, mechanism, and property evaluation, a material flow analysis of
recycling these batteries to recover graphite and the energy/cost savings are also illustrated
External Electric Field Induced Atomic Charge Migration and Surface Degradation of CsPbI3: A Reactive Molecular Dynamics Simulation based study
No full textCesium lead iodide, CsPbI3, is a promising material for solar cell manufacturing; nonetheless, it has numerous mechanical stability issues. Furthermore, due to low spatiotemporal resolution in experimental tests, the effect of several types of external loads, such as temperature and electric field-induced stresses, on the degradation mechanism of perovskite materials is poorly known. In this study, the electrical field-induced surface degradation mechanism of α, β, γ-CsPbI3 phases is simulated using advanced reactive molecular dynamics simulation. Our simulation results provide information about the rupture of atomic level unit cells and the subsequent erosion of materials from the surface (surface degradation) under the effect of an external electric field. The surface degradation is caused by electric field-induced stresses on Cs, Pb, and I atoms. The forces acting on the anion I are stronger than those acting on the cation Cs and the Pb atom. Atomic charge migration is strongly impacted by the magnitude of the electric field and the temperature of the system. Prior to surface degradation, charge migration occurs under a modest electric field. We investigated atomic charge migrations across various atoms and their unit cells. We anticipate that our findings will help researchers better understand the stability of perovskite materials under electric field and temperature-induced stress
Influence of mechanical activation on boehmite (γ-AlOOH) to γ-Al2O3 transformation: differential scanning calorimetric (DSC) analysis
No full textThe influence of mechanical activation on boehmite (γ-AlOOH) to γ-Al2O3 transformation is investigated using
differential scanning calorimetry (DSC). Boehmite prepared by the thermal decomposition of a typical Bayer
process gibbsite was mechanically activated (MA) in a planetary ball mill for different durations. The comparison
of heat flow curves of non-activated and the activated samples indicated shifting of the γ-Al2O3 transformation
endotherm towards a lower temperature. Based on peak area analysis, the enthalpy of phase transformation (ΔH)
decreased from 13.21 to 1.4 kJ/mol as the activation time increased from 0 to 240 min. The kinetic analysis
revealed a lowering of activation energy from 220 to 154 kJ/mol. A plausible explanation for the DSC results is
presented in terms of the presence of energetically different hydroxyl ions and changes in the bond character-
istics due to structural degradations occurring during MA. The nature of γ-Al2O3 formed changes with me-
chanical activation. Rietveld analysis revealed that the diffraction patterns of γ-Al2O3 are better explained if a
bimodal crystallite size distribution is assumed
Structural and thermal behaviors of iron‑based gas‑atomized powders
No full textThe present research is focused on the development of gas-atomized Fe-based amorphous alloy powders applicable for additive manufacturing of complex and critical shape components. The alloy of nominal composition Fe72.5B6Si3C4P10Cr2Mo2Mn0.5 (all in at%) was prepared as micron-sized powders by a gas atomizer (GA) under high pressure of nitrogen gas. After sieving analysis, the GA powders were separated in varying size ranges, and the particles of 25–93 μm size range were collected for further characterization. The X-ray diffraction pattern confirms a completely amorphous structure for powder particles
up to 80 μm in size and crystallinity above 80 μm in size range powders. The powders of different size ranges represent the
same glass transition temperature of 747 K and a little change in crystallization onset (801–804 K) and peak (804–806 K) temperatures with particle size. The powder particles above 80 μm in size require less activation energy for nucleation and growth of crystallites than those below that size range. The scanning electron microscopy of cross-sectional images reveals a featureless morphology in fine powders (40–55 μm), depicting its amorphous nature. In contrast, the coarser particles (~ 65 μm) represent the precipitation of crystallites in the amorphous matrix
Rhombohedral phase high-entropy alloy of AlMnCuZnBi as a photo-Fenton catalyst for methyl orange degradation
No full textThe formation of solid solutions with five or more elements having nearly equiatomic contributions termed as high entropy alloys (HEA), is recent strategy for the development of new materials. Such alloys have displayed superior properties than the conventional ones. The prepared alloys are generally face- or body-centered cubic structures with a few exceptions for orthorhombic and hexagonal close packed structure. In this, we report the synthesis of HEA of AlMnCuZnBi having rhombohedral crystal structure. The material was prepared by vacuum arc melting route. Both the diffractions (X-ray and electron) confirm its structure. The calculated thermodynamic empirical parameters e.g. Delta Smix, Delta Hmix, delta, VEC and Omega even validate the feasibility of this single phase solid solution. The HEA had shown feeble ferromagnetic behaviour. The rhombohedral structured HEA may open up new possibilities for various emerging applications. The proposed HEA acted as a catalyst for photo-Fenton like reaction and could degraded methyl orange dye completely in 170 minutes
Process upgradation and kinetic modeling of high-ash non-coking coal flotation using bio-based collector for enhanced clean coal recovery
No full textThe reduction of ash content, contributed by inorganic mineral matter,
and recovery of carbon values in a high ash non-coking coal was
studied in a laboratory-scale mechanical flotation cell using a biocollector
(PSO) derived from the pumpkin seeds for clean coal recovery.
Surface characterization of PSO (GCMS, FTIR) and untreated/PSOtreated
coal (contact angle, FTIR) indicated potential interaction
between PSO and the coal surface, enhancing its hydrophobicity,
while XRD analysis confirmed successful rejection of ash-forming
inorganic gangue minerals into tailings, signifying effective clean
coal separation from the gangue. The input parameters, such as
PSO dosage, frother MIBC dosage, and airflow rate (AFR), were
enhanced to attain best process responses, i.e. yield, ash, and fixed
carbon of the final clean coal. The use of PSO significantly reduced
the ash content of feed coal from 32% to as low as 9.86% in the final
clean coal while simultaneously increasing the fixed carbon content
from 35% to 61.15% and the gross calorific value from 4966 Kcal/Kg
to 6318 Kcal/kg. A clean coal product having high fixed carbon of
61.15% with 11.29% ash content and 70.14% yield was obtained at
PSO dosage of 10.73 Kg/t, MIBC dosage of 0.93 Kg/t and at AFR of
2.5lpm. The kinetic study revealed a high recovery of combustible
materials (~88%) and low ash recovery (~46%) at a flotation time of
480 seconds. Based on the kinetic model discrimination analysis, it
was found that the first-order fits well with the experimental data for
combustible and ash recovery. This study illustrates the efficacy of
pumpkin seed oil (PSO) as a potential bio-collector for the flotation of
non-coking coal, enhancing the coal quality by selectively reducing
mineral matter content and leading to substantial economic and
environmental advantages
Optimisation of process parameters for coal flotation using statistical technique
No full textThe ash content present in coal plays an important role in determining the quality or grade of the coal for its utilization in different industries. The maximum ash content allowed for steel grade I is 15%, while steel grade II requires ash content ranging from 15% to 18%. A sample of coking coal analysing 26.32% ash was subjected to froth flotation to reduce its ash content to below 18%. Optimization of flotation process parameters such as collector, frother dosages and airflow rate, was carried out using factorial design of experiments.
It was observed that the interaction of collector and frother dosages had the most significant impact on achieving the desired ash rejection, with collector dosage also playing an important role. Optimum process parameters identified are collector dosage of 0.0348 kg/t, 0.005 kg/t frother dosage and 2 lpm airflow rate, wherein the ash content of the sample was reduced to 14.58% from 26.32%
Special Issue on Corrosion and Coating Technology
No full textCorrosion causes the deterioration of metals and alloys by
the chemical or electrochemical reaction with their surrounding or service environment. During the process of corrosion, the candidate alloy which generates electrons accompanied by loss of metal ions becomes an anode whereas the electrode at which electrons are consumed by the chemical species (such as H+ and O2) becomes a cathode in corrosive media. While corrosion is one among the several factors that cause the failure of the components, it is often the only life-limiting attribute. Failure of the components and infrastructures due to corrosion and associated reasons enormously impacts the industries and society at large