Optimization of the Leaching Kinetics for Uranium Recovery from a Boltwoodite Ore as Emerging Solution to Nigerian Power Sector

The continuous rise of the population cum standard of living has resulted in Nigerians looking for a profound solution to the fast-growing demand for electrical energy with sustainability concerns including greenhouse gas emissions limitation. Thus, the investigation of uranium leaching kinetics and thermodynamics has become one of the most crucial topics in leach technology, where many distinct results have been obtained. In this study, the influence of sulfuric acid concentration, reaction temperature, solid-to-liquid ratio, and leaching time were all investigated. At established experimental conditions (2.5 mol/L H2SO4, 75 degrees C, 75 mu m), the uranium ore dissolution efficiency recorded was 89.1% within 120 min. The kinetic and thermodynamic tests of the leaching process coupled with the reaction mechanism between sulfuric acid and uranium were discussed. Hence, the results confirm that the dissolution mechanism of uranium was diffusion-controlled, exothermic, and spontaneous

Coal derived highly fluorescent N-Doped graphene quantum dots with graphitic and chemisorbed nitrogen

Graphene quantum dots (GQDs) constitute a novel category of quantum dots distinguished by their distinctive properties. The introduction of nitrogen heteroatom in GQD is an effective strategy for tuning its intrinsic properties and band gap toward its optoelectronic application. This work explores the synthesis and characterization of nitrogen-doped graphene quantum dots (N-GQDs) derived from low-cost precursor coal. The synthesized N-GQD contains both graphitic and chemisorbed nitrogen states along with pyrollic and pyridinic nitrogen states which is the key responsible factor for excellent photoluminescence properties. The excitation dependent photoluminescence of the synthesized N-GQD exhibited excellent emission at 520 nm in neutral and basic pH due to the additional conjugation provided by the doped nitrogen on the surface and functional groups as well. The pH dependent photophysical properties support the existence of doped graphitic and chemisorbed nitrogen states which is also well supported by the high resolution N1s XPS peaks at 402 eV (graphitic N) and 406 eV (chemisorbed N/N2). DFT calculations further showed the decrease in fermi energy level by introducing chemisorbed-N. TEM analysis evident the formation of quantum dots with an average diameter of 3 - 7 nm with d-spacing of 0.20-0.34 nm. Additionally, the cyclic voltammetry analysis of the synthesized N-GQDs sheds light on the participation of doped nitrogen in redox reactions

Graphite from Dead Li-Ion Batteries: A "Powerful" Additive for Fabrication of High-Performance Li-Ion Capacitors

Lithium-ion capacitors (LICs) are considered a promising next-generation energy storage system with high energy density and power capability. The conductive additive is a passive and indispensable material in deciding the electrochemical performance of an energy storage device during high current charging and discharging processes. The incorporation of a suitable conductive additive into the layers of an electrode improves electronic conductivity. It reduces the internal resistance and polarization of the electrode resulting in the enhanced performance of the charge-storage system. Herein, recovered graphite (RG) is reported from dead Li-ion batteries as an excellent conductive additive that can improve the electronic conductivity of the electrode material. Compared with commercial conductive additive acetylene black (AB), the TiO2 anode material with 5% RG delivered a high discharge capacity of 163 mAh g-1 at a current rate of 0.15 A g-1 with a coulombic efficiency of approximately to 99% after 500 cycles in half-cell assembly. The fabricated AC/TiO2@5%RG LIC displays an excellent electrochemical performance with a maximum energy density of approximately to 50 Wh kg-1 at a current density of 0.15 A g-1. Notably, the LIC rendered promising performance at different temperature conditions (0, 10, 25, and 50 degrees C). The role of graphitic and amorphous carbonaceous materials is explored as potential additives and their application to the Li-ion capacitor, especially for high rates. The graphitic carbon is recovered from the spent Li-ion battery and milled with TiO2 hybrid. imag

Low-Energy Processing of a Local Boltwoodite Ore as Intermediate in Nuclear Fuel Cell

The industrial demand for pure uranium and uranium compounds is tremendously increasing due to its wide array of utilities most especially in nuclear industries. Consequently, the treatment of a local boltwoodite ore containing albite (Na2.00Al2.00Si6.00O16.00: 96-900-1634), boltwoodite (Na2.00K2.77U3.00Si6.00O9.00H4.00: 96-900-7219), thorite (Th4.00Si4.00O16.00: 96-9007625), and quartz (Si6.00O6.00: 96-900-5019) was examined in sulphuric acid media. The experimental parameters such as leachant concentration, reaction temperature, and particle size on uranium ore dissolution were investigated. At optimal leaching conditions (2.5 mol/L H2SO4, 75 degrees C, and 75 mu m), an 89.1% dissolution rate was achieved within 120 min. The estimated activation energy of 20.70 kJ/mol supported the diffusion control reaction mechanism as the rate-determining step. The leach liquor obtained at established conditions was further beneficiated to produce an industrial grade sodium diuranate (Na2U2O7: 00-064-0473, density = 6.51 g/cm(3), melting point = 1654 +/- 2 degrees C) proposed to serve as intermediate raw-material in a nuclear fuel cell

Environmental Impact Assessment in the Entire Life Cycle of Lithium‑Ion Batteries

The growing demand for lithium-ion batteries (LIBs) in smartphones, electric vehicles (EVs), and other energy storage devices should be correlated with their environmental impacts from production to usage and recycling. As the use of LIBs grows, so does the number of waste LIBs, demanding a recycling procedure as a sustainable resource and safer for the environment. This review paper analyses and categorizes the environmental impacts of LIBs from mining their constituents, their usage and applications, illegal disposal, and recycling. Compared to recycling, reusing recovered materials for battery manufacturing would lessen the environmental footprints and reduce greenhouse gas emissions (GHG) and energy consumption. Thus, to prevent pollution and safeguard the environment, it is necessary to consider recycling spent LIBs and improving production and disposal methods. The present study offers a comprehensive overview of the environmental impacts of batteries from their production to use and recycling and the way forward to its importance in metal replenishment. The life cycle assessment (LCA) analysis is discussed to assess the bottlenecks in the entire cycle from cradle to grave and back to recycling (cradle)

Sour Service Domains of 13Cr Martensitic Stainless Steels: A Review of State-of-Art Knowledge vis-à-vis ANSI/NACE MR0175/ISO 15156

Hydrocarbons, water, carbon dioxide, hydrogen sulfide, chloride, high temperatures, and pressures are all involved in oil and gas production. Thus, corrosion, particularly sulfide stress cracking (SSC), poses a great threat to the integrity of well components such as tubing, casing, packer, and wellhead assembly. Sometimes, SSC can lead to catastrophic failures and must be addressed due to operational security and environmental concerns. Localized corrosion, including SSC, can be reduced greatly with the appropriate material selection and optimization of critical operational parameters. The material selection is performed according to service environments vis-a-vis mechanical/ metallurgical attributes of the alloys as prescribed in standards such as API 5CT and ANSI/NACE MR0175/ISO 15156. Currently, corrosion-resistant alloys (CRAs) such as martensitic and duplex stainless steels, nickel, titanium and other precipitation hardened alloys are available and used in oil and gas industries because of their superior mechanical and corrosion properties. Owing to the operating environmental reasons, designer often opt for more expensive CRAs as compared to relatively less expensive materials which fall close to the performance boundary of materials selection criteria, thereby increasing overall cost of crude oil production. Thus, there is a paramount requirement to ascertain the candidate materials appropriately without bearing the cost penalties of over-specifications or the performance shortfalls of under-specified alloys when new fields are discovered. In this paper, the application domains of 13Cr martensitic stainless steels are reviewed vis-a-vis limits prescribed in ANSI/NACE MR0175/ISO 15156 standard. The paper will aid in the selection of cost-effective materials for oil and gas production when temperature, pressure, hydrogen sulfide concentration, pH, and salinity vary in different directions and cannot be well defined within standard limits

Engineering lithium nickel cobalt manganese oxides cathodes: A computational and experimental approach to bridging gaps

Lithium-ion batteries (LIBs) have transformed our envisioned future into a reality where induction motor engines power electric vehicles (EVs). While LIBs offer impressive advantages compared to other energy storage systems for EVs, they face practical deployment challenges in performance, cost, and scalability. One critical component of LIBs that has garnered significant attention is the cathode, primarily due to its high cost, stemming from expensive cobalt metals and limited capacity, which cannot meet the current demand. However, layered lithium nickel cobalt manganese oxide (NCM) materials have achieved remarkable market success. Despite their potential, much current research focuses on experimental or theoretical aspects, leaving a gap that needs bridging. Understanding the surface chemistry of these oxides and conducting operando observations is crucial. Combining advanced surface analysis techniques with theoretical calculations (viz., quantum mechanics) is proposed to bridge this knowledge gap. This review delves into recent performance achievements (viz., projected driving performance, current EVs model, and battery specifications), challenges, and opportunities associated with various NCM materials as cathode materials. It also explores cutting-edge developments in experimental and theoretical techniques that analyze battery operations, address frontier challenges, and provide novel insights. Furthermore, the review comprehensively discusses the concept of single-crystal (SC) NCM and its practical implications in EVs. Finally, the review provides an outlook on future guidelines for designing NCM cathodes for LIBs, emphasizing the convergence of experimental and computational/theoretical approaches to achieve superior performance

Experimental and numerical study on the fatigue behaviour of pre and post heat treated additively manufactured SS 316L specimens

The success of 3D printing relies on developing components with desired strength that heat treatment processes can further improve. While SS 316L is a widely used structural material for several industrial applications, the fatigue behaviour of its 3D-printed version is investigated herein. The low cycle fatigue (LCF) behaviour of heat-treated (HT) 3D-printed SS 316L specimens was carried out and compared with the without heat-treated (WHT) specimens thereof. The heat treatment considerably affected its LCF behaviour, which can be attributed to the microstructural changes post heat treatment. The cyclic softening is observed in both HT and WHT specimens. However, the degree of softening is lower (12.35 %) for HT compared to WHT specimens (25.30 %) and 62 % higher fatigue life for HT compared to WHT specimens. Further, the hardness values obtained are 176 and 169 HV for WHT and HT, respectively, while it is 238 and 223 HV for the same, before and after fatigue tests. Fractography revealed fewer pores and reduced fatigue striations in the HT specimens. Considering the Chaboche non-linear model, finite element modelling was employed to capture the specimens' fatigue behaviour. The proposed model is found to be suitable for predicting the cyclic behaviour of 3D-printed austenitic steels

Special Issue on Corrosion and Coating Technology

Corrosion 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

Mini-Review on Organic Electrode Materials: Recent Breakthroughs and Advancement in Metal Ion Batteries

Redox-active organic materials/composites/polymers for next-generation energy storage systems have attracted significant attention for developing cost-efficient, lightweight, flexible, and sustainable batteries. Organic electrode materials (OEMs) can provide several advantages over traditional inorganic ones, such as increased energy density, improved cycle life, tunable energy storage and voltage output, and structural diversity. Herein, an in-depth knowledge of OEMs developed from carbonyl and conducting polymers is highlighted. The challenges and latest scientific strategies to build better organic batteries like covalent organic frameworks (COFs), donor-acceptor, and all acceptor-type material-based electrodes, modified electrolytes, organic-inorganic hybrids electrolytes, ceramic-type electrolytes, COF-based electrolytes, and organic liquid electrodes are highlighted. This Review also covers a brief overview of the present electrolytes and the recent advances in the field of electrolytes like organic-inorganic hybrids, ceramic-type electrolytes, and COFs-based electrolytes and their improvement directions