Reductant Research Articles

One-ElectronNO to N2O Pathways via Heme Models and Lewis Acid: Metal Effectsand Differences from the Enzymatic Reaction.

Some pathogens use heme-containing nitric oxide reductases (NORs) to reduce NO to N2O as their defense mechanism to detoxify NO and reduce nitrosative stress. This reduction is also significant in the global N cycle. Our previous experimental work showed that Fe and Co porphyrin NO complexes can couple with external NO to form N2O when activated by the Lewis acid BF3. A key difference from conventional two-electron enzymatic reaction is that one electron is sufficient. However, a complete understanding of the entire reaction pathways and the more favorable reactivity for Fe remains unknown. Here, we present a quantum chemical study to provide such information. Our results confirmed Fe's higher experimental reactivity, showing advantages in all steps of the reaction pathway: easier metal oxidation for NO reduction and N-O cleavage as well as a larger size to expedite the N/O coordination mode transition. The Co system, with a similar product energy as the enzyme, shows potential for further development in catalytic NO coupling. This work also offers the first evidence that this new one-electron NO reduction is both kinetically competitive and thermodynamically more favorable than the native pathway, supporting future initiatives in optimizing NO reduction agents in biology, environment, and industry.

Sulfuric Acid Leaching Recovery of Rare Earth Elements from Wizów’s Phosphogypsum in Poland

Rare earth elements (REEs) are considered vital raw materials for the economy and are on the European Union’s list of critical raw materials (CRMs). Europe is mainly dependent on REE imports. This dependence could be reduced if locally available primary or secondary resources would be processed. In Poland, there are, for instance, over 5 million metric tons of phosphogypsum (PG), a fine powdery byproduct from the fertilizer industry, available near the former Wizów Chemical Plant near Bolesławiec. This material that is considered a waste in Poland contains significant amounts of REEs that could theoretically be recovered and contribute to Europe’s economy. This work is the first systematic analysis of REE leaching studies with sulfuric acid and PG from Wizów. Process parameters such as temperature, particle size, concentration of the leaching solution, and the addition of oxidant and reductant agents were tested to determine the most efficient process. Ultimately, a leaching efficiency of 99% was obtained. Lanthanum exhibited the highest leaching efficiency at almost 100%, followed by Yttrium, Neodymium, Terbium, and Dysprosium. The results of the laboratory experiments are promising and suggest that larger pilot or commercial experiments can be performed next.

Direct regeneration of LiFePO4 cathode by inherent impurities in spent lithium-ion batteries

The direct regeneration method, recognized for its cost-effectiveness, has garnered considerable attentions in the field of battery recycling. In this study, a novel direct regeneration strategy is proposed to repair spent LiFePO4 (S-LFP) cathodes without the need for impurity removal. Instead, the residual conductive carbon and polyvinylidene fluoride (PVDF) in S-LFP are employed as inherent reductive agents. Systematic characterization and analysis reveal that the failure of S-LFP primarily originates from a substantial loss of Li+ and the conversion of LiFePO4 to FePO4. Meanwhile, it is demonstrated that both residual conductive carbon and PVDF play positive roles in promoting the regeneration of S-LFP through distinct mechanisms. As a result, the regenerated LFP exhibits significant recovery in crystal structure and chemical composition as compared to S-LFP, which leads to notably improved lithium storage performance. Furthermore, to further enhance the lithium storage property, a specific amount of glucose (10 %) is introduced during the regeneration of S-LFP, yielding a regenerated product that performs comparably to commercial LFP. Clearly, our approach, in contrast to traditional regeneration methods, maximizes the utilization of residual impurities within S-LFP, resulting in effective regeneration of S-LFP, thereby proving both informative and cost-effective.

Boosting low-temperature NH3-SCR performance via mixed-valence cobalt dual active sites

Nitrogen oxides (NOx) have become a critical environmental concern, necessitating the development of highly efficient catalysts for temperature which is lower than 300 °C. Selective catalytic reduction with NH3 (NH3-SCR) is a process where ammonia is the reducing agent for selective catalytic reduction of nitrogen oxides in exhaust gases. The mechanism-property relationship between catalytic active sites and low-temperature denitrification efficiency, however, remains unclear. In this study, we synthesized a series of cobalt-modified nanoparticle catalysts using a scalable citric acid sol-gel method and conducted comprehensive characterizations. Our findings indicate that an optimal cobalt doping rate significantly enhances catalytic activity due to the synergistic effects of reduced nanoparticle size and the dual active sites of Co0/Co2+. Specifically, at a cobalt doping ratio of 1.0, the catalyst demonstrates peak SCR activity, achieving 85.5% NOₓ conversion at 120 °C and complete conversion at 150 °C. These cobalt-modified nanoparticle catalysts feature high deposition of doped Co ions on their surfaces, predominantly as metallic cobalt and CoOx nanoclusters. Compared to undoped samples, the cobalt-doped nanoparticle catalysts exhibit a greater specific surface area, increased acidity, enhanced chemisorbed oxygen, and improved redox properties, all contributing to superior denitrification efficacy. Additionally, Density Functional Theory (DFT) calculations provide assertive evidence into the reaction mechanism, showing that Co2+ sites effectively adsorb and activate NH₃, while Co0 sites are crucial for NO adsorption and activation. The synergistic interaction between Co2+ and Co0 facilitates NN coupling, enhancing overall reaction efficiency. These findings underscore the potential of cobalt-modified catalysts for practical industrial applications, offering robust performance over a wide temperature range and meeting stringent environmental regulations.

In vial thin-film solid-phase microextraction using silver nanoparticles as coating for the determination of phenols in waters

A novel thin-film solid-phase microextraction (TF-SPME) device based on glass vials internally coated with silver nanoparticles (AgNPs) was developed for the first time, and used for determining five phenols in wastewater, bottled water, and irrigation water samples by high-performance liquid chromatography coupled to a photodiode array detector (HPLC-PDA). Different AgNPs were synthesized varying the ratio of metallic salt versus the reduction agent, and the pH of the synthesis. The preparation of the TF-SPME glass vial device was optimized in terms of the type of AgNPs used and the number of layers of AgNPs. Besides, the TF-SPME procedure was also optimized. The TF-SPME method was very simple, only requiring the addition of 18 mL of water and 5 min of agitation, followed by the disposal of the water and addition of the 750 µL as desorption solvent, and direct HPLC-PDA injection. The entire method showed adequate analytical performance, with limits of detection ranging from 3 to 8 μg·L-1, and intra-day and inter-day precision (as RSD), both evaluated with different vials and therefore showing inter-batch precision, with values between 8.70 and 16.4 %, and 6.0 and 19.7 %, respectively. The TF-SPME-HPLC-PDA procedure was compared with previous methods for the determination of phenols, both in terms of analytical performance and greenness assessments applying different metrics, showing clear advantages.

Corrigendum: Deepening insights into cholinergic agents for intraocular pressure reduction: systems genetics, molecular modeling, and in vivo perspectives

Corrigendum: Deepening insights into cholinergic agents for intraocular pressure reduction: systems genetics, molecular modeling, and in vivo perspectives

Antidiabetic Potential and Chemical Profiling of Chloroform Fraction from Euclea racemosa subsp. schimperi In Vitro

Background: The chloroform fraction (CHCl3 Fr.) of Euclea racemosa subsp. schimperi has enormous interest for its potential therapeutic properties in managing diabetes and oxidative stress-related conditions. This study aimed to evaluate the chemical composition and biological activities of CHCl3 Fr. through LC-ESI-MS/MS and GC-MS analyses. Methods: The CHCl3 Fr. was analyzed using LC-ESI-MS/MS for identification of bioactive compounds, and its inhibitory effects on α-amylase and α-glucosidase were assessed in vitro. Additionally, the impact on insulin secretion, C-peptide levels, and oxidative stress markers (MDA and NO) were measured. Results: Nineteen bioactive compounds, including flavonoids, pentacyclic triterpenes, and monounsaturated fatty acids, were identified in the chloroform fraction (CHCl3 Fr.). It significantly inhibited α-amylase and α-glucosidase, with IC50 values of 21.16 ± 2.13 and 13.49 ± 0.83 µg/ml, respectively. In insulin-resistant Huh7 cells, CHCl3 Fr. reduced glucose levels and increased insulin and C-peptide levels (p < 0.05). While it decreased malondialdehyde and nitric oxide, it did not significantly enhance catalase or total antioxidant capacity (p > 0.05). Compared to metformin, CHCl3 Fr. showed less efficacy but may improve insulin resistance and reduce oxidative stress, likely due to its bioactive compounds. Conclusion: The presence of diverse bioactive compounds contributes to the antidiabetic effects of CHCl3 Fr. from E. r. ssp. shimperi, showed its potential as a natural therapeutic agent for diabetes management and oxidative stress reduction. Further investigations are warranted to explore its clinical applications and underlying mechanisms.

Application of drag reduction agents as a method for reducing heat loss during pumping through a pipeline

Relevance. The need to maintain the temperature regime of product pumping under increasingly complex conditions of pipeline routes by reducing heat losses of oil and petroleum product pipelines, as well as expanding the scope of application of anti-turbulence additives. Aim. To determine the effect of anti-turbulence additives on heat and hydraulic losses in the pipeline and to propose cost-effective ways to use additives when pumping through pipelines. Objects. Heat and hydraulic losses in pipelines pumping oil and oil products. Methods. Mathematical analysis of the influence of anti-turbulence additives on the thermohydraulic properties of the flow to assess the prospects for increasing the energy efficiency of pumping liquid through pipelines by introducing polymer additives. Results. The flow temperature was calculated using anti-turbulence additive depending on its concentration and efficiency, taking into account the dependence of the properties of the pumped product on temperature. The authors have constructed the graphic dependences of the economic components of heat and hydraulic losses on the concentration of anti-turbulence additives. The economic feasibility of the decision was estimated in terms of calculating the difference in pumping costs with and without anti-turbulence additives. The authors identified the relationship between the impact of losses from friction heat and heat exchange with the environment on heat losses, and analyzed the change in these parameters after the introduction of anti-turbulence additives. For the pipeline under consideration, the parameters of which correspond to standard pumping ones, the сonclusions were drawn on the predominance of the contribution of the additive hydraulic efficiency over the thermal one. This indicates the advisability of using an anti-turbulence additive as an agent for reducing heat losses at high values of the efficiency of the polymer additive, however, the overall economic efficiency is maximum at lower concentrations of the agent. The authors constructed a planar graph reflecting the dependence of the temperature at the end of the pipeline section on two coordinates: the length of the section and the hydraulic efficiency of the introduced additive.

Investigating thermal and UV ageing effects on crumb rubber modified bitumen enhanced with emission reduction agents and carbon black

Over time, bitumen experiences deterioration due to factors like the exposure to oxygen, solar irradiation, and temperature fluctuations. While laboratory techniques like rolling thin film oven (RTFO) and pressure ageing vessel (PAV) were developed to simulate field ageing, they do not accurately replicate environmental factors normally occurring in the field, particularly solar irradiation. Limited research has focused on understanding the ageing processes of crumb rubber modified bitumen (CRMB). This study investigated how different ageing conditions affect the chemo-rheological properties of CRMB and CRMB with geopolymer-based fly ash (GFA), Portland cement paste (PCP), and carbon black (CB). GFA and PCP were added to reduce noxious fumes and VOC emissions from CRMB whereas CB is commonly employed as an antioxidant agent. RTFO and PAV were used to simulate short- and long-term ageing, while a SUNTEST XLS+ weatherometer was used for thermal and UV ageing simulations. A dynamic shear rheometer and attenuated total reflectance Fourier transform infrared spectroscopy were employed for rheological and chemical analysis. Results indicated that extended exposure to thermal conditioning and UV irradiation had the most impact on the chemo-rheological properties of the binders. The incorporation of CR into bitumen enhanced ageing resistance and mitigated the potential for stiffening and embrittlement. The addition of GFA, PCP, and CB to CRMB had a negligible impact on the chemo-rheological properties when subjected to RTFO, PAV, and thermal conditioning. However, following UV ageing, these additives led to a slight increase in carbonyl bonds and greater stiffness compared to pure CRMB

Copper-perovskite interfacial engineering to boost deNOx activity

By adjusting the Cu doping level and calcination temperature during synthesis of a series of noble metal-free lanthanum copper manganite perovskites LaCuxMn1-xO3, we show the importance of tuning the redox chemistry for optimum steering of the catalytic activity and N2 selectivity in the catalytic reduction of NO by CO. A prerequisite is the in situ formation of an extended copper-perovskite phase boundary. The associated improvement of redox and surface properties by Cu addition leads to an optimized balance of the reduction of the catalyst in the NO+CO reaction mixture. The creation of oxygen vacancies improves the reaction kinetics and initiates the NO dissociation. Strongly dependent on the calcination temperature, the Cu/Mn ratio, the reducing agent, as well as the reaction temperature as parameters for Cu-perovskite interfacial control, surface reduction can induce partial copper exsolution, significant perovskite reduction, agglomeration of exsolved Cu particles and eventual decomposition of the catalyst structure. We show that increasing the amount of initial copper incorporated into the perovskite structure can beneficially extend the phase boundary, but exceeding the amount of copper leads to increased sintering of the copper particles at the expense of catalyst activity, especially in repeated catalytic cycles. Increasing the calcination temperature, in addition to the initial sintering of the catalyst and shifting the reaction onset temperature to higher temperatures in the first cycle, improves the reduction resistance of the catalyst. Consequently, in order to form a higher amount of phase boundary-bound active sites, stronger reducing conditions than provided by the NO+CO reaction mixture are needed. This effect can be counterbalanced by using stronger reduction agents prior to performing subsequent catalytic cycles by inducing the exsolution process.

Bay Leaf Extract as a Potential Therapeutic Agent for LDL Reduction in Hypercholesterolemia: A Dose-Response Study

Bay Leaf Extract as a Potential Therapeutic Agent for LDL Reduction in Hypercholesterolemia: A Dose-Response Study

Tracing the odor source of crumb rubber modified asphalt emissions and evaluating the deodorization effect of attapulgite

Crumb rubber modified asphalt (CRMA) is widely used in road construction due to its excellent performance. However, it generates significant odorous gases during paving. To analyze the odor contribution, both untreated crumb rubber and desulfurized rubber were involved in this study to prepare CRMA and desulfurized rubber modified asphalt (DRMA). Attapulgite was selected as an emission reduction agent to reduce the odorous emissions released from CRMA and DRMA. An indoor fume collection system and gas chromatography-mass spectrometry (GC-MS) analysis were used to trace the odor source and quantify the odorous emissions. A comprehensive olfactory thresholds database for CRMA emissions was further established to evaluate the odor level of various rubberized asphalt binders by using three-point comparative odor bag method, along with known olfactory thresholds of certain compounds reported in the literature. Dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), bending beam rheometer (BBR) and Brookfield viscosity tests were used to analyze the effect of attapulgite on rheological properties of CRMA and DRMA. Results indicated that odor emission rate of CRMA containing 1 %, 3 %, and 5 % attapulgite was decreased by 42.62 %, 63.29 %, and 71.06 %, respectively. Benzothiazole, derived from tire rubber vulcanization accelerator, can be reduced by 60.25 % with 1 % attapulgite, demonstrating excellent performance in terms of reducing target odor emissions. Although DRMA has a lower emission rate than that of conventional CRMA, the addition of 1 % attapulgite can further reduce the odor emission rate of DRMA by 37.92 %. The addition of attapulgite has less impact on the overall performance of CRMA and DRMA. Besides, it was found that attapulgite can reduce the viscosity of rubberized asphalt binders, which is beneficial for rubberized asphalt mixture paving and compaction. Considering odor reduction, performance, and economic factors, the optimal attapulgite content was determined to be 5 % for CRMA and 1 % for DRMA. This approach successfully reduces odorous emissions while maintaining the desirable properties of CRMA, making it a viable solution for environmentally friendly road construction.

A Green Synthesis of Au-Ag Alloy Nanoparticles using Polydopamine Chemistry: Evaluation of their Anticancer Potency Towards Both MCF-7 Cells and their Cancer Stem Cells Subgroup.

Limited chemotherapy efficacy and cancer stem cells (CSCs)-induced therapeutic resistance are major difficulties for tumour treatment. Adopting more efficient therapies to eliminate bulk-sensitive cancer cells and resistant CSCs is urgently needed. Based on the potential and functional complementarity of gold and silver nanoparticles (AuNPs or AgNPs) on tumour treatment, bimetallic NPs (alloy) have been synthesized to obtain improved or even newly emerging bioactivity from a combination effect. This study reported a facile, green and economical preparation of Au-Ag alloy NPs using biocompatible polydopamine (PDA) as a reductant, capping, stabilizing and hydrophilic agent. These alloy NPs were quasi-spherical with rough surfaces and recorded in diameters of 80 nm. In addition, these alloy NPs showed good water dispersity, stability and photothermal effect. Compared with monometallic counterparts, these alloy NPs demonstrated a dramatically enhanced cytotoxic/pro-apoptotic/necrotic effect towards bulk-sensitive MCF-7 and MDA-MB-231 cells. The underlying mechanism regarding the apoptotic action was associated with a mitochondria-mediated pathway, as evidenced by Au3+/Ag+ mediated Mitochondria damage, ROS generation, DNA fragmentation and upregulation of certain apoptotic-related genes (Bax, P53 and Caspase 3). Attractively, these Au-Ag alloy NPs showed a remarkably improved inhibitory effect on the mammosphere formation capacity of MCF-7 CSCs. All the positive results were attributed to incorporated properties from Au, Ag and PDA, the combination effect of chemotherapy and photothermal therapy and the nano-scaled structure of Au-Ag alloy NPs. In addition, the high biocompatibility of Au-Ag alloy NPs supported them as a good candidate in cancer therapy.

In-situ enrichment of ARGs and their carriers in soil by hydroxamate siderophore: A promising biocontrol approach for source reduction

Pathogenic microorganisms with antibiotic resistance genes (ARGs) pose a serious threat to public health and soil ecology. Although new drugs and available antibacterial materials can kill ARG carriers but accidentally kill beneficial microorganisms. Therefore, the rapid enrichment and separation of ARGs and their carriers from soil is becoming an important strategy for controlling the diffusion of ARGs. Hydroxamate siderophore (HDS) has gained widespread attentions for its involvement in trace element transfer among microorganisms in the soil environment, we thus explored an in-situ trapping-enrichment method for ARGs and their carriers via a small molecular HDS secreted by Pseudomonas fluorescens HMP01. In this study, we demonstrate that HDS significantly in-situ traps and enriches certain ARGs, including chloramphenicol, MLS, rifamycin, and tetracycline resistance genes in the soil environment. The enrichment efficiencies were 1473-fold, 38-fold, 17-fold, and 5-fold, respectively, higher than those in the control group. Specifically, the primary enriched ARGs were rpoB, mphL, catB2, and tetA(60), and Bacillus, Rhizobium, Rossellomorea, and Agrobacterium were hosts for these ARGs. This enrichment was caused by the upregulation of chemotaxis genes (e.g., cheW, cheC, and cheD) and rapid biofilm formation within the enriched bacterial population. Notably, representative ARGs such as cat, macB, and rpoB were significantly reduced by 36%, 85.7%, and 72%, respectively, in the paddy soil after HDS enrichment. Our research sheds light on the potential application of siderophore as a rapping agent for the eco-friendly reduction of ARGs and their carriers in soil environments.

Deepening insights into cholinergic agents for intraocular pressure reduction: systems genetics, molecular modeling, and in vivo perspectives.

Parasympathetic activation in the anterior eye segment regulates various physiological functions. This process, mediated by muscarinic acetylcholine receptors, also impacts intraocular pressure (IOP) through the trabecular meshwork. While FDA-approved M3 muscarinic receptor (M3R) agonists exist for IOP reduction, their systemic cholinergic adverse effects pose limitations in clinical use. Therefore, advancing our understanding of the cholinergic system in the anterior segment of the eye is crucial for developing additional IOP-reducing agents with improved safety profiles. Systems genetics analyses were utilized to explore correlations between IOP and the five major muscarinic receptor subtypes. Molecular docking and dynamics simulations were applied to human M3R homology model using a comprehensive set of human M3R ligands and 1,667 FDA-approved or investigational drugs. Lead compounds from the modeling studies were then tested for their IOP-lowering abilities in mice. Systems genetics analyses unveiled positive correlations in mRNA expressions among the five major muscarinic receptor subtypes, with a negative correlation observed only in M3R with IOP. Through modeling studies, rivastigmine and edrophonium emerged as the most optimally suited cholinergic drugs for reducing IOP via a potentially distinct mechanism from pilocarpine or physostigmine. Subsequent animal studies confirmed comparable IOP reductions among rivastigmine, edrophonium, and pilocarpine, with longer durations of action for rivastigmine and edrophonium. Mild cholinergic adverse effects were observed with pilocarpine and rivastigmine but absent with edrophonium. These findings advance ocular therapeutics, suggesting a more nuanced role of the parasympathetic system in the anterior eye segment for reducing IOP than previously thought.

Research Progress on Bacteria-Reducing Pretreatment Technology of Meat.

Reducing the initial bacteria number from meat and extending its shelf life are crucial factors for ensuring product safety and enhancing economic benefits for enterprises. Currently, controlling enzyme activity and the microbial survival environment is a common approach to reducing the rate of deterioration in raw meat materials, thereby achieving the goal of bacteria reduction during storage and preservation. This review summarizes the commonly used technologies for reducing bacteria in meat, including slightly acidic electrolyzed water (SAEW), organic acids, ozone (O3), ultrasound, irradiation, ultraviolet (UV), cold plasma, high-pressure processing (HPP), and biological bacterial reduction agents. This review outlines the mechanisms and main features of these technologies for reducing bacteria in meat processing. Additionally, it discusses the status of these technologies in meat storage and preservation applications while analyzing associated problems and proposing solutions. The aim is to provide valuable references for research on meat preservation technology.

Pd octahedra nanocubes mediated photo-fenton catalytic performance for sustainable degradation of methylene blue

This research utilized a typical solvothermal approach, by employing Na2PdCl4 as the synthetic precursor, L-ascorbic acid (AA) as the reductant agent, and polyvinylpyrrolidone (PVP) as the practical surfactant, palladium (Pd) octahedra was finally effectively synthesized by the hydrothermal and solvothermal methods. Subsequently, characterizations of Pd octahedra were conducted by using TEM, XPS, XRD, and other analytical methods. Whereafter, Pd octahedra displayed a consistent shape and size, featuring a distinctive tip-shaped structure, which conferred upon them outstanding optical absorption properties within the near-infrared (NIR) region. Consequently, under NIR laser exposure, Pd octahedra could elevate local reaction temperature via in-situ photothermal conversion, thereby stimulating the formation of active sites of Fenton catalysts. The Photo-Fenton catalytic activity of Pd octahedra was investigated by using methylene blue (MB) as a model pollutant. The degradation efficiency of MB reached 94.8 % within 35 min under 808 nm laser irradiation, and the removal rate of MB by Pd octahedra could still reach more than 90 % after five cycles of use. All the results manifest that Pd octahedra exhibit excellent purification performance for MB dyestuff wastewater.

Assessment of sulfuric acid as pH control agent in catalytic nitrate reduction in drinking waters

H2SO4 was thoroughly assessed as an alternative to CO2 as pH controller, as it allows for to a much precise dosage control. Catalytic nitrate reduction tests using a Pd-Cu catalyst supported on a carbon black were performed using both Milli-Q grade and real natural drinking waters spiked with NO3– in batch reactors. Conversion and selectivity results were equivalent to those obtained for CO2 use, obtaining total NO3– conversion and final NH4+ selectivity around 30 % for a pH range of 5.5–6 using a 0.05 M H2SO4 solution. Good stability of the catalyst in natural drinking water with the higher salt content studied was observed through reaction cycles, despite the presence of SO42- in the reaction medium, with total NO3– conversion after four reaction cycles and final NH4+ concentration of less than 16 mg/L were obtained, making H2SO4 a promising alternative to CO2 as pH controller in the catalytic NO3– reduction.

Investigating battery black mass leaching performance as a function of process parameters by combining leaching experiments and regression modeling

The current paper investigates the leaching phenomena of industrially produced Li-ion battery waste in hydrometallurgical recycling processes. Specifically, it studies the leaching reactions of NMC111-type (LiNi1/3Mn1/3Co1/3O2) black mass, as well as the statistical behavior of cathode material leaching yields under varying process conditions. The investigated process variables include reductive agent concentrations (Fe2+, Cu, H2O2) as well as process temperature, whereas S/L ratio (200 g/L) and initial acidity (2 M H2SO4) were kept constant. At lower temperatures (T = 30 °C), copper was found to act as the predominant reductant, enabled by the presence of sufficient solution iron concentrations (≥0.4 g/L Fe). Conversely, at higher temperatures (T ≥ 50 °C), the reductive capability of aluminum was substantially increased due to its decreased tendency for passivation. In contrast to copper, dissolved iron did not notably affect the reductive behavior of aluminum. The efficiency of metallic reductants initially present within the black mass was high, reaching cathode metal leaching yields above 90 % at 70 °C. A predictive leaching model for black mass leaching yields was built via regression analysis and can be used to indicate pregnant leach solution (PLS) composition – via leaching yields – after two hours of processing as a function of the investigated process variables. The model showed leaching temperature to be the most impactful parameter, while also indicating a higher reductive efficiency of copper when compared to equimolar additions of H2O2. As a case example, LFP (LiFePO4) cathode powder was also investigated as an alternative reductant/catalysis species (Fe2+) source in the system and was found to increase cathode metal leaching yields almost as much as FeSO4 while also resulting in a remarkable increase in Al dissolution in the process.

Cathode performance of novel γ-LixV2O5/carbon composite in organic and aqueous electrolyte

Preparation of in-situ composites with carbon by pyrolysis of an organic precursor is an effective strategy to improve performances of insulating and semiconducting cathode materials. However, due to the property of organic precursor to act as a strong reductive agent during carbonization process, the in-situ synthesis of LiV2O5/C composite cathode material is delicate and presents a challenge for researchers, since vanadium in LiV2O5 coexists in two oxidation states, V4+ and V5+. In our research, we utilized an adopted conventional solid state method for the in-situ preparation of LixV2O5/C composite (x ≈ 0.86). By using methylcellulose polymer as a carbon source, LixV2O5/C was synthesized via two-step solid state reaction at elevated temperatures. LixV2O5 crystallized as gamma polymorph phase, and the amount of in-situ formed carbon does not exceed 3wt%. The electrochemical characteristics of the as-prepared LixV2O5/C were investigated in aqueous and non-aqueous electrolyte via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) tests and electrochemical impedance spectroscopy (EIS). On lithium insertion/removal, the LixV2O5/C composite exhibits stable cycling performance and achieves significant storage capacity enhancement when compared to pristine LixV2O5 obtained under similar conditions. Under current densities of 0.1, 0.2, 0.3 and 1 A/g, the specific capacity enhancement is around 112, 91, 80 and 62 %, respectively. Replacing the organic electrolyte with the aqueous one has a negligible effect on the mechanism and efficiency of lithium intercalation within the LixV2O5/C, which opens up the possibility of using this material in aqueous as well as in organic-electrolyte batteries. The decay of cathode's activity evidenced during electrochemical exchange of lithium with sodium in aqueous environment comes as a result of the formation of electrochemically inactive β-NaxV2O5.