Chemical Characterization Techniques Research Articles

A hierarchically porous and SLIT3-releasing scaffold for bone tissue engineering applications

AbstractOne of the most fundamental characteristics of a biomaterial tailored for bone repair and regeneration is its ability to promote bone regeneration and healing of large defects. This work reports producing a functionalized and hieratically porous bone scaffold that significantly supports cell adhesion and proliferation by providing bone mimicry structure and controlled release of protein. The Slit Guidance Ligand 3 (SLIT3) protein was previously tested to promote bone formation and control the resorption process in natural bone healing. In this study, our goal was to design a nanocomposite bone scaffold to be functionalized with SLIT3 protein and then evaluate the uptake and release profile from surface into culture media to support bone marrow-derived mesenchymal stem cells (MSC) 3D culture. Indirect 3D printing of a polylactic-co-glycolic acid (PLGA), hydroxyapatite nanoparticles, and polydopamine coated (PLGA-HANPs-PDA) was utilized to obtain a hierarchically porous and SLIT3 protein-releasing scaffold. The produced scaffold was evaluated and optimized using chemical, architectural, mechanical, and biological characterization techniques. Optimal physicochemical properties resulted in a unique microstructure with an average pore size of 178.06 ± 45 µm, 63% porosity, and stable and homogenous chemical composition. Mechanical testing demonstrated a compression strength up to 1.5 MPa at 75% strain, with a compression modulus of 0.58 ± 0.05 MPa. Preliminary biological experiments showed that the scaffold exhibited gradual SLIT3 protein release, biodegradability, and reliable biocompatibility for MSC cell culture. Finally, we showed for first time the bioactivity of SLIT3 protein within PLGA-HANPs-PDA scaffold to promote attachment and growth of mesenchymal stem cell (MSCs) seeded in bone mimicry scaffold matrix. The collected findings will serve as a bedrock for thorough and targeted in vitro studies to evaluate anticipated osteogenesis the MSCs.

Green Synthesis of Silver-Incorporated Rutile TiO2 for Enhanced Photocatalytic Degradation of Ciprofloxacin and Carmine G Dye Pollutants

Developing sustainable TiO2-based photocatalysts for environmental remediation is an increasingly significant area of research. However, a limited understanding of the long-term ecological impact of these photocatalysts poses a barrier to their practical and industrial-scale applications. To address this challenge, this work employed a green synthesis approach to prepare an Ag/TiO2 photocatalyst designed to improve environmental compatibility and enhance efficiency in pollutant degradation. Ag/TiO2 was synthesized using mushroom biomass as a natural capping to evaluate its effectiveness in the degradation of ciprofloxacin (CIP) and azo Carmine G dye (ACGD). The mushroom biomass served as a renewable cost-effective support for Ag incorporation, while the Ag modification of TiO2 could enhance the photocatalyst’s performance. Structural, chemical, and morphological characterization techniques were applied and showed that the Ag/TiO2 particles consisted of irregularly shaped nanoparticles. The CIP removal reached 82.46% after 300 min and ACGD removal efficiency went up to 83.64%. The enhanced performance is attributed to the unique electronic and structural properties of Ag-modified TiO2. This study highlights the potential of Ag/TiO2 synthesized via green methods as a high-performance photocatalyst for the effective remediation of pharmaceutical and dye pollutants in wastewater treatment applications.

Graphene-based Nanomaterials As Catalysts for the Synthesis of Medicinally Privileged Heterocycles: Importance and Outlook

: Catalysis is an integral part of sustainable and green chemical processes. During the last two decades, the wonder 2D carbon material with honeycomb structure, graphene, and other functionalized graphenes have emerged as extremely versatile and robust nanomaterials in heterogeneous catalysis. The incredible catalytic efficacy of such carbon nanomaterials relies on their unique physicochemical properties, including large surface area, diverse catalytic active sites, multiple chemical functionalities, tunable electron density, synergistic effect, etc., making them noteworthy as metal-free catalysts and catalytic supports. : The article presents an overview of the catalytic applications of various graphene-based nanomaterials (GBNs), either metal-free or embedded with metal/metal oxide NPs, in synthesizing medicinally privileged heterocyclic compounds. It also summarizes the general methodologies for preparing graphene and various GBNs, their chemical structures, characterization techniques, and discussions on the potential active sites that are responsible for wider catalytic activity. Overall discussions unequivocally establish a promising paradigm for uncovering more innovative graphene-based materials and their subsequent applications in diverse fields, including heterogeneous catalysis.

Highly Active Cerium Oxide Supported Solution Combustion Cu/Mn Catalysts for CO-PrOx in a Hydrogen-Rich Stream

Mono- and di-substituted cerium oxide catalysts, viz. Ce0.95Cu0.05O2-δ, Ce0.90Cu0.10O2-δ, Ce0.90 Cu0.05Mn0.05O2-δ, Ce0.85Cu0.10Mn0.05O2-δ, and Ce0.80Cu0.10Mn0.10O2-δ, were synthesized via a one-step urea-assisted solution combustion method. The elemental composition and textural and structural properties of the catalysts were determined by various physical, electronic, and chemical characterization techniques. Hydrogen temperature-programmed reduction showed that co-doping of copper and manganese ions into the CeO2-δ lattice improved the reducibility of copper. Powder XRD, XPS, HR-TEM, and Raman spectroscopy showed that the catalysts were a singled-phased, solid-solution metal oxide with a cerium oxide cubic fluorite (cerianite) structure, and evidence of oxygen vacancies was observed. Catalytic results in the preferential oxidation of CO in a hydrogen-rich stream showed that complete CO conversion occurred between 150 and 180 °C. Furthermore, at 150 °C, Ce0.90Cu0.05Mn0.05O2-δ, Ce0.90 Cu0.10O2-δ, and Ce0.85Cu0.10Mn0.05O2-δ catalysts were the most active, achieving complete CO conversion and CO2 selectivity of 81, 79, and 71%, respectively. The catalysts performed moderately in the presence of CO2 and water, with the Ce0.90Cu0.05Mn0.05O2-δ catalyst giving a CO conversion of 80% in CO2, which decreased to about 60% when water was added.

KOH-treated tire pyrolyzed carbon as green and easily available adsorbent for Bisphenol A and Methylene blue adsorption.

The occurrence of micropollutants and dyes in water sources has sparked alarm due to their significant impacts on aquatic ecosystems and human health. This study aims to utilize the tire pyrolyzed carbon (TPC) as a source of the adsorbent for removing Bisphenol A (BPA) and Methylene Blue (MB). The adsorbent was synthesized by chemical activation of TPC with KOH at 750°C. The activated TPC was characterized for different physical and chemical characterization techniques such as XRD, FTIR, SEM, BET, XPS, and TPD and exhibits a higher adsorption capacity of 49.2 and 72.1mg/g respectively for BPA and MB. The effect of initial concentration, dosage of adsorbent, and initial pH are evaluated for BPA and MB. The adsorption is mainly driven by hydrophobic, electrostatic, π-π interactions, and hydrogen bonding. The removal process follows the second order and Langmuir isotherms. The adsorbent shows excellent recyclability which makes it a potential source of removal of different water-borne pollutants. The production of activated carbon from tirewaste is advocated for its economic and environmental benefits.

Exploring the Benefits of Yashada Bhasma (Zinc Oxide) in Sunscreen Formulations: Bridging Classical Wisdom with Scientific Validation

The utilization of minerals in cosmetic formulations has been a longstanding tradition, with Yashada Bhasma (zinc oxide) emerging as a prominent ingredient in modern sunscreen formulations due to its remarkable properties. This article provides a comprehensive examination of Yashada Bhasma historical significance, chemical composition, and therapeutic attributes as described in classical literature. The scientific analysis validates its efficacy as a physical barrier against UVA and UVB radiation, highlighting its photostability and compatibility with sensitive skin. Structural and chemical characterization techniques illuminate its nano-scale transformation during the purification process, enhancing its effectiveness. Comparative analyses with other sunscreen ingredients emphasize its superiority in terms of UV protection spectrum, skin compatibility, and regulatory approval. A market survey reveals the widespread incorporation of Yashada Bhasma into various Ayurvedic and herbal cosmetic products, reflecting its acceptance and popularity among consumers. Overall, this article bridges the gap between Classical wisdom and scientific validation, showcasing Yashada Bhasma as a versatile and effective component in sunscreen formulations, poised to meet the evolving needs of skincare and sun protection in contemporary times.

Solute and phase heterogeneous distribution at different scales and its effect on ageing physical phenomena in a laser powder bed fusion produced maraging steel

The Laser Powder Bed Fusion process involves complex thermodynamic and heat transfer mechanisms which results in a complicated understanding of the material’s microstructure and phase transformation processes. In the case of additive manufacturing maraging steels, these present heterogeneous structures which mainly consist of Body-Centred Tetragonal (BCT) martensite and retained austenite (Face-Centred Cubic (FCC) phase structure), unlike conventionally processed material. Research has already been done on the competitive or collaborative nature of austenite growth/reversion and precipitation in these materials. However, for Laser Powder Bed Fusion maraging steels, studies have focused on either the effect of the heterogeneous structures on austenite reversion kinetics or the formation, evolution and behaviour of precipitation. Still, no comprehensive research exists that covers in detail the relation between solute heterogeneity from the meso- to the nanoscale and its influence on both phase distribution and ageing physical phenomena. To do so, multiscale chemical analyses and microstructural characterisation techniques were used to investigate a maraging steel M300 in different transformed conditions: as-built, aged at 480 and 540 °C. The results showed that competing mechanisms during printing caused segregation at the mesoscale, which remains in aged samples. Vaporisation led to Cr segregation, while melt convections caused Ni and Ti depletion at melt pool boundaries. Retained austenite location was found at melt pool boundaries and away from them on the as-built structure. Its preferential location remains unclear. Dissimilarities from conventional material were identified in nanosized clustering and precipitates on aged samples.

Paracoccus kondratievae produces poly(3-hydroxybutyrate) under elevated temperature conditions.

As part of ongoing efforts to discover novel polyhydroxyalkanoate-producing bacterial species, we embarked on characterizing the thermotolerant species, Paracoccus kondratievae, for biopolymer synthesis. Using traditional chemical and thermal characterization techniques, we found that P. kondratievae accumulates poly(3-hydroxybutyrate) (PHB), reaching up to 46.8% of the cell's dry weight after a 24-h incubation at 42°C. Although P. kondratievae is phylogenetically related to the prototypical polyhydroxyalkanoate producer, Paracoccus denitrificans, we observed significant differences in the PHB production dynamics between these two Paracoccus species. Notably, P. kondratievae can grow and produce PHB at elevated temperatures ranging from 42 to 47°C. Furthermore, P. kondratievae reaches its peak PHB content during the early stationary growth phase, specifically after 24 h of growth in a flask culture. This is then followed by a decline in the later stages of the stationary growth phase. The depolymerization observed in this growth phase is facilitated by the abundant presence of the PhaZ depolymerase enzyme associated with PHB granules. We observed the highest PHB levels when the cells were cultivated in a medium with glycerol as the sole carbon source and a carbon-to-nitrogen ratio of 10. Finally, we found that PHB production is induced as an osmotic stress response, similar to other polyhydroxyalkanoate-producing species.

Low temperature catalytic activity of molybdenum promoted two-dimensional boron nitride in propane oxidative dehydrogenation reaction

The catalytic oxidation dehydrogenation of propane to propylene, achieved at low temperatures and with high selectivity on catalysts supported by non-noble metals, exhibits significant potential for a wide range of applications. The performance of boron-based catalysts in ODHP is remarkable; however, there is a dearth of research on their low-temperature range performance. The present study employed a straightforward impregnation method to synthesize a range of Mo/h-BN-γ-Al2O3 catalysts with varying molybdenum loadings, focusing on the comparison between commercial h-BN and h-BN-γ-Al2O3 mixed support. The Mo/h-BN-γ-Al2O3 catalyst demonstrates remarkable low-temperature ODHP activity, with an initial conversion rate of 2.36 % and a propylene selectivity of 96 % at a reaction temperature of 260 ℃, exhibiting good stability over 50 h, the catalytic performance of Mo/h-BN-γ-Al2O3 in the low-temperature range surpasses that of commercial h-BN by a significant margin. Comparative experiments, along with physical and chemical characterization techniques, demonstrate that the incorporation of an appropriate quantity of Mo enhances the catalyst's acidity and redox capability. Furthermore, the synergistic effect between MoOx and BOx promotes low-temperature ODHP. The mechanism underlying the catalyst's low-temperature reaction was investigated using in-situ infrared spectroscopy technology.

Sono-assisted adsorption of nitrate by Fe-modified chitosan–zeolite composite material

The negative consequences of nitrate pollution on the environment and human health, that gained substantial attention. The purpose of this work is to formulate and evaluate the potential of the Fe-modified chitosan–zeolite composite (CZFC) as an efficient adsorbent for the removal of nitrate. Physical and chemical characterization techniques such as SEM, XRD, and FTIR were used to analyze the surface and structural properties of the CZFC. The effects of several variables, including the pH, contact time, initial concentration, and adsorbent dosage, were investigated under ultrasonication treatment throughout experiments. When compared to the Freundlich and Temkin models, the Langmuir models had the highest R 2 value (0.99), indicating that they had the best fitting for all the experimental data. The maximum adsorption capacity was found to be 5.18 ± 0.30 mg g−1 with 95.37 ± 2.11% of nitrate removal at pH 3 and 2 g L−1 of adsorbent dose. The pseudo-second-order model exhibited the highest R 2 value (0.99) and proved the chemisorption mechanism for nitrate removal. The thermodynamic properties indicated that the adsorption was spontaneous and exothermic. The regeneration capacity of the CZFC was found to be 80.86 ± 4.17% at pH 10 due to the weakening of electrostatic attraction. According to experimental results, ultrasonication treatment was crucial for increasing nitrate absorption on synthesized CZFC.

A critical comparison of the main characterization techniques for microplastics identification in an accelerated aging laboratory experiment

Many studies have reported the occurrence of microplastics in different environmental compartments, through the description of their morphological characteristics and chemical identification, obtained mainly by spectroscopic techniques. However, the scientific community still lacks the implementation of standardized analytical methods that aim to assess not only the identification of the particle, but also its stage of degradation. It is understood that this information would be extremely useful in helping elucidate the main sources of pollution and contributing to strategies and mitigating measures for the management of solid waste and microplastics in the environment. In this respect, the aim of this study was to evaluate the efficiency of Fourier-transform infrared spectroscopy, Raman spectroscopy, carbon elemental analysis coupled with mass spectrometry, and scanning electron microscopy with energy dispersive X-ray spectrometry for the characterization of virgin and aged polyethylene and polypropylene microplastics samples. The degraded samples were subjected to accelerated aging in a QUV chamber in accordance with American standard for measuring accelerated weather testing (ASTM G-154). This work discusses the efficiency and limitations of each technique for the detailed chemical characterization of microplastic samples collected from the environment.

Synthesis, characterization, and corrosion protection potential of a highly effective and water‐miscible surfactant for mild steel in sulfuric acid solution

AbstractIn the current study, a tetracationic quaternary ammonium salt (TCQAC) was synthesized and characterized and its ability to suppress corrosion on mild steel (MS) in a 0.5 M H2SO4 solution was examined. Various chemical, electrochemical, and surface characterization techniques were utilized to study the inhibition efficiency of TCQAC. The TCQAC manifests 99.83% efficiency at 20 ppm concentration. Out of all the examined isotherm models, the Langmuir isotherm offered the best fit for the TCQAC adsorption on the MS surface. A very high negative value of ΔGads (−45.18 kJ mol−1) suggests that the adsorption of TCQAC followed the chemisorption mechanism. Electrochemical studies indicate that TCQAC increases the linear and charge transfer resistances (LPR and Rct, respectively). TCQAC slows down the anodic and cathodic Tafel reactions; however, it acts as an anodic‐type inhibitor at 5, 10, and 20 ppm. The appearance of extra Cl and N signals in the energy dispersive x‐ray (EDX) spectrum and an improvement in surface smoothness in the scanning electron microscope (SEM) image of the inhibited sample corroborated the adsorption method of corrosion inhibition. X‐ray photoelectron spectroscopy (XPS) study indicates that TCQAC creates corrosion preventive layers by chemical adsorption. In Frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were delocalized around the central part that comprises two benzyls, four allyls, and one hydrocarbon ((CH2)6) moieties and two quaternary nitrogen atoms. The outcomes of XPS and density functional theory (DFT) analyses indicate that the chemisorption of TCQAC occurs by dπ–pπ bonding with the surface iron atoms. The π‐electrons of aryl and allyl moieties extensively participate in the bonding.

Indolin-2-one derivatives as corrosion inhibitors: Structural insights and evaluation through experimental and computational techniques

Effective corrosion management is a pivotal challenge facing various industries and holds crucial importance in aligning industrial processes with sustainability goals. This study focused on the synthesis and evaluation of two indolin-2-one derivatives: (E)-1-allyl-3-(2-(5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazol-2-yl)hydrazono)indolin-2-one (AIHI) and (E)-3-(2-(5-oxo-4,4-diphenyl-4,5-dihydro-1H-imidazol-2-yl)hydrazono)-1-(prop‑2-yn-1-yl)indolin-2-one (PIHI), as sustainable corrosion inhibitors for N80 carbon steel (N80CS) in a 15 wt. % HCl medium. Chemical, electrochemical, and surface characterization techniques were utilized to evaluate the corrosion inhibition mechanism and the performance of the compounds under investigation. The weight loss method highlighted that tested compounds exhibited promising inhibition efficiencies: 91.54 % for AIHI and 81.97 % for PIHI, respectively, at 303 K, with an outstanding performance of 87.17 % at 363 K for AIHI. The simultaneous addition of AIHI and PIHI in HCl led to a substantial increase in the polarization resistance (RP) and a remarkable decrease in the corrosion current density (icorr). The potentiodynamic polarization (PDP) technique validated that both indolin-2-one compounds function as anodic/cathodic corrosion inhibitors with remarkable anodic effect. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that inhibitors altered steel surface morphology, forming a protective layer, and significantly reduced surface roughness. Atomistic simulations (DFT and SCC-DFTB methods) pointed out that the inhibitors AIHI and PIHI acted by physico-chemical adsorption through donor-acceptor interactions between AIHI or PIHI molecules (s and p orbitals) and the 3d orbitals of Fe(110). The insights obtained serve as a foundation for future advancements in greener corrosion management strategies for sustainable industrial applications, thus reinforcing our commitment to bio-circular economies and sustainable chemistry.

DNA barcoding of herbal supplements on the US commercial market associated with the purported treatment of COVID-19.

The COVID-19 pandemic was associated with an increased global use of traditional medicines, including Ayurvedic herbal preparations. Due to their growing demand, their processed nature, and the complexity of the global supply chain, there is an increased risk of adulteration in these products. The objective of this study was to assess the use of DNA barcoding for species identification in herbal supplements on the US market associated with the Ayurvedic treatment of respiratory symptoms. A total of 54 commercial products containing Ayurvedic herbs were tested with four DNA barcoding regions (i.e., rbcL, matK, ITS2, and mini-ITS2) using two composite samples per product. Nine categories of herbs were targeted: amla, ashwagandha, cinnamon, ginger, guduchi, tribulus, tulsi, turmeric, and vacha. At least one species was identified in 64.8% of products and the expected species was detected in 38.9% of products. Undeclared plant species, including other Ayurvedic herbs, rice, and pepper, were detected in 19 products, and fungal species were identified in 12 products. The presence of undeclared plant species may be a result of intentional substitution or contamination during harvest or processing, while fungal DNA was likely associated with the plant material or the growing environment. The greatest sequencing success (42.6-46.3%) was obtained with the matK and rbcL primers. The results of this study indicate that a combination of genetic loci should be used for DNA barcoding of herbal supplements. Due to the limitations of DNA barcoding in identification of these products, future research should incorporate chemical characterization techniques.

Transition Metal Doped BiVO4 Photoanodes: A Mechanistic Study

BiVO4 has emerged as one of the most promising materials to fabricate efficient photoanodes for photoelectrochemical (PEC) solar water splitting. BiVO4 is an n-type semiconductor, with a 2.4 eV bandgap and a theoretical solar to hydrogen (STH) efficiency of 9.2% with a maximum photocurrent of 7.5 mA cm2 under AM 1.5 G illumination, low overpotential and favourable band-edge positions towards the Oxygen Evolution Reaction (OER).1 However, BiVO4 also presents poor electron transport, high surface recombination and slow water oxidation kinetics. Hence, enormous efforts have been made in the past few years to mitigate these drawbacks through different approaches such as nanostructuring,2 doping,3 heterostructuring,4 and the use of efficient co-catalysts.5 The present study proposes a transition metal doping (Ni, Fe and Co) of BiVO4 photoelectrodes that boosts their water oxidation performance. The origin of this enhanced performance towards Oxygen Evolution Reaction (OER) was studied by a combination of a suite of structural, chemical, and mechanistic advanced characterization techniques including X-Ray Photocurrent Spectroscopy, Electrochemical Impedance Spectroscopy and Transient Absorption Spectroscopy, among others.[1] J. Li and N. Wu, Catal. Sci. Technol., 2015, 5, 1360–1384.[2] S. P. Berglund, D. W. Flaherty, N. T. Hahn, A. J. Bard and C. B. Mullins, J. Phys. Chem. C, 2011, 115, 3794–3802.[3] S. K. Pilli, T. E. Furtak, L. D. Brown, T. G. Deutsch, J. A. Turner and A. M. Herring, Energy Environ. Sci., 2011, 4, 5028–5034.[4] J. Su, L. Guo, N. Bao and C. A. Grimes, Nano Lett., 2011, 11, 1928–1933.[5] D. K. Lee and K.-S. Choi, Nat. Energy, 2018, 3, 53–60.

Batteries Worth Their Salt: Targeting Next Generation Stationary Storage with Molten Salt Electrolytes

There is an imminent need for batteries capable of meeting the evolving demands of a growing stationary storage landscape, one rich in renewable energy sources and challenged with unprecedented global electrification. Key to our future electrical grid, desirable large-scale, long-duration batteries must not only meet demands for high power and energy density, but they must be safe, cost-effective, and should be sustainably sourced from earth-abundant materials. Here, we will highlight our research and development of low temperature molten salt batteries that employ active materials such as sodium, aluminum, iron, chloride, and iodide. We will demonstrate the promise of our approach through a low-temperature (100°C) molten sodium battery that comprises a molten sodium anode, a solid-state NaSICON ceramic separator, and a low-cost molten metal-halide salt catholyte. These batteries, with remarkable voltages greater than 3.1V, are capable of months of cycling as well as high current charge and discharge behavior, greater than 50mA/cm2. Here, we will not only highlight these performance metrics, but we will describe how we used specialized electrochemical and chemical characterization technique to understand the impacts of molten salt electrolyte composition, electrochemistry, and interfacial interactions on battery performance. By understanding the connections between specific electrochemical phenomena and battery chemistry, we have learned to improve battery performance through tuning of properties, such as molten salt Lewis acidity and current collector composition. This scientifically-motivated battery design approach continues to enable agile innovation and advances to realize the potential of molten salt batteries as a new, impactful stationary storage technology.Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Carbon quantum dot-nanocomposite hydrogel as Denovo Nexus in rapid chondrogenesis

The incapability of cartilage to naturally regenerate and repair chronic muscular injuries urges the development of competent bionic rostrums. There is a need to explore faster strategies for chondrogenic engineering using mesenchymal stem cells (MSCs). Along these lines, rapid chondrocyte differentiation would benefit the transplantation demand affecting osteoarthritis (OA) and rheumatoid arthritis (RA) patients. In this report, a de novo nanocomposite was constructed by integrating biogenic carbon quantum dot (CQD) filler into synthetic hydrogel prepared from dimethylaminoethyl methacrylate (DMAEMA) and acrylic acid (AAc). The dominant structural integrity of synthetic hydrogel along with the chondrogenic differentiation potential of garlic peel derived CQDs led to faster chondrogenesis within 14 days. By means of extensive chemical and morphological characterization techniques, we illustrate that the hydrogel nanocomposite possesses lucrative features to influence rapid chondrogenesis. These results were further corroborated by bright field imaging, Alcian blue staining and Masson trichome staining. Thus, this stratagem of chondrogenic engineering conceptualizes to be a paragon in clinical wound care for the rapid manufacturing of chondrocytes.

Electrochemical Residence Time Distribution as a Diagnostic Tool for Redox Flow Batteries

The fluid dynamic and electrochemical performance of redox flow batteries (RFBs) stems from the relationship between the flow field and the porous electrode, whose interplay determines how active species move and react during device operation. While characterization techniques, such as residence time distribution, offer insights into species mobility within a reactive volume for a traditional chemical reactor, electrochemical reactors also enable simultaneous measurement of the redox reactions, unlocking another dimension of analysis. Herein, we demonstrate how potentiodynamic measurements, using injections of electrolyte examined through moment analysis, can provide electrode-specific performance scaling relationships across a matrix of carbon paper and cloth electrodes with flow through and interdigitated flow fields. We further combine experimental campaigns with multiphysics simulations to demonstrate how electrode surface area can be estimated with this technique, which we then validate with activated and unactivated commercial carbon cloth electrodes. These studies reveal the multiscale observations that potentiodynamic measurements afford, augmenting existing electrochemical techniques for holistic electrochemical reactor diagnostics.

Corrosion behavior and failure mechanism of ball grid array packages in fire smoke atmospheres

Ball grid array (BGA) packages is a common type of electronic packaging and a crucial component in electronic devices. However, its reliability is significantly compromised when exposed to fire smoke atmospheres, thereby reducing the overall reliability of electronic equipment. Therefore, the study of failure mechanisms of BGA packages in fire smoke environments is of paramount importance for the recovery and maintenance of electronic devices post-fire. In this study, we conducted fire smoke experiments and employed electrical performance measurements along with chemical characterization techniques to delve into the failure behaviors and mechanisms of BGA packages in different fire smoke atmosphere. The results reveal that nitrile-butadiene rubber and polycarbonate smoke do not affect the electrical conductivity of BGA packages. However, the accumulation of smoke particles and water between the interconnecting solder joints temporarily reduces the insulation performance. That is induced by the deposition of smoke particles and can be restored after cleaning. On the other hand, under polyvinyl chloride smoke, BGA packages experiences insulation failure and permanent open-circuit failure. This irreversible permanent open-circuit failure is caused by the interconnection of corrosion products in solder joints. Chemical characterization analysis results indicate that solder joints dissolve due to the galvanic corrosion mechanism, transforming the solder from a spherical shape into a rose-like structure. The corrosion products primarily consist of flake-like SnO and Sn3O(OH)2Cl2. This research contributes to a deeper understanding of the failure mechanisms of electronic devices in fire smoke and provides essential guidance for post-fire equipment maintenance.

Towards sustainable management of end-of-life membranes: Novel transformation of end of life (EoL) reverse osmosis membranes for efficient dye/salt separation

Effective management of end-of-life (EoL) membranes is crucial for addressing environmental and economic concerns. A novel approach has been proposed in this study to transform discarded EoL reverse osmosis (RO) membranes into loose nanofiltration (NF) membranes that exhibit high flux and effective dye/salt fractionation. The proposed method involves oxidative treatment followed by a one-step co-deposition of polydopamine (PDA) and polyethylene glycol (PEG). Rigorous chemical and morphological characterization techniques have verified the successful transformation of the EoL membranes. The study's findings demonstrate the great potential of this method, as the transformed EoL membranes achieved high pure water permeability of 67 LMH/bar after only a 5-hour coating process, representing a remarkable 2.5-fold increase in permeability compared to the uncoated membrane. A 20-hour coating produced a denser film that reduced the permeability to 19 LMH/bar but increased the potential for dye/salt separation. The transformed membranes exhibited high rejection rates of dyes and ultra-low salt rejection, making them highly efficient for dye/salt separation. Moreover, the enhanced hydrophilicity of the transformed membranes inhibited foulant accumulation, resulting in excellent fouling resistance with a flux recovery ratio of 93.6 %. This novel approach offers a promising solution for treating dye-contaminated wastewater and promoting circular economy in membrane technology.