Scanning Electron Microscopy And Energy Dispersive X-ray Spectroscopy Research Articles

Enhanced susceptibility of high-strength fastener nuts to hydrogen-induced stress corrosion cracking

Abstract High-strength HV-fastener sets of dimensions M48 and M64 with property class 10.9 were employed in offshore wind turbine frameworks. The M64 were used in coupling flanges within monopiles. The M48 were employed in another offshore wind farm and encountered natural weathering. In both installations, time-delayed fractures of the nuts were observed. Owing to the presence of macroscopically visible corrosion products, hydrogen-induced stress corrosion cracking (Hi-SCC) was established as the probable cause of failure. However, a nut fracture in a properly pre-tensioned bolt assembly is atypical since the stresses in the bolt threads are higher than those in the nuts. Based on the Hi-SCC theory, the fracture should occur at the most stressed component, which is the bolt. During the root cause analysis, extensive examinations were conducted to determine the cause of the nut fractures. The focus was on investigating whether the nut material was more prone to Hi-SCC than the bolt material. The examination program included scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS) analysis of the fracture surfaces, optical microscopy of microspecimens, mechanical tests, and stress rupture tests of hydrogen-charged specimens. While the results suggest that the tested nuts comply with the requirements of the applicable standards regarding material properties, they also reveal that the nut material is, despite its lower tensile strength, significantly more susceptible to Hi-SCC than the bolt material. Therefore, a direct relationship between material susceptibility to Hi-SCC and the tensile strength, as standards and guidelines imply, is not given.

The Effects of Reusing Cobalt-Chromium Alloy Powder on Its Mechanical Properties and Grain Size: An In Vitro Study.

To characterize material changes that may occur in virgin cobalt-chromium (Co-Cr) alloy powder when it is blended with alloy powders that have been reused multiple times. Initially, 20 kg of virgin Co-Cr powder was loaded into a laser-sintering device. The tensile test specimens were fabricated in the first (Group 1), fourth (Group 2), seventh (Group 3), tenth (Group 4), and thirteenth (Group 5) production cycles (N = 15). Prior to fabricating the specimens, powder alloy samples were collected from the powder bed for analysis. The tensile strength, elastic modulus, and percent elongation were calculated with tensile testing. Scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS) and laser particle size distribution (LPSD) were used to analyze the alloy powder samples. The fracture surface of one tensile test specimen from each group was examined via SEM/EDS. One-way ANOVA followed by Dunnett T3 test was used for statistical analysis (α = .05). No difference was observed between groups in terms of tensile strength. A statistically significant difference was observed between Groups 1 and 2 in terms of percent elongation. Groups 2 and 4 were statistically significantly different in terms of both elastic modulus and percent elongation (P ≤ .05). SEM images of the powder alloy showed noticeable differences with increasing numbers of cycles. SEM images and the EDS analysis of the fractured specimens were in accordance with the strength data. Reusing Co-Cr alloy powder increased the particle size distribution. However, there was no correlation between increased cycle number and the mechanical properties of the powder.

Manufacturing technique analysis of Early Harappan painted pottery from the Jhang Bahatar Site, Pakistan, by using a multi-analytical approach

Only a limited number of scientific or technological studies regarding Harappan pottery have been conducted so far. To address the knowledge gap, this study investigates the raw materials and manufacturing techniques evidenced in the painted pottery sherds excavated from the Jhang Bahatar site, Pakistan of the late period of early Harappan culture (also identified as the Kot Diji period 2800-2600BC). This study employs a variety of integrated analytical methods including production process observation, X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and Scanning Electron Microscopy, and Energy Dispersive X-ray spectroscopy (SEM-EDS). The investigation revealed that the raw materials in the pastes used to manufacture these painted potteries are common fusible clay characterized by minimal levels of silicon oxide and alumina and elevated levels of flux oxide. The pottery was decorated with an initial basecoat of ochre consisting of hematite (Fe2O3), mixed with pottery paste clay, while the main mineral material of black pigment was magnetite (Fe3O4) and the white pigment was created using dolomite (CaMg (CO3)2).

Enhancing Hydrogen Storage in AZ31 Alloy through Pd/G Composite

In this research, we investigated the catalytic effects of Palladium/Graphene(Pd/G) on AZ31 alloy for hydrogen storage. X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (SEM-EDS) were employed to confirm the homogeneous distribution of AZ31 and observe phase changes after mechanical alloying with the catalysts. The hydrogen storage properties of AZ31 with catalysts were systematically examined, and the time of maximum reaction rate for nucleation was determined using Avarami Plot. The results of the study show that the incorporation of 2% Pd/G resulted in the fastest hydrogen absorption and desorption time, taking 200 seconds to achieve 90% hydrogen storage with a maximum of 6.04 wt%. The corresponding maximum hydrogen desorption occurred in 694 seconds, reaching 6.03 wt%. Consequently, the introduction of 2% Pd/G catalyst proved to be effective in significantly enhancing the hydrogen ab/desorption rates of AZ31 alloy.

Development of polyaniline/chitosan (PANI/CTS) and TiO2-PANI/CTS nanocomposites as anti-corrosion coatings: Synthesis and characterization

Polyaniline/chitosan (PANI/CTS) and TiO2-PANI/CTS nanocomposites were synthesized via in situ oxidative polymerization and characterized by different spectroscopies techniques. The interaction of PANI with the CTS structure and that of the TiO2 nanoparticles with the PANI/CTS copolymer matrix were confirmed by Fourier transform infrared spectroscopy (FT-IR). X-ray diffraction (XRD) analyses of the synthesized nanocomposites show a crystalline structure like their base materials (CTS, PANI and TiO2). The incorporation of PANI, CTS, and TiO2 in the formation of nanocomposites was confirmed by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS). Thermogravimetric and differential scanning calorimetry (TGA and DSC) analyses indicate that the PANI/CTS and TiO2-PANI/CTS nanocomposites present greater resistance to thermal decomposition in relation to the CTS and PANI polymers, as well as the highest glass transition temperature (Tg). The anti-corrosion coatings were made by mixing the polymers and synthesized nanocomposites in an alkyd resin (AR) and deposited on 1018 carbon steel and evaluated in 3.5 wt% NaCl solution by linear polarization and electrochemical impedance spectroscopy (EIS) techniques. The best performance against corrosion was observed for the coating made from TiO2-PANI/CTS, since it shows the noblest values in potential, as well as the highest protection efficiencies, even after its immersion for 30 days, which is attributed to the high degree of cross-linking that the nanocomposite has, forming a dense protective film on the steel surface.

Influence of partial substitution of metakaolin by palm oil fuel ash and alumina waste ash on compressive strength and microstructure in metakaolin-based geopolymer mortar

Geopolymer is recognized as an alternate binder that compounds silica-rich and alumina-rich materials as raw materials and is produced by alkaline activation. In general, biomass ashes in particular for palm oil fuel ash (POFA) is an ideal starting material on the grounds of its high silica concentration, while industrial by-products, especially alumina waste (AW) is also employed as starting material due to its high alumina content. The objective of this research is to address the effects on the compressive strength and also the microstructure of metakaolin-based geopolymer mortar studied through the adaptability of the substitution of metakaolin (MK) by POFA and AW. In order to investigate the effects of POFA and AW substitution on the polymerization reaction and its outcomes, metakaolin-based geopolymers were produced. The most recent data suggests that POFA and AW probably serve as feedstocks for geopolymers with a little strength reduction. The partial substitution of MK by POFA reduces the polymerization reaction rate while maintaining the same water/binder ratio. However, because of the long-lasting polymerization reaction, it is still obtainable to reach a significant degree of polymerization reaction and also provides a comparable 28-day curing age compressive strength for 20 % replacement of MK by POFA. Considering 10 % substitution of POFA by AW, it results in 22.08 % improvement in the compressive strength after 28 curing days. On top of that, the compressive strength development of the geopolymer sample was investigated using scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS), x-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). It was discovered that the density and the compressive strength were induced by the particle morphologies, the surface area of POFA and AW, and the chemical composition as a result of the geopolymerization.

Removal of Pharmaceuticals from Water Using Laccase Immobilized on Orange Peels Waste-Derived Activated Carbon

The ongoing discharge of containments into the environment has raised concerns about the potential harm they pose to various organisms. In the framework of eliminating pharmaceutical chemicals from aqueous solutions, enzymatic degradation by laccase is an environmentally friendly option. In this investigation, laccase immobilized on biochar derived from agricultural waste (orange peels, OPs) was used for the first time to remove carbamazepine and diclofenac from aqueous media. Different characterizations, such as Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-Ray diffraction (XRD), specific surface area (SBET), Boehm titration, proximate and ultimate analysis, as well as the point of zero-charge (pHPZC) analysis, were used in this study. The immobilization of laccase results in enhanced stability with respect to storage, temperature, and pH compared to laccase in its free form. The findings showed that the ideal conditions for immobilization were a pH of 4, a temperature of 30 °C, and a laccase concentration of 4.5 mg/mL. These parameters led to an immobilization yield of 63.40%. The stability of laccase immobilized on biochar derived from orange peels (LMOPs) was assessed over a period of 60 days, during which they preserved 60.2% and 47.3% of their initial activities when stored at temperatures of 25 °C and 4 °C, respectively. In contrast, free laccase exhibited lower stability, with only 33.6% and 15.4% of their initial activities maintained under the same storage conditions. Finally, the use of immobilized laccase proved to be effective in eliminating these pollutants in up to five cycles. Upon comparing the two systems, namely LMOPs and modified orange peels (MOPs), it becomes apparent that LMOPs exhibit an estimated 20% improvement in removal efficiency. These results affirmed the viability of activated carbon derived from OPs as a cost-effective option for immobilizing laccase. This approach could potentially be further scaled up to effectively eliminate organic pollutants from water sources.

Effect of sulfidization on the surface property and flotation behavior of heterogenite

Heterogenite is an important cobalt oxide mineral, however, few investigations on the surface properties and flotation recovery of heterogenite were conducted. In this study, the effect of sulfidization on the surface property and flotation behavior of heterogenite was studied for the first time, using X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), Fourier-transform infrared spectroscopy (FT-IR) analysis, zeta potential measurements, adsorption amount tests, and micro-flotation experiments. Micro-flotation experiments proved that the flotation recovery of heterogenite is quite difficult. Zeta potential and sulfur ions adsorption tests proved that sulfur could be adsorbed on the surface of heterogenite, but the adsorption amount was very limited, and FT-IR indicates that the adsorption of PAX was also enhanced after sulfidization. XPS and SEM-EDS analysis further showed that the high O/Co ratio, special micromorphology, and Co3+ sites with strongly oxidizing properties on the surface heterogenite hinder the adsorption of sulfur ions being unfavorable sulfidization, which might be the reason why it is difficult to benefit heterogenite. The results are of far-reaching significance for deepening the understanding of the flotation behavior of heterogenite and taking corrective measures to recover this type of cobalt oxide ore.

The effect of 2% chlorhexidine iontophoresis on dentin sealing ability of etch-and-rinse adhesive: An in vitro study

Background/purposeIontophoresis could enhance the delivery of chlorhexidine into oral tissue. This study aimed to determine the effect of 2% chlorhexidine iontophoresis (CHI) on the sealing ability of etch-and-rinse adhesive in human dentin using hydraulic conductance (HD) measurement, scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM-EDS). Materials and methodsThirty-nine sound dentin specimens were prepared from 39 extracted intact third molars. Thirty specimens were used for HD measurement and randomly divided into 3 equal-sized groups; (1) No chlorhexidine treatment (control), (2) passive chlorhexidine treatment (CHT) and (3) CHI on acid-etched dentin. Each dentin surface was treated with etch-and-rinse adhesive. HD of each specimen was measured before treatment, after immediate bonding and after 14 days. The other 9 specimens were subjected to SEM-EDS analysis of the acid-etched dentin and the dentin treated with CHT and CHI. ANOVA test and Student-Newman-Keuls method were used for statistical analysis. ResultsAfter bonding, there was no significant difference in percentage decrease of HD among the treatment groups (P > 0.05). After 14 days, CHI and CHT groups had greater percentage decrease of HD than the control (P < 0.001 and P = 0.009, respectively). Under SEM-EDS analysis, acid-etched dentin with CHI presented opened dentinal tubule orifices and more chlorhexidine precipitates on dentin than the dentin with CHT, which strongly related to a higher percentage of chloride ions on the CHI dentin surface (P < 0.001). ConclusionThe use of CHI on acid-etched dentin had a positive effect on dentin sealing ability of etch-and-rinse adhesive.

Design of symmetric supercapacitor from biowaste derived carbon for flashlight applications with superior cycle’s stability

Extraction of biodiesel from Pongamia pinnata seeds is a vital “Green” synthesis process which is reliable, sustainable, and eco-friendly. The cake obtained during this process is generally utilized as a fertilizer and rich in carbon & nitrogen content. In the present work, initially the material was subjected to carbonization process (PC) was activated with three different porogens such as KOH, KCl, K2HPO4 (K+ as common ion) and labeled as PC-1, PC-2 & PC-3 respectively. The physico-chemical properties of all the carbon materials were investigated by various analytical techniques such as Powder X-Ray diffraction (P-XRD), Brunner Emmett Teller (BET), Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), Transmission Electron Microscopy and Selected Area Electron Diffraction (TEM-SAED), & Raman spectroscopy. PC-1 exhibited better electrochemical performance than the other activated carbons (ACs) & PC with specific capacitance (Cs) of 253F/g at 2.5 A/g, retained 75% Cs at the end of 10,000th cycle and 100% coulombic efficiency in 1 M KOH solution. The symmetric supercapacitor coin cell (SSC) using PC-1 (1 M KOH) exhibited a high Cs of 112F/g at scan rate of 2 mV/s, a maximum energy density (ED) of 38.6 Wh/kg and power density (PD) of 9 kW/kg. Interestingly, the coin cell demonstrated a total of 100 k cycles at high current density of 25 A/g with time gap of fifteen days for 50 k cycles. Six SSCs connected in series were successfully used to power up a flashlight with 15 white LED’s (each 4 V) connected in series for 3 min.

The influence of magnetic particle incorporation on bisphenol A removal by β-cyclodextrin-derived sorbent

A novel, biomass-derived hybrid sorbent Ban-CD-EPI-Fe was successfully synthesized in a coprecipitation method, in which β-cyclodextrin copolymerized with banana peel extract and epichlorohydrin was grafted onto an iron oxide surface. The composition, presence of functional groups, morphology, thermal stability, and magnetic properties of the obtained material were characterized by Powder X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Thermogravimetric Analysis (TGA), and Physical Properties Measurement System (PPMS). The material bearing around 28% of β-cyclodextrin units has mesoporous structure with plate-like morphology and active surface area determined by BET and Langmuir models equal to 38.35 and 53.59 m2 g−1, respectively. The sorption studies aimed to remove an endocrine disruptor – bisphenol A (BPA), from water. The results showed that the time evolution could be fitted with pseudo-second kinetic order with a rate constant k equal to 0.05 g mg−1 min−1. According to the Langmuir isotherm, a monolayer is created during BPA sorption, and the maximum sorption capacity was estimated as 93.5 mg g−1. After BPA sorption, the hybrid material could be easily separated by an external magnet and regenerated under mild conditions keeping its recyclability in at least eight cycles.

Investigation of the Bimodal Leaching Response of RAM Chip Gold Fingers in Ammonia Thiosulfate Solution.

Oxidative thiosulfate leaching using Cu(II)-NH3 has been explored for both mining and recycling applications as a promising method for Au extraction. This study seeks to understand the dissolution behavior of Au from waste RAM chips using a Cu(II)-NH3-S2O3 solution. In the course of this work, bimodal leaching and Au loss were observed in a manner that we have not identified in the literature. Identification of the existence of a specific Au-Ni-Cu lamellar structure in the gold fingers from RAM chips by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) revealed the possibility of interference between Au recovery and the existence of Cu and Ni. During leaching, the co-extraction of Ni was found to predict a negative impact on the Au recovery, as a result of chemical interactions from the Au-Ni-Cu interlayer. Decopperization as a pretreatment was found necessary to remove the pre-existing Cu and promote Au leaching. As part of the study parameters, such as Cu(II) concentration, aeration rates, thiosulfate and ammonia concentrations, particle sizes, and temperatures, were investigated. A satisfactory Au recovery of 98% was achieved using 50 mM Cu(II), 120 mL/min aeration rate, 0.5 M (NH3)2S2O3, and 0.75 M NH4OH (i.e., AT/AH ratio of 0.67) for 4 h residence time at room temperature (25 °C). However, there were several high recoveries prior to Au loss from the lixiviant. It was revealed that the main cause of lower Au recovery was due to a precipitation or cementation reaction that included a sulfur species formation. Because of the bimodal leaching, a composite response comprised of the time to Au loss and maximum recovery was developed, termed leaching proclivity, to facilitate statistical analysis. Furthermore, this study explores the interactions between Au-Ni-Cu and provides suggestions for improving Au thiosulfate leaching under the interference of co-existing metals from waste PCB materials.

Deposition of GdSmTi Coating for Corrosion Control of SS 316L in Bio-Field

The corporation of rare earth metals (lanthanides series) with other metals gives good properties in different fields, such as protecting the metallic surface from corrosion risk. In this work, the investigation on adding gadolinium (Gd) and samarium (Sm) as rare metals to bio-inert titanium (Ti) as transition metal was done to protect stainless steel (SS 316L) as bio metallic implant which is used in biofield because of its excellent mechanical properties, low costs, biocompatibility, inertness, and mechanical properties, chemical stability, workability, and high corrosion resistance. The corporation was done through coating using direct current (DC) sputtering technique from the target of these metals mixture to measure some properties. The surface characterization by X-ray diffraction (XRD) gave many phases represented by different GdxNiy in addition to the Ni3Ti phase and Ni5Sm phase. The scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) results showed the distribution of coating metals as a dense thin film with a good ratio of coating metals; this dense film gave lower surface roughness as illustrated through Atomic force microscopy (AFM) examination from 25.20 nm for the uncoated sample to 15.12 nm for the coated sample with a reduction in the hardness from 187 HV for the uncoated sample to 119 HV for the coated sample as well as increasing contact angle test (wettability) from 90° for base stainless steel surface to 117.723° for coated surface, these results enhanced the compatibility with giving good resistance from corrosion test, with achieving protection efficiency equal to 99.02%.

An improved method for feeding ash model compounds to a bubbling fluidized bed – CLC experiments with ilmenite, methane, and K2CO3

AbstractBiomass conversion with carbon capture and storage (Bio‐Energy CCS; BECCS) is one of the options considered for mitigating climate change. In this paper, the carbon capture technology chemical‐looping combustion (CLC) is examined in which the CO2 is produced in a stream separate from the combustion air. A central research topic for CLC is oxygen carriers; solid metal oxides that provide oxygen for the conversion process. Biomass and waste‐derived fuels contain reactive ash compounds, such as potassium, and interactions between the oxygen carrier and the ash species are critical for the lifetime and performance of the oxygen carrier. This work develops and demonstrates an improved method for studying the interactions between ash species and oxygen carriers. The method uses a lab‐scale reactor operating under fluidized conditions, simulating CLC batch‐wise by switching between feed gas. The novelty of the setup is the integrated system for feeding solid particles of ash model compounds, enabling the simulation of ash species accumulating in the bed. Ilmenite is a benchmark oxygen carrier for solid fuel conversion and was used in this study to evaluate the method using K2CO3 as a model ash compound. Experiments were done at 850 and 950°C. Methane conversion in CLC cycles and fluidization was evaluated with gas analysis and pressure drop measurements. Scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM‐EDS) and X‐ray diffraction (XRD) analysis of bed particles were done after the experiments to establish changes in the morphology and composition of the ilmenite. The method for feeding the ash model compound was concluded to be satisfactory. At 950°C, K accumulated in the particles forming K‐titanates and agglomeration was enhanced with K2CO3 addition. The agglomeration mechanism was solid‐state sintering between the Fe‐oxides forming on the particle surfaces. The bed defluidized at 950°C, but no such effect was seen at 850°C. The method is suitable for studying the Fe‐Ti‐K system with ilmenite and potassium without the influence of other ash species. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley &amp; Sons Ltd.

Carbon capture and storage potential of biochar-enriched cementitious systems

A promising solution to nullify the net embodied greenhouse gas emissions of civil infrastructure is the use of carbon-negative materials for concrete manufacturing. Carbon-neutral coal ash and agriculture/forestry by-products, such as biochar, exhibit a high carbon dioxide (CO2) uptake potential. The aim of the study is to explore the viability of using biochar as a carbon sink and to develop carbon-neutral concrete with improved performance. Experimental findings suggest that the optimal amount of biochar (1%) slightly improves hydration and mechanical properties, but the combination with mineral additives significantly enhances the performance. Thermogravimetric analysis (TGA) revealed that compared to OPC, the addition of 1% biochar contributes to a 42% increase in CO2 uptake, while the combination of biochar with 10% class C fly ash further increases CO2 capture capacity of the mix by 92%. Under accelerated carbonation conditions, the biochar-enriched mortars exhibit a 20% higher modulus of elasticity indicating an effectively increased stiffness over the reference carbonated OPC. The carbonated biochar mortars also exhibit up to 64% increased toughness indices indicating the material's great resistance to crack coalescence and propagation at the strain softening stage. Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS) results validated our prediction that the porous morphology of biochar promoted enhanced CO2 absorption and in-situ mineralization of calcium carbonate, resulting in a denser and stronger cement matrix.

Investigation of cadmium and nickel biosorption by Pseudomonas sp. via response surface methodology.

The environmental contamination of heavy metals has grown over the last several decades along with global industrialization and now constitutes a serious threat to human health. In this research, high cadmium (Cd) and nickel (Ni) resistant bacteria that were chosen for heavy metal biosorption were isolated from the Industries Factory in Sari, Mazandaran, Iran. Pseudomonas aeruginosa was recognized as the isolated bacterium based on its morphological, physiological, biochemical, antibiotic resistance testing, and 16S rRNA sequences. The bacteria had the highest concentrations of resistance to Cd (up to 1600ppm) and Ni, according to the Minimum Inhibition Concentration (MIC) test (up to 2000ppm). Single-factor studies in single and binary systems were used to examine the effects of temperature, contact duration, pH value, starting Cd and Ni concentration, and biomass dose on the Cd and Ni adsorption by P. aeruginosa. The Cd and Ni biosorption in binary solutions was optimized using the response surface methodology (RSM) based on Central Composite Design (CCD). The investigation revealed that at pH 7.0, 45°C, and 1.5 gL-1 biomass dose, the greatest biosorption efficiency for Cd and Ni was 92.43 percent and 88.45 percent, respectively. According to the adsorption of Cd and Ni in urban water, under these similarly extreme conditions, Cd adsorption drops to 54% and Ni to 60%. Analysis Potential functional groups involving interactions between cells and metal ions were identified using Fourier transform infrared spectroscopy (FTIR). Different compounds and heavy metal ions were found to have been adsorbed to the surface of the biosorbent by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDS). It was determined that P. aeruginosa had a high rate of Cd and Ni adsorption and that variations in pH level had a greater impact than other parameters. The findings imply that P. aeruginosa biomass may be an effective, economical, and environmentally friendly method for removing Cd and Ni from contaminated settings. It also has a reasonable capacity for biosorption in both a natural environment and a laboratory environment.

Polyphosphazene Based Inorganic‐Organic Hybrid Cathode Containing Pyrene Tetraone Sides for Aqueous Zinc‐Ion Batteries

AbstractAqueous rechargeable zinc‐ion batteries (ARZBs) are intriguing for electrochemical energy storage applications because of their safety and cost‐effectiveness. Regarding cathode materials, rapid development has been observed with the organic‐based cathode materials that offer much higher structural integrity upon successive (de‐)insertion of charge carries ions. Even though promising results demonstrated with organic electrodes, they still suffer from the short cycle‐life due to their discharge products solubility in electrolyte. Herein, electrochemical performance and charge storage mechanism of the synthesized polyphosphazene‐based inorganic‐organic hybrid electrode containing pyrene‐4,5,9,10‐tetraone (PTO) redox active lateral group, poly[(bis(2‐amino‐4,5,9,10‐pyrenetetraone)], abbreviated as (PPAPT), were investigated in ARZBs. The charge storage mechanism of PPAPT was examined by variousex‐situ[Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM‐EDS), X‐ray photoelectron spectroscopy (XPS)] andin‐situ[pH change with bromocresol green indicator and electrochemical quartz crystal microbalance (EQCM)] characterization techniques as well as computational density functional theory (DFT) revealing that the PPAPT electrode (de‐)coordinates both zinc and proton. The electrode and its discharge product are insoluble in the electrolyte demonstrated by UV‐vis analysis and exhibited a stable cycling performance with a discharge capacity of 125.4 mAh g−1after 1000 cycles at a current density of 10 C.

Electrochemical Deposition with Redox Replacement of Lanthanum with Uranium in Molten LiCl-KCl

Electrochemical recovery of dilute concentrations of actinides from spent nuclear fuel would reduce the longevity of storing high-level nuclear waste. Electrochemical deposition with redox replacement (EDRR) is used in a molten salt medium for the selective electrochemical recovery of uranium in the presence of excess concentrations of lanthanum. In each EDRR cycle, after a short electrodeposition pulse, the deposited lanthanum is spontaneously replaced by uranium at open circuit. After repeated cycles, uranium metal was obtained on a tungsten electrode immersed in a LiCl-KCl melt that contained 1 wt% lanthanum chloride—0.15 wt% uranium (IV) chloride. Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) analysis revealed uranium particles approximately 0.5−1 μm with well-defined rectangular shapes; and with 20–60 times more uranium recovered on the surface of the electrode than lanthanum.

Removal of Methylene Blue from Water Using Magnetic GTL-Derived Biosolids: Study of Adsorption Isotherms and Kinetic Models.

Global waste production is significantly rising with the increase in population. Efforts are being made to utilize waste in meaningful ways and increase its economic value. This research makes one such effort by utilizing gas-to-liquid (GTL)-derived biosolids, a significant waste produced from the wastewater treatment process. To understand the surface properties, the biosolid waste (BS) that is activated directly using potassium carbonate, labelled as KBS, has been characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), and Brunauer-Emmett-Teller (BET). The characterization shows that the surface area of BS increased from 0.010 to 156 m2/g upon activation. The EDS and XPS results show an increase in the metal content after activation (especially iron); additionally, XRD revealed the presence of magnetite and potassium iron oxide upon activation. Furthermore, the magnetic field was recorded to be 0.1 mT using a tesla meter. The magnetic properties present in the activated carbon show potential for pollutant removal. Adsorption studies of methylene blue using KBS show a maximum adsorption capacity of 59.27 mg/g; the adsorption process is rapid and reaches equilibrium after 9 h. Modelling using seven different isotherm and kinetic models reveals the best fit for the Langmuir-Freundlich and Diffusion-chemisorptionmodels, respectively. Additional thermodynamic calculations conclude the adsorption system to be exothermic, spontaneous, and favoring physisorption.

Effects of Fe(II) on As(III) oxidation in Fe(II)-As(III) co-oxidation: Limiting and driving roles

The co-oxidation of Fe(II) and As(III) occurs under aerobic conditions, and Fe(II) may largely determine the fate of As(III), but the effect of Fe(II) on the As(III) oxidation is barely explored. In this research, the limiting and driving roles of Fe(II) in As(III) oxidation were systematically studied through batch kinetic studies in combination with X-ray photoelectron spectroscopy (XPS) depth profiling, scanning electron microscopy and energy dispersive X-ray spectrometry (SEM-EDS), and quenching experiments. The results showed that As(III) oxidation efficiency increased with the increase of Fe/As molar ratio (from 63.1% to 98.3%), but decreased with the increase of pH (from 96.0% to 44.2%) and the increase of air flow rate (from 88.1% to 75.1%). The Fe(II) oxidation rate increased with the increase of pH and air flow rate. When Fe(II) was oxidized rapidly, As(III) was more likely to be immobilized in the “inner sphere” of formed Fe (hydr)oxides, limiting As(III) oxidation. On the other hand, Fe(II) was oxidized to produce Fe (hydr)oxides to adsorb or fix As(III); meanwhile, the ROS generated by Fenton-like reaction of Fe(II) promoted As(III) oxidation, especially, •O2− and H2O2 were important ROS that drove the As(III) oxidation. These findings might provide a new insight for Fe(II) and As(III) geochemistry cycling in naturally occurring environment.