Search Results (286)

Purity analysis of parent gases used to produce reference gas mixtures is fundamental to assure the metrological traceability of the certified gas composition, and the use of purity data in the calculation of the mixture composition should be performed in accordance with the requirements of international standards. Purity analysis can be difficult to realize since limited measurement standards are available for the determination of trace levels of gaseous compounds. The first step of purity analysis is the definition of the impurities considered critical or significant to the final composition of a mixture. In this work, we present the activity carried out for the identification and quantification of impurities of carbon dioxide and water in some ultrapure gases used for the preparation of primary certified reference gas mixtures of carbon dioxide at atmospheric amount fraction (400–800 µmol·mol⁻¹), by means of different spectroscopic techniques (Fourier Transform IR, Non-Dispersive IR and Cavity Ring-Down). Dynamic dilution was used for the generation of reference mixtures for the calibration of the analyzers by using calibrated Mass Flow Controllers. The certified reference gas mixtures produced with the tested pure gases will also be applied to characterization studies and calibration protocols for gas sensors used both for outdoor and indoor monitoring. Full article

This study presents a sustainable upcycling strategy to convert “Pit,” a carbon-rich coke oven by-product from steel manufacturing, into high-purity graphite for use as an anode material in lithium-ion batteries. Despite its high carbon content, raw Pit contains significant impurities and has irregular particle morphology, which limits its direct application in batteries. We employed a multi-step, additive-free refinement process—including jet milling, spheroidization, and high-temperature graphitization—to enhance carbon purity and structural properties. The processed Pit-derived graphite showed a much-improved particle size distribution (D50 reduced from 25.3 μm to 14.8 μm & Span reduced from 1.72 to 1.23), increased tap density (from 0.54 to 0.80 g/cm³), and reduced BET surface area, making it suitable for high-performance lithium-ion batteries anodes. Structural characterization by XRD and TEM confirmed dramatically enhanced crystallinity after graphitization (graphitization degree increasing from ~13 for raw Pit to 95.7% for graphitized Pit at 3000 °C). The fully processed graphite (denoted S_Pit3000) delivered a reversible discharge capacity of 346.7 mAh/g with an initial Coulombic efficiency of 93.5% in half-cell tests—comparable to commercial artificial graphite. Furthermore, when composited with silicon oxide to form a hybrid anode, the material achieved an even higher capacity of 418.0 mAh/g under high mass loading conditions. These results highlight the feasibility of transforming industrial coke waste into value-added electrode materials through environmentally friendly physical processes. The upcycled graphite anode meets industrial performance standards, demonstrating a promising route toward circular economy solutions in both the steel and battery industries. Full article

In response to the dust pollution issue during the harvesting operations of peanut pickup combines, this study involved conducting bench tests to explore the variation patterns of dust emission parameters and harvesting operation indicators under diverse working parameter conditions of the combine’s working components. A multi-factor mathematical model was established to predict both the dust emission rate of peanut pickup combines and the quality of harvesting operations. The model was utilized to identify the optimal combination of operation parameters for achieving high-quality and low-emission performance. The optimal parameter combination was determined as follows: a pod threshing roller speed of 313 r/min, a cleaning fan speed of 2535 r/min, a vine crushing roller speed of 1970 r/min, and a lifting fan speed of 1604 r/min. Under these conditions, the theoretical dust emission rate was calculated to be 10,603 mg/s, with a pod loss rate of 4.73% and a pod impurity rate of 5.21%. Compared to previous settings, the optimized operation parameters effectively reduced the combine’s dust emissions by 9.95%. Notably, the harvesting operation quality still complies with the industry standards for peanut harvesters. These research findings offer theoretical insights and robust technical support for minimizing dust pollution during the whole-feed harvesting of peanuts, contributing to more environmentally friendly and efficient peanut harvesting practices. Full article

Hay quality is a key factor in equine respiratory health, with microbiological contaminants in inhaled organic dust posing significant risks. Sensory assessment has been used to evaluate hay hygiene, but its value to identify deficiencies remains unclear. This study aimed to explore the potential of sensory assessment to predict both particulate matter (PM) dust concentrations and microbiological contamination. Fifty hay samples were collected from horse owners and evaluated using a structured sensory examination, microbiological analyses, and dust concentration measurements obtained with the Hay-Shaker device and a DustTrak DRX 8534. Sensory examination rated only 28% of samples as adequate, with 52% showing minor and 20% major deficiencies. Microbiological analysis found that 46% of samples met acceptable standards. Regression analysis showed that abnormal musty odor was the strongest predictor of increased dust concentrations, including the respirable fraction (PM4, <4 µm), while visible impurities were associated with microbial contamination. These findings suggest that sensory attributes such as odor and impurity are valuable indicators of hay hygiene. Structured protocols for sensory examination may offer a simple and cost-effective tool for assessing hay quality in equine environments. Full article

The construction and demolition (C&D) industry generates nearly one-third of the total global waste. In response, the European Union is driving urgent efforts to enhance material circularity through the promotion of renewable materials. However, research primarily targets materials such as concrete, plastics, steel, bricks, and gypsum, while wood as a renewable material presents a clear research gap. This study aims to bridge the gap by identifying key barriers and potentials for reusing wood waste in the C&D sector. As a result, factors influencing wood reusability are categorized into economic, societal, environmental, technical, and regulatory dimensions. Economic and environmental factors addressing high costs, unstable markets, and contamination are the most discussed barriers for an enhanced circular use of wood. Specifically, material irregularities and impurities represent technical barriers that may make wood demand less attractive. Societal barriers, such as knowledge gaps regarding the quality of secondary materials, established standards, and legal limits are further barriers that are mentioned in the literature. Therefore, potential future indicators to support a circular approach in the construction sector, including regulatory actions and incentives, are recommended to promote recovered secondary materials. This approach would facilitate shared stakeholder cooperation, knowledge sharing, and market development. Full article

The cooling medium of the guide bearing heat exchanger in hydro generator sets comes from the upstream dam area, which contains numerous impurities even though it has undergone preliminary treatment. These impurities settle, accumulate, and adhere and form scaling layers in the heat exchanger, seriously affecting its heat transfer performance. This paper presents an innovative investigation of heat exchanger performance under impurity-laden cooling water conditions and proposes an optimization by replacing the conventional round tube structure with a spiral flat tube structure. Numerical simulations are conducted to analyze the flow velocity, pressure, impurity deposition, and temperature distribution of the cooler under actual operating conditions. The results show that the optimized cooler achieves improved velocity uniformity with a lower standard deviation, effectively reducing sediment accumulation. Compared to the prototype, the maximum pressure increases by 55.2% (from 0.562 MPa to 0.872 MPa), which enhances turbulence and improves heat transfer. The sediment volume fraction is significantly reduced by 49% in low-flow operating conditions and 73.7% in high-flow operating conditions. Furthermore, the maximum temperature drops by 5.43 °C, indicating improved thermal performance. These findings confirm the effectiveness of the spiral flat tube design in impurity-rich environments. Full article

The effective removal of oxygen (O), nitrogen (N), sulfur (S), and oxide inclusions from superalloy reverts is crucial for enhancing service life and achieving cost efficiency. However, refining DZ125 superalloy presents particular challenges, as conventional processes prove ineffective against hafnium (Hf) oxides. This study introduces an innovative purification method combining droplet electron-beam melting (EBM) with centrifugal directional solidification. Through this advanced EBM technique, we successfully produced ultrapure DZ125 superalloy with nitrogen content reduced below 5 ppm and total O + N + S content below 10 ppm. Most significantly, the process nearly eliminated Hf oxides from the reverts, meeting the stringent purity standards for DZ125 superalloy. We conducted a comprehensive analysis of inclusion morphology and composition in three distinct regions: the top slag layer, final solidification zone, and interior section of the ingot processed at varying EBM power levels. Our findings reveal that MC-type carbides at the slag–crucible interface were formed. There are HfO₂, TaC, and Al₂O₃ in the final solidification zone, with notable encapsulation of HfO₂ particulates within Al₂O₃ particles; and few HfO₂ and Al₂O₃ inclusions exist in the ingot interior. It is also found that increasing EBM power from 36 kW to 46 kW significantly improved impurity removal efficiency, as evidenced by substantial reductions in both inclusion quantity and size. This enhanced purification stems from two primary mechanisms: (1) flotation of inclusions during EBM melting, facilitated by Marangoni convection, droplet stirring effects, and centrifugal forces generated by ingot rotation; and (2) decomposition of stable oxides enabled by the high-energy density characteristic of EBM and high-vacuum processing environment. This combined approach demonstrates superior capability in overcoming the limitations of traditional refining methods, particularly for challenging Hf oxide removal, while establishing an effective pathway for superalloy revert recycling. Full article

The Multi-Mode Model (MMM) is a physics-based anomalous transport model integrated into TRANSP for predicting electron and ion thermal transport, electron and impurity particle transport, and toroidal and poloidal momentum transport. While MMM provides valuable predictive capabilities, its computational cost, although manageable for standard simulations, is too high for real-time control applications. MMMnet, a neural network-based surrogate model, is developed to address this challenge by significantly reducing computation time while maintaining high accuracy. Trained on TRANSP simulations of DIII-D discharges, MMMnet incorporates an updated version of MMM (9.0.10) with enhanced physics, including isotopic effects, plasma shaping via effective magnetic shear, unified correlation lengths for ion-scale modes, and a new physics-based model for the electromagnetic electron temperature gradient mode. A key advancement is MMMnet’s ability to predict all six transport coefficients, providing a comprehensive representation of plasma transport dynamics. MMMnet achieves a two-order-of-magnitude speed improvement while maintaining strong correlation with MMM diffusivities, making it well-suited for real-time tokamak control and scenario optimization. Full article

The acquisition of high-purity impurities is pivotal for structural identification and an origin analysis, thereby laying a critical foundation for subsequent toxicological evaluation, quality standard development, and process optimization. This study investigated the feasibility of using a solvent gradient twin-column recycling chromatography technique for the separation and purification of multiple trace impurities in iohexol. In this approach, a modifier with a weaker elution strength than the mobile phase is introduced between two chromatographic columns to form a step gradient solvent system. This gradient slows down the leading edge of the elution band relative to the rear edge, inducing a band compression effect that counteracts band broadening and enhances the chromatographic resolution. By optimizing parameters such as the mobile phase composition, elution mode, and modifier flow rate, three trace impurities were successfully separated and purified from iohexol. Their respective purities were improved from initial concentrations of 0.36%, 0.35%, and 0.15% to 97.82%, 91.56%, and 81.56%, respectively. Leveraging the band compression effect on the target components, the impurities were simultaneously purified and concentrated. These results demonstrate that the proposed method is highly effective for the rapid isolation and preparation of trace pharmaceutical impurities. Full article

This study evaluates the potential use of reclaimed sand from municipal wastewater treatment plants (WWTP), categorized as waste under code 19 08 02, as a full substitute for natural sand in cement mortars. The sand was subjected to alkaline pretreatment using sodium hydroxide (NaOH) at concentrations of 0.5%, 1% and 2% to reduce organic impurities and improve surface cleanliness. All mortar mixes were prepared using CEM I 42.5 R as the binder, maintaining a constant water-to-cement ratio of 0.5. Mechanical testing revealed that mortars produced with 100% WWTP-derived sand, pretreated with 0.5% NaOH, achieved a mean compressive strength of 51.9 MPa and flexural strength of 5.63 MPa after 28 days, nearly equivalent to reference mortars with standardized construction sand (52.7 MPa and 6.64 MPa, respectively). In contrast, untreated WWTP sand resulted in a significant performance reduction, with compressive strength averaging 30.0 MPa and flexural strength ranging from 2.55 to 2.93 MPa. The results demonstrate that low-alkaline pretreatment—particularly with 0.5% NaOH—allows for the effective reuse of WWTP waste sand (code 19 08 02) in cement mortars based on CEM I 42.5 R, achieving performance comparable to conventional materials. Although higher concentrations, such as 2% NaOH, are commonly recommended or required by standards for the removal of organic matter from fine aggregates, the results suggest that lower concentrations (e.g., 0.5%) may offer a better balance between cleaning effectiveness and mechanical performance. Nevertheless, 2% NaOH remains the obligatory reference level in some standard testing protocols for fine aggregate purification. Full article

Phosphogypsum, a byproduct of orthophosphoric acid production, is one of the large-tonnage wastes. Since phosphogypsum mainly consists of CaSO₄ 2H₂O, it can be considered as an alternative gypsum-bearing raw material in the production of gypsum binders. However, its features, such as particle morphology and the presence of impurities, can negatively affect the characteristics of phosphogypsum-based binders. Identification of these factors will allow us to develop methods for their minimization and increasing the efficiency of phosphogypsum use from the required source as a raw material for the production of phosphogypsum-based binders. In this regard, the manuscript contains a comprehensive and comparative analysis of phosphogypsum and natural gypsum, which makes it possible to establish their differences in chemical composition and structural and morphological features, which subsequently affect the properties of the phosphogypsum-based binder. It has been established that the key factor negatively affecting the strength of phosphogypsum-based paste (2.58 MPa) is its high water demand (0.89), which is due to the high values of the specific surface area of the particles and the presence of a large number of conglomerates with significant porosity in phosphogypsum. It has been suggested that preliminary grinding of phosphogypsum can help reduce the amount of water required to obtain fresh phosphogypsum-based paste with a standard consistency and improve its physical and mechanical properties. Full article

This study focuses on the optimization of valve assemblies in downhole rod pumping units (DRPUs), which remain the predominant artificial lift technology in oil production worldwide. The research addresses the critical issue of premature failures in DRPUs caused by leakage in valve pairs, i.e., a problem that accounts for approximately 15% of all failures, as identified in a statistical analysis of the 2022 operational data from the Uzen oilfield in Kazakhstan. The leakage is primarily attributed to the accumulation of mechanical impurities and paraffin deposits between the valve ball and seat, leading to concentrated surface wear and compromised sealing. To mitigate this issue, a novel valve assembly design was developed featuring a flow turbulizer positioned beneath the valve seat. The turbulizer generates controlled vortex motion in the fluid flow, which increases the rotational frequency of the valve ball during operation. This motion promotes more uniform wear across the contact surfaces and reduces the risk of localized degradation. The turbulizers were manufactured using additive FDM technology, and several design variants were tested in a full-scale laboratory setup simulating downhole conditions. Experimental results revealed that the most effective configuration was a spiral plate turbulizer with a 7.5 mm width, installed without axis deviation from the vertical, which achieved the highest ball rotation frequency and enhanced lapping effect between the ball and the seat. Subsequent field trials using valves with duralumin-based turbulizers demonstrated increased operational lifespans compared to standard valves, confirming the viability of the proposed solution. However, cases of abrasive wear were observed under conditions of high mechanical impurity concentration, indicating the need for more durable materials. To address this, the study recommends transitioning to 316 L stainless steel for turbulizer fabrication due to its superior tensile strength, corrosion resistance, and wear resistance. Implementing this design improvement can significantly reduce maintenance intervals, improve pump reliability, and lower operating costs in mature oilfields with high water cut and solid content. The findings of this research contribute to the broader efforts in petroleum engineering to enhance the longevity and performance of artificial lift systems through targeted mechanical design improvements and material innovation. Full article

Nanomaterials possess unique physicochemical properties that position them as promising candidates for environmental remediation, particularly in the removal of persistent organic pollutants (POPs) from aqueous systems. Their high surface area, tunable functionality, and strong adsorption capabilities have attracted significant attention. In this context, this paper reviews the mechanisms of nanomaterial-based POP decontamination, also providing a critical overview of the limitations and challenges in applying these methods. Specifically, issues of stability, reusability, and aggregation are discussed, which can lead to performance decay during repeated use. In addition, the practical application requires nanocomposites to enable efficient separation and mitigate agglomeration. Environmental concerns also arise from nanomaterials’ fate, transport, and potential toxicity, which may impact aquatic ecosystems and non-target organisms. When checking for large-scale application feasibility, impurities typically add to production costs, recovery problems, and general infrastructure limitations. In addition to these points, there are no standard guidelines or clear risk assessment procedures for registering a product. Unprecedented cross-disciplinary research between natural, human, and technological studies and outreach programs is needed to facilitate the development and diffusion of the results. The barriers will eventually be breached to move from laboratory success in developing the desperately needed new water purification technologies to field-ready water treatment solutions that can address the global POP contamination problem. Full article

Electrolytic manganese residue (EMR) is a byproduct of electrolytic manganese production, rich in soluble pollutants such as manganese and ammonia nitrogen. Traditional stockpiling methods result in contaminant leaching and water pollution, threatening ecosystems. Meanwhile, EMR has significant resource-recovery potential. This paper systematically reviews the harmless process and resource technology of EMR, efficiency bottlenecks, and the current status of industrial applications. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed. Among these, electrochemical purification stands out for its efficiency and environmental benefits, positioning it as a promising option for broad industrial use. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed, revealing the complementarity between building materials and chemical materials (microcrystalline glass) in scale and high-value-added production. But the lack of impurity separation accuracy and market standards restricts its promotion. Finally, it proposes future directions for EMR resource utilization based on practical and economic considerations. Full article

L-thyroxine (T4) is an important hormone for diagnosing and evaluating thyroid function disorders. As outlined in ISO17511, having a certified reference material (CRM) is crucial for ensuring that the results of clinical tests are traceable to the SI-unit. This study employed two principal methods to evaluate the purity of T4, mass balance (MB) and quantitative nuclear magnetic resonance (qNMR), both of which are SI-traceable (International System of Units) approaches. The MB method involved a detailed analysis of impurities, including water, structurally related compounds, and volatile and non-volatile substances. A variety of techniques were employed to characterize T4 and its impurities, including liquid-phase tandem high-resolution mass spectrometry, ultraviolet spectrophotometry, infrared spectroscopy, and both ¹H-NMR and ¹³C-NMR. Additionally, impurities were quantified using Karl Fischer coulometric titration, ion chromatography, gas chromatography–mass spectrometry, and inductively coupled plasma–mass spectrometry. In qNMR, ethylparaben was used as the internal standard for direct value assignment. The results showed T4 purities of 94.92% and 94.88% for the MB and qNMR methods, respectively. The water content was determined to be 3.563% (n = 6), representing the highest impurity content. Ten structurally related organic impurities were successfully separated, and five of them were quantified. Ultimately, a purity of 94.90% was assigned to T4 CRM, with an expanded uncertainty of 0.34% (k = 2). Full article