Search Results (1,280)

The transition of adsorbent materials from laboratory synthesis to industrial application requires a rigorous assessment of their durability under high concentrations. This study evaluates composite alginate hydrogels incorporating mill scale-derived magnetite (Fe₃O₄), activated carbon, and L-ascorbic acid (Fe₃O₄/AC/VitC alginate hydrogels) for the detoxification of highly concentrated chromium effluents. We investigated the operational limits of these hydrogel bubbles through three distinct scenarios: (1) Single-Batch Adsorption–Regeneration Cycling in Fresh Cr(VI) Solutions, (2) Sequential Reuse of Single-Batch Hydrogel Bubbles in the Same Effluent for Complete Cr(VI) Removal, and (3) the Multi-Batch Treatment Capacity Test for highly concentrated Cr(VI) loads. The composite demonstrated exceptional robustness, maintaining >80% removal efficiency over five cycles for 100 mg/L Cr(VI) without chemical treatment. For higher loads (150–400 mg/L), a simple regeneration protocol effectively restored performance, reducing Cr(VI) levels to below stringent discharge limits (<0.25 mg/L). Furthermore, in “worst-case” scenarios involving synthetic solutions (2500 mg/L) and real electroplating wastewater (~2000 mg/L), a multi-batch approach achieved complete abatement within 8–9 cycles. Notably, the treatment simultaneously neutralized the effluent pH from ~1.0 to 7.0, confirming the potential of this waste-derived material as a resilient, multi-functional solution for complex industrial wastewater management. Beyond performance, a techno-economic analysis was conducted to evaluate the economic feasibility of industrial-scale production. The results indicate that by utilizing industrial-grade reagents and waste-derived precursors, the production cost of the dry adsorbent can be estimated at ~45 EUR/kg. These findings confirm the potential of this material as a cost-effective, multi-functional solution for SMEs struggling with high operational costs and stringent environmental regulations. Full article

Keratin is an abundant, recalcitrant structural protein that constitutes the primary component of several animal wastes, particularly chicken feathers. Because of their potential and availability, various technologies, such as anaerobic biodigestion, have been used to degrade keratin and transform feathers into biogas and other value-added products. However, due to their fibrous architecture and rigid structure, keratinous materials are elastic, water-insoluble, and enzymatically resistant, which makes natural degradation difficult. In this sense, before using chicken feathers as feedstock in biodigesters, the keratin in the residue must be cleaved in pretreatment steps. Whether as a single substrate or in co-digestion processes, the keratin breakdown is critical for enhancing biogas production from feathers. In this context, there is growing emphasis on developing pretreatment methods to facilitate protein hydrolysis and digestion, thereby improving biogas generation. To evaluate progress in recycling waste keratin, a bibliometric analysis of original scientific publications on the pretreatment of chicken feathers for anaerobic digestion was conducted using the Scopus database. The findings indicate that researchers apply chicken feathers in processes, including standard biodigestion, co-digestion with food waste, animal manure, and slaughterhouse waste, for biomethane and biohydrogen production. Across the evaluated studies, the pretreatment methods showed notable improvements in feather solubilization and subsequent biogas yield; however, they still encounter key limitations, including ammonia (NH₃) inhibition, high chemical/reagent costs, and high energy demand. Full article

Many genotoxic impurities (GTIs) remain “invisible” to conventional LC-MS due to poor ionization or chemical instability under electrospray ionization, yet their sub-ppm acceptable intake limits under ICH M7(R2) demand exceptional analytical sensitivity. Derivatization—the chemical introduction of ionizable moieties, stable tags, or MS/MS information carriers—offers a powerful strategy to overcome this limitation. This review provides a critical systematic overview of derivatization techniques for LC-MS analysis of GTIs over the past decade (2015–2025, based on a literature search across PubMed, Web of Science, and Scopus). We construct a functional-group-based strategic framework covering alkyl halides, nitroaromatics, sulfonyl chlorides, hydroxylamine, alcohols, aldehydes, carboxylic acids, and amines, while placing specific emphasis on typical impurities within these classes such as methyl iodide, methyl chloride, nitrobenzene, and benzenesulfonyl chloride, and discuss the evolution of reagents from simple “reaction tags” to “MS/MS information carriers” that provide characteristic neutral losses or product ions for enhanced selectivity. Quantitative analysis reveals that derivatization typically enhances ESI response by 2–3 orders of magnitude, consistently achieving LODs below 1 ppm—the ICH M7(R2) threshold. Key analytical trade-offs are critically evaluated, including the balance between derivatization efficiency and reaction time, by-product management, and the fundamental kinetic and chromatographic constraints that render post-column derivatization impractical for most GTIs. We conclude with perspectives on high-throughput automation, smart multifunctional reagents, online integration, and green chemistry, aiming to provide a practical roadmap for developing robust, sensitive, and regulatory-compliant LC-MS methods for GTI control. Full article

This study optimised and validated a microplate Ferric-Reducing Antioxidant Power (FRAP) assay for honey that incorporates a honey-specific matrix-matched blank—a paired absorbance measurement lacking the chromogenic probe 2,4,6-tris(2-pyridyl)-s-triazine (TPTZ)—to separate true ferric reduction from non-reductive Fe³⁺–matrix interactions that otherwise inflate apparent antioxidant capacity. A 30 min incubation at 37 °C in the dark was selected as the optimal compromise between reaction completeness and reagent/matrix stability, using 20 µL sample and 180 µL FRAP reagent per well (absorbance at 620 nm). The assay was validated according to International Council for Harmonisation (ICH) principles, showing linearity for FeSO₄·7H₂O from 200–1200 µM (R² ≥ 0.9988), Limit of detection/limit of quantification (LOD/LOQ) of 0.28/0.94 mmol Fe²⁺ equivalents kg⁻¹, recoveries of 101–103%, and precision ≤ 5% relative standard deviation (RSD). All tested individual sugars except maltodextrin and the artificial honey matrix produced FRAP responses below the LOQ. Flavonoids, however, showed pronounced, time-dependent, non-reductive Fe³⁺ interactions and were markedly overestimated under conventional water blanking, while phenolic acids were less affected. Applied to 47 Western Australian honeys, the validated assay yielded FRAP activities of 2.80–9.52 mmol Fe²⁺ kg⁻¹; matrix-matched blanking gave consistently lower, more chemically specific values than conventional water blanking, with corrections ranging up to >30% depending on honey type. Matrix-matched blanking is therefore essential, not optional, for accurate FRAP measurement in honey, and the same principle should apply directly to other phenolic-rich foods like wine, tea, and fruit extracts—wherever iron–polyphenol interactions confound conventional antioxidant assays. Full article

Ilmenite is the core carrier of titanium resources in China. Conventional flotation systems generally have the problems of insufficient collector adsorption efficiency and limited separation index. Microwave pretreatment can strengthen the flotation process by activating the surface of minerals, but its regulation mechanism on the interface properties of ilmenite and the adsorption behavior of collectors remains to be systematically elucidated. Based on the previous research on the flotation separation effect of the ‘OHA + HDPA composite collector + microwave pretreatment (power of 800 W and irradiation time of 180s)’ system, this paper uses the OHA + HDPA (mass ratio 3:1) composite system as the collector and uses surface tension, contact angle, Zeta potential, infrared spectroscopy and X-ray photoelectron spectroscopy, and other multi-scale complementary characterization methods to systematically study the effect of microwave activation on the wettability of ilmenite surface and the adsorption of collector interface. The results show that the wettability of ilmenite surface by microwaves presents a two-way regulation characteristic. In a pure water system, microwave activation increases the surface polar active sites, the water contact angle decreases from 48.44° to 46.65°, and the hydrophilicity is slightly enhanced. Under the action of the collector, microwaves promoted the directional adsorption and orderly arrangement of reagents, the contact angle of minerals increased to 85.24°, the adhesion work reached 0.560 J/m², and the surface hydrophobicity and solid–gas adhesion ability were significantly improved. Interfacial electrokinetic analysis showed that microwave activation enhanced the positive surface charge of ilmenite, and the isoelectric point shifted from pH 5.1 to alkaline to pH 6.3. In the range of pH 2–10, the Zeta potential of the sample after microwave treatment shifted more negatively, which was due to the synergistic enhancement of electrostatic attraction and chemical chelation sites. Microscopic characterization confirmed that the collector was attached to the surface of ilmenite in the form of chemical adsorption. Microwaves did not change the essential properties of adsorption but increased the adsorption capacity of the collector by 10.9%, and the adsorption layer was more compact and orderly. A mechanism analysis reveals that microwave irradiation induces the oxidation of surface Fe²⁺ to Fe³⁺, and its atomic proportion increases from 23.91% to 38.64%, which significantly enhances the chelation between the collector and the iron site and the stability of the chemical bond. At the same time, combined with the change of XPS coordination environment, it is speculated that microwaves can induce lattice distortion, change the coordination environment of titanium atoms, increase the proportion of Ti-O-Fe bridge oxygen structure, increase the unsaturated titanium active site, and strengthen the coordination between the collector and the titanium site. The synergistic activation of iron–titanium multi-sites together enhances the adsorption strength and adsorption capacity of the collector. This study can provide theoretical support at the interface chemical level for the development of high-efficiency ilmenite flotation process. Full article

Excessive nitrate discharge causes water eutrophication and public health risks, which has become a core challenge in global water environment governance. Conventional nitrogen removal technologies suffer from limitations such as carbon source dependence and secondary pollution, and can hardly meet the requirements of low-carbon water treatment. Driven by electric energy and free of additional chemical reagents, electrocatalytic nitrate reduction enables flexible regulation of product selectivity. Among all possible reaction pathways, selective N₂ production is the nitrogen removal route with the highest environmental benefits. However, constrained by the high energy barrier of N–N coupling and intense competition from side reactions, achieving highly selective N₂ production remains a major technical difficulty, and most existing reviews in this field focus on ammonia synthesis. This paper systematically reviews the research progress in this field, elucidates the reaction network and nitrogen production mechanism, compares the advantages and disadvantages of three types of selectivity evaluation methods, summarizes the design strategies of multi-scale electrocatalysts, and analyzes how operational parameters (including applied potential, electrolyte composition, pH, etc.) and reactor configuration regulate the reaction selectivity. Finally, the existing challenges are concluded and future development directions are prospected, so as to provide a reference for the research, development and engineering application of electrocatalytic nitrogen removal technology. Full article

Spent cathode carbon (SCC), a hazardous waste generated during primary aluminium production, contains valuable graphitic carbon resources but remains difficult to recycle because carbon purification is governed by complex interactions among multiple leaching parameters. Conventional process optimization relies on extensive laboratory experimentation, resulting in high chemical consumption, energy use, and development costs. This study presents an explainable machine learning framework for cleaner and more resource-efficient carbon purification from SCC under limited-data conditions. Six machine learning algorithms (GBDT, CatBoost, XGBoost, LightGBM, Random Forest, and Decision Tree) were evaluated using experimental data from alkaline leaching. The LightGBM model was systematically optimized by combining Response Surface Method (RSM), Orthogonal Experimental Design (OED), and local parameter optimization methods. The optimized model (min_child_samples = 2, num_leaves = 32, n_estimators = 500, and learning_rate = 0.5) achieved an R² of 0.8015, RMSE of 0.9163, and MAE of 0.6599. SHAP analysis identified initial alkali concentration, liquid–solid ratio, stirring rate, and leaching time as the dominant factors controlling carbon purification, whereas temperature had a comparatively smaller influence within the investigated operating range. The results indicate that improving reagent utilization and hydrodynamic conditions offers greater potential for enhancing carbon purification than increasing thermal input alone. By integrating statistical experimental design with explainable machine learning, this study establishes an efficient, interpretable, and transferable decision-support framework for optimizing hazardous waste recycling and other resource recovery processes under limited-data conditions, thereby supporting cleaner production and circular economy practices. Full article

Rare earth elements (REEs) are critical for advanced manufacturing and clean energy, yet their separation remains extremely challenging due to the nearly identical ionic radii of adjacent lanthanides. Conventional solvent extraction, ion exchange, and precipitation methods are limited by their high reagent consumption, slow kinetics, poor selectivity, and environmental burdens. Nanofiltration (NF) offers a green and efficient alternative—operating in the aqueous phase with low energy demand and continuous high throughput. This review systematically summarizes NF-based REE separation. We first elucidate the fundamental mechanisms (size exclusion, Donnan exclusion, dielectric exclusion, and complexation enhancement), and discuss how lanthanide hydration chemistry underpins these synergistic effects. Membrane materials, from commercial to biomimetic, are critically surveyed, with an emphasis on strategies to overcome the trade-off between permeability and selectivity. The impacts of operating conditions and solution chemistry are analyzed, and NF applications ranging from single REE systems to real leachates are assessed. A comparative evaluation positions NF against conventional technologies. Key challenges remain: poor adjacent REE selectivity, membrane fouling, performance loss at high salinity, chemical instability, and a gap between model and real feeds. Future directions include designing high-selectivity membranes, integrating machine learning optimization, establishing standardized protocols, and realizing closed-loop process integration. Full article

The study presents a sustainable, metal-free tanning system based on 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and N-methylmorpholine (NMM), which stabilizes collagen through a zero-length crosslinking mechanism. Reactive triazine intermediates, generated in situ, selectively activate collagen carboxyl groups, forming active esters that subsequently react with amine functionalities to form amide bonds. Unlike conventional tanning systems, no metals or toxic chemicals are incorporated into the tanned leather. Optimization of reagent concentration, temperature, and dosing strategy revealed that the gradual formation of reactive intermediates is essential to balance reaction kinetics and diffusion throughout collagen. Under pickle-free conditions, hydrothermal stability was achieved with only 2.5–3.4 wt% CDMT/NMM, yielding shrinkage temperatures of 81–85 °C that surpass most reported chrome-free tanning systems. The resulting leather displayed a bright white appearance, excellent dyeability, and outstanding physical-mechanical performance, including superior tear resistance and competitive tensile strength. These properties are consistent with the formation of a homogeneous collagen network reinforced by direct covalent amide crosslinks while maintaining fiber flexibility. Furthermore, avoiding pickling significantly reduces chemical consumption and improves wastewater biodegradability, enhancing the environmental sustainability of the process. Overall, CDMT/NMM emerges as a scalable, environmentally friendly tanning technology that combines mechanistically controlled collagen crosslinking with excellent leather performance. Full article

The detection of organic carbon in wastewater is essential for process monitoring and regulatory assessment. Yet conventional chemical oxygen demand (COD) and total organic carbon (TOC) methods remain reagent-dependent, slow, and unsuitable for inline operation. Photoelectrochemical (PEC) sensing based on TiO₂ offers a reagent-free alternative, but its response to wastewater-relevant dissolved organic matter (DOM) and real effluent matrices is still poorly understood. In this study, a TiO₂-based PEC system was systematically evaluated using four representative model compounds—glucose, potassium hydrogen phthalate, L-tryptophan, and urea—covering major fractions typically present in municipal wastewater. For the first time, representative wastewater-associated organic compound classes, conductivity effects, and the transferability of the PEC response to real wastewater effluent were systematically investigated. The photocurrent response showed distinct, highly linear concentration–signal relationships for each substance, suggesting a dominant contribution of surface-associated electronic effects. Conductivity variations across a relevant range had no measurable influence on sensitivity or photocurrent magnitude, indicating that the PEC response is not governed by bulk ionic transport but primarily is an interfacial process at the site of TiO₂. When applied to real wastewater effluent, the sensor exhibited an excellent linear correlation with dilution level (R² = 0.9954), demonstrating a linear response within a defined matrix and an LOD of 1.12 mg L⁻¹ COD. For the investigated model compounds, LOD values ranged from 1.06 to 3.00 mg L⁻¹ COD, while a linear response was maintained up to approximately 80–100 mg L⁻¹ COD. These findings establish TiO₂-based PEC sensing as a promising platform for the reagent-free, online monitoring of organic loads in wastewater treatment. Full article

A modern approach to the organization of wastewater disposal systems ensures the sustainable development of resort areas. Warm mineral springs (WMSs) located in suburban areas are not only recreational facilities for the population, but also sources of used mineral and communal wastewater. Preventing or reducing the discharge of pollutants in this type of liquid waste can reduce the anthropogenic impact on the environment. The article proposes a method for the chemical precipitation of ammonium ions in a mixture of mineral and domestic wastewater, and the production of struvite, a complex agricultural fertilizer. Three series of experiments were conducted: (1) on a model solution of ammonium ions; (2) on a mixture of a model solution and real mineral water; and (3) on real wastewater and spent mineral water taken from a thermal resort. As a result of an experiment with water samples at an initial concentration of no more than 85 mg/L, optimal doses of reagents were identified: 5.67 g/L of sodium hydrophosphate and 3.21 g/L of magnesium chloride to achieve a residual concentration of ammonium ions in purified water of no more than 1.5 mg/L at pH = 9–10. In the case of mixing of domestic wastewater and used mineral water, it was possible to reduce the use of magnesium chloride by 80%. At the same time it was possible to obtain the amount of sediment containing struvite, which is a valuable agricultural fertilizer. With the introduction of this technology, it is possible to reduce the expenses of reagents and reduce the damage caused by the discharge of liquid waste from a thermal resort, while the profit earned through the sale of fertilizer can partially offset the cost of wastewater disposal. Full article

Screening assays for discovering Candida albicans biofilm inhibitors typically measure either metabolic activity or attached biomass. Although biomass staining with Crystal Violet or Safranin is affordable and easy to perform, standard protocols often require toxic solvents for biofilm fixation and dye extraction. We developed and evaluated an alternative Safranin staining method that uses heat fixation and direct absorbance measurement of stained biofilms without a dye-extraction step. Under the experimental conditions tested, the proposed method reduced solvent use and plate handling and minimized reagent use while offering assay consistency and reliability for primary screening campaigns. The assay quality was verified using positive and negative inhibition controls, with acceptable Z′-factor values supporting its use for primary drug screening. The protocol was further evaluated by screening 1520 compounds from the Prestwick Chemical Library to identify inhibitors of C. albicans biofilm formation. The proposed Safranin method provides a simplified, extraction-free alternative for biofilm-inhibitor screening under the experimental conditions evaluated in this study. Full article

316L stainless-steel capillary tubes are important in medical devices, precision fluid transport and micro heat exchangers, but their slender geometry and dense passivation film make inner-surface finishing inefficient. This study proposes a stepwise chemical-assisted magnetorheological finishing (CMRF) process for 316L capillaries. The inner surface was first pretreated with hydrogen peroxide/oxalic acid to form a removable reaction layer, and then finished by magnetorheological abrasives. The effects of the two reagents on material removal and surface integrity were evaluated, and the optimal pretreatment was determined to be 2.25 wt.% oxalic acid and 1.5 wt.% H₂O₂. Compared with conventional magnetorheological finishing, CMRF increased the material removal rate by approximately 54% and reduced the final inner-surface roughness Sa to 0.116 μm. Characterization results show that hydrogen peroxide and oxalic acid generate a dynamic oxidation–complexation–dissolution–reoxidation cycle, converting the dense passive film into an oxygen-rich, porous, low-crystallinity reaction layer and reducing surface hardness by about 30%. This softened layer promotes preferential abrasive removal instead of direct cutting of the metallic substrate, thereby improving finishing efficiency and surface quality. Full article

The formation of asphalt–resin–paraffin deposits (ARPDs) and gas hydrate deposits (GHDs) in oil wells equipped with electric submersible pumps (ESPs) remains a significant challenge in the oil and gas industry. This study aims to develop an inhibitory technology to prevent these deposits by utilizing the synergistic effect of chemical reagents combined with the optimization of ESP operating parameters. Based on previously published mathematical modeling and laboratory studies by the authors, this work presents the technological implementation of the inhibition system and its economic assessment. Specifically, optimal reagent dosages were calculated considering their synergistic interactions, a periodic injection regime was established, and the impact on the well’s mean time between failures (MTBF) was evaluated. Results demonstrate that optimizing ESP parameters shifts the onset depth of GHD formation by 119.4 m (25%) and ARPD formation by 72.6 m (6%). The application of the selected ARPD inhibitor at 0.055 wt.% reduced the thermodynamic hydrate inhibitor (methanol) dosage by 12.17% and enabled a transition from continuous to periodic methanol injection. Consequently, the predicted MTBF increased from 277 to 419 days (+50%). An eight-year economic analysis showed a positive net present value with a payback period of 14 months. Thus, the proposed technology is recommended for field testing in high-paraffin, low-resin oil fields operating under permafrost conditions. Full article

Plasma–liquid interactions (PLIs) have emerged as a rapid and reagent-minimized platform for the synthesis of gold nanomaterials (GNMs) with tunable size, morphology, crystallinity, and surface chemistry. In contrast to conventional wet-chemical routes, non-thermal atmospheric-pressure plasmas reduce HAuCl₄ through highly reactive species generated at the gas–liquid interface. This review consolidates the field by classifying PLIs systems into four categories based on the discharge configuration, including plasma electrochemistry, plasma jet, solution plasma, and plasma aerosol, and critically compares their mechanisms and operational parameters. We show that the relative weighting of key process variables is strongly configuration-specific, with short-lived species initiating burst nucleation and long-lived neutrals sustaining autocatalytic growth. Furthermore, the review highlights how the distinct characteristics of each PLI configuration affect nanoparticle formation, morphology evolution, and physicochemical properties, providing practical guidance for selecting appropriate plasma systems for the controlled synthesis of gold nanomaterials. Full article