Search Results (523)

Ziziphus jujuba Mill. cv. Jinsi (Z. jujuba), a commercially significant cultivar of Chinese jujube, is extensively cultivated across diverse regions of China. However, comprehensive evaluations addressing the quality disparities of Z. jujuba originating from different geographical regions have received limited attention. To systematically evaluate quality variations in Z. jujuba across origins, 14 commercially cultivated commercial batches from 7 Chinese provinces were collected, with comprehensive parameters determined, including appearance, color, safety, aroma, flavor, and functional components. Multivariate statistical analyses, specifically Principal Component Analysis (PCA), Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA), and the entropy weight Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), were employed for data interpretation. All samples met national standards for aflatoxin and SO₂ residues. Shanxi samples had the largest length and weight, while Jiangsu and Shaanxi showed optimal color. Key volatiles included nitrogen oxides and sulfides, with sweetness as the main sensory trait. Ningxia samples had the highest total triterpenes, Jiangxi the highest flavonoids, and Shandong the highest polysaccharides, and Shaanxi samples possessed the highest total oligosaccharides. Entropy weight TOPSIS ranked quality as Ningxia > Shaanxi > Jiangsu > Jiangxi > Shanxi > Shandong > Henan. These findings confirm origin-related environmental effects on Z. jujuba quality, providing a scientific basis for its quality evaluation and sustainable development. Full article

During sulfite delignification of wood, sulfo derivatives of lignin—lignosulfonates (LS)—are formed as a byproduct. Due to their amphiphilic nature, LS are used as plasticizers, dispersants, and stabilizers. The functions and performance characteristics of this surface-active polyelectrolyte are determined by its behavior in aqueous solution, at surfaces and interfaces, which, in turn, is determined by its chemical composition. This study investigated the effect of LS with various molecular weight compositions (M_w 9–50 kDa) on the behavior and aggregation stability of aqueous dispersions of elemental sulfur (S⁰) under conditions simulating hydrothermal leaching of sulfide ores. Using conductometry, potentiometry, tensiometry, and viscometry, a detailed study of the physicochemical properties of aqueous LS solutions (C_LS 0.02–1.28 g/dm³) obtained from a few sources (Krasnokamsk, Solikamsk, and Norwegian Pulp and Paper Mills) was conducted. The composition, molecular weight, and concentration of LS were found to significantly affect their specific electrical conductivity, pH, intrinsic viscosity, and surface activity. LS introduction during the formation of sulfur sols is shown to promote their stabilization through electrostatic and steric mechanisms. Optimum dispersion stability (293 K, pH 4.5–5.5) was observed at moderate LS concentrations (0.02–0.32 g/dm³), when a stable adsorption layer forms on the surface of sulfur particles. High-molecular-weight LS samples provided more effective spatial stabilization of sulfur particles. It has been established that increasing temperature (293–333 K) and changing pH (1–7) significantly affect the aggregative stability of systems; specifically, the sol stability decreases with increasing temperature, and the stabilizing effect of different LS types reverses upon changing pH. The obtained results highlight the potential of using naturally occurring polymeric dispersants to control the aggregation stability of sulfur-containing heterophase systems and can be applied to the design of stable colloidal systems in chemical engineering and hydrometallurgy. Full article

The synthesis and electrocatalytic properties of amorphous first- and third-row transition metal sulfides (a-TMS) for green hydrogen generation have been comprehensively reviewed. These electrocatalysts can be prepared by several solution processes, including chemical bath deposition, electrodeposition, sol–gel, hydrothermal reaction and thermolysis. The deposition method strongly influences the electrochemical properties of the synthesized a-TMS electrocatalyst. Based on overpotential at 10 mA/cm², the electrocatalytic activity of mono-metallic a-TMS for hydrogen evolution is ranked as follows: a-NiS_x > a-CuS_x > a-CoS_x > a-WS_x > a-FeS_x. The best performing a-NiS_x prepared by chemical bath deposition has an overpotential at 10 mA/cm² of 53 mV and Tafel slope of 68 mV/dec in 1 M KOH electrolyte. The integration of Ni into the a-TMS network structure is crucial to achieving high activity in multi-metallic a-TMS electrocatalyst, as demonstrated by the bifunctional (NiFe)S_x/NiFe(OH)_y nanocomposite catalyst. The critical role of Ni in a-TMS catalyst design can be attributed to the lower free energy change for hydrogen adsorption on Ni. Finally, the emerging catalyst design strategy of amorphous–crystalline heterostructures with a three-dimensional morphology will be discussed together with the need to identify hydrogen adsorption sites on a-TMS electrocatalysts in future. Full article

Triazine solvent desulfurization is a highly efficient technology for removing hydrogen sulfide from natural gas. In this study, we used ASPEN HYSYS V11 with the Peng-Robinson (PR) equation to investigate the triazine consumption under different natural gas flow rates and hydrogen sulfide concentrations, as well as the sulfur capacity resulting from the reaction between triazine and H₂S at varying solution concentrations. Additionally, CFD simulations were employed to optimize the injection process of the triazine solvent by examining four key factors: gas flow velocity, injection volume, injection angle, and injection method. The results indicate that the required triazine dosage follows an exponential model, with a margin of error within 10%. A triazine mass fraction between 0.4 and 0.6 was found to be optimal. Among the factors studied, gas flow velocity has the most significant influence on desulfurization efficiency, while the injection rate plays a secondary role. An injection angle of 45° proved most effective, and the use of dual vertical symmetric nozzles achieved more uniform mixing between the natural gas and triazine solvent. Full article

Optimizing copper recovery from sulfide minerals such as chalcopyrite, which constitutes over 70% of global copper reserves, is essential due to the depletion of conventional copper oxide resources. This study aimed to establish optimal ferric leaching conditions for a chalcopyrite-rich concentrate to maximize copper recovery and to evaluate the regeneration of the oxidizing potential in the residual leaching solution for reuse. Ferric sulfate (Fe₂(SO₄)₃), as a ferric ion (Fe³⁺) carrier, was used as oxidizing agents at a concentration of [0.1 M] in sulfuric acid ([0.5 M] H₂SO₄), using a CuFeS₂ concentrate (75% chalcopyrite) leached over 80 h. Copper was recovered through cementation with metallic iron, while the residual leaching solution, containing ferrous ions, was analyzed to determine total iron content via atomic absorption spectroscopy and to assess the presence of ferrous ions through KMnO₄ titration. This step was crucial, as an excess of ferrous ions would indicate a loss of oxidizing potential of the ferric ion (Fe³⁺). Catalytic oxidation was conducted with microporous activated carbon (30 g/L) to regenerate Fe³⁺ for a second leaching cycle, achieving 90.7% Fe²⁺ oxidation. Optimal leaching conditions resulted in 95% soluble copper recovery at 1% solids, d80: 74 μm, pH < 2, Eh > 450 mV, 92 °C, [0.5 M] H₂SO₄, and [0.1 M] Fe₂(SO₄)₃. In the second cycle, the regenerated solution reached 75% copper recovery. These findings highlight temperature as a critical factor for copper recovery and demonstrate catalytic oxidation as a viable method for regenerating ferric solutions in industrial applications. Full article

This work involved the laboratory modeling of biogenic and biogenically mediated corrosion of AISI 304 stainless steel under geochemical conditions representative of the geological disposal of radioactive waste at the Yeniseisky site (Russia). Experiments with a single glucose stimulation of a microbial community sampled from a depth of 450 m established that the initial dominance of organotrophic microflora (primarily genera such as Xanthobacterium, Novosphingobium, Hydrogenophaga, and Pseudomonas) during the first stage (up to 30 days) led to the formation of a microbial biofilm. This biofilm resulted in uniform surface corrosion at a rate of up to 16 µm/year, which is more than 30 times higher than the corrosion rate in the abiotic control. This acceleration is attributed to the accumulation of microbial metabolites, including acetate, ethanol, formate, succinate, n-butyrate, and lactate. The subsequent development of chemotrophic iron- and sulfur-cycling microflora (dominated by genera such as Sideroxydans, Pseudomonas, Geobacter, Desulfuromonas, Desulfovibrio, and Desulfomicrobium) during the second stage of microbial succession (days 60–120) led to the formation of a pit density 10 times greater than that in the abiotic control. It is important to note that the maximum corrosion rates and pit densities were observed upon the addition of a mixture of glucose and sulfate. An assessment of the role of various microbial metabolites and medium components using the potentiodynamic method demonstrated that the combined presence of hydrocarbonate, sulfide, and microbial metabolites in the solution caused a more than fivefold increase in the corrosion current. Thus, the results demonstrate the complex nature of corrosion processes under conditions modeling the geological disposal of radioactive waste, where biological and abiotic factors interact, creating a synergistic effect that significantly enhances corrosion. Full article

Biochar activation is achieved by removing tar formed in the pores during the thermal treatment of biomass, thereby increasing pore volume. This process typically involves entraining tar with steam at elevated temperatures for extended durations. In this study, a reduction in lignin content in grape seeds through partial solubilization, prior to thermal treatment, is proposed. Initially, grape seeds were treated with a basic sodium sulfide solution, followed by conditioning with either phosphoric acid or zinc chloride and then drying and calcination. The synthesized adsorbents were characterized using scanning electron microscopy (SEM), textural analysis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and evaluation of toluene adsorption capacity. Textural analysis indicated that conditioning with phosphoric acid or zinc chloride increased the specific surface area of biochar by over 20%, with a higher increase observed for phosphoric acid treatment. The toluene adsorption capacity of the adsorbents was assessed in a continuous fixed-bed system. Biochar pretreated with ZnCl₂ exhibited an adsorption capacity of 0.11 cm³ of toluene per gram, while biochar pretreated with phosphoric acid demonstrated a capacity of 0.14 cm³ per gram. These results indicate that preliminary delignification of grape seed biomass maintains its adsorption capacity of toluene at levels comparable to other adsorbents, despite a lower activation temperature. Full article

The development of cheap and efficient photocatalysts for the degradation of organic pollutants in textile printing and dyeing wastewater is of great importance for addressing environmental issues, although it remains challenging. In this study, nano-CuS particles were doped on cotton linter aerogels using a straightforward method for the degradation of methylene blue (MB) and organic pollutants in textile wastewater. Material morphology and structure were analyzed using XRD, SEM/EDS mapping, XPS, BET surface area measurements, and UV-Vis spectroscopy, while their performance was evaluated through various tests. The results demonstrated that a 10 mg catalyst material achieved complete degradation of a 20 mL methylene blue solution (15 mg/L) within 120 min. Moreover, the degradation rates of two types of textile wastewater, reactive red wastewater and reactive yellow wastewater, were both above 90% within 120 min and reached complete degradation within 150 min using the 10 mg catalyst material. The experimental results demonstrate that copper sulfide nanoparticles anchored in cotton linter carbon aerogel can increase the contact area of the photocatalytic reaction system, improve the photoelectron transfer, and thus enhance the photocatalytic reaction efficiency, providing a useful foundation for developing economical photocatalysts and effective dye degradation technologies. Full article

The low recovery of fine chalcopyrite particles and the limited Cu/Fe selectivity with conventional thiol collectors prompted the evaluation of a Polystyrene–Divinylbenzene–Cetyltrimethylammonium Bromide–Potassium Amyl Xanthate (PS-DVB-CTAB-PAX) polymeric nanocollector. The copolymer was synthesized by emulsion polymerization and characterized using Total Organic Carbon (TOC) analysis, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Particle Size Analysis, and contact angle measurement. Its performance was tested in a Hallimond cell (150 mL) using a synthetic industrial water solution (0.010 mol/L NaCl + 0.005 mol/L CaCl₂) at a natural pH range of 6.0 to 8.0. PAX concentrations ranged from 0 to 16.19 mg L⁻¹, and nanocollector doses equivalent to 0 to 45 mg g⁻¹ of solid were tested. The nanocollector increased chalcopyrite recovery to 98 ± 1% for the −53 + 38 µm size fraction and maintained values greater than 95% in the coarse fractions, outperforming PAX across the entire dosage range. The PAX + nanocollector combination achieved the same recovery by reducing the total xanthate dosage by one-third, demonstrating a synergistic effect. TOC assays showed preferential adsorption of 96.6% on chalcopyrite versus 86.4% on pyrite, a difference that explains the observed Cu/Fe selectivity (pyrite floatability < 70%). The contact angle of chalcopyrite increased from 56.4° (water) to 86.5° in the presence of the nanocollector, demonstrating the generation of localized superhydrophobicity that reduces interfacial free energy and favors bubble–particle adhesion, whereas pyrite showed lower values of 51.1°, 58.3°, and 75.1°, confirming its more hydrophilic nature. These findings indicate that PS-DVB-CTAB-PAX enables optimized copper sulfide recovery, reduced thiol collector consumption, and improved metallurgical selectivity, making it a promising alternative for flotation circuits with high ionic strength water and for scaling up to pilot tests. Full article

The Evevpenta gold–silver epithermal deposit, belonging to an adularia–sericite or low-sulfidation type, is in the northern part of the Kamchatka Peninsula within the Oligocene–Quaternary Central Kamchatka volcanic belt. Variously native gold, silver, and Au–Ag chalcogenides, including calaverite, petzite, hessite, acanthite, uytenbogaardtite-petrovskaite, and naumannite, constitute its Au–Ag mineralization. Extensive fluid inclusion studies, involving fluid inclusion petrography, Raman spectroscopy, and microthermometry, revealed that quartz from gold-bearing adularia–quartz veins crystallized from low-salinity fluids (T ice melting from −0.1 to −3.3 °C) at moderate to low temperatures (140 to 364 °C). The mineralizing fluids consisted of Na, K, and Mg sulfate and bicarbonate-bearing aqueous solutions and low-density CO₂. The gold-bearing mineral assemblages were formed within narrower temperature ranges. The gold–telluride–quartz assemblage was deposited between 325 and 175 °C, while the telluride–sulfide–quartz formed between 219 and 258 °C. Possible influx of meteoric waters led to progressive cooling and a decrease in salinity from the early to late fluid generations during mineral deposition. Overall data on ore and associated with metasomatic alteration mineralogy indicate that the ore formation occurred under relatively reduced or neutral conditions from weakly acidic to near-neutral aqueous solutions, possessing relatively high sulfur and tellurium fugacity. Full article

With the weathering of iron sulfide minerals, acid rock drainage (ARD) emanates from the 60-millon tonne Main Waste Stockpile (MWS) at the Red Dog Mine. Following completion of the stockpile, a collection trench was constructed in 2012–2013 to capture and treat a portion of the ARD, and a cover system was emplaced from 2021 to 2025 to cover 90% of the stockpile. Select wells in the collection trench are associated with the different cover phases. Analysis of the water chemistry of samples collected at the wells indicates increased pH and decreased dissolved solids with each phase of the cover along with significant changes in flow and solutes such as aluminum, iron, sulfate, and zinc. Although the cover should continue to decrease ARD volume, acidity, and solute concentrations, an evaluation of historical acid production and iron sulfide consumption in the stockpile indicates a likely majority of the iron sulfide content remains available for weathering and acid production. Continued MWS ARD monitoring is necessary to evaluate the multi-year effect of the cover because of the variability of the pre-cover ARD, identification of seasonal and multi-year precipitation influences on ARD generation, and a yet to be determined influence of the cover on the volume of infiltrating precipitation. Full article

The advancement of overall water-splitting technologies relies on the development of earth-abundant electrocatalysts that efficiently produce H₂ as a chemical fuel while offering high catalytic efficiency, structural robustness, and low-cost synthesis. Therefore, we aim to develop a cost-effective and durable non-noble electrocatalyst for overall water splitting. A straightforward hydrothermal approach was employed to fabricate freestanding polyhedral Co₃O₄ on a microporous Ni foam scaffold, followed by anion-exchange transformation in the presence of Na₂S solution to yield its conductive sulfide analog. The engineered Co₃S₄ electrode delivers remarkable HER activity in 1.0 M KOH, requiring a low overpotential (<100 mV) to drive 10 mA cm⁻², far outperforming its pristine oxide counterpart and even closely benchmarking with a commercial Pt/C catalyst. This exceptional performance is governed by the synergistic effects of enhanced electrical conductivity, abundant catalytic sites, and accelerated charge-transfer kinetics introduced through sulfur substitution. Furthermore, the optimized Co₃S₄ electrodes enable a bifunctional overall water-splitting device that achieves a cell voltage of >1.76 V at 100 mA cm⁻² and maintains prolonged operational stability for over 100 hrs. of continuous operation. Post-stability analyses confirm insignificant phase preservation during testing, ensuring sustained activity throughout the electrolysis process. This study highlights the potential of anion-exchanged Co₃S₄ as a cost-effective and durable catalyst for high-performance HER and full-cell water-splitting applications. Full article

Facing the increasingly scarce supply of rare-earth resources, a cobalt-doped metal–organic framework-derived carbon–metallic sulfide composite (Co-FeS₂@C) was successfully synthesized via the hydrothermal method and the following carbonization/sulfidation treatments and used for the efficient electrosorption of rare earths from aqueous solution. Comparative characterizations revealed that Co doping effectively expanded the interlayer spacing of FeS₂, introduced crystalline defects, and optimized the electronic structure, thereby synergistically enhancing active site exposure and electron transfer kinetics. In addition, the electrochemical analysis demonstrated a significant increase in the surface-controlled capacitive contribution from 57.1% to 83.3%, indicating the markedly improved electric double-layer effects and mass transport efficiency. Under the optimal conditions, the Co-FeS₂@C electrode achieved a high Yb³⁺ adsorption capacity of 129.2 mg g⁻¹ along with an exceptional cycling stability (92.63% retention after 20 cycles), substantially outperforming the undoped counterpart FeS₂ (88.4 mg g⁻¹ and 74.61%). Furthermore, the mechanistic investigations confirmed that the electrosorption process follows a monolayer physico-chemical synergistic mechanism, primarily driven by the pseudo-capacitive effect arising from the redox reaction of FeS₂ and the enhanced charge-transfer driving force resulting from the higher electronegativity of cobalt. This work provides an innovative electronic structure modulation strategy for developing the high-performance capacitive deionization electrodes for rare earth recovery via the electrosorption process. Full article

Cucumis sativus L. is a globally important vegetable crop that occupies a significant position in protected agriculture due to its high nutritional value, short cultivation cycle, and considerable economic benefits. As a cold-sensitive plant, however, cucumber is highly susceptible to low-temperature stress. which can severely inhibit growth and development, hinder seed germination, and reduce photosynthetic efficiency. Under low-temperature stress, cucumber plants typically incur damage to cellular membrane structures, experience an accumulation of reactive oxygen species (ROS), exhibit a disruption in hormonal homeostasis, and suffer from the inhibition of pivotal metabolic pathways. In response, cucumber plants activate an array of resistance mechanisms, encompassing osmotic adjustment, reinforcement of the antioxidant system, and modulation of cold-responsive gene expression. This review summarizes the physiological and molecular mechanisms underlying cucumber’s response to low-temperature stress, aiming to provide effective strategies for improving abiotic stress resistance. The main findings are as follows: (1) Low-temperature stress damages cucumber cell membranes, suppresses photosynthesis and respiration, suppresses water and nutrient uptake/transport, and suppresses growth retardation. (2) Cucumber counters these adverse effects by orchestrating the accumulation of osmoregulators (e.g., soluble sugars, proline), activating activation defenses (e.g., SOD, CAT), and rebalancing its phytohormone network (e.g., ABA, GA, SA, ethylene). (3) At the molecular level, cucumber activates low-temperature-responsive genes (e.g., COR, GoIS) through transcription factors such as CBF, MYB, and WRKY, thereby enhancing cold tolerance. (4) Application of exogenous protectants (e.g., hydrogen sulfide, melatonin, oligosaccharides) significantly improves cucumber’s low-temperature tolerance by modulating the antioxidant system, promoting osmoregulatory substances accumulation, and regulating hormone signaling pathways. Future research should focus on elucidating the molecular regulatory network in cucumber under low-temperature stress and developing gene editing with multi-omics techniques to advance the development of cold-resistant cultivars and cultivation practices. This study offers a scientific foundation for research on cucumber cold tolerance and proposes potential solutions to agricultural challenges in the context of global climate change. Full article

The recovery of copper from metallurgical effluents is critical for advancing sustainable mining and circular economy practices. This study evaluated a hybrid process combining copper sulfide precipitation with clarification using polymeric polyvinylidene fluoride (PVDF) microfiltration membranes. Laboratory-scale experiments were performed under controlled cyanide conditions (100 mg/L free CN⁻, 1800 mg/L Cu²⁺), focusing on permeate flux behavior, fouling mechanisms, and cleaning strategies. Optimal performance was achieved at moderate transmembrane pressures (<2.0 bar) and higher flow rates, which provided a balance between productivity and fouling control. Flux decline was attributed to a combination of pore blocking and cake layer formation, confirming the multifactorial nature of fouling dynamics. Cleaning tests revealed that oxidizing solutions (HCl + H₂O₂) restored up to 96% of the initial permeability, while combined treatments with NaCN achieved complete recovery (>100%), albeit with potential risks of membrane aging under prolonged exposure. A techno-economic assessment comparing polymeric and ceramic membranes revealed similar capital and operational costs, with polymeric membranes offering slight reductions in CAPEX (10%) and OPEX (2.3%). Overall, the findings demonstrate the technical feasibility and economic competitiveness of polymeric membranes for copper sulfide clarification, while emphasizing the need to improve long-term chemical resistance to ensure reliable industrial-scale implementation. Full article