Search Results (703)

Microbial degradation of organic matter is a key driver of iodine enrichment in groundwater. Using stable carbon isotopes (δ¹³C-DIC and δ¹³C-DOC), this study investigates the role of microbial processes and organic matter biodegradation in the formation of high-iodine groundwater downstream of the Kuitun River, China. The groundwater is weakly alkaline and reducing, with Cl⁻ and Na⁺ as the dominant ions, and is mainly slightly saline. I⁻ concentrations range from 51.66 to 552.79 µg/L (mean 177.68 µg/L), with 61.54% of samples classified as high-iodine water. Dissolved inorganic carbon (DIC, 22.97–100.85 mg/L, dominated by HCO₃⁻) originates primarily from microbial degradation of organic matter and silicate weathering. Dissolved organic carbon (DOC, 2.01–4.22 mg/L) is mainly derived from C3 plants. In this reducing, organic-rich aquifer, microbial decomposition of organic matter and reductive dissolution of iron minerals are the primary hydrobiogeochemical processes that release solid-phase iodine into groundwater. The high-iodine groundwater in the study area follows a burial–dissolution genesis model. Full article

This article proposes a sustainable approach to producing eco-friendly paper from fibers derived from water hyacinth (Eichhornia crassipes), an invasive aquatic species with potential high lignocellulose content. The research evaluated the possibility of using its biomass as a non-wood raw material for papermaking through an industrial-oriented processing framework. About 10 groups of water hyacinth samples were analyzed by separating their components (roots, leaves, and stems) to determine moisture content, dry biomass yield, fiber distribution, and performance in papermaking. Mechanical pulping and mild alkaline treatment with sodium hydroxide were compared to evaluate their effects on fiber behavior and paper quality. The results showed a high moisture content in the biomass, averaging approximately 88%, while the remaining dry matter represented the usable fibrous material fraction. After fiber classification, it was revealed that the long fibers predominated over the short fibers and the fine fibers (waste), favoring the hydrogen bonding and structural anchoring during sheet formation. Mechanical quality analyses were conducted using the Corrugating Medium Test (CMT), Concora Crush Test (CCT), Ring Crush Test (RCT), and Short Compression Test (SCT). Untreated water hyacinth paper demonstrated mechanical properties comparable to those of an industrial reference paper, including consistent compression resistance and corrugating performance. In contrast, the alkaline-treated sample showed greater structural uniformity but lower mechanical strength due to fiber fragmentation and increased fine production. Overall, the findings showed that Eichhornia crassipes represents a viable and sustainable alternative to non-wood fibers for paper production, offering potential environmental benefits by serving as an invasive species and reducing dependence on wood-based raw materials. Full article

This study investigated the potential of microbial-assisted phytoremediation using Eichhornia crassipes (water hyacinth) to reduce heavy metal and salinity pollution in produced water collected from Aadi Oil Field in Gujar Khan, Pakistan. Produced water was analyzed for physicochemical parameters and heavy metal content using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) to establish baseline data. E. crassipes plants augmented with indigenous, contaminant-tolerant microbial isolates were employed in a 15-day laboratory experiment. The results showed a resilient growth response, with plant height increasing to approximately 11–15 cm and root length extending up to 10–13 cm across treatments. Biomass also improved, with wet weights reaching 21–24 g from an initial 20 g. The treatment effectively reduced key physicochemical parameters: pH was stabilized from an initial alkaline value of 9.14 to near-neutral values (7.0–7.5), and total dissolved solids (TDSs) were reduced by approximately 50%. Heavy metal removal rates varied, with the highest efficiency of 79.2% for Silver (Ag) and the lowest (18.5%) for Mercury (Hg) This study demonstrates that E. crassipes actively participated in phytoremediation by absorbing and accumulating heavy metals and reducing salinity. The association with contaminant-tolerant microbes appeared to enhance the plant’s tolerance and overall treatment efficacy, indicating that plant–microbe interactions offer a sustainable strategy for the treatment of produced water. Full article

Alkaline water electrolysis has become a major technology for large-scale photovoltaic (PV) hydrogen production due to its maturity and low cost. However, PV power fluctuations can cause short-term load imbalances and long-term degradation imbalances in alkaline water electrolyzer (AWE) clusters. To address this problem, this paper proposes an adaptive rotation operation strategy based on a composite degradation model. The model considers energy throughput, hot starts, cold starts, and low-load operation to characterize the relative degradation stress of AWEs under fluctuating PV input. Based on this model, virtual rotation is first used to redistribute power among online AWEs, while physical rotation is performed when necessary according to optimal start–stop decisions. A PV hydrogen production experimental platform is built to verify the feasibility of power redistribution, physical rotation, and load balancing. The measured PV power curve is further used for simulation–experiment comparison, and the results show that the model can capture the main operating process of the PV hydrogen production system. Large-scale simulation results show that, compared with S1, S2, and S4, the proposed strategy increases PV utilization by 8.13%, 4.91%, and 2.85%, improves system efficiency by 5.42%, 3.10%, and 1.56%, reduces start–stop cycles by 12.16%, 8.49%, and 3.39%, reduces the average composite degradation index by 29.4%, 21.4%, and 10.1%, and reduces the composite degradation imbalance index by 56.9%, 40.4%, and 22.2%, respectively. The proposed strategy can improve PV utilization and system efficiency while reducing start–stop frequency and degradation imbalances among AWEs. Full article

The utilization of saline–alkali lands and the competition between medicinal plants and grain crops are urgent issues. This study aimed to evaluate the effects of combined biochar and phosphogypsum application on soil physicochemical properties, microbial communities, and safflower growth, yield, and bioactive component accumulation in moderately saline–alkali soil of western Jilin, and to identify key soil factors driving these responses. To achieve this, outdoor pot experiments were conducted using safflower (Carthamus tinctorius L.), with the application of 1% biochar + 1% phosphogypsum to moderately saline–alkali soil. The results showed that the amendment significantly reduced bulk density (BD), pH, sodium adsorption ratio (SAR), total alkalinity (TA), and exchangeable sodium percentage (ESP), while increasing soil water content (SWC), soil organic matter (SOM), nitrogen, phosphorus, potassium, and beneficial ions. Soil sucrase, urease, alkaline phosphatase, and catalase activities were enhanced. Copiotrophic taxa (Pseudomonadota, Sphingomonas, Vicinamibacter) increased, whereas oligotrophic taxa (Gemmatimonadetes, Longimicrobium, Luteitalea) decreased, with stronger effects on bacteria than fungi. Safflower growth indices improved; leaf Na⁺/K⁺ ratio, superoxide radicals, and malondialdehyde decreased; and soluble protein, proline, and antioxidant enzyme activities increased. Bioactive components (hydroxysafflor yellow A, kaempferol) and yield reached 1.41%, 0.056%, and 343.23 mg/plant, representing 1.74–27.68-fold increases over moderate and mild saline–alkali soils. Correlation analysis identified SOM, total nitrogen (TN), available phosphorus (AP), BD, SWC, pH, SAR, TA, and ESP as key factors. In conclusion, co-application of 1% biochar and 1% phosphogypsum improves soil physicochemical and microbial properties, alleviates saline–alkali stress, and enhances safflower quality and yield. Full article

For the removal of hexavalent chromium [Cr(VI)] from drinking water, a hybrid biosorbent designated chitosan–natural diatomaceous earth (CNDE) was developed and thoroughly characterized. The material couples the ion-exchange and chelating capacity of chitosan—applied at an 85% degree of deacetylation—with the high-surface-area mineral framework of natural diatomaceous earth, onto which the polymer was deposited as a conformal coating. Surface morphology and internal microstructure were examined by scanning and transmission electron microscopy (SEM/TEM), while elemental composition across the hybrid matrix was resolved by energy-dispersive X-ray spectroscopy (EDX). Fourier transform infrared (FTIR) spectroscopy was employed to identify the surface functional groups responsible for chromate binding, and streaming current measurements established the pH of zero charge (pH_pzc), which governs the electrostatic environment at the sorbent–solution interface. Specific surface area was quantified by the Brunauer–Emmett–Teller (BET) method, and the balance of surface acidic and basic sites was determined through titrimetric analysis of total acidity and alkalinity. Thermogravimetric analysis (TGA) was conducted to assess thermal stability. Batch equilibrium isotherm experiments were performed to evaluate Cr(VI) uptake from model drinking water prepared using dilute potassium dichromate solutions adjusted to target pH levels. The effects of solution pH and competing anions (chloride and sulfate) were also investigated. Kinetic studies were conducted to determine the rate of Cr(VI) adsorption, and residual metal concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that CNDE containing 30% chitosan (CNDE30) achieved effective Cr(VI) removal at pH 5. Adsorption was strongly pH-dependent, decreasing as pH increased from 5 to 8. Equilibrium data were well described by both Langmuir and Freundlich isotherm models, while kinetic data followed a pseudo-second-order model. The presence of chloride ions (15 mg/L) reduced adsorption capacity by approximately one-third, whereas sulfate at the same concentration significantly inhibited Cr(VI) removal. Overall, the isotherm results suggest that CNDE30 is a promising material for Cr(VI) removal from drinking water. Its cost-effectiveness, ease of synthesis, and potential for reuse make it particularly attractive for small-scale and decentralized water treatment applications. Full article

In this study, a functional surface coating composed of Fe-Mn binary oxide (FM) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, PP) was applied to a PVDF membrane (PP-FM-PVDF) for efficient arsenate (As(V)) removal. PP acts as a dispersant and hydrophilic modifier, ensuring uniform FM distribution and reducing the water contact angle to 50.1°. The PP-FM-PVDF membrane achieves a maximum As(V) adsorption capacity of 30.43 mg/g, outperforming pristine and singly modified membranes. The batch adsorption data fit the Langmuir isotherm (R² = 0.999) and pseudo-second-order kinetic model (R² = 0.99), indicating monolayer chemisorption. The coating increases the specific surface area to 27.33 m²/g and the tensile strength to 6.41 MPa. Dynamic filtration shows that 2.70 L (2149.7 L/m²) of 100 μg/L As(V) solution can be treated before the permeate concentration exceeds the WHO guideline of 10 μg/L. After alkaline regeneration (pH 11), 62.9% of the initial capacity is retained. Complementary surface-sensitive analyses (zeta potential, XPS, and EXAFS) reveal that arsenate adsorption occurs primarily through ligand exchange between arsenate oxyanions and Fe/Mn surface hydroxyl groups on the coating, forming inner-sphere bidentate complexes (Fe–O–As and Mn–O–As), while electrostatic interactions play a secondary, pH-dependent role. This surface engineering strategy—synergistically integrating a conductive hydrophilic polymer with a metal oxide as a functional coating on PVDF—offers a reusable, high-performance platform for arsenate remediation, underscoring the critical role of interface design in environmental membrane applications. Full article

Chromium-related hazard in mine wastes depends strongly on oxidation state, with hexavalent chromium [Cr(VI)] representing the most mobile and toxicologically relevant chromium form. Abandoned tailings dumps can develop sharp pH and redox gradients that favour either Cr(VI) persistence or attenuation, yet field-based evidence from Eastern European post-mining sites remains limited. This study evaluates the Defor Petrila tailings dump, Jiu Valley, Romania, as a first-tier environmental hazard-screening case study based on repeated monitoring performed during 2022–2024 at twelve permanent sampling points and two local operational control samples. Field pH and redox potential (Eh), moisture, organic matter, acid-extractable Mn and Fe, pseudo-total Cr, and method-defined extractable Cr(VI) were determined. Here, pseudo-total Cr refers to chromium released by microwave-assisted acid digestion and does not represent complete decomposition of the silicate matrix, while extractable Cr(VI) refers to the operationally defined fraction obtained by alkaline extraction. In addition, a conservative redox-based prioritisation score (R_redox) was applied only as an internal ranking layer to identify sectors where Cr(VI) is more likely to persist. The upper dump sector (P1–P4) was alkaline (pH 7.5–8.2), strongly oxidising (+280 to +412 mV), and enriched in Mn and Fe, whereas the lower sector (P9–P12) was wetter, slightly acidic to near-neutral, and reducing (−59 to −10 mV). Extractable Cr(VI) reached 18.7 mg kg⁻¹ at P2 in 2024, while both control samples remained below the quantification limit. Exploratory repeated-site statistics, sector-based comparison, and correlation analysis supported a coherent association between Eh, Mn enrichment, and extractable Cr(VI), but these relationships are interpreted as spatially structured screening evidence rather than proof of a single mineralogical oxidation pathway. No direct exposure, leachability, bioaccessibility, ecotoxicity, airborne dust, water, vegetation, or biomonitoring measurements were included; therefore, the results identify priority zones for confirmatory toxicological and exposure-based assessment, not receptor-specific risk estimates. This study demonstrates that combining chromium speciation with field redox zonation can support conservative monitoring prioritisation at abandoned mine-waste sites where the toxic form of chromium may remain environmentally active. Full article

Tomato processing generates large amounts of by-products, with seeds representing an underutilized yet protein-rich fraction. This study investigated direct enzyme-assisted protein extraction from non-defatted tomato seeds. Various enzymes, enzyme/substrate ratios, pre-treatments, and incubation temperatures were evaluated and optimized. An enzyme/substrate ratio of 5% (w/w) was found to be optimal, with proteases alone outperforming cell wall-degrading enzymes and two-step extraction strategies. Bromelain, Protamex, and Trypsin, for the first time applied directly to non-defatted tomato seeds, achieved the highest protein recoveries (average 110.56 mg BSA eq/g DW). Among them, Trypsin also produced the highest reducing sugar content (25.07 mg GLU eq/g DW), indicating effective cell wall disruption. Digestates obtained from defatted and non-defatted tomato seeds showed comparable protein contents, demonstrating that defatting was unnecessary. Avoiding the defatting step improved process sustainability by reducing solvent use and energy consumption without significantly affecting protein extraction efficiency. Incubation at 37 °C was preferred over 60 °C, as similar yields were achieved under milder conditions while also reducing energy consumption by approximately three-fold (54,340 kJ vs 150,480 kJ for a 1000 L water-based scale-up simulation). These digestates showed significantly higher antioxidant and, for the first time in tomato seed extracts, anti-tyrosinase activities compared with controls. Protamex-derived samples exhibited the highest bioactivities (7.40 mg AA eq/g DW; 101.36 μg KA eq/g DW). Compared to conventional alkaline–acid extraction followed by enzymatic digestion, the direct enzymatic approach provided higher protein recovery. Overall, this method represents a sustainable strategy for producing bioactive peptide-rich extracts for food and non-food applications. Full article

Polysaccharide-based pre-emulsions offer a promising strategy for reducing saturated fat in emulsified meat products. In this study, a pre-emulsion stabilized by rice bran dietary fiber modified with alkaline hydrogen peroxide (MRF) was used to replace pork back fat in emulsified meat gels. Four model systems were prepared, varying in fat content (20% and 50%) and chopping intensity (low vs. high). MRF pre-emulsion significantly reduced fat globule size (e.g., D_[4,3] decreased by 18–34%, D_[3,2] by up to 83%) and improved shear stability, as reflected in the weaker frequency dependence of the storage modulus (G′). In high-chopping systems, MRF substitution increased gel elasticity but lowered hardness (by 25–30%), chewiness, and shear force (by 20–25%). Low-field NMR analysis revealed a partial shift from immobilized to free water, which raised cooking loss by 2–4 percentage points while enhancing perceived juiciness. Color measurements indicated that MRF effectively offset the loss of lightness typically associated with fat reduction. Both quantitative descriptive analysis (QDA) and temporal dominance of sensations (TDS) confirmed that MRF-substituted samples showed a markedly lower dominance of fatty sensation during the late oral processing stage (30–40% reduction in dominance rate), whereas the overall dynamic sensory profile remained similar to that of full-fat controls. Collectively, these results demonstrate that MRF, as a functional polysaccharide, stabilizes the system through hydration-induced swelling, hydrogen bonding with myofibrillar proteins, and the formation of a composite interfacial film around fat globules. These mechanisms enhance emulsion stability and successfully mimic the oral textural properties of animal fat, supporting the use of MRF as an effective polysaccharide-based fat replacer in reduced-fat meat products. Full article

Electrochemical water splitting stands as a feasible approach for sustainable hydrogen production, but its industrial implementation is restricted by sluggish oxygen evolution reaction (OER) kinetics and excessive dependence on freshwater resources. As a widely existing alternative, seawater contains a high concentration of chloride ions (Cl⁻), which give rise to serious electrode corrosion and catalyst deactivation, bringing great challenges to actual electrolysis applications. Herein, we report a facile room-temperature two-step soaking strategy to fabricate sulfur-modified NiFe layered double hydroxide (S-NiFe-LDH) catalysts for efficient OER in both alkaline freshwater and seawater electrolytes. The introduction of sulfur not only optimizes the electronic structure of NiFe-LDH to strengthen intrinsic catalytic activity and speed up charge transfer, but also promotes the formation of a Cl⁻-resistant layer, thus significantly improving corrosion resistance. In addition, DFT calculations show sulfur modification in NiFe layered double hydroxide upshifts the O 2p-band center to activate lattice oxygen, switches the oxygen evolution reaction pathway to the lattice oxygen mechanism with reduced thermodynamic barriers, and realizes the selective adsorption of OH⁻ over Cl⁻. As a result, the as-prepared S-NiFe-LDH catalyst exhibits exceptional OER performance, requiring overpotentials (η) of 250, 270, and 290 mV to reach current densities of 50, 100, and 200 mA·cm⁻² in 1 M KOH, respectively, with a Tafel slope of 22.3 mV·dec⁻¹. Moreover, it maintains remarkable stability for more than 200 h in alkaline seawater electrolytes and achieves nearly 100% Faradaic efficiency for water splitting, effectively avoiding the parasitic chlorine evolution reaction (CER). This work provides a scalable and energy-efficient synthetic route for designing advanced non-noble metal catalysts, paving the way for industrial-scale hydrogen production from seawater. Full article

A two-year field experiment was conducted in an organic vineyard in Tuscany (Italy), to evaluate the effects of micronized biochar (0.5% v/v) applied via fertigation on soil fertility/biological quality and Vitis vinifera performance. The biochar, derived from pyrogasified mixed wood, was compared to watered controls (CTR) following a randomized plot design. Soil chemical properties, dehydrogenase (DHA) and alkaline phosphatase (APA) activities, and plant parameters (biomass, leaf area, gas exchange, chlorophyll, flavonols, and foliar nutrients) were assessed in samples collected in July and September (2021 and 2022). Biochar did not significantly alter total and dissolved organic carbon contents or nitrogen fractions but enhanced DHA and APA activities, alongside increased available phosphorous content (+37.5%) and exchangeable potassium content (+7.1 and +19.7% in September 2021 and July 2022, respectively), indicating improved microbial activity and nutrient availability. Conversely, exchangeable calcium and magnesium contents decreased, likely due to biochar adsorption properties. Plant responses included increased leaf area and dry biomass in 2022, elevated net photosynthesis rate (+14.4%) and apparent carboxylation efficiency, and transient increases in foliar nitrogen, phosphorous and potassium contents, with reduced magnesium concentration (–27%) but stable chlorophyll levels. These findings suggest that low doses of micronized biochar may enhance soil quality and vine physiology, supporting its efficient and effective use in organic vineyards. Full article

The transition toward low-carbon energy systems has intensified interest in sustainable hydrogen production technologies. One of the most promising methods for producing green hydrogen is water electrolysis powered by renewable energy. This work reviews recent advances in electrode materials used in four major electrolysis technologies: alkaline (ALK), proton exchange membrane (PEM), solid oxide electrolysis cells (SOEC), and anion exchange membrane (AEM). A bibliometric analysis of scientific publications from 2021 to 2025 highlights the rapid growth of research and the increasing importance of electrode materials in improving electrolysis performance. Operating environments, material requirements, and catalytic properties are compared across these systems. Recent developments in electrocatalysts—including transition-metal alloys, heterostructured catalysts, defect-engineered materials, and nanostructured systems—are evaluated in terms of catalytic activity, durability, and scalability. Particular attention is given to reducing noble metal usage while maintaining high electrochemical performance. Results indicate that transition-metal-based catalysts and engineered interfaces can achieve activity comparable to noble-metal systems while offering better cost efficiency. However, challenges related to long-term durability, large-scale synthesis, and standardized testing persist. Continued interdisciplinary research in materials design and electrochemical engineering is essential to enable efficient, durable, and cost-effective green hydrogen production. Full article

The declining productivity, fertilizer inefficiencies, and rising energy cum production costs are the key issues in crop production, especially in semi-arid regions with alkaline soils. Integration of crop management strategies needs to be adopted to address these issues within the water–energy–food nexus (WEFN). For this purpose, a case study was conducted in semi-arid region of central Punjab, Pakistan, to evaluate the interactive effects of irrigation water source [canal water (CW) and tubewell water (TW)], phosphorus fertilizer source [diammonium phosphate (DAP) vs. phosphoric acid_25% (PA)], and fertilizer application levels [100% and 80% of recommended dose of fertilizer (RDF)] on maize productivity, energy efficiency and economic performance. The experiment comprises eight treatments under raised bed planting (RBP) and one control treatment under ridge-furrow sowing (RFS). Each treatment had three replicates, and the experiment was laid out under a randomized complete block design (RCBD). Maize growth, yield, water productivity, energy efficiency, and economic performance were analyzed using field measurements, energy equivalents, and partial budget analysis. The T1 (RBP+CW+PA+100%RDF) produced the highest maize yield, and it varied from 6.36 to 7.90 t ha⁻¹ under other treatments. CW significantly showed better water productivity (1.14–1.37 kg m⁻³) than that under TW (1.13–1.31 kg m⁻³); however, total energy input was higher under TW-based treatments (29,269–41,033 MJ t ha⁻¹) than that under CW-based treatments (24,129–29,681 MJ ha⁻¹). This results in lower energy productivity under TW-based treatments compared with CW-based treatments (0.17–0.23 kg MJ⁻¹ vs. 0.25–0.31 kg MJ⁻¹, respectively). Moreover, T2 (RBP+CW+PA+80%RDF) produced the highest energy use efficiency (0.59). Economic analysis revealed that production costs were nearly 15–17% higher under TW-based treatments, mainly due to the cost associated with groundwater pumping, and it reduced net profit to USD 1134–1385 ha⁻¹. Better net profits were achieved by CW-based treatments (USD 1244–1593 ha⁻¹), while those produced by BCR ranged from 3.11 to 3.69, with the highest value under T2 (RBP+CW+PA+80%RDF). Overall, irrigation water source emerged as the dominant driver of WEFN performance, while phosphoric acid significantly improved phosphorus availability, energy productivity, and economic returns, particularly under reduced fertilizer input. This study evidenced better maize productivity, less energy consumption, and improved farm profitability in semi-arid irrigated systems through the integration of canal water irrigation with optimized phosphorus management. Full article

Developing low-cost, non-noble-metal electrocatalysts to replace platinum-based benchmarks for the alkaline hydrogen evolution reaction (HER) remains a critical challenge. Using density functional theory (DFT) calculations combined with the computational hydrogen electrode (CHE) model, we systematically investigate the thermodynamics, kinetics, and intrinsic reaction mechanism of HER on a TiO₂-supported Ni₃ trimer (Ni₃/TiO₂) in alkaline media. We find that the Ni₃ trimer, rather than the TiO₂ support, provides multiple active sites for intermediate adsorption. The trimeric Ni₃ motif generates delocalized electronic states, leading to electron-rich active sites that significantly lower the barrier for water dissociation, facilitate intermediate desorption, and sustain catalytic turnover. The reaction proceeds predominantly via the Volmer–Heyrovsky pathway, where either water dissociation or H₂ desorption can be the rate-determining step, depending on the applied potential. Crucially, the significantly reduced reaction barrier heights demonstrate that the alkaline HER activity of Ni₃/TiO₂ is comparable to that of benchmark Pt₁/TiO₂ single-atom catalysts (SACs). This work establishes a promising design strategy for constructing high-performance non-noble metal few-atom catalysts (FACs) to replace noble metal SACs for multi-step electrocatalytic reactions. Full article