Search Results (544)

Platinum has emerged as an optimal catalyst for the selective hydrogenation of nitroarenes owing to its high hydrogenation activity, selectivity, and stability. In this study, we report the fabrication of platinum nanoparticles stabilized on a composite support consisting of gum acacia polymer (GAP) and TiO₂. It was engineered for the targeted reduction of nitroarenes to arylamines via selective hydrogenation in methanol at ambient temperature. The non-toxic and biocompatible properties of GAP enable it to act as a reducing and stabilizing agent during synthesis. The synthesized nanocatalyst was characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Morphological and structural analyses revealed that the fabricated catalyst consisted of minuscule Pt nanoparticles integrated within the GAP framework, accompanied by the corresponding TiO₂ nanoparticles. Inductively coupled plasma optical emission spectrometry (ICP-OES) was employed to ascertain the Pt content. The mild reaction conditions, decent yields, trouble-free workup, and facile separation of the catalyst make this method a clean and practical alternative to nitroreduction. Selective hydrogenation yielded an average arylamine production of 97.6% over five consecutive cycles, demonstrating the stability of the nanocatalyst without detectable leaching. Full article

Agricultural soil contaminated with mercury (Hg) poses a serious threat to ecosystems and human health. Although adding an appropriate amount of selenium (Se) can reduce the toxicity and mobility of Hg in soil, Se alone is prone to leaching into groundwater through soil runoff. Therefore, Se-enriched compound fertilizers were developed, and their remediation effect on Hg-contaminated agricultural soil was determined. The Se-enriched compound fertilizers were prepared by combining an organic fertilizer (vinegar residue, biochar, and potassium humate), inorganic fertilizer (urea, KH₂PO₄, ZnSO₄, and Na₂SeO₃), and a binder (attapulgite and bentonite). A material proportioning experiment showed that the optimal granulation rate, organic matter content, and compressive strength were achieved when using 15% attapulgite (Formulation 1) and 10% bentonite (Formulation 2). An analysis of Se-enriched compound fertilizer particles showed that the two Se-enriched compound fertilizers complied with the standard for organic–inorganic compound fertilizers (China GB 18877-2002). Compared with the control, Formulation 1 and Formulation 2 significantly reduced the Hg content in bulk and rhizosphere soil following diethylenetriaminepentaacetic acid (DTPA) extraction by 40.1–47.3% and 53.8–56.0%, respectively. They also significantly reduced the Hg content in maize seedling roots and shoots by 26.4–29.0% and 57.3–58.7%, respectively, effectively limiting Hg uptake, transport, and enrichment. Under the Formulation 1 and Formulation 2 treatments, the total and DTPA-extractable Se contents in soil and maize seedlings were significantly increased. This study demonstrated that Se-enriched compound fertilizer effectively remediates Hg-contaminated agricultural soil and can promote the uptake of Se by maize. The results of this study are expected to positively contribute to the sustainable development of the agro-ecological environment. Full article

This study investigates the effectiveness of geopolymer-based binders for the stabilization of silty sand, aiming to improve its strength and durability under cyclic environmental conditions. A composite binder consisting of Ground Granulated Blast-furnace Slag (GGBS) and Recycled Glass Powder (RGP), modified with nano poly aluminum silicate (PAS), was used to treat the soil. The long-term performance of the stabilized soil was evaluated under cyclic wetting–drying (W–D) conditions. The influence of PAS content on the mechanical strength, environmental safety, and durability of the stabilized soil was assessed through a series of laboratory tests. Key parameters, including unconfined compressive strength (UCS), mass retention, pH variation, ion leaching, and microstructural development, were analyzed using field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Results revealed that GGBS-stabilized specimens maintained over 90% of their original strength and mass after eight W–D cycles, indicating excellent durability. In contrast, RGP-stabilized samples exhibited early strength degradation, with up to an 80% reduction in UCS and 10% mass loss. Environmental evaluations confirmed that leachate concentrations remained within acceptable toxicity limits. Microstructural analysis further highlighted the critical role of PAS in enhancing the chemical stability and long-term performance of the stabilized soil matrix. Full article

Strobilurins are a prominent class of fungicides capable of entering aquatic environments via runoff and leaching from the soil. Findings from previous studies suggest that strobilurins are highly toxic in aquatic environments, and evidence of acute developmental toxicity and altered behavioral responses have been emphasized. The objective here was to determine the effects of a new strobilurin, metyltetraprole (MTP), on zebrafish using developmental endpoints, gene expression, and behavioral locomotor assays. We hypothesized that MTP would cause developmental toxicity and induce hyperactivity in zebrafish (Danio rerio). To test this, developing zebrafish embryos/larvae were exposed to environmentally relevant levels of MTP (0.1, 1, 10, and 100 µg/L) until 7 days post-fertilization. Survival percentages did not differ among the treatment groups. No change in reactive oxygen species production was detected, but two genes involved in the mitochondrial electron transport chain (mt-nd3 and uqcrc2) were altered in abundance following MTP exposure. Moreover, the highest concentration (100 µg/L) of MTP caused notable hyperactivity in the zebrafish in the visual motor response test. Overall, results from this study increase our knowledge regarding sub-lethal effects of MTP, helping inform risk assessment for aquatic environments. Full article

Tebuconazole (TBZ), a triazole-class fungicide widely used in agriculture, is frequently detected in aquatic environments due to runoff and leaching, where it poses a threat to non-target aquatic organisms. This study investigates the acute toxicity of TBZ on juvenile rainbow trout (Oncorhynchus mykiss), a commercially important cold-water fish species. The 96 h LC₅₀ value was determined to be 9.05 mg/L using probit analysis. In addition to mortality, the physiological responses of fish exposed to both LC₅₀ and maximum tolerance concentration (MTC; 6 mg/L) were evaluated through haematological and histological assessments. TBZ exposure significantly suppressed key haematological parameters, particularly WBC, RBC, HGB, HCT, and LYM, indicating immunosuppression and potential hypoxia. Histological examination revealed progressive and regressive damage in gill tissues, including epithelial lifting, hyperplasia, and hypertrophy, which were more severe in the LC₅₀ group. These alterations were quantified using a semi-quantitative scoring system. Additionally, significant changes in biochemical parameters such as ALT, AST, creatinine, total protein, and glucose levels were observed, further indicating hepatic and renal dysfunctions induced by TBZ exposure. The findings demonstrate that TBZ exposure induces substantial physiological and structural impairments in rainbow trout, highlighting the importance of assessing the ecological risks of fungicide contamination in aquatic environments. The study also provides a dose–response model that can be used to estimate mortality risk in aquaculture operations exposed to TBZ. Full article

This study aims to investigate the release of potentially toxic elements from disposable paper and plastic cups when exposed to hot water, simulating the scenario of their use in hot beverage consumption, and to assess the associated health risks. By using ICP-MS, twelve potentially toxic elements, namely As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Pb, Sb, V, and Zn, were determined in leachates, revealing significant variability in mass fractions between paper and plastic cups, with plastic cups demonstrating greater leaching potential. Health risk assessments, including hazard quotient (HQ) and excess lifetime cancer risk (ELCR), indicated minimal non-carcinogenic and carcinogenic risks for most elements, except Pb, which posed elevated non-carcinogenic risk, especially in plastic cups. Children showed higher relative exposure levels compared to adults due to their lower body weights (the HQ in children is two times greater than in adults). Overall, the findings of the current study underscore the need for stricter monitoring and regulation of materials used in disposable cups, especially plastic ones, to mitigate potential health risks. Future investigations should assess the leaching behavior of potentially toxic elements under conditions that accurately mimic real-world usage. Such investigations ought to incorporate a systematic evaluation of diverse temperature regimes, varying exposure durations, and different beverage types. Full article

Lithium-ion batteries (LiBs) are utilized in numerous applications due to advancements in technology, and the recovery of end-of-life (EoL) LiBs is imperative for environmental and economic reasons. Pyrometallurgical and hydrometallurgical methods have been used in the recovery of metals such as Li, Co, and Ni in the EoL LiBs. Hydrometallurgical methods, which have been demonstrated to exhibit higher recovery efficiency and reduced energy consumption, have garnered increased attention in recent research. Inorganic acids, including HCl, HNO₃, and H₂SO₄, as well as organic acids such as acetic acid and citric acid, are employed in the hydrometallurgical recovery of these metals. It is imperative to acknowledge the environmental hazards posed by these acids. Consequently, solvometallurgical processes, which involve the use of organic solvents with minimal or no water, are gaining increasing attention as alternative or complementary techniques to conventional hydrometallurgical processes. In the context of solvent systems that have been examined for a range of solvometallurgical methods, deep eutectic solvents (DESs) have garnered particular interest due to their low toxicity, biodegradable nature, tunable properties, and efficient metal recovery potential. In this study, the leaching process of black mass containing graphite, LCO, NMC, and LMO was carried out in a short time using the ternary DES system. The ternary DES system consists of choline chloride (ChCl), glycolic acid (GLY), and ascorbic acid (AA). As a result of the leaching process of cathode powders in the black mass without any pre-enrichment process, Li, Co, Ni, and Mn elements passed into solution with an efficiency of over 95% at 60 °C and within 1 h. Moreover, the kinetics of the leaching process was investigated, and Density Functional Theory (DFT) calculations were used to explain the leaching mechanism. Full article

Mining waste presents significant environmental and public health risks due to the potential release of toxic substances when improperly managed. In this study, four tailings samples were taken to evaluate the environmental risks in the Ponce Enríquez mining area in Ecuador. Chemical characterization and X-ray Fluorescence Spectrometry (XRF) were used to analyze the content of potentially toxic elements (PTEs) of interest (As, Cd, Cr, Cu, Ni, Pb, and Zn), and X-ray Diffraction (XRD) for mineralogical characterization. The contamination index (IC) was calculated to assess the potential hazard associated with the content of PTEs in the mining wastes. To assess environmental risks, leaching tests were carried out to evaluate the potential release of PTEs, and Acid-Base Accounting (ABA) tests were conducted to determine the likelihood of acid mine drainage formation. The results revealed that the PETs concentration exceeded the maximum permissible limits in all samples, according to Ecuadorian regulations: As, Pb, and Cd were identified as critical contaminants. Mineralogically, quartz was the dominant phase, followed by carbonates (calcite, dolomite and magnesite), phyllosilicates (chlorite and illite), and minor amounts of pyrite and talc. The IC indicated high to very high contamination risk levels, with As being the predominant contributor. Although leaching tests met the established limits for non-hazardous mining waste, the ABA test showed that all samples had a high potential for long-term acid generation. These results underscore the need for implementing management strategies to mitigate the environmental impacts and the development of plans to protect local ecosystems and communities from the adverse effects of mining activities. Full article

There is an increasing demand for the development of efficient and sustainable battery recycling processes. Currently, many recycling processes rely on toxic inorganic acids to recover materials from high-value battery chemistries such as lithium nickel manganese cobalt oxides (NMCs) and lithium cobalt oxide (LCOs). However, as cell manufacturers seek more cost-effective battery chemistries, the value of the spent battery value chain is increasingly diluted by chemistries such as lithium iron phosphate (LFPs). These cheaper alternatives present a difficulty when recycling, as current recycling processes are geared towards dealing with high-value chemistries; thus, the current processes become less economical. To date, much research is focused on treating a single battery chemistry; however, often, the feed material entering a battery recycling facility is contaminated with other battery chemistries, e.g., LFP feed contaminated with NMC, LCO, or LMOs. This research aims to selectively leach various battery chemistries out of a mixed feed material with the aid of a green organic acid, namely oxalic acid. When operating at the optimal conditions (2% solids, 0.25 M oxalic acid, natural pH around 1.15, 25 °C, 60 min), this research has proven that oxalic acid can be used to selectively dissolve 95.58% and 93.57% of Li and P, respectively, from a mixed LFP-NMC mixed feed, all while only extracting 12.83% of Fe and 8.43% of Mn, with no Co and Ni being detected in solution. Along with the high degree of selectivity, this research has also demonstrated, through varying the pH, that the selectivity of the leaching system can be altered. It was determined that at pH 0.5 the system dissolved both the NMC and LFP chemistries; at a pH of 1.15, the LFP chemistry (Li and P) was selectively targeted. Finally, at a pH of 4, the NMC chemistry (Ni, Co and Mn) was selectively dissolved. Full article

The formation of acidic goaf water in abandoned coal mines poses significant environmental threats, especially in karst regions where the risk of groundwater contamination is heightened. This study investigates the geochemical processes responsible for the generation of acidic water through batch and column leaching experiments using coal mine surrounding rocks (CMSR) from Yangquan, China. The coal-bearing strata, primarily composed of sandstone, mudstone, shale, and limestone, contain high concentrations of pyrite (up to 12.26 wt%), which oxidizes to produce sulfuric acid, leading to a drastic reduction in pH (approximately 2.5) and the mobilization of toxic elements. The CMSR samples exhibit elevated levels of arsenic (11.0 mg/kg to 18.1 mg/kg), lead (69.5 mg/kg to 113.5 mg/kg), and cadmium (0.6 mg/kg to 2.6 mg/kg), all of which exceed natural crustal averages and present significant contamination risks. The fluorine content varies widely (106.1 mg/kg to 1885 mg/kg), with the highest concentrations found in sandstone. Sequential extraction analyses indicate that over 80% of fluorine is bound in residual phases, which limits its immediate release but poses long-term leaching hazards. The leaching experiments reveal a three-stage release mechanism: first, the initial oxidation of sulfides rapidly lowers the pH (to between 2.35 and 2.80), dissolving heavy metals and fluorides; second, slower weathering of aluminosilicates and adsorption by iron and aluminum hydroxides reduce the concentrations of dissolved elements; and third, concentrations stabilize as adsorption and slow silicate weathering regulate the long-term release of contaminants. The resulting acidic goaf water contains extremely high levels of metals (with aluminum at 191.4 mg/L and iron at 412.0 mg/L), which severely threaten groundwater, particularly in karst areas where rapid cross-layer contamination can occur. These findings provide crucial insights into the processes that drive the acidity of goaf water and the release of contaminants, which can aid in the development of effective mitigation strategies for abandoned mines. Targeted management is essential to safeguard water resources and ecological health in regions affected by mining activities. Full article

Potato (Solanum tuberosum L.) is a chlorine-sensitive crop. When soil Cl⁻ concentrations exceed optimal thresholds, the yield and quality of potatoes are limited. Consequently, chloride-containing fertilizers are rarely used in actual agricultural production. Therefore, two years of field experiments under natural rainfall regimes with three chlorine application levels (37.5 kg ha⁻¹/20 mg kg⁻¹, 75 kg ha⁻¹/40 mg kg⁻¹, and 112.5 kg ha⁻¹/60 mg kg⁻¹) were conducted to investigate the leaching characteristics of Cl⁻ in field soils with two typical textures for Northeast China (loam and sandy loam soils). In this study, the reliability of Cl⁻ residual estimation models across different soil types was evaluated, providing critical references for safe chlorine-containing fertilizer application in rain-fed potato production systems in Northeast China. The results indicated that the leaching efficiency of Cl⁻ was significantly positively correlated with both the rainfall amount and the chlorine application rate (p < 0.01). The Cl⁻ migration rate in sandy loam soil was significantly greater than that in loam soil. However, the influence of soil texture on the Cl⁻ leaching efficiency was only observed at lower rainfall levels. When the rainfall level exceeded 270 mm, the Cl⁻ content in all the soil layers became independent of the rainfall amount, soil texture, and chlorine application rate. Under rain-fed conditions, KCl application at 80–250 kg ha⁻¹ did not induce Cl⁻ accumulation in the primary potato root zone (15–30 cm), suggesting a low risk of toxicity. In loam soil, the safe application range for KCl was determined to be 115–164 kg ha⁻¹, while in sandy loam soil, the safe KCl application range was 214–237 kg ha⁻¹. Furthermore, a predictive model for estimating Cl⁻ residuals in loam and sandy loam soils was validated on the basis of rainfall amount, soil clay content, and chlorine application rate. The model validation results demonstrated an exceptional goodness-of-fit between the predicted and measured values, with R² > 0.9 and NRMSE < 0.1, providing science-based recommendations for Cl-containing fertilizer application to chlorine-sensitive crops, supporting both agronomic performance and environmental sustainability in rain-fed systems. Full article

Flotation was investigated to treat incineration fly ash with diesel, kerosene, TX-100, or SDS as a collector and methyl isobutyl carbinol (MIBC) or 2-Octyl alcohol as a frother. Fly ash was separated into light and residual materials. Comparison of yield, carbon and sulfur removal showed that kerosene and MIBC showed the best performance. The results revealed that flotation was a method that could simultaneously achieve the removal of organics and S-containing compounds. Specifically, approximately 7.63–9.45% of the total mass was collected as light material, which was enriched with organic carbon. Contents of organic carbon reached 14.35 wt%–14.56 wt% in the light materials from those of 2.74 wt%–3.52 wt% in the original fly ash. Elemental analysis further proved that sulfur was also accumulated in light material. Approximately 78.84–81.69% of the organic carbon and 80.47–82.66% of the sulfur were removed. Decarbonization was primarily achieved through the flotation of organic materials, while desulfurization resulted from both flotation and the dissolution of soluble salts. Furthermore, the contents of the chloride and heavy metals in the residual fly ash also decreased. Particle size analysis showed that flotation was effective in the removal of smaller particles, and those particles were also rich in heavy metals. Overall, by selecting the right collector and frother, flotation was also able to reduce the leaching toxicity of heavy metals. The residual fly ash was safe for further disposal. Organic carbon, sulfur and heavy metals were accumulated in the light materials, which accounted for less than 10% of the original mass. The portion of fly ash needing further treatment was therefore greatly reduced. Full article

4-Aminodiphenylamine (4-ADPA) is a common additive in rubber tires, known for its antioxidant properties. It plays a crucial role in enhancing tire durability by preventing issues such as drying, cracking, and degradation from prolonged exposure to environmental factors like heat, oxygen, and ozone. However, despite its advantages in extending tire lifespan, the use of 4-ADPA raises significant environmental concerns. As tires wear down, microscopic tire wear particles (TWPs) containing 4-ADPA are released into the environment with substantial leaching, contaminating the waterways. The 4-ADPA leachates pollute and pose a threat to aquatic ecosystems, affecting various forms of marine life. The current study investigates the ecotoxicological effects of 4-ADPA on the aquatic plant Lemna minor (L. minor), focusing on its impact on relative growth and physiological biomarkers. Several parameters were assessed to evaluate ecotoxicity, including frond morphology, fresh biomass, total frond number, chlorophyll content, and starch accumulation. L. minor was grown for 7 and 14 days under controlled laboratory conditions using Hoagland media with varying concentrations of 4-ADPA (10–100 μg/L), while a control group was maintained in media without 4-ADPA. The results indicate that exposure to 4-ADPA led to a dose-dependent reduction in fresh biomass, total frond number, and chlorophyll levels. Lugol’s staining revealed increased starch accumulation in the fronds after exposure to 4-ADPA. The biological effects observed in L. minor following exposure to 4-ADPA, even at environmentally relevant concentrations, demonstrate a significant ecotoxicological impact on aquatic ecosystems. Further research involving additional species and investigating the mechanisms behind 4-ADPA toxicity is recommended to better understand its long-term consequences. Full article

The global population is rising at an alarming rate and is projected to reach 10 billion by 2050, necessitating a substantial increase in food production. However, the overuse of chemical pesticides, including antibacterial agents and synthetic fertilizers, poses a major threat to sustainable agriculture. This review examines the ecological and health impacts of antibacterial agents (e.g., streptomycin, oxytetracycline, etc.) in horticultural crops, focusing on their effects on non-target organisms such as beneficial microbes involved in plant growth promotion and resistance development. Certain agents (e.g., triclosan, sulfonamides, and fluoroquinolones) leach into water systems, degrading water quality, while others leave toxic residues in crops, leading to human health risks like dysbiosis and antibiotic resistance. To mitigate these hazards, sustainable alternatives such as integrated plant disease management (IPDM) and biotechnological solutions are essential. Advances in genetic engineering including resistance-conferring genes like EFR1/EFR2 (Arabidopsis), Bs2 (pepper), and Pto (tomato) help combat pathogens such as Ralstonia solanacearum and Xanthomonas campestris. Additionally, CRISPR-Cas9 enables precise genome editing to enhance inherent disease resistance in crops. Emerging strategies like biological control, plant-growth-promoting rhizobacteria (PGPRs), and nanotechnology further reduce dependency on chemical antibacterial agents. This review highlights the urgent need for sustainable disease management to safeguard ecosystem and human health while ensuring food security. Full article

Tetracycline (TC) is widely used in medicine and livestock farming. TC is difficult to degrade and tends to persist and accumulate in aquatic environments, and it has gradually become an emerging pollutant. Biochar (BC) has strong potential for removing TC from water. This potential arises from its excellent surface properties, low-cost raw materials, and renewable nature. However, raw biomass materials are highly diverse, and their preparation conditions vary significantly. Modification methods differ in specificity and the application scenarios are complex. These factors collectively cause unstable TC removal efficiency by biochar. The chemical activation process using KOH/H₃PO₄ significantly enhanced porosity and surface functionality, transforming raw biochar into an activated carbon material with targeted adsorption capacity. Adjusting the application dosage and environmental factors (particularly pH) further enhanced the removal performance. Solution pH critically governs the adsorption efficiency: optimal conditions (pH 5–7) increased removal by 35–40% through strengthened electrostatic attraction, whereas acidic/alkaline extremes disrupted ionizable functional groups. The dominant adsorption mechanisms of biochar involved π–π interactions, pore filling, hydrophobic interactions, hydrogen bonding, electrostatic interactions, and surface complexation. In addition, the main challenges currently hindering the large-scale application of biochar for the removal of TC from water are highlighted: (i) secondary pollution risks of biochar application from heavy metals, persistent free radicals, and toxic organic leaching; (ii) economic–environmental conflicts due to high preparation/modification costs; and (iii) performance gaps between laboratory studies and real water applications. Full article