Environmental Science: Nano最新文献

Nanoparticles have attracted widespread attention for their positive role in suppressing plant diseases. In the present work, the impact of solid silica nanoparticles (SNPs) on the bacterial community of tomato root endophytes under Ralstonia solanacearum (Rs) infection was investigated. Tomato infection by Rs led to a 17.78% reduction in shoot fresh weight and a 66.44% reduction in root fresh weight. Repeated three soil applications of 650 mg L⁻¹ SNPs significantly suppressed bacterial wilt, with a 40.27–48.96% reduction in the disease index. SNPs also significantly increased the shoot fresh and dry weight by 17.43% and 17.13%, respectively. In the roots, SNPs altered the structure and increased the diversity of the endophytic bacterial community in infected plants. Notably, Mitsuaria, Sphingobium, Streptococcus, and Rhizobium were enriched with SNPs–Rs treatment; these are identified as beneficial bacteria that facilitate plant resistance to pathogens. Additionally, SNPs' application significantly increased the concentrations of N (27.01%), K (8.34%), and Si (11.01%) in roots under Rs infection. A correlation analysis indicated that nutrient concentration in roots was positively correlated with bacterial community diversity. These data show that SNPs can enhance plant resistance to disease by regulating the structure and diversity of root endophyte communities and improving plant nutrition. Our findings have important implications for the application of nanoparticles in sustainable nano-enabled agriculture.

An excessive concentration of greenhouse gases, most significantly carbon dioxide (CO₂), in the atmosphere has led to the serious environmental issue of global warming. Carbon capture is a suitable strategy to reduce the increase of CO₂ in the atmosphere due to fossil fuel combustion. Innovative technologies for CO₂ capture are urgently required and this is an area of intensive study in order to improve efficiency and reduce operational costs. In this work, we applied molecular dynamics simulations to demonstrate the ability of single-walled carbon nanotubes (SWCNT) and double-walled carbon nanotubes (DWCNT) to capture CO₂ from flue gases. Both SWCNTs and DWCNTs prefer to adsorb CO₂ rather than N₂ and O₂, resulting in a separation effect. CO₂ molecules form a solid ice structure in the carbon nanotubes (CNT) while N₂ and O₂ remain gaseous. As a result, the potential energy of the CO₂ structure inside the CNTs is lower than that of the N₂ or O₂ structures. This implies that CO₂ is more stable in the CNTs. Therefore, the formation of these solid CO₂ structures plays an important role in the process of capturing CO₂via CNTs. Moreover, the van der Waals interactions between CO₂ molecules and the CNT walls make a significant contribution to the separation of CO₂ as well. The potential energy of the CO₂–CNT wall interactions is significantly lower than those of N₂–CNT wall or O₂–CNT wall interactions. In addition, the presence of a second wall in DWCNTs causes even stronger attractive CO₂–CNT wall van der Waals interactions than those found in SWCNTs. As a result, the CO₂ capturing effect of DWCNT is greater than that of SWCNT.

As the global population steadily increases, the need to increase agricultural productivity has become more pressing. It is estimated that agricultural production needs to double in less than 30 years to meet the projected food demand. However, crop species are being cultivated under a range of increasingly challenging environmental stressors, including the effects of climate change and factors. To address these issues, nanotechnology has emerged as an enabling strategy to bolster plant resistance to the adverse effects of stressors and improve their overall performance. In this review, we evaluate recent research in this field, examining the strategies by which nanomaterials (NMs) and nanoparticles (NPs) have been used to facilitate enhanced tolerance to pests, excessive salinity in soil, pathogenic fungi, and other stressors. The intent is to focus on the mechanisms by which plants cope with environmental stressors at the physiological and molecular levels. We also examine how plants interact with and acquire NMs, with a specific focus on the mechanisms behind their beneficial effects regarding stress response. Our review also evaluates key knowledge gaps and offers suggestions on how to address them. Additionally, we discuss the potential of NMs to enhance agricultural production systems and highlight essential considerations for mitigating crop stress and promoting sustainable agriculture at a global scale. While the use of nanotechnology in the agricultural sector is growing and shows tremendous promise, more mechanistic studies and field-scale demonstrations are needed to fully understand and optimize the use of nanomaterials on plants stress tolerance in a changing climate. In addition, few studies conducted life cycle field experiments to verify the effects of nano-agrichemicals on yield and nutritional quality, and importantly, there is a lack of multiple-year and multiple-location experiments. Only by doing this can the technology-readiness-level of nano-enabled agro-technologies be improved and forwarded to commercial application.

The widespread plastic pollution has raised significant concerns. The breakdown process of plastic debris during weathering not only generates microplastics and nanoplastics but also releases large quantities of harmful chemical additives such as phthalates and organophosphate esters (OPEs). Metal oxides, particularly those in the form of nanoparticles, play an essential role in mediating the environmental transformation of plastic additives. However, the key structure–activity relationships governing metal oxide-mediated transformation processes remain poorly understood. Here, we demonstrate that oxygen vacancies (OVs), which are common in metal oxide nanomaterials, significantly contribute to the enhanced catalytic performance of α-MnO₂ nanoparticles in promoting the hydrolysis of 4-nitrophenyl phosphate (pNPP), a model OPE pollutant. α-MnO₂ nanorods with different OV concentrations (obtained by calcination under different atmospheres, i.e., N₂versus air) promote pNPP hydrolysis to different degrees, and the α-MnO₂ material with a higher OV concentration shows higher catalytic activity. The results from spectroscopic and theoretical investigations reveal that OVs regulate the adsorption affinity to pNPP by adjusting the coordination saturation of the Mn sites on the α-MnO₂ surface. Additionally, the enhanced Lewis acidity at these sites (as confirmed by pyridine adsorption infrared spectroscopy and temperature-programmed desorption of ammonia) promotes the electron redistribution in pNPP, which decreases the stability of the P–O bond and enhances the reactivity of α-MnO₂ towards pNPP. The findings demonstrate that metal oxide nanomaterials can significantly influence the fate and transformation of microplastic additives and highlight the potential of defect engineering in amplifying metal oxides' efficacy for environmental cleanup.

The current and continued influx of engineered nanoparticles (NPs) into the environment is significant, including the release of NPs that have been historically stored or retained in soils to various waterbodies. However, the reactivity and dynamic nature of NP transformation processes are poorly understood due to the lack of long-term environmentally relevant experiments that accurately represent ecosystem complexity. Here, we established a two-year mesocosm system to quantify the relative reactivity of silver sulfide NPs using stable isotope tracers, with more recent ¹⁰⁹Ag₂S-NPs inputs to the 80 L water column (water-borne NPs, 141 mg) and historically stored Ag₂S-NPs in soils (soil-borne NPs, 4.5 ± 0.3 μg g⁻¹). Soil-borne NPs accounted for 59.4–92.1% of the Ag accumulation in the grain of rice Oryza sativa L. (31.4–112.4 μg kg⁻¹), radish roots Raphanus sativus L. (106.2–396.7 μg kg⁻¹), and rice borers Chilo suppressalis (21.5–30.7 μg kg⁻¹), highlighting the significance of soil-borne NPs in agricultural ecosystems. Based on the measured soil-to-plant transfer factors, recommended concentrations of soil-borne NPs should be less than 2.4 μg Ag g⁻¹ for rice growth and 0.7 μg Ag g⁻¹ for radish growth to minimize human exposure to silver via consumption of these edible tissues. This work demonstrates that quantifying the reactivity of NP transformation processes and different NP fractions in the environment is not only important for accurately characterizing the risk of these materials but also for ensuring the safety and sustainability of agriculture.

In this study, a novel Ce-doped hydrotalcite (Ce–NiFe-LDHs) was synthesized by co-precipitation, which completely removed tetracycline hydrochloride (TC-HCl) in the photo-Fenton system within 60 min, and showed excellent stability and durability in cycling tests. In addition, the catalyst has demonstrated a wide range of adaptability to environmental conditions in the photo-Fenton system, maintaining efficient catalytic performance regardless of water quality differences, environmental factors or different types of antibiotics. The introduction of rare earth element Ce can not only effectively reduce the band gap width of the catalyst and broaden its absorption capacity in the visible light range, but also promote the efficient migration and separation of photogenerated carriers by optimizing the optical properties, further improving the catalytic efficiency. The free radical quenching experiment and electron spin resonance test revealed the core role of the photogenerated hole as the main active substance. Combined with high performance liquid chromatography-mass spectrometry and density functional theory calculations, the degradation pathways were proposed. Meanwhile, through the Toxicity Estimation Software Tool and germination and growth test of soybean, it was found that the reaction was a process of toxicity reduction. This study provides a new strategy and theoretical basis for the future study of heterogeneous catalytic decomposition of antibiotic residues.

Zinc oxide (ZnO) nanoparticles are extensively utilized across various industries due to their versatile applications. However, the widespread use of these nanoparticles raises concerns regarding their potential release into soil environments, and also into the soil solution. Therefore, this study aims to delve into the interplay between different soil solution properties and the stability as well as photocatalytic activity of commercially available ZnO nanoparticles. It is observed that these interactions precipitate a reduction in the primary crystallite sizes of ZnO, primarily attributed to the release of Zn²⁺ ions under acidic conditions, and the formation of zinc complexes or hydroxides in alkaline environments. In acidic media, there is a concomitant decrease in the hydrodynamic diameter of ZnO, serving as further confirmation of Zn²⁺ release, which is corroborated by analytical measurements. Conversely, in alkaline media, the hydrodynamic diameter remains unaltered, suggesting the formation of an amorphous layer on the nanoparticle surface in such conditions. Further analyses into the surface chemistry of ZnO nanoparticles reveal the adsorption of various organic substances onto their surfaces. These organic compounds potentially function as electron traps or occupy active sites, however, after the interaction with soil solutions, the material was still able to degrade the model pollutant. So, the interaction with soil solutions reduced the activity, but the catalyst retained its efficiency. In essence, this study underscores the importance of comprehensively understanding the behavior of ZnO nanoparticles in soil environments. Such insights are pivotal for informed decision-making regarding the sustainable utilization of ZnO nanoparticles across various industrial domains.

Chlorophenols (CPs) have strong toxicity because of the presence of chlorine atoms. Although dechlorination can eliminate their toxicity, their by-products may cause secondary pollution. In this study, a two-step process of pre-reduction dechlorination and oxidation, reductive dechlorination by sulfidated nanoscale zero-valent iron (S-nZVI) and advanced oxidation by S-nZVI-activated peroxydisulfate (PDS), was innovatively adopted to achieve efficient and complete mineralization of 2,4-dichlorophenol (2,4-DCP). The pre-reduction of S-nZVI achieved 80% dechlorination of 2,4-DCP. With the subsequent addition of PDS, 2,4-DCP and its dechlorination by-products in the solution were almost completely removed, and the mineralization rate reached 91.5% under the optimal conditions of unadjusted initial pH (5.4), S-nZVI dosage 2.5 g L⁻¹, and PDS concentration of 1.8 mM. The electron spin resonance (ESR) and radical quenching experiments demonstrated that both ·OH and SO₄⁻ were involved in the degradation of 2,4-DCP, while SO₄⁻ played a more predominant role. Based on the transformation products of 2,4-DCP identified by GC-MS, the degradation mechanism of 2,4-DCP in this system included two steps, namely, reductive dechlorination induced by electron transformation and oxidation degradation involving single electron transfer, radical adduct formation, and hydrogen atom abstraction. This study demonstrated that the novel S-nZVI pre-reduction and sequential S-nZVI/PDS process is a very promising and efficient approach for the complete removal of CPs in water.

With the development of persulfate-based Fenton-like catalysis, how to control the PDS reaction pathway is a great challenge. Herein, we prepared catalysts with nitrogen-rich porous carbon (NPC) layers and oxygen vacancy (O_v) sites for PDS activation to degrade sulfamethazine (SMZ). Results revealed that the ZnO@NPC/PDS system exhibited only non-radical pathways, which comprised the singlet oxygen (¹O₂) and electron transfer process. The intrinsic mechanism underlying the production of active species was further verified by comparing the results of the ZnO@NPC/PDS and ZnO@NPC-Etch/PDS systems, Raman analysis and DFT calculations. Adsorption of PDS by carbon layers resulted in the formation of a catalyst–PDS complex, which not only elongated the S–O bond and accelerated the decomposition of PDS to generate ¹O₂ but also provided access for electron transfer. Meanwhile, O_v sites increased electron density and electron migration strength, which promoted more electron transfer from O_vs to PDS molecules through nitrogen-rich porous carbon layers. Moreover, the ZnO@NPC/PDS system could maintain a degradation rate of >90% for SMZ in real water matrixes. T. E. S. T software prediction and toxicity tests were used to investigate environmental implications of degradation intermediates, which showed reduced ecological toxicity compared with SMZ. This work fabricated the ZnO@NPC/PDS system and explored the interaction between nitrogen-rich porous carbon layers and O_v to regulate the occurrence of non-radical pathways, which could provide a strategy to control the PDS reaction pathway.

Hematite displays diverse crystal structures and often coexists with Fe(II), both of which are crucial in controlling the fate and mobility of Cr(VI). However, the mechanisms underlying Cr(VI) removal in the presence of Fe(II) on various hematite facets remain elusive. This study aims to elucidate the facet-dependent reactivity of hematite nanocrystals in conjunction with Fe(II) for the removal of Cr(VI) from aqueous solutions. Hematite nanoplates (HNPs), predominantly composed of {001} facets, and nanorods (HNRs), exposing both {001} and {110} facets, were synthesized and characterized. Their Cr(VI) removal capabilities were evaluated in hematite–Cr(VI) and hematite–Fe(II)–Cr(VI) systems, as well as the Fe(II)–Cr(VI) system. The adsorption of Fe(II) and Cr(VI) on hematite surfaces was highly dependent on the crystal facets and pH, with HNRs demonstrating superior Cr(VI) adsorption over HNPs, especially under acidic conditions. Neutral pH favored Fe(II)–Cr(VI) redox reactions and Fe(II) adsorption. The hematite–Fe(II) couple displayed a synergistic effect in removing Cr(VI) under acidic conditions, which was not observed under neutral conditions. The presence of Fe(II) notably enhanced Cr(VI) adsorption onto hematite, and bound Fe(II) facilitated electron transfer, accelerating Cr(VI) reduction. HNRs–Fe(II) exhibited higher Cr(VI) removal efficiency than HNPs–Fe(II) due to their lower free corrosion potential and improved electron transport properties. This research underscores the potential of facet engineering in optimizing hematite nanocrystals for environmental remediation, specifically in Cr(VI)-contaminated environments.