Journal of Environmental Sciences-china最新文献

Monotonic pore size and particles inseparability of metal-organic frameworks (MOFs) caused serious effects on its light absorption ability and charge separation, restricting its application for antibiotic such as levofloxacin (LEV) degradation in water. In this study, a magnetically detachable nano-photocatalyst (ZnFe₂O₄@MIL-88A(Fe)) was synthesized using a simple two-step hydrothermal technique. The morphology and microstructure analyses showed that n-type ZnFe₂O₄ catalyst particles were efficiently assembled onto the surface of MIL-88A(Fe) crystal. Photocatalytic activity studies indicated that the ZnFe₂O₄@MIL-88A(Fe) plus H₂O₂ exhibiting a significantly boosted photo-Fenton activity toward LEV at visible light irradiation, compared to the pure ZnFe₂O₄ and MIL-88A(Fe), the degradation efficiency accordingly reached up to nearly 82% and 25% within 60 min. This excellent photocatalytic performance was ascribed to the synergistic effects of the heterogeneous structure of ZnFe₂O₄ and MIL-88A(Fe), whereby the efficient separation of charge carriers in the catalytic system is mutually reinforced with the efficient reduction of Fe³⁺ and Fe²⁺. Meanwhile, the degradation mechanism and intermediates of LEV during the photo-Fenton reaction process were also studied in depth through free radical burst, electron paramagnetic resonance, and mass spectrometry analyses, etc. Additionally, the ZnFe₂O₄@MIL-88A(Fe) composite catalyst displayed significant stability and ease of separation, indicating potential for the photo-oxidative degradation of organic pollutants.

The effectiveness of Elodea nuttallii combined with a mixture of hydrous ferric oxide, zeolite and calcite (HZC) to reduce the internal loading of phosphorus (P) from sediment and its mechanism were studied, and the effect of Elodea nuttallii combined with HZC on the composition and function of the microbial communities in the surface sediment was also investigated. The results showed that the combination utilization of Elodea nuttallii and HZC can decrease the risk of phosphorus liberation from sediment to the overlying water, and the controlling efficiency of Elodea nuttallii combined with HZC was higher than that of Elodea nuttallii or HZC alone. The passivation of labile P measured by diffusive gradient in thin film device and mobile P played a crucial role in the control of internal P loading from sediment by the combined Elodea nuttallii + HZC treatment. HZC capping had a promoting effect on the growth of Elodea nuttallii. This was beneficial to the absorption of phosphorus from sediment by Elodea nuttallii. The combined application of Elodea nuttallii and HZC not only had a certain negative effect on the diversity of bacteria in the surface sediment, but also changed the microbial compositions of the surface sediment at the levels of phylum and genus. However, the microbial communities in the surface sediment still can perform good ecological function. The above results suggest that the combined application of Elodea nuttallii and HZC has a high potential in the management of internal P loading from sediment.

Herein, the association between the dynamic adsorption capacity of toluene and several important characteristic values on activated carbon (AC) samples was investigated by multidimensional linear regression. Among the characteristic values, the carbon tetrachloride (CTC) adsorption value has demonstrated relatively stronger correlation with the toluene adsorption capacity on AC samples with diverse sources and forms, particularly in exposure to high-concentration toluene. Notably, the relevance of the toluene adsorption capacity to the CTC value could also be extended to a series of other porous adsorbents, which proved the wide applicability of CTC value in characterizing the adsorption behaviors. Based on these results, a mathematical and visual model was then established to predict the toluene adsorption saturation under different conditions (inlet concentration, adsorption time, initial CTC value, etc.) on diverse AC samples, of which the accuracy has later been verified by experimental data. As such, a fast and accurate estimation of the adsorption behaviors over AC samples, and possibly other porous adsorbents, was realized.

Halocarbons play a vital role in ozone depletion and global warming, and are regulated by the Montreal Protocol (MP) and its amendments. China has been identified as an important contributor to the halocarbon emissions, but the regional sources of halocarbons in China are not yet well comprehended. To investigate the characteristics, emissions, and source profiles, this study conducted a field campaign in Xiamen, a coastal city in southeastern China. Higher enhancements were found in the unregulated halocarbons (CH₃Cl, CH₂Cl₂, CHCl₃) than in the MP eliminated species (CCl₄, CH₃Br) and the MP controlled species (HCFCs, HFCs). Many of the measured halocarbons varied seasonally and regionally, depending on the anthropogenic sources and atmospheric transport. Backward trajectory analysis showed that the air masses from inland were polluted over Shandong, Hebei, and northern Fujian in the cold season, while the air masses from the sea in the warm season were clean. Different air masses in two seasons were associated with the halocarbon patterns in the study area. Industrial activities, especially solvent usage, were the primary sources of halocarbons. The emission hot spots in Fujian Province were concentrated in Sanming, Fuzhou, and Xiamen, and the unregulated halocarbons made the largest contribution. This study provides an insight for a deep understanding of the characteristics and potential sources of halocarbons, and for strengthened management of halocarbons in China.

This study presents a novel approach, the Supercapacitor Microbial Electrolysis Cell (SC-MEC), which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater. The results demonstrated that the SC-MEC system, operating under anaerobic conditions and devoid of any organic carbon source, exhibited exceptional performance in ammonia oxidation and total nitrogen (TN) removal when solely relying on ammonia nitrogen as the electron donor. Operating at a voltage of 1.8 V with a capacitance capacity of 30 F, ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day, in which 97% of ammonium nitrogen was converted to gaseous nitrogen. Furthermore, the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials. Cyclic voltammetry (CV) analysis showed the significantly enhanced electrochemical activity of the SC-MEC system during the reaction process. Based on in-situ CV test results, it was inferred that this enhancement was associated with extracellular electron transfer mediators. The microbial community analysis revealed a process of synchronous nitrification and denitrification (SND) coupled with anammox, involving multiple genera, such as Candidatus Kuenenia, Nitrosomonas, Truepera, and Bosea. In conclusion, this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal, offering more feasible and economical solutions for addressing low C/N water pollution issues.

The manufacture and obsolescence of smartphones produce numerous waste plastic accessories (e.g., waste smartphone protective film (WSPF)), possessing immense potential for recycling. However, available recycling technologies have limitations such as substrate damage and secondary pollutant generation. The present study aimed to develop a green disposal method that not only recycled polyethylene terephthalate (PET) from WSPF, but also reused the stripped polyacrylate (PAA) adhesive as an adsorbent to reduce solid waste generation. When the WSPF was treated in 1 mol/L NaOH solution at 90 °C, the PAA hydrolyzed to two main by-products of 1-butanol and 2-ethylhexanol, weakening the binding strength between PAA and PET and then efficient separation of them. Further bench-scale test revealed that over 97.2% of detachment efficiency toward PAA was achieved during continuous treatment of 17 batches of WSPF (200 g for each) without supplement of NaOH and generation of wastewater. Meanwhile, the economic evaluation indicated that the recycling method would generate a net profit margin of 647% for the second year without considering the incurrence of new cost and input. Additionally, the pyrolysis of waste PAA enabled its conversion into potential adsorbent, which showed 2 to 4 times enhanced adsorption capacity toward styrene and ethyl acetate after modification with NaOH solution. This study provides a green method for recycling waste plastics and inspires a referable solution for solid waste treatment in the smartphone industry.

A chain of GdCe oxides boosted biochars derived from maize straw and sewage sludge (Gd_yCe_1-y/MPBs) were fabricated for formaldehyde (HCHO) catalytic decomposition. The ingenerate relationship between the abatement performance and corresponding structural feature was comprehensively evaluated by XPS, in situ DRIFTS, BET, XRD, SEM and H₂-TPR. Meanwhile, 10%Gd_0.25Ce_0.75/MPB exhibited excellent performance, favorable SO₂ and moisture toleration over a broad temperature range from 160 to 320 ℃, where it achieved 96.8% removal efficiency with 90.5 % selectivity at 200 ℃. The single or united effects of O₂, SO₂, H₂O on HCHO abatement over 10 %Gd_0.25Ce_0.75/MPB were tested, and the findings demonstrated that the suppressive effects of SO₂ and H₂O outweighed the promoting influence of O₂ within a specific range. Gd and Ce co-modified MPB revealed superior HCHO removal capability in contrast to that of Gd or Ce severally modified MPB, ascribing to the synergistic effect of GdO_x and CeO_x and benefitting from the augmentation of surface area and total pore volume, the aggrandizement of surface active oxygen species, the promotion of redox ability and the inhibition crystallization of CeO_x. According to in situ DRIFTS, a series of intermediates including formate species and dioxymethylene (DOM) were produced, which would eventually decompose into H₂O and CO₂. In addition, the mass transfer and diffusion of the reactants along with the accessibility of the catalytic sites were enlarged by the hierarchical porous structure of the support, which were also answerable for its distinguished catalytic performance. Furthermore, 10%Gd_0.25Ce_0.75/MPB possessed remarkable potential for industrial applications.

Organic amine pesticides (OAPs) are widely used in modern agriculture and these compounds can contaminate drinking water sources in different ways. However, there is a lack of data on the occurrence of OAPs in drinking water and their potential human health risks. In this study, tap water (TW) and bottled water (BW) samples were collected from eight cities in the Yangtze River Delta urban agglomeration in China, and their OAP levels were analyzed using high-throughput organic analysis testing coupled with high-volume solid-phase extraction (Hi- throat/Hi-volume SPE techniques). This study is the first to systematically characterize the trace levels of OAPs in drinking water in China. Our findings indicated that the total concentration of OAPs (∑OAPs) in TW (average 11.06 ± 4.99 ng/L) was 29.4% higher than in BW (average 8.55 ± 3.98 ng/L) and fewer kinds (7) of OAPs were detected in BW. Furthermore, the long-term intake of TW in some areas was linked to carcinogenic risks even at an acceptable OAP range, particularly in males, with molinate being the major contributor (61.3%) to OAP exposure. Further analysis revealed that the occurrence and health risks of OAPs in drinking water were mainly influenced by the quality of water sources and the technologies adopted in drinking water treatment plants (DWTPs). Furthermore, our findings demonstrated that advanced treatment technologies such as nanofiltration could more effectively remove OAPs in raw water (up to 87.5%). Therefore, our findings highlighted the importance of selecting appropriate advanced treatment technologies in DWTPs.

Environmental monitoring systems based on remote sensing technology have a wider monitoring range and longer timeliness, which makes them widely used in the detection and management of pollution sources. However, haze weather conditions degrade image quality and reduce the precision of environmental monitoring systems. To address this problem, this research proposes a remote sensing image dehazing method based on the atmospheric scattering model and a dark channel prior constrained network. The method consists of a dehazing network, a dark channel information injection network (DCIIN), and a transmission map network. Within the dehazing network, the branch fusion module optimizes feature weights to enhance the dehazing effect. By leveraging dark channel information, the DCIIN enables high-quality estimation of the atmospheric veil. To ensure the output of the deep learning model aligns with physical laws, we reconstruct the haze image using the prediction results from the three networks. Subsequently, we apply the traditional loss function and dark channel loss function between the reconstructed haze image and the original haze image. This approach enhances interpretability and reliability while maintaining adherence to physical principles. Furthermore, the network is trained on a synthesized non-homogeneous haze remote sensing dataset using dark channel information from cloud maps. The experimental results show that the proposed network can achieve better image dehazing on both synthetic and real remote sensing images with non-homogeneous haze distribution. This research provides a new idea for solving the problem of decreased accuracy of environmental monitoring systems under haze weather conditions and has strong practicability.

To understand the differences in the composition and sources of PM_2.5 and PM₁₀ caused by coarse particles, integrated PM_2.5 and PM₁₀ samples were synchronously collected in Nanjing, East China, in summer 2020 and winter 2020/2021. Bulk and molecular speciation and light absorption measurements of aerosol extracts were performed, followed by positive matrix factorization (PMF) based on the PM_2.5 and PM₁₀ data sets, respectively. The difference in average concentrations of total bulk species between PM_2.5 and PM₁₀ was mainly caused by the distribution of considerable NO₃^–, SO₄^2–, Ca²⁺, and organic carbon (OC) in coarse particles. Coarse PM influenced by abrasion products from tire wear and leaves contributed about half of the low-volatility n-alkanes in summer. The contribution of coarse PM to biomass burning tracers and water-soluble OC increased in winter when biomass combustion was excessively active. More than 70% of sugar polyols were attributable to coarse PM in summer, and biomass burning could be an important source in winter. The light-absorbing organic chromophores were almost entirely associated with PM_2.5, but water-soluble organic carbon (WSOC) exhibited stronger light absorption in PM₁₀ extracts than in PM_2.5 extracts possibly due to the influence of coarse PM on pH. PMF analysis indicated that biomass burning, aqueous-phase reactions, and processed dust were the main contributors of organic matter and its light absorption in winter. Biogenic primary and secondary sources made discernable contributions only in summer. The differences between PM_2.5 and PM₁₀ were likely attributed to mixing of crustal dust, combustion particles, and surface reactions.