查看更多>>摘要：This study investigates the photocatalytic degradation of Crystal Violet (CV) dye using Zeolitic Imidazolate Framework-67 (ZIF-67) and its composites, Graphene Oxide/ZIF-67 (GO/ZIF-67) and Nickel/ZIF-67 (Ni/ZIF-67). The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and Ultraviolet-Visible (UV-Vis) spectroscopy, confirming their crystalline structure, morphology, and optical properties. GO/ZIF-67 exhibited exceptional photocatalytic activity, achieving 96.91% degradation of 5 mg/L CV in 36 min under visible light at pH 4 with 0.25 g/L catalyst, following a pseudo-first-order rate constant of 0.94 min~(-1), compared to 0.91 min~(-1) for ZIF-67 and 0.64 min~(-1) for Ni/ ZIF-67. This enhanced performance is linked to its reduced bandgap energy of 1.7 eV (vs. 1.93 eV for ZIF-67 and 1.81 eV for Ni/ZIF-67). Parametric studies identified optimal conditions at 2.5-20 mg/L dye concentration and 0.25 g/L catalyst dosage. Reusability tests with GO/ZIF-67 showed 90% efficiency in the first cycle, declining to 23% after four cycles. These findings highlight GO/ZIF-67's potential as an effective photocatalyst for water remediation.
查看更多>>摘要：This study investigates the photocatalytic degradation of Crystal Violet (CV) dye using Zeolitic Imidazolate Framework-67 (ZIF-67) and its composites, Graphene Oxide/ZIF-67 (GO/ZIF-67) and Nickel/ZIF-67 (Ni/ZIF-67). The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and Ultraviolet-Visible (UV-Vis) spectroscopy, confirming their crystalline structure, morphology, and optical properties. GO/ZIF-67 exhibited exceptional photocatalytic activity, achieving 96.91% degradation of 5 mg/L CV in 36 min under visible light at pH 4 with 0.25 g/L catalyst, following a pseudo-first-order rate constant of 0.94 min~(-1), compared to 0.91 min~(-1) for ZIF-67 and 0.64 min~(-1) for Ni/ ZIF-67. This enhanced performance is linked to its reduced bandgap energy of 1.7 eV (vs. 1.93 eV for ZIF-67 and 1.81 eV for Ni/ZIF-67). Parametric studies identified optimal conditions at 2.5-20 mg/L dye concentration and 0.25 g/L catalyst dosage. Reusability tests with GO/ZIF-67 showed 90% efficiency in the first cycle, declining to 23% after four cycles. These findings highlight GO/ZIF-67's potential as an effective photocatalyst for water remediation.
查看更多>>摘要：Dissolved organic matter (DOM), an active organic component in the soil, plays a pivotal regulatory role in mercury methylation within wetland ecosystems. This process, particularly amid escalating influences from climate change and anthropogenic activities, carries significant implications for global environmental health. To elucidate the key factors influencing mercury methylation in soil, sampling surveys were conducted in May, July, and September at the Qixing Wetland in Shenyang. The findings indicated that the average concentrations of methylmercury (MeHg) and total mercury (THg) at Qixing Wetland were 3.91 ng·g~(-1) and 173.45 ng·g~(-1), respectively, with notably lower concentrations observed during the summer months. The highest rate of soil mercury methylation (%MeHg) was recorded in May at 4.43%, yielding an overall methylation rate of 2.91%. Correlation analysis, principal component analysis, and random forest modeling revealed that %MeHg is jointly influenced by the sampling month and various environmental parameters within the wetland ecosystem. In May, pH and dissolved organic carbon (DOC) emerged as primary determinants, whereas in July, fulvic-like substance proportions (%Fmax(A)) alongside soil organic carbon (SOC) were predominant; conversely, DOM spectral characteristics were the dominant influence in September. This study underscores the intricate seasonal dynamics and environmental factors affecting mercury methylation processes within wetlands while highlighting their critical role in regulating the biogeochemical cycling of mercury. Consequently, safeguarding wetland ecosystems is essential for preserving their regulatory functions for environmental health while mitigating risks associated with mercury bioaccumulation.
查看更多>>摘要：Dissolved organic matter (DOM), an active organic component in the soil, plays a pivotal regulatory role in mercury methylation within wetland ecosystems. This process, particularly amid escalating influences from climate change and anthropogenic activities, carries significant implications for global environmental health. To elucidate the key factors influencing mercury methylation in soil, sampling surveys were conducted in May, July, and September at the Qixing Wetland in Shenyang. The findings indicated that the average concentrations of methylmercury (MeHg) and total mercury (THg) at Qixing Wetland were 3.91 ng·g~(-1) and 173.45 ng·g~(-1), respectively, with notably lower concentrations observed during the summer months. The highest rate of soil mercury methylation (%MeHg) was recorded in May at 4.43%, yielding an overall methylation rate of 2.91%. Correlation analysis, principal component analysis, and random forest modeling revealed that %MeHg is jointly influenced by the sampling month and various environmental parameters within the wetland ecosystem. In May, pH and dissolved organic carbon (DOC) emerged as primary determinants, whereas in July, fulvic-like substance proportions (%Fmax(A)) alongside soil organic carbon (SOC) were predominant; conversely, DOM spectral characteristics were the dominant influence in September. This study underscores the intricate seasonal dynamics and environmental factors affecting mercury methylation processes within wetlands while highlighting their critical role in regulating the biogeochemical cycling of mercury. Consequently, safeguarding wetland ecosystems is essential for preserving their regulatory functions for environmental health while mitigating risks associated with mercury bioaccumulation.
查看更多>>摘要：The electrokinetic remediation (EKR) technique was employed for cadmium (Cd)-contami-nated soil to study the cross-effect of voltage gradient and electrolyte concentration on removal efficiency. Response Surface Methodology over Central Composite Design (CCD) was used to design the experiments. In addition, the effect of electrode material on EKR was investigated using two different electrodes, graphite, and stainless steel. The distribution and migration behavior of Cd in soil was explored through chemical speciation and sequential extraction procedure. The findings revealed that the voltage gradient and EDTA concentration were positively correlated with the removal efficiency at the optimized conditions of 2.5 V/cm and 0.15 M EDTA to achieve 27.8% removal in 10 h. The voltage gradient had a more profound effect on the removal efficiency as compared to EDTA concentration. The EKR treatment effectively reduced the bioavailability of Cd by removing water-soluble and exchangeable fractions and rendering the transformation of Cd to reducible and residual fractions. The Human Health Risk Assessment study was performed which revealed that EKR was successful in reducing the non-carcinogenic adverse effects by 29% and total carcinogenic risks from one in a thousand to one in a hundred thousand in adults, while children still exposed to high potential non-carcinogenic effects. The economic evaluation of all experiments concluded that the stainless steel electrode was more suited for Cd removal as compared to the graphite electrode with better removal (30%) and low specific cost (5.8 US$/g Cd). The study shows that EKR is successful in reducing the overall toxicity of Cd in soil and humans at a relatively low cost and less treatment time.
查看更多>>摘要：The electrokinetic remediation (EKR) technique was employed for cadmium (Cd)-contami-nated soil to study the cross-effect of voltage gradient and electrolyte concentration on removal efficiency. Response Surface Methodology over Central Composite Design (CCD) was used to design the experiments. In addition, the effect of electrode material on EKR was investigated using two different electrodes, graphite, and stainless steel. The distribution and migration behavior of Cd in soil was explored through chemical speciation and sequential extraction procedure. The findings revealed that the voltage gradient and EDTA concentration were positively correlated with the removal efficiency at the optimized conditions of 2.5 V/cm and 0.15 M EDTA to achieve 27.8% removal in 10 h. The voltage gradient had a more profound effect on the removal efficiency as compared to EDTA concentration. The EKR treatment effectively reduced the bioavailability of Cd by removing water-soluble and exchangeable fractions and rendering the transformation of Cd to reducible and residual fractions. The Human Health Risk Assessment study was performed which revealed that EKR was successful in reducing the non-carcinogenic adverse effects by 29% and total carcinogenic risks from one in a thousand to one in a hundred thousand in adults, while children still exposed to high potential non-carcinogenic effects. The economic evaluation of all experiments concluded that the stainless steel electrode was more suited for Cd removal as compared to the graphite electrode with better removal (30%) and low specific cost (5.8 US$/g Cd). The study shows that EKR is successful in reducing the overall toxicity of Cd in soil and humans at a relatively low cost and less treatment time.
查看更多>>摘要：Studying the combined phytotoxicity of PFOA with Fe_2O_3 or MnO_2 nanoparticles (NPs) is paramount for addressing the remediation of PFOA-contaminated agricultural soils and assessing the efficacy of nanoparticle-assisted phytoremediation strategies. By exposing radish plants to PFOA with/without Fe_2O_3 or MnO_2 NPs for 60 days, this study delved into radish biomass, PFOA accumulation, chlorophyll pigments, antioxidant defenses, and nutrient contents. Key findings showed that PFOA at environmentally relevant levels (20 μg/kg) were highly toxic to radish plants. PFOA accumulated significantly in radish organs, especially in the shoots. Additionally, PFOA exposure had a detrimental impact on radish growth. However, the application of Fe_2O_3 and MnO_2 NPs facilitated the translocation of PFOA up to shoots, thereby reducing its accumulation in the edible roots. Additionally, they could significantly increase radish biomass and mitigate the damages caused by PFOA, evidenced by lower MDA contents and higher amino acid contents. This study highlights the potential of nanoparticle-enhanced phytoremediation as an effective approach for PFOA-polluted agricultural soils. By promoting the translocation of harmful pollutants away from edible plant parts and enhancing plant growth and resilience, Fe_2O_3 and MnO_2 NPs offer a promising avenue for sustainable soil remediation strategies.
查看更多>>摘要：Studying the combined phytotoxicity of PFOA with Fe_2O_3 or MnO_2 nanoparticles (NPs) is paramount for addressing the remediation of PFOA-contaminated agricultural soils and assessing the efficacy of nanoparticle-assisted phytoremediation strategies. By exposing radish plants to PFOA with/without Fe_2O_3 or MnO_2 NPs for 60 days, this study delved into radish biomass, PFOA accumulation, chlorophyll pigments, antioxidant defenses, and nutrient contents. Key findings showed that PFOA at environmentally relevant levels (20 μg/kg) were highly toxic to radish plants. PFOA accumulated significantly in radish organs, especially in the shoots. Additionally, PFOA exposure had a detrimental impact on radish growth. However, the application of Fe_2O_3 and MnO_2 NPs facilitated the translocation of PFOA up to shoots, thereby reducing its accumulation in the edible roots. Additionally, they could significantly increase radish biomass and mitigate the damages caused by PFOA, evidenced by lower MDA contents and higher amino acid contents. This study highlights the potential of nanoparticle-enhanced phytoremediation as an effective approach for PFOA-polluted agricultural soils. By promoting the translocation of harmful pollutants away from edible plant parts and enhancing plant growth and resilience, Fe_2O_3 and MnO_2 NPs offer a promising avenue for sustainable soil remediation strategies.
查看更多>>摘要：The Northern Key Economic Zone (NKEZ) of Vietnam, a critical region for national development, experiences significant particulate matter pollution. This study investigates aerosol pollution and its transboundary effects across the NKEZ by integrating the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) dataset and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results reveal: (1) Anthropogenic aerosols exhibit statistically significant upward trends (p<0.05), with sul-fate concentrations ranging from 7.59 to 9.29 μg.m~(-3) and organic carbon from 4.79 to 10.87 ug.m~(-3); (2) MERRA-2 captures PM_(2.5) seasonal trends, with correlation coefficients (p<0.01) of 0.83 in spring and 0.71 in winter, though it significantly underestimates PM_(2.5) level in winter in Hanoi; (3) combined analyses of trajectory frequency and pollution concentration correlations delineate five levels of impact (level 1-5, from minimal to very high) on Hanoi's air quality and identify key black carbon (BC) source regions. These include coal-fired power plants in Thai Binh, Thanh Hoa (levels 3-4, in spring), biomass burning in east-northern mountainous region of Vietnam (levels 4-5, in autumn), biomass burning in central-southern Laos (levels 2-3, peak Fire Detection Counts in March-April) and transboundary contributions from central-southern China (levels 2-3, in autumn). The integration of MERRA-2 and HYSPLIT establishes a robust methodology for classifying pollution sources affecting Hanoi, providing a technical framework for future regional air quality investigations.
查看更多>>摘要：The Northern Key Economic Zone (NKEZ) of Vietnam, a critical region for national development, experiences significant particulate matter pollution. This study investigates aerosol pollution and its transboundary effects across the NKEZ by integrating the Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) dataset and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. The results reveal: (1) Anthropogenic aerosols exhibit statistically significant upward trends (p<0.05), with sul-fate concentrations ranging from 7.59 to 9.29 μg.m~(-3) and organic carbon from 4.79 to 10.87 ug.m~(-3); (2) MERRA-2 captures PM_(2.5) seasonal trends, with correlation coefficients (p<0.01) of 0.83 in spring and 0.71 in winter, though it significantly underestimates PM_(2.5) level in winter in Hanoi; (3) combined analyses of trajectory frequency and pollution concentration correlations delineate five levels of impact (level 1-5, from minimal to very high) on Hanoi's air quality and identify key black carbon (BC) source regions. These include coal-fired power plants in Thai Binh, Thanh Hoa (levels 3-4, in spring), biomass burning in east-northern mountainous region of Vietnam (levels 4-5, in autumn), biomass burning in central-southern Laos (levels 2-3, peak Fire Detection Counts in March-April) and transboundary contributions from central-southern China (levels 2-3, in autumn). The integration of MERRA-2 and HYSPLIT establishes a robust methodology for classifying pollution sources affecting Hanoi, providing a technical framework for future regional air quality investigations.
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