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Preparation of AgCl/TNTs nanocomposites for organic dyes and inorganic heavy metal removal
2019
Tsai, Cheng-Yen | Liu, Chen-Wuing | Hsi, Hsing-Cheng | Lin, Kuen-Song | Lin, Yi-Wen | Lai, Li-Chi | Weng, Tsung-Nan
In this study, TiO₂ nanotubes (TNTs) and AgCl-modified TNTs nanocomposites with multiple crystal phases were synthesized through a hydrothermal method without calcination. The resultant samples had a large Brunauer-Emmett-Teller surface area. Additionally, the Ag modification process reduced the recombination rate of electron-hole pairs in the synthesized sample and possessed more oxygen vacancy sites. The surface area of the AgCl-modified TNTs was smaller than that of non-modified TNTs sample; however, the nanocomposites exhibited outstanding photocatalytic performance and adsorption properties. AgCl compounds present on the TNTs surface effectively interacted with Hg⁰, improving the dye photodegradation efficiency. The Hg⁰ removal efficiencies of the TNTs and AgCl-modified TNTs samples were about 63% and 86%, respectively. The crystal violet (CV) and malachite green (MG) removal efficiencies of the AgCl-modified TNTs sample were around 57% and 72%, respectively. Both dyes photodecomposition efficiencies for AgCl-modified TNTs sample are higher than those of TNTs sample. The oxygen vacancy on the AgCl-modified TNTs surface was determined to be advantageous for OH⁻ and arsenate adsorption through ligand exchange. The maximum adsorption quantity of As⁵⁺ calculated by Langmuir equation was 15.38 mg g⁻¹ (TNTs) and 21.10 mg g⁻¹ (AgCl-modified TNTs).
Show more [+] Less [-]Anaerobic ammonium oxidation coupled to ferric iron reduction in the sediment of a eutrophic lake
2019
Yao, Zongbao | Wang, Fang | Wang, Chunliu | Xu, Huacheng | Jiang, Helong
Anaerobic ammonium oxidation coupled to ferric iron reduction (Feammox) has been assumed to play an important role in nitrogen removal from ecosystems. This study assessed the potential role of Feammox in nitrogen transformation in eutrophic lake sediment using an isotope tracing technique in sediment slurry incubation experiments. Feammox was discovered in eutrophic lake sediment. A significant correlation was found between Feammox rates and iron-reducing rates. Furthermore, the positive correlations between the abundance of iron-reducing bacteria (FeRB), such as Geobacteraceae spp. and Shewanella spp., and Feammox rates indicate that Feammox was mediated by FeRB. The potential rate of Feammox in the isotopic tracer incubation treatment was 0.23–0.43 mg N kg⁻¹ day⁻¹. The estimated nitrogen loss caused by Feammox accounts for 5.0–9.2% of the human-induced N input annually into the eutrophic lake. Feammox alone or coupled with anaerobic ammonium oxidation (anammox) and/or denitrification may have an essential role in the nitrogen cycle within eutrophic lake sediment.
Show more [+] Less [-]Short-term effects of ambient fine particulate air pollution on inpatient visits for myocardial infarction in Beijing, China
2019
Wu, Yao | Li, Man | Tian, Yaohua | Cao, Yaying | Song, Jing | Huang, Zhe | Wang, Xiaowen | Hu, Yonghua
The effects of ambient fine particulate matter (PM₂.₅) on the incidence of myocardial infarction have been reported, but little is known about this association in China. We conducted a time-series study of ambient PM₂.₅ concentrations and inpatient visits for myocardial infarction in Beijing. A generalized additive model with a Poisson link was applied to estimate the percentage change in inpatient visits for myocardial infarction following a 10-μg/m³ increase in PM₂.₅ concentrations. A total of 15,432 inpatient visits for myocardial infarction were identified between January 1, 2010, and June 30, 2012. A 10-μg/m³ increase in PM₂.₅ concentrations was associated with a 0.46% (P ≤ 0.001) increase in daily inpatient visits for myocardial infarction. Males were more sensitive to the adverse effects, and the association was more significant during the warm season (May through October). Short-term exposure to PM₂.₅ was associated with increased risk of inpatient visits for myocardial infarction in Beijing. The findings may be useful in developing more accurate targeted interventions.
Show more [+] Less [-]Economic development and environmental sustainability—the case of foreign direct investment effect on environmental pollution in China
2019
Haibo, Chen | Ayamba, Emmanuel Caesar | Agyemang, Andrew Osei | Afriyie, Stephen Owusu | Anaba, Aganda Oswin
This research reviews and analyses the environmental catastrophes in China with regard to its adherence of global environmental policies and practices. The research makes available evidence of the present policy regime and institutions, strategies for curbing emission, environmental legislations and regulations and measures to provide a sustainable environment for the present and future generations. This paper reviewed how the environment is affected by the emissions. The findings revealed that China adheres to global policies and practices. China also receives local and international support in terms of assistance in dealing with environmental challenges. It was also revealed that carbon dioxide was not included in the list of pollutants to be taxed by the environmental protection tax law. Furthermore, the government needs to be strict at the local and district levels in enforcing the law to ensure professionalism and attainment of set standards.
Show more [+] Less [-]Effects of layered combined substrates on plant growth and treatment performance and its spatiotemporal variation of vertical-flow constructed wetlands
2019
Wu, Junmei | Xu, Dong | Zhou, Qiaohong | Zhang, Liping | He, Feng | Wu, Zhenbin
Layered combined bio-ceramic, zeolite, and anthracite were used as substrates in vertical-flow constructed wetlands (VFCWs) for enhancing contaminant removal from synthetic municipal wastewater. Plant growth and propagation and the removal of organic matter, nitrogen, and phosphorus as well as its spatiotemporal variation were evaluated systematically. The results demonstrated that three different substrates were adequate for the establishment of Canna indica L., especially for zeolite. All small-scale VFCW units were simultaneous efficient in removing CODCᵣ (73.9–78.7%), NH₄⁺-N (83.8–89.9%), TN (88.3–91.5%), SRP (93.8–98.6%), and TP (87.1–90.9%) with a little significant difference on treatment performance. Different pollution removal processes followed a different trend because of their different removal mechanisms driven by the synergy of substrate, plant, and microorganism. Purification space moved down due to the adsorption capacity consumption of upper layer substrate over time. It was concluded that VFCWs filled with layered combined bio-ceramic, zeolite, and anthracite had great potential for treating municipal wastewater.
Show more [+] Less [-]Chemical composition of essential oils from four Rhododendron species and their repellent activity against three stored-product insects
2019
Bai, Li | Jiao, Mei-Ling | Zang, Hong-Yuan | Guo, Shan-Shan | Wang, Yang | Sang, Yu-Li | Du, Shu-Shan
The objective of this work was to analyze four essential oils (EOs) from Rhododendron species in China and evaluate their repellent activity against Tribolium castaneum, Lasioderma serricorne, and Liposcelis bostrychophila adults. These four EOs from Rhododendron species, including R. capitatum, R. przewalskii, R. mucronulatum, and R. micranthum, were obtained by hydrodistillation. Major components of four EOs were identified as sesquiterpenoids by GC-MS. The relatively high components included cedrene (22.20%), borneol (36.64%), 4-(2,3,4,6-tetramethylphenyl)-3-buten-2-one (27.74%), and germacrene D (27.60%). Repellent activity of EOs from Rhododendron species was investigated against T. castaneum, L. serricorne, and L. bostrychophila adults for the first time. In this study, EOs had demonstrated their repellent activities against three stored-product insects in 2- and 4-h exposure. The above results can not only provide comprehensive utilization of plant resources of Rhododendron genus but also establish a very good perspective of novel application to control stored-product insects.
Show more [+] Less [-]Green sol–gel synthesis of novel nanoporous copper aluminosilicate for the eradication of pathogenic microbes in drinking water and wastewater treatment
2019
Hemdan, Bahaa Ahmed | El Nahrawy, Amany Mohamed | Mansour, Abdel-Fatah M. | Hammad, Ali Belal Abou
We used a green sol–gel synthesis method to fabricate a novel nanoporous copper aluminosilicate (CAS) material. Nanoporous CAS was characterized using X-ray powder diffraction (XRD), field emission transmission and scanning electron microscopies (FE-TEM/FE-SEM), Fourier transform infrared (FTIR) spectroscopy, and optical analyses. The CAS was also evaluated for use as a promising disinfectant for the inactivation of waterborne pathogens. The antimicrobial action and minimum inhibitory concentration (MIC) of this CAS disinfectant were determined against eight microorganisms (Escherichia coli, Salmonella enterica, Pseudomonas aeruginosa, Listeria monocytogenes, Staphylococcus aureus, Enterococcus faecalis, Candida albicans, and Aspergillus niger). An antimicrobial susceptibility testing of CAS was measured. Results of disc diffusion method pointed out that the diameters of the zone using well diffusion were wider than disc diffusion methods, and the findings also showed that the MIC of the CAS disinfectant against E. coli, S. enterica, and P. aeruginosa was 100 mg/L within 20 min of contact time. Meanwhile, the MIC of the CAS disinfectant was 100 mg/L within 40 min of contact time for the other strains. The efficacy of antimicrobial action (100%) reached within 20 to 40 min against all tested microbes. Herein, the antimicrobial susceptibility testing of CAS disinfectant showed no toxicity for human and bacterial cells. It can be concluded that nanoporous CAS is a promising, economically, and worthy weapon for water disinfection.
Show more [+] Less [-]Lead content in soils and native plants near an abandoned mine in a protected area of south-western Spain: an approach to determining the environmental risk to wildlife and livestock
2019
Oropesa, Ana-Lourdes | Gala, Juan-Alberto | Fernandez-Pozo, Luis | Cabezas, José | Soler, Francisco
A study of the impact of an abandoned lead (Pb) mine (“Las Musas”), located in SW Spain, on the contamination of the surface soil and pastures in its vicinity revealed the presence of widely distributed, high levels of Pb contamination. The total Pb concentrations in soils sampled at distances from 3 to 998 m from the mine ranged between 129 and 1053 mg/kg, when it has been reported that non-polluted soils have concentrations of 29–40 mg/kg. These exceed the maximum tolerable levels in agricultural soils for the protection of environmental and human health as established in international and regional regulations. While the concentrations of potentially bioavailable Pb in the soils also surpassed the regulatory levels, the effective bioavailable fractions were low. The Pb concentrations measured in native plants ranged from 1.70 to 129 mg/kg dry weight, with Cynosurus echinatus, Philadelphus coronarius, and Fraxinus angustifolia being the species that bioaccumulated the greatest concentrations of this metal. Estimation of the environmental risk to wildlife and livestock grazing in the studied area showed no potential toxicity for these animals.
Show more [+] Less [-]The impact of differentiated technological innovation efficiencies of industrial enterprises on the local emissions of environmental pollutants in Anhui province, China, from 2012 to 2016
2019
Zhang, Kerong | Jiang, Wulin | Zhang, Shuai | Xu, Yasong | Liu, Wuyi
The study was designed to evaluate the impact of differentiated technological innovation efficiencies of industrial enterprises on the local emissions of environmental pollutants in Anhui province, China, during the period of 2012–2016. The econometric models of DEA and SEM-PLS and Malmquist index are used to explore the potential impacts of differentiated technological innovation efficiencies of industrial enterprises on the local emissions of environmental pollutants in Anhui province. After an initial analysis of SEM-PLS model, the models of DEA and Malmquist index are used to evaluate the differentiated degrees and dynamic development levels of local technological innovation efficiencies of industrial enterprises in different regions of Anhui province. With these analyses, the study presents three main results as follows. There is a positive correlation between the technological innovation efficiencies of industrial enterprises and the technological performance levels of environmental disposal. Meanwhile, there is a large gap among the environmental disposing performances of industrial enterprises in different regions of Anhui province. There is also a large gap between the expected and actual technological performances of industrial enterprises’ environmental disposal, according to the results of SEM-PLS analysis. Furthermore, there are several obvious characteristics of geographical distribution in the impact of differentiated technological innovation efficiencies of industrial enterprises on local environmental pollutant emissions observed from the results of the DEA and Malmquist index models. However, it is not consistent with the overall provincial development trend and regional distribution pattern of industrial economics in Anhui province over the period of 2012–2016. Under the rapid development of social economics and modern technological advance, there is a weak impact of differentiated technological innovation efficiency on the technological performance of industrial environmental disposal in different regions of Anhui province. Meanwhile, the environmental disposal capacity of enterprises’ technological innovation become declining too. Finally, some countermeasures and policy suggestions are put forward based on the investigation and comprehensive analyses of the DEA and SEM-PLS and Malmquist index models.
Show more [+] Less [-]Modeling farmers’ responsible environmental attitude and behaviour: a case from Iran
2019
Yaghoubi Farani, Ahmad | Mohammadi, Yaser | Ghahremani, Fatemeh
There is an increasing concern over the environmental degradation caused by agricultural activities especially in developing countries which mostly linked to farmer’s behavior. Thus, this study aimed to model the responsible attitude and behavior of Iranian farmers in respect to environment. The Theory of Planned Behavior (TPB) was used as a basis for identification of the main determinants of the farmers’ responsible environmental behavior. A survey of 400 farmers in the Hamedan Province, selected through a multistage stratified random sampling method. Data was gathered using a questionnaire which its validity and reliability were confirmed by a panel of agricultural and environmental experts and calculated Cronbach’s alpha (0.65 ≤ α ≤ 0.80), respectively. Data were analyzed using structural equation modeling (SEM) to evaluate the strength of relationship between the constructs and test the overall model fit. Results of study showed that “using animal manure in the farms” was the most important behavior which farmers are responsibly doing to respect their environment but their least attention is given to “disposing cans and bottles after spraying.” Also, the fitness indices of the model revealed that the TPB partially supported the farmers’ responsible environmental behavior as perceived behavioral control and environmental attitude positively influenced the farmers’ responsible environmental behavior but there was not observed any significant influence by subjective norm. Among the additional incorporated constructs, environmental awareness, ethical commitment, and environmental concern significantly had a positive influence on farmers’ behavior by mediating role of the environmental attitude. The inclusion of new constructs in the TPB model was supported through improving the predictive power of the modified model in predicting farmers’ responsible environmental behavior.
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