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Removal and Recovery of Phosphorus from Contaminated Water Using Novel, Reusable, Renewable Resource-Based Aluminum/Cerium Oxide Nanocomposite
2020
Nakarmi, Amita | Moreira, Rebecca | Bourdo, Shawn E. | Watanabe, Fumiya | Toland, Alan | Viswanathan, Tito
The combination of cerium oxide and aluminum oxide nanocomposites in quaternary ammonium–modified wood has been shown to be excellent for phosphorus (as phosphate) removal from contaminated waters. The results are better than using single metal oxides in the nanocomposite based on the adsorption capacity and kinetic rate. The mixed metal oxide nanocomposite on pine wood chips (a renewable resource) represent a green technology for phosphorus remediation. The process of preparation of nanocomposite of this material is straightforward, economically feasible, and environmentally friendly. There are no harmful chemicals or petroleum reagents used during the synthesis. In this study, adsorption isotherms (Langmuir and Freundlich, Temkin and Dubinin-Radushkevich) and kinetic studies (Lagergren pseudo-first and pseudo-second order, Elovich and Weber-Morris) were performed to determine the adsorption capacity and mechanism of the phosphorus removal by the nanocomposite. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface area, and Fourier-transfer infrared (FTIR) spectroscopy were analyzed to determine the size and structure of the nanocomposite as well as elements present on the surface of the wood chips. The maximum adsorption capacity was found to be 70.42 mg/g. The results from this study demonstrate that phosphorus levels in polluted water can be reduced from 10,000 parts per billion to 10 parts per billion. We also demonstrated that the phosphorus could be desorbed and the media regenerated for repeated use without loss of efficiency.
显示更多 [+] 显示较少 [-]Desulfurization Performances of Activated Coke Prepared from Fine Blue-Coke
2020
Tian, Yuhong | Hu, Shudi | Jing, Xian de | Xue, Juanqin | Song, Yonghui | Lan, Xinzhe
Activated coke was prepared by CO₂ activation using solid waste fine blue-coke as main raw material and coal direct liquefaction residue (DCLR) as binder. The activated coke was characterized by BET, XRD, and infrared analysis. The flue gas desulfurization experiment was carried out with a fixed bed reactor and activated coke as the adsorbent. The experimental results show that coal direct liquefaction residue pyrolysis process will produce a large number of cohesive colloids, further increasing the strength of the activated coke. BET analysis shows that there is abundant microporous structure in the activated coke, infrared analysis shows that the activated coke contains abundant surface functional groups, and XRD shows that the crystallization degree of the activated coke is high. At lower temperature, SO₂ and O₂ have competitive adsorption on the surface of activated coke, if the concentration of water vapor is too high, a water film will be formed on the surface of activated coke, which will hinder the adsorption of SO₂ by activated coke. The initial concentration of SO₂ is 700 ppm, the adsorption temperature is 80 °C, the oxygen concentration is 9%, and the concentration of water vapor is 8%. The removal of SO₂ by activated coke is better, and the desulfurization rate reaches 97%.
显示更多 [+] 显示较少 [-]Nexus among CO2 emissions, remittances, and financial development: a NARDL approach for India
2020
Neog, Yadawananda | Yadava, Anup Kumar
The nexus of remittances and CO2 emission is very important and gathers a significant place in empirical research. This paper tries to find out the asymmetric relationship between carbon emissions, remittances, and financial development in India for the period 1980–2014. Based on the theoretical linkages, we develop a nonlinear ARDL model with the use of time series data in this study. The results of the NARDL bound test suggest that there is long-run cointegration among the variables. The findings show that positive shock in remittances causes an increase in CO2 emissions, where negative shock reduces it. The coefficient for financial development is positive but becomes statistically insignificant. Empirical results also support the existence of asymmetric long-run relationship among the variables. Based on the findings, the paper recommends the proper channelization of remittances and financial development towards environment-friendly energy sources and projects without compromising economic growth.
显示更多 [+] 显示较少 [-]The protective effects of Terminalia laxiflora extract on hepato-nephrotoxicity induced by fipronil in male rats
2020
Khalaf, Abdelbaset Abdelrahem | Ibrahim, Marwa A. | Galal, Mona K. | Abdallah, Amr A. | Mansour, Ragaa | Afify, Mostafa M.
The present study was led to investigate the defensive role of Terminalia laxiflora extract (TLE) on fipronil (FPN) induced hepatotoxicity and nephrotoxicity in male rats. Rats were administered with TLE (100 mg/kg) against the renal toxicity and hepatotoxicity induced by administration of FPN (10.5 mg/kg) for 30 days. At the end of the experimental period, the serum, liver, and kidneys were harvested and assessed for subsequent analysis. FPN administration to rats resulted in a significant elevation of serum transaminases, urea, and creatinine. Also, FPN-treated groups exhibited a marked reduction in total protein and albumin levels. Compared with the control group, the level of malondialdehyde (MDA) was elevated in groups treated with FPN, whereas superoxide dismutase (SOD), catalase (CAT) activities, and glutathione levels were distinctly reduced in this group. Significant increases in genomic DNA fragmentation and the expression level of the caspase-3 gene were also recorded. The biochemical result was supported by histopathological findings. Co-administration of TLE along with FPN significantly diminished the liver and kidney function tests decreased the level of lipid peroxidation, and enhanced all the antioxidant enzymes, while also diminishing the expression of caspase-3 and DNA laddering, indicating amelioration of DNA damage. These results indicate that TLE plays a vital role in diminishing FPN-induced hepatotoxicity and nephrotoxicity.
显示更多 [+] 显示较少 [-]Biogeochemical transformation of greenhouse gas emissions from terrestrial to atmospheric environment and potential feedback to climate forcing
2020
Shakoor, Awais | Ashraf, Fatima | Shakoor, Saba | Muṣṭafá, ʻAdnān | Rehman, Abdul | Altaf, Muhammad Mohsin
Carbon dioxide (CO₂) is mainly universal greenhouse gas associated with climate change. However, beyond CO₂, some other greenhouse gases (GHGs) like methane (CH₄) and nitrous oxide (N₂O), being two notable gases, contribute to global warming. Since 1900, the concentrations of CO₂ and non-CO₂ GHG emissions have been elevating, and due to the effects of the previous industrial revolution which is responsible for climate forcing. Globally, emissions of CO₂, CH₄, and N₂O from agricultural sectors are increasing as around 1% annually. Moreover, deforestation also contributes 12–17% of total global GHGs. Perhaps, the average temperature is likely to increase globally, at least 2 °C by 2100—by mid-century. These circumstances are responsible for climate forcing, which is the source of various human health diseases and environmental risks. From agricultural soils, rhizospheric microbial communities have a significant role in the emissions of greenhouse gases. Every year, microbial communities release approximately 1.5–3 billion tons of carbon into the atmospheric environment. Microbial nitrification, denitrification, and respiration are the essential processes that affect the nitrogen cycle in the terrestrial environment. In the twenty-first century, climate change is the major threat faced by human beings. Climate change adversely influences human health to cause numerous diseases due to their direct association with climate change. This review highlights the different anthropogenic GHG emission sources, the response of microbial communities to climate change, climate forcing potential, and mitigation strategies through different agricultural management approaches and microbial communities.
显示更多 [+] 显示较少 [-]Estrogenic Hormones in São Paulo Waters (Brazil) and Their Relationship with Environmental Variables and Sinapis alba Phytotoxicity
2020
Coelho, Lucia Helena Gomes | de Jesus, Tatiane Araújo | Kohatsu, Marcio Yukihiro | Poccia, Geovana Tognella | Chicarolli, Vitor | Helwig, Karin | Hunter, Colin | Roberts, Joanne | Teedon, Paul | Pahl, Ole
The present study evaluated the relationship between estrogenic hormone concentrations (17α-ethinylestradiol and 17β-estradiol) in surface waters in the Metropolitan Area of São Paulo (Brazil) and environmental variables. Four sampling stations were monitored ranging from a protected area to streams discharging human effluent in and around Billings Reservoir. Four sampling campaigns were carried out in each seasonal period: dry and wet. Samples for hormone analysis (in ng L⁻¹) were concentrated (1000×) using solid-phase extraction C₁₈ cartridges and analyzed by liquid chromatography coupled to quadrupole mass spectrometry detection, with 100 ng L⁻¹ limit of quantification. Water temperature, pH, electrical conductivity (EC), and total dissolved solids were determined in situ; total phosphorus and Sinapis alba bioassays were performed subsequently. Reservoir active capacity (AC) and precipitation were also obtained. Estrogenic hormone concentrations were always below limit of quantification at pristine site; at the other sampling stations, 17β-estradiol concentrations varied from below limit of quantification to 1720 ng L⁻¹ and 17α-ethinylestradiol from below limit of quantification to 1200 ng L⁻¹, with the highest concentrations found in the streams discharging into the reservoir. These streams showed higher Pearson’s correlation between 17α-ethinylestradiol, total phosphorus, and electrical conductivity when compared with reservoir stations. Germination index and EC presented negative correlation (Pearson’s r = − 0.61), denoting a phytotoxicity increase with EC increment. AC influenced the dilution of pollutants and showed negative correlations with total phosphorus (Pearson’s r = −0.56). These results highlight the relevance of including streams in water-monitoring programs, since they are important pollutants loads into watersheds.
显示更多 [+] 显示较少 [-]Isolation of Cultivable Bacteria Associated with the Root of Typha latifolia in a Constructed Wetland for the Removal of Diclofenac or Naproxen
2020
Zapata Morales, Ana Laura | Alfaro-De la Torre, Ma Catalina | Hernández Morales, Alejandro | García-De la Cruz, Ramón F.
In this work, we designed at the level of microscale, subsurface flow wetlands planted with Typha latifolia, and used to remove diclofenac and naproxen from solutions that contained them. The wetlands were operated for 105 days with a hydraulic residence time (TRH) of 5 days. In these conditions, the removal efficiencies for diclofenac and naproxen were 98.4% and 97.7%, respectively. Moreover, we identified cultivable bacteria associated with the roots of plants exposed to either diclofenac or naproxen. We obtained 898 isolates that clustered in 9 morphotypes from the roots of Typha latifolia exposed to diclofenac, and 563 isolates grouped in 7 morphotypes, in the case of naproxen. All isolates were identified by 16S ribosomal sequencing. The BLASTn analysis indicated that 16 morphotypes showed an identity higher than 95% with the 16S rDNA gene of bacteria belonging to the genus Pseudomonas. Biochemical characterization based on plant growth-promoting activities suggests that bacteria contribute to plant growth in the wetland conditions. The results indicate that Typha latifolia and bacteria associated with their roots removed diclofenac and naproxen in subsurface flow wetlands.
显示更多 [+] 显示较少 [-]Mathematical Models of Inverse Problems for Finding the Main Characteristics of Air Pollution Sources
2020
Zaporozhets, Artur O. | Khaidurov, Vladyslav V.
The paper describes optimization of mathematical models for determining the main characteristics of the source of environmental pollution. A modification of the classical Newton’s method for finding a numerical solution of the constructed mathematical models for identifying the parameters of an environmental pollutant has been developed. A modification of the classical Newton’s method is obtained, which makes it possible to reduce the total number of calculations in the process of determining the main characteristics of the pollution source. A number of software-implemented computational experiments have been carried out for the model for determining the height of the pipe of the pollution source and the concentration of emissions on it, the model for determining the full location of the pipe of the pollution source and the concentration of emissions from the source. The possibility of complete localization of the pollution source in less than 40 measurement iterations using 1 post of the air pollution monitoring system has been established. The proposed method makes it possible to reduce by 3 times the number of simulation iterations for detecting a source of pollution in comparison with classical methods for solving inverse problems during monitoring of air pollution.
显示更多 [+] 显示较少 [-]A Novel Solid Platform–Based Ag Nanoparticles Chemically Impregnated Activated Carbon for Selective Separation of Tungstate Species in Water: Kinetics and Thermodynamic Study
2020
The level of tungstate in freshwater is disturbing due to its toxicity and its impact to human health. Thus, the current study explores the use of Ag nanoparticle (AgNP)–treated activated carbon (AgNPs/AC) nanocomposite as solid phase extractor (SPE) for removal of trace levels of tungstate ions in water. The AgNPs/AC was synthesized by chemical binding of Ag nanoparticles onto AC. The microstructure image indicated that the AgNPs were uniformly dispersed on AC surface and thus maintaining high surface area. Scanning electron micrographs of AgNPs/AC revealed a three-dimensional structure which is suitable as SPE. The AgNPs/AC nanocomposite was used as a low-cost and effective SPE for tungstate removal from water. Adsorption of tungstate from aqueous media reached maximum at pH ≈ 4 and reached equilibrium in < 20 min. Tungstate sorption followed pseudo-second-order kinetic with an overall rate constant (k) of 0.72 min.⁻¹ The negative values of ΔH and ΔG are interpreted as exothermic and spontaneous reaction of tungstate sorption by the adsorbent, respectively. The positive value of ΔS (R² = 0.999) reflected good absorption and/or adsorption of the oxyanion [WO₄]²⁻ as an ion associate with the bulky cations and the surface area available in the nanocomposite. The sorbent AgNPs/AC was also packed column for preconcentration of trace levels of tungstate in tap water samples. Tungstate species were satisfactorily recovered with NaOH (1.0 mol L⁻¹) and subsequently ICP-OES analyzed.
显示更多 [+] 显示较少 [-]Quantitative analysis of the relationship between land use and urbanization development in typical arid areas
2020
Hou, Gang | Wen, Jiafeng
As the most sensitive and typical oasis city in the arid region of China, Jiayuguan, the role of land use change and urbanization in this region is prominent, which is an important epitome of China’s urbanization process, and has certain special characteristics. Based on RS and GIS technology, this study interpreted the land use data from 1992 to 2012 and analyzed its dynamic change process according to the land use change model. Meanwhile, this study established an indicator system that included demographic, economic, and urbanization data. By analyzing the relationship between the types of land use and the main indicators of urbanization, the interaction between urbanization and land use was quantitatively studied. The results showed that in the past 20 years, the annual growth rate of woodland has reached the largest, reaching 11.39%. At the same time, the annual reduction rate of water body was 1.28%, and the annual reduction rate of unutilized land was only 0.53%. However, since the area occupied by unutilized land far exceeds the sum of other types, the minimum annual rate of change was sufficient to affect the land use pattern of the entire area. From 1992 to 2012, the R index of Jiayuguan was less than 0, indicating that the rate of change in land use during this period was small and in an adjustment period. According to the correlation analysis, the area ratios of land use types were significantly correlated with urbanization indicators. This study provided a feasible model for quantitatively analyzing the relationship between urbanization expansion and land use, which had a relatively universal applicability.
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