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Résultats 3311-3320 de 6,535
Removal of antipyrine through two-dimensional and three-dimensional electrolysis: comparison, modification, and improvement
2020
Liu, Pengxiao | Wang, Xu | Lü, Jing | Li, Ying | Hou, Bin | Feng, Ling
In this work, removal of antipyrine was studied through two-dimensional (2D) and three-dimensional (3D) electrolysis. 2D electrolysis was firstly studied with the Ti/SnO₂-Ta₂O₅-IrO₂ anode as working electrode. Operating parameters affecting antipyrine removal, such as current density, electrode distance, and initial concentration of antipyrine, were investigated and optimized. As the limited antipyrine removal efficiency of 48.0% was not satisfying, 3D electrolysis with γ-Al₂O₃ as particle electrodes was introduced in the purpose of improving the antipyrine removal. An obviously enhanced removal efficiency of 78.3% was obtained, which seemingly validated the effect of particle electrodes in improving antipyrine removal. Hence, an effort to further enhance the antipyrine removal efficiency was made through improving the electrochemical characteristics of γ-Al₂O₃ as particle electrodes. Modified Sn-Sb-Bi/γ-Al₂O₃ particles were thus prepared through impregnation method. And a desirable antipyrine removal efficiency of 94.4% and energy consumption of 0.18 kWh/g antipyrine were achieved in the 3D electrolysis with Sn-Sb-Bi/γ-Al₂O₃ as particle electrodes. Furthermore, possible mechanism and pathway of antipyrine degradation in 3D electrolysis were explored through detection of ·OH using terephthalic acid fluorescent probe method and detection of antipyrine degradation intermediates using LC-MS.
Afficher plus [+] Moins [-]Environmental concerns and switching toward electric vehicles: geographic and institutional perspectives
2020
Sajjad, Aqsa | Asmi, Fahad | Chu, Jianxun | Anwar, Muhammad Azfar
Smog pollution deteriorates environmental quality and has severe health risks. This affects the daily lives of people in China, particularly in urban areas. Along with other factors, a large portion for smog comes from transportations, making it dense and more hazardous in urban areas. The Chinese government aims to reduce air pollution by promoting electric vehicles and green modes for mobility along with other environmental protection measures. The study explores the switching intentions of people from motorized vehicles to electric vehicles by integrating push-pull-mooring model and institutional theory. The study incorporates environmental quality, regulative environment, alternative attractiveness, normative environment, self-(decision)efficacy, and willingness to pay into an integrated framework. The study further analyzes the green behavior of consumers by extending switching intentions for electric vehicles. The integrated framework explains mooring as the most influential factor followed by normative environment from pull factors and environmental quality from push factors. The effect of regulative environment remains weak and significant, but the effect of alternative attractiveness remains weak and insignificant. The switching intentions strongly and significantly explain green behavior. Furthermore, mooring moderates the relationship between push factors, some of the pull factors, and switching intentions.
Afficher plus [+] Moins [-]Speciation and migration of heavy metals in sediment cores of urban wetland: bioavailability and risks
2020
Shao, Shuai | Liu, Huan | Tai, Xiuquan | Zheng, Feng | Li, Jianbing | Li, Yubao
To examine the status and risk of heavy metal pollution in an urban wetland in China, the distribution and speciation of chromium (Cr) and other metals (Cd, Cu, Pb, and Zn) were examined. We investigated the impact of three major land uses (residential and industrial (RI), orange plantation (OP), and mixed OP and RI (OPRI)) on the heavy metal characteristics using sediment cores (0–60 cm below water/sediment interface) collected in Sanyang Wetland, China. It was found that all the metals (Cr, Cd, Cu, Pb, and Zn) had lower concentrations in the top layers but higher contents in the bottom layers of sediments. Species of metals in sediments were dominated by their secondary phase (i.e., exchangeable and carbonate bound, Fe-Mn bound and organic bound) with relatively low contents of primary phase (i.e., residual form), except for Cr in RI affected river sediments that had a relatively high content of primary phase (20.97–36.07%). The ratio of secondary phase to primary phase (RSP) and risk assessment code (RAC) methods were applied to assess environmental risk. The results implied that the metal mobility and bioavailability could significantly cause urban wetland environmental quality decline, and thus enhanced strategies should be required to target the capture and removal of metals.
Afficher plus [+] Moins [-]Synthesis and characterization of eco-friendly cellulose beads for copper (II) removal from aqueous solutions
2020
Maaloul, Najeh | Oulego, Paula | Rendueles, Manuel | Ghorbal, Achraf | Díaz, Mario
In this study, novel cellulose-bead-based biosorbents (CBBAS) were successfully synthesized from almond shell using a simple three-step process: (i) dissolution of bleached almond shell in ionic liquid (1-butyl-3-methylimidazolium chloride), (ii) coagulation of cellulose-ionic liquid solution in water and (iii) freeze-drying. Their morphological, structural and physicochemical properties were thoroughly characterized. These biomaterials exhibited a 3D-macroporous structure with interconnected pores, which provided a high number of adsorption sites. It should be noted that CBBAS biosorbents were efficiently employed for the removal of copper (II) ions from aqueous solutions, showing high adsorption capacity: 128.24 mg g⁻¹. The biosorption equilibrium data obtained were successfully fitted to the Sips model and the kinetics were suitably described by the pseudo-second-order model. Besides, CBBAS biosorbents can be easily separated from the solution for their subsequent reuse, and thus, they represent a method for the removal of copper (II) from aqueous solutions that is not only eco-friendly but also economical.
Afficher plus [+] Moins [-]The role of sense of place, risk perception, and level of disaster preparedness in disaster vulnerable mountainous areas of Gilgit-Baltistan, Pakistan
2020
Khan, Garee | Qureshi, Javed Akhter | Khan, Anwar | Hashmi, S. Attaullah Shah | ʻAlī, Sājid | Bano, Iram | Alam, Muhammad
The study endeavored to analyze the risk perception, sense of place, and disaster preparedness in response to landslide disaster–prone mountain areas of Gilgit-Baltistan, Pakistan. To this end, we surveyed 315 rural residents of two vulnerable landslide districts (Hunza and Nagar) of Gilgit-Baltistan. To explore the relationships between the dimensions of risk perception, sense of place, and disaster preparedness, we used partial least squares (PLS) structural equation modeling (SEM) to test the hypotheses. The results derived from PLS-SEM have implied that there is a significant negative relationship between risk perception (apprehension and unidentified) with a sense of place (bond with society and place dependence). It was observed that the residents usually overestimate the risks of disasters due to their limited scientific knowledge regarding disaster occurrence, which reduces their dependencies on the place. We revealed that disaster preparedness enhances the place attachment and reduces the apprehension of landslides in the study area. This study devotes to government and relevant agencies to devise policies that can help relocate the vulnerable rural settlements, develop, and educate the masses on disaster mitigation and prevention strategies, and help prepare a suitable landslide management plan.
Afficher plus [+] Moins [-]Detection of Prorocentrum minimum by hyperbranched rolling circle amplification coupled with lateral flow dipstick
2020
Liu, Fuguo | Zhang, Chunyun | Yang, Yuchen | Yang, Yudan | Wang, Yuanyuan | Chen, Guofu
A novel method referred to as hyperbranched rolling circle amplification (HRCA) coupled with lateral flow dipstick (LFD) (HRCA-LFD) here was developed for specific, sensitive, rapid, and simple detection of Prorocentrum minimum. HRCA-LFD relies on a padlock probe (PLP) consisting of a common ligation sequence, two terminal sequences that complement the target DNA, and a manually designed detection probe (LFD probe). The two terminal sequences of the PLP were designed against the species-specific sites of the large subunit ribosomal DNA (LSU rDNA) D1-D2 region of P. minimum. The optimum parameters for HRCA were as follows: PLP concentration of 20 pM, ligation time of 30 min, ligation temperature of 59 °C, enzymic digestion time of 105 min, amplification time of 45 min, and amplification temperature of 58 °C. The HRCA-LFD displaying high specificity could accurately distinguish P. minimum from other microalgae. The detection limit of HRCA-LFD was as low as 1.42 × 10⁻⁷ ng μL⁻¹ for genomic DNA, 1.03 × 10⁻⁷ ng μL⁻¹ (approximately 27 copies) for recombinant plasmid containing the inserted LSU rDNA D1-D2, and 0.17 cells for crude DNA extract of P. minimum, which was consistently 100 times more sensitive than regular PCR. Interfering test suggested that the performance of HRCA-LFD is stable and would not be affected by other non-target species. The HRCA-LFD results of field samples that are comparable with microscopic examination confirmed that the developed method is competent for detection of target cells in field samples. In conclusion, the developed HRCA-LFD exhibiting stable performance is specific, sensitive, and rapid, which provides a good alternative to traditional microscopic examination for the detection of P. minimum cells in field samples.
Afficher plus [+] Moins [-]Genotoxicity in American kestrels in an agricultural landscape in the Baja California peninsula, Mexico
2020
Frixione, Martín G. | Rodríguez Estrella, Ricardo
Raptors as top predators have been used as effective sentinels of environmental stressors in agricultural areas worldwide. Pollutants in agricultural areas have negative effects on top predator populations. Biomarkers such as erythrocyte nuclear abnormalities have been used as an effective measure of genotoxicity caused by exposure—particularly short-term exposure—to pollutants. We took blood samples from 54 wild specimens of American kestrel (Falco sparverius) captured in an agricultural area in Valle de Santo Domingo, Baja California Sur, Mexico in the autumns of 2018 and 2019 (n = 25) and the winters of 2019 and 2020 (n = 29). We prepared and examined blood smears to look for erythrocyte abnormalities as a means to evaluate genotoxicity. The number of abnormality types and the total frequency of abnormalities (MNs and NAs: notched, symmetrically or asymmetrically constricted, displaced, or indented nuclei) per 10,000 erythrocytes were calculated for all the specimens. We found a high frequency of abnormalities in numerous individuals, similar to those found in raptors from highly polluted areas. The best-fit generalized linear model for the number of abnormality types included season-of-the-year as the main significant predictor; the model for the total frequency of abnormalities included season and wing chord, an indicator of body size and health condition, as significant predictors. MNs frequencies were significantly related to season; NAs frequencies were related to season, wing chord length, and coverage of native vegetation around the area where the birds were captured. Abnormalities observed in the autumn closely coincide with the time when agrochemicals are applied in the area, mainly after the rains and during hot spells in late summer and early autumn. Small-sized kestrels showed higher frequencies of NAs, with an additional impact if native vegetation had been cleared for agriculture; this suggests both that resident birds are more exposed, and the observed genotoxicity has a local origin. These results, together with the ecological and physiological characteristics of the American kestrel suggest that this charismatic and widely distributed species might constitute a suitable biomonitor of genotoxicity in rural landscapes.
Afficher plus [+] Moins [-]Estimation and analysis of municipal food waste and resource utilization potential in China
2020
Yang, Yuanyuan | Chen, Dingjiang | Hu, Shanying | Chen, Xin
With rapid urbanization, municipal food waste (MFW), which is an important part of municipal solid waste, has attracted considerable attention owing to its environmental impact and polluting nature. There has been little research on the quantity and distribution of food waste (FW) produced in China. This study focused on a systematic estimation and analysis of MFW produced in administrative divisions at the prefecture-level and above in China for the first time. From the national level to the prefectural level, with the shrinking of the research units, more intuitive support was obtained for relevant decisions. On the basis of the estimated results, suggestions are provided for proper FW treatment technologies and operational scale of the facilities, and the resource utilization potential has also been estimated. The distribution results indicated that FW characteristics have great variability in the different economic regions of China. Furthermore, it was found that the available FW has a resource utilization potential that is equivalent to 4669.1 million m³ of biogas, 3.6 million tons of biodiesel, and 1.5 million tons of organic fertilizer (dry weight). It is worth mentioning that this amount of biogas can replace 7.5 million tons of standard coal. However, only a small part of the generated MFW can be treated in the existing treatment plants in China. Finally, current key bottlenecks of FW treatment in China have been discussed, and detailed suggestions are presented for further improvement of MFW management.
Afficher plus [+] Moins [-]Comparative Study of Iron-Oxidizing and Sulfur-Oxidizing Bioleaching Processes for Heavy Metal Removal and Nutrient Leaching from Pig Manure
2020
Wei, Xiaocheng | Li, Jiajia | Huang, Wenli | Zheng, Xiangqun | Li, Songrong | Chen, Xi | Liu, Dongfang
The potential of using iron-oxidizing and sulfur-oxidizing bioleaching process for removal of heavy metals (HMs) was investigated at initial unadjusted pH of pig manure (PM). The indigenous iron-oxidizing and sulfur-oxidizing microorganisms enriched from PM were primarily Alicyclobacillus and Acidithiobacillus thiooxidans, respectively. After 12 days of bioleaching, 95% of Cu, 96.5% of Zn, 93.6% of Mn, and 92.7% of Cd were removed from the PM in sulfur-oxidizing bioleaching process. Besides, 92.9% of Cu, 94.1% of Zn, 91.9% of Mn, and 90.5% of Cd were removed in iron-oxidizing bioleaching process. Furthermore, 18.1% of TN, 63.3% of TP, 65.4% of TK, and 45.6% of TOC were leached from the PM in the sulfur-oxidizing bioleaching process, whereas only 21.6% of TN, 32.8% of TP, 4% of TK, and 49% of TOC were solubilized in the iron-oxidizing bioleaching process. The X-ray diffraction analysis results demonstrated that there was a large amount of sulfur remained in bioleached manure from the sulfur-oxidizing process which poses a potential risk of soil re-acidification. The Standards, Measurements and Testing Program extraction protocol study on fraction of P in PM showed that the amount of bioavailable P in the sulfur-oxidizing bioleaching process was dramatically declined, whereas it was elevated by 25.9% in the iron-oxidizing bioleaching process. The results obtained in this study indicated that both the sulfur- and iron-oxidizing bioleaching process were able to efficiently remove HMs from PM at initial unadjusted pH, whereas the iron-oxidizing process was proved better method in reserving the fertilizing property and more friendly to the environment.
Afficher plus [+] Moins [-]The Potential Use of Rice Husk for Reducing the Genotoxic Effects of Iron and Aluminum Oxides Nanoparticles in Oreochromis niloticus
2020
Abdel-Khalek, Amr Adel | Dajem, Saad Bin | Morsy, Kareem
Metal oxide nanoparticles have wide applications, which have elevated serious alarms about their impacts on the environment. Therefore, we investigated the potential adsorptive capacity of rice husk toward Fe₂O₃ and Al₂O₃ nanoparticles to reduce their genotoxic effects. Fish were subjected to 10 mg/l of Fe₂O₃ and Al₂O₃ nanoparticles in single and combined doses with and without rice husk water treatment for 7 days. The genotoxic effects were evaluated using the micronucleus test in the peripheral blood and comet assay in liver tissues. Significant elevation of micronuclei induction in addition to eight nuclear and cytoplasmic abnormalities (P < 0.05) was observed in all fish groups compared to the control groups. Fish that exposed to Fe₂O₃ nanoparticle showed the maximum induction of all recorded anomalies. Moreover, two indices of DNA damage were evaluated by the comet assay (comet score and % tail DNA) in liver tissues. The scoring of comet cells indicated that the highest frequencies of stage 0 (undamaged DNA) were in control and Al₂O₃ exposed groups, while stage 4 (extensive DNA damage) was significantly elevated in Fe₂O₃ exposed fish. The % of DNA damage was maximized in the Fe₂O₃ nanoparticles exposed fish and minimized in Al₂O₃ nanoparticles exposed fish. Based on the frequencies of nuclear anomalies, degree, and percentage of DNA damage, all rice husk treated groups showed a marked reduction in the genotoxic damage compared with untreated groups. Finally, both nanoparticles showed genotoxic potential and the rice husk had an efficient absorptive capacity for both of them individually or combined.
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