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Résultats 3701-3710 de 4,937
The sedimentary record of polycyclic aromatic hydrocarbons in Yamzho Yumco Lake: evolution of local sources and adsorption dynamic in the Tibetan Plateau Texte intégral
2019
Wang, Qi | Li, Jun | Duan, Xu-Chuan | Yuan, Guo-Li | Fang, Bin | Wang, An-Ting
With the rapid increase in anthropogenic activities, the local emissions of polycyclic aromatic hydrocarbons (PAHs) in background regions, such as the Tibetan Plateau (TP), have attracted great attention. The deposition of PAHs in lake sediments provides a historical evolutionary record of such compounds in these regions. To investigate the evolution of PAHs in the TP, two sedimentary cores from Yamzho Yumco Lake were collected and dated at high resolution, and the concentrations of 16 PAHs and sediment properties were also analyzed. The total concentrations of the 16 PAHs ranged from 6.52 to 57.97 ng/g (dry weight) in YC1 and from 0.91 to 4.57 ng/g (dry weight) in YC2. According to the methods of principal component analysis (PCA) followed by multilinear regression analysis (MLRA), four sources of PAHs in the sediments were qualitatively and quantitatively identified, such as petroleum combustion, petrogenic, coal combustion, and biomass burning. Thus, the historical evolution of PAHs was summarized. In addition, the transported distance from local PAH emission sources was found to greatly affect the composition and concentration of PAHs in sites YC1 and YC2. Specifically, local sources contributed a greater proportion of heavy molecular weight (HMW) PAHs in YC1 and a higher proportion of light-molecular-weight (LMW) PAHs in YC2. Moreover, fine particles (size < 20 μm) were found to play a significant role in adsorbing PAHs in sediments. Furthermore, ∑₁₆PAHs in sediments were linearly correlated with the percentage of fine particles (size < 20 μm). This study provides a first example to investigate the historical evolution of PAH local emission in background regions by using lake sedimentary records, especially in the TP. Specifically, different local sources were identified using the methods of PCA followed by MLRA, and PAHs in TP sediments were predominantly adsorbed by fine particles rather than by total organic carbon (TOC) because the amount of TOC was limited.
Afficher plus [+] Moins [-]Comparative efficiency of peanut shell and peanut shell biochar for removal of arsenic from water Texte intégral
2019
Sattar, Muhammad Sohail | Shakoor, Muhammad Bilal | Ali, Shafaqat | Rizwan, Muhammad | Niazi, Nabeel Khan | Jilani, Asim
Contamination of surface water and groundwater streams with carcinogenic chemicals such as arsenic (As) has been a major environmental issue worldwide, and requires significant attention to develop new and low-cost sorbents to treat As-polluted water. In the current study, arsenite (As(III)) and arsenate (As(V)) removal efficiency of peanut shell biochar (PSB) was compared with peanut shell (PS) in aqueous solutions. Sorption experiments showed that PSB possessed relatively higher As removal efficiency than PS, with 95% As(III) (at pH 7.2) and 99% As(V) (at pH 6.2) with 0.6 g L⁻¹ sorbent dose, 5 mg L⁻¹ initial As concentration, and 2 h equilibrium time. Experimental data followed a pseudo-second-order model for sorption kinetics showing the dominance of chemical interactions (surface complexation) between As and surface functional groups. The Langmuir model for sorption isotherm indicated that As was sorbed via a monolayer sorption process. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy analyses revealed that the hydroxyl (–OH) and aromatic surface functional (C=O, C=C–C, and –C–H) groups contributed significantly in the sorption of both As species from aqueous solutions through surface complexation and/or electrostatic reactions. We demonstrate that the pyrolysis of abandoned PS yields a novel, low-cost, and efficient biochar which provides dual benefits of As-rich water treatment and a value-added sustainable strategy for solid waste disposal.
Afficher plus [+] Moins [-]Competitive immunoassay for simultaneous detection of imidacloprid and thiacloprid by upconversion nanoparticles and magnetic nanoparticles Texte intégral
2019
Tao, Zhexuan | Deng, Jiaqi | Wang, Yan | Chen, He | Ding, Yuan | Hua, Xiude | Wang, Minghua
A rapid and sensitive immunoassay for the simultaneous detection of imidacloprid and thiacloprid was developed by using magnetic nanoparticles (MNPs) and upconversion nanoparticles (UCNPs). The UCNPs of NaYF₄:Yb, Er and NaYF₄:Yb, Tm were synthesized and conjugated with anti-imidacloprid monoclonal antibody (mAb) and anti-thiacloprid mAb as signal labels, while the MNPs were conjugated with antigens of thiacloprid and imidacloprid as separation elements. The fluorescence intensities of Yb/Er- and Yb/Tm-doped UCNPs were detected simultaneously in 544 nm and 477 nm under the excitation of NIR light (980 nm). The amounts of mAb-conjugated UCNPs that were separated by antigen-conjugated MNPs were determined based on competitive immunoassays. Under the optimal conditions, the 50% inhibiting concentration (IC₅₀) and limit of detection (LOD, IC₁₀) were 5.80 and 0.32 ng/mL for imidacloprid and 6.45 and 0.61 ng/mL for thiacloprid, respectively. The immunoassay exhibited negligible cross-reactivity with analogs of imidacloprid and thiacloprid except imidaclothiz (86.2%). The average recoveries of imidacloprid and thiacloprid in environmental and agricultural samples, including paddy water, soil, pears, oranges, cucumbers, and wheat, ranged from 78.4 to 105.9% with relative standard deviations (RSDs) of 2.1–11.9% for imidacloprid and ranged from 82.5 to 102.3% with RSDs of 1.0–16.5% for thiacloprid. In addition, the results of the immunoassay correlated well with high-performance liquid chromatography for the detection of the authentic samples.
Afficher plus [+] Moins [-]Revisiting the social cost of carbon after INDC implementation in Malaysia: 2050 Texte intégral
2019
Sarkar, Md Sujahangir Kabir | Al-Amin, Abul Quasem | Leal Filho, Walter
This article projects the social cost of carbon (SCC) and other related consequences of climate change by using Malaysia’s intended nationally determined contribution (INDC) and climate vision 2040 (CV2040) by 2050. It compares the projections derived from the Dynamic Integrated Model of the Climate and Economy (DICME) based on the respective INDC and CV2040 scenario. The results reveal that industrial emissions would incur a substantial increase every 5 years under the scenario CV2040, while Malaysia would experience lower industrial emissions in the coming years under the scenario INDC. Emission intensity in Malaysia will be 0.61 and 0.59 tons/capita in 2030 for scenario CV2040 and scenario INDC respectively. Malaysia would face climate damage of MYR456 billion and MYR 49 billion by 2050 under CV2040 and INDC scenario respectively. However, climate damage could be much lower if the INDC regime were adopted, as this scenario would decrease climatic impacts over time. The estimated SSC per ton of CO2 varies between MYR74 and MYR97 for scenario CV2040 and MYR44 and MYR62 for scenario INDC in 2030 and 2050 respectively. Considering different aspects, including industrial emissions, damage cost, and social cost of carbon, INDC is the best policy compared to CV2040. Thus, Malaysia could achieve its emissions reduction target by implementing INDC by 2050.
Afficher plus [+] Moins [-]Plant selection for roadside design: “the view of landscape architects” Texte intégral
2019
Guneroglu, Nilgun | Bekar, Makbulenur | Kaya Sahin, Elif
Losses in urban green spaces due to population increase and urbanization became one of the most important problems in contemporary cities. Efforts to increase green zones require the establishment of parks and extension of planting activities in urban areas. The planting work conducted on streets, roads, avenues, and traffic islands is significant in the development of urban green spaces. Determination of the plant species that would be used in planting work and assessment of these species by experts and authorities based on scientific approaches are significant for the success of these efforts. In the present study, the issue of plant selection criteria for roadside planting was investigated with a hybrid decision-making approach based on landscape architects’ perspectives. To solve the plant selection problem of decision-makers and to obtain reliable quantitative data, a set of criteria that included 5 main and 41 sub-variables was determined. Pairwise comparison technique was used by experts for evaluation of the involved criteria. The study findings revealed that the “structural criteria” were the most effective main factor in plant selection for roadside planting, followed by the “economic and ecological” criteria. Furthermore, it was determined that the growth length and diameter of the plants (10.2%), selection of indigenous species that reflect the urban identity (7.30%), and the climatic requirements of the plants (7.20%) were the sub-criteria that should be considered in selection of the plants. In conclusion, it was determined that quantitative assessment of plant selection decisions would help planting design decisions on roadside planting.
Afficher plus [+] Moins [-]Novel approach for connecting real driving emissions to the European vehicle laboratorial certification test procedure Texte intégral
2019
Varella, Roberto A. | Ribau, João P. | Baptista, Patrícia C. | Sousa, Luís | Duarte, Gonçalo O.
Vehicle emission certification is evaluated under laboratorial conditions, where vehicles perform a standard driving cycle in controlled conditions leading to several critics, which have resulted in the implementation of the Worldwide harmonized Light Vehicle Test Procedure (WLTP) and the Real Driving Emissions (RDE) testing procedure, as a complementary certification procedure. RDE is still under debate since boundary conditions; evaluation and trip selection methods are still being studied to allow test reproducibility. Currently, the official data analysis method uses the moving average window (MAW_EC), based on the WLTP CO₂ emissions for trip validity evaluation (RDE package 4) and emissions (RDE package 3). However, this does not consider the impact of vehicle dynamics. Consequently, this work focuses on developing a novel method to relate certification driving cycle dynamics and on-road test vehicle dynamics, to evaluate RDE tests fuel use and exhaust emissions in a comparable way to certification driving cycles, indicating how close, or far, real-world driving is from the laboratorial certification test. For this, a new method was developed called road vehicle evaluation method (ROVET), which relies on the cycle vehicle dynamic and on-road trip dynamics for assessing if both tests are comparable. Results from 5 measured vehicles with a portable emissions measurement system (PEMS) through reproducibility tests and 2 case studies, show that the ROVET provides results closer to the certification calculated reference than the most commonly used method in Europe (1% avg. difference for ROVET while 8% avg. difference for MAW_EC, regarding CO₂ emission, for example). The use of vehicle dynamics on construction and references of a method could be used to incentivize the regulators to review the references used by the current used methods, which suffers several criticisms since their release. As the regulated methods are in constant update, this study could be useful for helping to improve or to be used as additional method for future vehicle certification procedures. Graphical abstract
Afficher plus [+] Moins [-]Influence of preparation method on structural, optical, magnetic, and adsorption properties of nano-NiFe2O4 Texte intégral
2019
Selima, Samah Samy | Khairy, Mohamed | Bayoumy, Wafaa Abdallah | Mousa, Mahmoud Ahmed
Nickel ferrite (NiFe₂O₄) nanoparticles are prepared through different routes (microwave, co-precipitation, and pyrolysis) and tested for water purification applications through adsorption removal of an acid red dye B as a model organic pollutant. The characterizations of the prepared samples were done using XRD, FT-IR, SEM, TEM, BET, UV-Vis absorbance, Raman spectrum, and vibrating sample magnetometer (VSM). All samples showed an inverse spinel crystal structure. The obtained results pointed out to the effect of the synthetic route on the morphology, particle size, optical, and magnetic properties of the prepared ferrites. Magnetic measurements showed super-paramagnetic behavior for all samples. The magnetic saturation (Mₛ) of the sample prepared by pyrolysis, was found to possess the highest saturation value, 34.8 emu/g. Adsorption experiments were performed under the change in several parameters, such as pH, adsorbent dosage, and initial dye concentration. A dye removal percentage of 99% was reached under the optimum state. The isothermal adsorption of the acid red dye was investigated using several models, in which the experimental data could be best described by the Freundlich model. Several kinetic and equilibrium models were inspected by linear regression analysis and showed best fitting for the adsorption data through pseudo-second-order model. The calculated thermodynamic parameters indicated that the adsorption of acid red dye onto all the ferrite samples is a spontaneous and endothermic physical adsorption process.
Afficher plus [+] Moins [-]Membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol- and quinoline-containing wastewater: granular activated carbon vs polyaluminum chloride Texte intégral
2019
Wang, Shun | Ma, Cong | Pang, Chao | Hu, Zhenhu | Wang, Wei
Although anaerobic membrane bioreactor (AnMBR) has been proposed for the treatment of phenolic wastewater, the membrane fouling is still a major obstacle. The effects of dosing of granular activated carbon (GAC) and polyaluminum chloride (PACl) on the treatment performance and membrane fouling of anaerobic ceramic membrane bioreactor were investigated for treating phenol- and quinoline-containing wastewater. The results suggested that the one-off dosing of GAC resulted in a decrease of protein/carbohydrate ratio, which might account for the aggravation of membrane fouling alongside with the decreased flocs size. Nevertheless, the substrate uptake rates (SUR) of phenol and quinoline, and the specific methanogenic activity of sludge at the GAC dosing stage of experimental reactor (R1) were 8.79 ± 0.63 mg phenol g⁻¹ MLVSS d⁻¹, 7.01 ± 0.09 mg quinoline g⁻¹ MLVSS d⁻¹ and 0.27 ± 0.01 g CODCH₄ g⁻¹ MLVSS d⁻¹, which were 1.69, 3.59 and 1.93 times higher than that of the control reactor (R2). The dosing of PACl reduced the membrane fouling rate by changing the floc structure of sludge, as well as the component of SMP and EPS. However, the substrate uptake rate of quinoline was declined. This work provides a comprehensive evaluation on the effect of GAC and PACl dosing on membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol-and quinoline-containing wastewater.
Afficher plus [+] Moins [-]Nitrate removal from groundwater using negatively charged nanofiltration membrane Texte intégral
2019
Zou, Lianpei | Zhang, Sitong | Liu, Jianyong | Cao, Yi | Qian, Guangren | Li, Yu-You | Xu, Zhi Ping
A commercial nanofiltration (NF) membrane was modified using poly(sodium 4-styrenesulfonate) (PSS) to improve the nitrate rejection from groundwater. Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential, and water contact angle analyses were performed, showing that PSS was successfully coated onto the membrane with the surface negative charge density being enhanced. The results of nitrate removal tests showed that the best PSS concentration was 1.5 mg/L, with the nitrate rejection rate of 88.8% and the permeate flux of 27.0 L/m² h. The effect of initial nitrate concentration and solution pH on the nitrate removal performance of the modified NF membrane was investigated. The results indicate that the modified NF membrane can improve nitrate removal from actual groundwater, with little membrane permeate flux loss. Graphical abstract
Afficher plus [+] Moins [-]Application of Fe-based metal-organic framework and its pyrolysis products for sulfonamide treatment Texte intégral
2019
Van Tran, Thuan | Nguyen, Duyen Thi Cam | Nguyen, Hong-Tham T. | Nanda, Sonil | N. Vo, Dai-Viet | Do, Sy Trung | Van Nguyen, Tuyen | Thi, Tuyet Anh Dang | Bach, Long Giang | Nguyen, Trinh Duy
The occurrence and fate of antibiotic compounds in water can adversely affect human and animal health; hence, the removal of such substrates from soil and water is indispensable. Herein, we described the synthesis method of mesoporous carbon (MPC) via the pyrolysis route from a coordination polymer Fe-based MIL-53 (or MIL-53, shortly). The MPC structure was analyzed by several physical techniques such as SEM, TEM, BET, FT–IR, VSM, and XRD. The response surface methodology (RSM) was applied to find out the effects of initial concentration, MPC dosage, and pH on the removal efficiency of trimethoprim (TMP) and sulfamethoxazole (SMX) antibiotics in water. Under the optimized conditions, the removal efficiencies of TMP and SMX were found to be 87% and 99%, respectively. Moreover, the adsorption kinetic and isotherm studies showed that chemisorption and the monolayer adsorption controlled the adsorption process. The leaching test and recyclability studies indicated that the MPC structure was stable and can be reused for at least four times without any considerable change in the removal efficiency. Plausible adsorption mechanisms were also addressed in this study. Because of high maximum adsorption capacity (85.5 mg/g and 131.6 mg/g for TMP and SMX, respectively) and efficient reusability, MPC is recommended to be a potential adsorbent for TMP and SMX from water media.
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