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Forward and backward critical sectors for CO2 emissions in China based on eigenvector approaches Texte intégral
2020
Wang, Xiao | Wang, Zhen | Cui, Can | Wei, Liyuan
China had taken measures to reduce the emissions of CO₂ these years as a staunch supporter of the Paris Agreement. However, it is not such an easy task for the authority to decide which sectors should take responsibility on the process of CO₂ emissions reduction in the context of highly connected supply chains. Based on the sectoral CO₂ emissions and input-output table of China, this study provided both forward and backward perspectives based on eigenvector approaches to identify the critical sectors that are critical for the CO₂ emissions in value chains, including a backward method called power-of-pull method that identifies the pulling effect of demand side and a forward method called power-of-push method that identifies the pushing power of supply side. The results showed that the electricity and hot water production and supply was the most influential pulling sector in the studying period, followed by the metal mining in the backward direction. In the forward direction, the electricity and hot water production and supply was also the top 1 important sector while coal mining ranked the second. The results suggest that electricity and hot water production and supply played a vital role in the CO₂ emission in the system. During the studied period from 2007 to 2015, the power of nonmetal mining to pull CO₂ emissions showed a notable increase. Our proposed approach could be helpful for policy-making because of its user-friendliness comparing with other method as well as providing a new perspective.
Afficher plus [+] Moins [-]Removal of boron and silicon by a modified resin and their competitive adsorption mechanisms Texte intégral
2020
Bai, Shuqin | Han, Jue | Du, Cong | Li, Jiaxin | Ding, Wei
Boron and silicon are essential trace elements for living organisms. However, these are undesirable in excess amounts owing to the toxic effects of boron on plants, animals, and humans, and the silica scale formation by silicon in water treatment processes. Herein, a new diol-type adsorbent (T-resin) was synthesized by grafting tiron (disodium 4,5-dihydroxy-1,3-benzenedisulfonate) onto an ion-exchange resin (grafting amount is 1.2 mmol/g dry) to separate boron and silicon from a solution. The effects of pH, initial concentration, and coexisting anions, particularly, the effect of the coexistence of silicate ion on the adsorption of boron, were investigated. T-resin showed good adsorption properties for both boron and silicon in a wide pH range (pH 2–10). The adsorption of boron and silicon was effectively described by the Langmuir isotherm, and the maximum adsorption capacities of boron and silicon were 21.25 mg/g and 8.36 mg/g, respectively. In a competitive adsorption system, boron and silicon were simultaneously adsorbed on the T-resin, but the adsorption rate of boron was faster than silicon. However, silicon could replace the boron adsorbed on the resin, indicating that the adsorption of silicon was more stable than boron. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1:2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃]. Graphical abstract A new diol-type absorbent was synthesized by grafting tiron onto an ion-exchange resin to separate boron and silicon from a solution. Boron and silicon competitively adsorbed on the T-resin, and silicon could replace the boron adsorbed on the resin. ¹¹B and ²⁹Si solid state NMR data confirmed the different adsorption mechanisms of the two elements. Boron was adsorbed via two types of complexes, a triangular complex of [LB(OH)], as well as 1:1 tetrahedral complex of [LB(OH)₂] and 1: 2 tetrahedral complex of [BL₂], whereas silicon was only adsorbed via a 1:3 octahedral complex of [SiL₃].
Afficher plus [+] Moins [-]Fate and migration of polybrominated diphenyl ethers in a workshop for waste printed circuit board de-soldering Texte intégral
2020
Guo, Jie | Patton, Luorong | Wang, Jianbo | Hsu, Chen-Min
Polybrominated diphenyl ethers (PBDEs) are released from the recycling process of PBDE-containing waste printed circuit board (WPCB), but studies on the mechanism of PBDE emission and migration are limited. In this study, PBDE concentrations in particulate matter (PM), dust, and fumes collected in a pilot-scale workshop for the WPCB de-soldering process were measured, and PBDE emission after gas treatment was estimated. The results showed that the mean concentrations of ∑₈PBDEs in TSP and PM₂.₅ in the workshop were 20.3 ng/m³ (24.7 μg/g) and 16.1 ng/m³ (115 μg/g), respectively. In practice, the fumes containing gaseous and particulate PBDEs were treated by the combination of alkaline solution absorption and activated carbon adsorption. Compared to PBDE concentration in workshop floor dust (2680 ng/g), PBDE concentrations in solution scum (68,000 ng/g) and hood inside dust (20,200 ng/g) were condensed. The concentrations of ∑₆PBDEs at the stack outlet (416 pg/m³) after gas treatment were lower than those in the stack pipe (1310 pg/m³) and hood inside (7440 pg/m³). The PBDEs in fumes were removed through physical adsorption of alkaline solution and activated carbon, and solution scum constituted the main mass discharges of PBDEs. The emission factor of PBDEs at the stack outlet was 47.3 ng ∑₆PBDEs/kg WPCB. As a result, the WPCB de-soldering process is an important source of PBDE pollution, and gas treatment of solution absorption and activated carbon adsorption can reduce PBDE emission to some extent.
Afficher plus [+] Moins [-]Performance evaluation of conventional and hybrid woven fabrics for the development of sustainable personal protective clothing Texte intégral
2020
Memon, Arshad Hussain | Peerzada, Mazhar Hussain | Brohi, Khan Muhammad | Memon, Sheeraz Ahmed | Mangi, Sajjad Ali
This study examines the performance level of hybrid woven protective clothing (HWPC), manufactured from Kevlar® (K) and Ramie (R) yarns. The weave structures (plain, twill 1/3) and variables fiber ratios were used to produce HWPC. The performance level of HWPC was measured according to EN 388:2016. We came to the conclusion that blade cut resistance of plain and twill structure sustained protection level up to increase of KR 80:20 and KR 70:30, respectively; puncture resistance of K100% and HWPC remained in the same level of protection for plain and twill weaves; Abrasion resistance of K100% and HWPC of plain and twill weaves samples presented abrasive performance of same protection level, but the average number of cycles sustained for twill weave samples was slightly higher than plain weave. However, comparing the plain and twill weaves sample for tear resistance, twill weave samples have higher tear resistance than plain weave. A gray relational analysis and Taguchi method was performed to optimize the performance of two structures with variable fiber ratios. It was established that the article produced with K&R yarns with KR 80:20 ratio and twill weave presented the best performance against all test runs. The main objective of this study is to reduce plastic pollution by reducing the amount of synthetic fiber proportion in personal protective clothing and thereby reducing the dependence on nonrenewable sources for synthetic fiber. The 41 g/m² reduction of Kevlar® fiber has been made in a conventional PC with ramie fiber, without compromising the protection level. This will enhance the sustainability of HWPC.
Afficher plus [+] Moins [-]Interactions between heavy metals and other mineral elements from soil to medicinal plant Fengdan (Paeonia ostii) in a copper mining area, China Texte intégral
2020
Shen, Zhangjun | Chen, Yansong | Xu, Decong | Li, Lingling | Zhu, Yong
In order to analyze the interaction relationship between heavy metals and other mineral elements during the processes of absorption and translocation by plant grown on heavy metal–contaminated area, the concentrations of Cu, Zn, Mn, Cd, Pb, Ca, Mg, Fe, and K in the medicinal plant Paeonia ostii T. Hong et J. X. Zhang and its rhizospheric soil were determined, which grow around an abandoned copper tailings reservoir in Tongling City, China. Geo-accumulation index (Igₑₒ) calculation indicated that Cu and Pb are the main pollution elements in the rhizospheric soil. Moreover, the Cu and Pb concentrations in the cortex moutan of P. ostii exceeded the maximum permissible limits for food product safety. The bioaccumulation factor values of the tested metals in plant roots were found < 0.50, with the exception of Ca (maximum 5.99). The translocation factor values of detected heavy metals Cd and Pb were more than 1.00, which indicated that P. ostii could be considered a potential accumulator plant for Cd and Pb. Significant positive correlations including Cu-Cd, Cu-Zn, Cu-Pb, Cd-Zn, Cd-Fe, Cd-Fe, Zn-Pb, Pb-Fe, Mn-Fe, and Ca-Mg in the cortex moutan and Cu-Zn, Cu-Fe, Zn-Mg, Zn-Fe, and Mn-K in the leaves were observed (P < 0.05). Significant positive correlation between Cu, Zn, Mg, and Fe was also confirmed in the processes of absorption and translocation from the soil to plant (P < 0.05), which evidenced that synergistic element interactions of the essential elements Cu, Zn, Mg, and Fe are a result of the similarity in their ionic radii and octahedral coordination geometry.
Afficher plus [+] Moins [-]Assessment of phytostabilization potential of two Salix L. clones based on the effects of heavy metals on the root anatomical traits Texte intégral
2020
Hrkić Ilić, Zorana | Pajević, Slobodanka | Borišev, Milan | Luković, Jadranka
Willow species (Salix L.) are a useful tool for assessing phytostabilization of the sites polluted by heavy metals. Phytostabilization potential of two willow genotypes (Salix alba L. clone ‘68/53/1’ and Salix nigra Marshall clone ‘0408’) has been evaluated in a 45-day hydroponic experiment, using stem cuttings (diameter 12 to 14 mm, length 20 cm) exposed to two concentrations (10⁻⁴ M and 10⁻⁵ M) of individually applied Cd, Ni, and Pb. Metals were diluted in 25% Hoagland’s solution, in forms of CdCl₂·H₂O, NiSO₄·6H₂O, and Pb-EDTA. The control group of cuttings was grown in 25% Hoagland’s solution without heavy metals. High Cd concentrations in willow roots, 8637 mg/kg (clone ‘68/53/1’) and 6728 mg/kg of dry weight (clone ‘0408’), have indicated a high phytostabilization potential. However, detailed analyses of cross-sectional area of the root cortex and the central cylinder revealed that the excess concentration of Cd led to a significant reduction of measured anatomical rootʼs traits of clone ‘68/53/1’ in comparison with the control samples. Excessive concentration of Ni and Pb in nutrient solution increased the values of quantitatively measured rootʼs traits of clone ‘0408’, implying stimulatory effects of the applied concentrations. Concentration of 10⁻⁴ M of each metal had more negative effects on the rootsʼ anatomical traits, notably on parenchymal and exodermal cells and vessels. Deposits of metals were observed in root tissues. Clone ‘0408’ demonstrated an increased tolerance to heavy metals, which could potentially make this clone useful in phytostabilization.
Afficher plus [+] Moins [-]Determinants of renewable and non-renewable energy consumption in hydroelectric countries Texte intégral
2020
Ponce, Pablo | López-Sánchez, Michelle | Guerrero-Riofrío, Patricia | Flores-Chamba, Jorge
In the past decades, renewable energy consumption has grown considerably because of environmental degradation caused by non-renewable energy consumption. This research aims to find the causal link between renewable and non-renewable energy consumption, human capital, and non-renewable energy price for the 53 most renewable energy-consuming countries worldwide (hydroelectric) during the period 1990–2017. We use data collected from the World Bank (http://data.worldbank.org/data-catalog/world-development-indicators , 2018) and Statistical Review of World Energy (https://www.bp.com/ , 2018). We test simultaneously two types of regressions in order to measure the degree of elasticity of the two types of energy by using econometric techniques for panel data. The results of the GLS models indicate that human capital has a stronger significant effect on renewable energy consumption at the global level, in the middle high-income countries and low-middle income countries, compared with non-renewable energy consumption. Besides, at the global level, there is a positive and statistically significant relationship between the non-renewable energy price and the two types of energy consumption. There is a long-run consumption of both types of energy. On the other hand, the one-way relationship between human capital and non-renewable energy price and renewable energy consumption is stronger than the relationship with non-renewable energy consumption. The policy implications derived from this study should be designed to promote human capital development in order to promote renewable energy consumption and increase the investment in renewable energy sources to guarantee their access to lower prices that reduce non-renewable energy consumption.
Afficher plus [+] Moins [-]Enhanced interlayer trapping of Pb(II) ions within kaolinite layers: intercalation, characterization, and sorption studies Texte intégral
2020
Maged, Ali | Ismael, Ismael Sayed | Kharbish, Sherif | Sarkar, Binoy | Peräniemi, Sirpa | Bhatnagar, Amit
Lead (Pb(II)) pollution in water poses a serious threat to human health in many parts of the world. In the past decades, research has been aimed at developing efficient and cost-effective methods to address the problem. In this study, dimethyl sulfoxide (DMSO) and potassium acetate (K-Ac) intercalated kaolinite complexes were synthesized and subsequently utilized for Pb(II) removal from water. The intercalation of kaolinite with DMSO was found to be useful for expanding the interlayer space of the clay mineral from 0.72 to 1.12 nm. Kaolinite intercalation with K-Ac (KDK) increased the interlayer space from 1.12 to 1.43 nm. The surface area of KDK was found to be more than threefold higher as compared to natural kaolinite (NK). Batch experimental results revealed that the maximum Pb(II) uptake capacity of KDK was 46.45 mg g⁻¹ which was higher than the capacity of NK (15.52 mg g⁻¹). Reusability studies showed that KDK could be reused for 5 cycles without substantially losing its adsorption capacity. Furthermore, fixed-bed column tests confirmed the suitability of KDK in continuous mode for Pb(II) removal. Successful application of intercalated kaolinite for Pb(II) adsorption in batch and column modes suggests its application in water treatment (especially removal of divalent metals).
Afficher plus [+] Moins [-]The role of ICT and financial development in CO2 emissions and economic growth Texte intégral
2020
Raheem, Ibrahim D. | Tiwari, Aviral Kumar | Balsalobre-Lorente, Daniel
This study explores the role of the information and communication technology (ICT) and financial development (FD) in both carbon emissions and economic growth for the G7 countries for the period 1990 to 2014. Using PMG, we found that the ICT has a long-run positive effect on emissions, while FD is a weak determinant. The interactive term between the ICT and FD produces negative coefficients. Also, both the variables are found to impact negatively on economic growth. However, their interaction shows that they have mixed effect on economic growth, i.e., positive in the short run and negative in the long run. Policy implications were designed based on these results.
Afficher plus [+] Moins [-]Urinary paraben concentrations and their implications for human exposure in Iranian pregnant women Texte intégral
2020
Hajizadeh, Yaghoub | Kiani Feizabadi, Ghasem | Ebrahimpour, Karim | Shoshtari-Yeganeh, Bahareh | Fadaei, Saeid | Darvishmotevalli, Mohammad | Karimi, Hossein
Parabens are widely used as preservatives in cosmetics, medicines, and foods due to its antimicrobial properties. Concerns have been raised regarding the estrogenic activity and potential endocrine disruption effects of parabens. Studies on monitoring of paraben exposure in the Iranian population are very scarce. This study was carried out to measure urinary concentrations of parabens, to estimate their daily intake, and to identify some of the sociodemographic factors affecting exposure to these compounds. The concentrations of methylparaben (MP), ethylparaben (EP), propylparaben (PP), and butylparaben (BP) were measured in urine samples collected from 95 Iranian pregnant women by gas chromatography mass spectrometry. The highest median concentration was 87.0 μg/L for MP, followed by PP, EP, and BP with median concentrations of 15.6, 9.64, and 8.57 μg/L, respectively. Except BP, the urinary concentrations of other parabens were comparable to those in other countries. Also, the highest daily intake was related to MP (median = 16.5 μg/kg-BW/day), which is less than the acceptable daily intake (ADI). A significant positive correlation was observed between the measured parabens. Significant negative associations were observed between age and BP, BMI and EP as well as parity and PP. On the other hand, income and smoking were significantly positively associated with MP, BP and EP, BP, respectively. The urinary MP and BP concentrations were higher among the subjects with diploma education (P = 0.003 and P = 0.006, respectively), and during the spring, urinary MP concentration was higher than other seasons. The results showed that Iranian pregnant women are more prone to parabens and their urinary paraben concentrations are associated with sociodemographic factors. This result could serve as a basis for evaluating the rate of exposure of the Iranian population to parabens in future studies.
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