Refine search
Results 4091-4100 of 8,010
Mechanism and Optimization of Polyepoxysuccinic Acid in Washing Cd-, Pb-, and Zn-Contaminated Soils Full text
2021
Zhong, Qinmei | Li, Linxian | Zhang, Shirong | Li, Ting | Xu, Xiaoxun | Wang, Guiyin | Li, Yun
Soil washing is an important technique for remediating metal-contaminated soils, and screening promising eluant and optimizing its washing conditions can enhance the restoration efficiencies. Biodegradable polyepoxysuccinic acid (PESA) was employed to remove Cd, Pb, and Zn from two contaminated soils. FTIR analysis suggested that PESA washing process may be dominated by dispersion effect and associated with chelating function. The effects of PESA concentration, pH of solution, and washing time on heavy metal removal were conducted. Single-factor experiments showed that Cd, Pb, and Zn removal was 72.8, 75.7, and 47.7% for soil A and 61.1, 70.2, and 43.3% for soil B at PESA concentration of 30.0 mmol L⁻¹, pH 3.0, and washing time of 2.0 h. Furthermore, rotatable orthogonal central combination design (ROCCD) was conducted to optimize the washing parameters. The optimal experiment intervals of PESA concentration, pH, and washing time were 38.0–39.0 mmol L⁻¹, 3.0, and 2.0–2.4 h. Under these conditions, Cd, Pb, and Zn could be removed 80.4, 66.0, and 47.8% from soil A and 64.9, 67.4, and 43.3% from soil B, respectively. Therefore, PESA is a potential extracting agent to remove heavy metals from contaminated soils, and ROCCD is an effective reliable tool for optimization washing parameters.
Show more [+] Less [-]A subchronic low-dose exposure of a glyphosate-based herbicide induces depressive and anxious-like behavior in mice: quercetin therapeutic approach Full text
2021
Bicca, Diogo Ferreira | Spiazzi, Cristiano Chiapinotto | Ramalho, Juliana Bernera | Soares, Melina Bucco | Cibin, Francielli Weber Santos
In this study, we investigated the possible role of pesticide exposure in contributing to neurological diseases such as depression. Here, we evaluated whether a subchronic low dose of a glyphosate-based herbicide (GBH) could induce alterations in the central nervous system, using the flavonoid quercetin as a therapeutic strategy. Forty mice were divided into four treatment groups: control, GBH, quercetin, and GBH+Quer groups and received 50 mg/kg of GBH solution, 30 mg/kg of quercetin, and/or vehicles for 30 days via gavage. After performing behavioral tests, such as the open field (OF), elevated plus maze (EPM), forced swim test (FST), and sucrose preference test (SPT), the mice were euthanized and their hippocampal tissues were collected to measure the levels of oxidative stress markers such as reactive species (RS), total antioxidant capacity (FRAP), reduced glutathione (GSH), and acetylcholinesterase activity (AChE), as well as for histological evaluation. The GBH group showed anxious and depressive-like behavior in the EPM and FST tests, as well as increased levels of RS and decreased GSH levels in the hippocampus. Quercetin treatment in the GBH+Quer group allowed partial or total improvement in behavioral tests (EPM and FST) and in the levels of oxidative stress markers (RS and GSH). However, the quercetin group showed similar behavior to the GBH group after treatment. The results revealed that oral exposure to a subchronic low dose of GBH was capable of promoting effects on behavior and oxidative stress in the hippocampus of mice. In addition, despite quercetin having a neuroprotective role, caution is needed when considering the possible per se effects of its continuous supplementation.
Show more [+] Less [-]Laboratory experimental study of the evaporation and mechanical behaviour of deposited tailings Full text
2021
Zheng, Binbin | Wang, Jiahe | Zhang, Dongming | Zhao, Lei | Wang, Wensong
Surface deposition has been widely used in the mining industry to manage mill tailings. Tailings are generally discharged in the form of a slurry into tailings ponds. The slurried tailings are deposited in layers that undergo complex processes, e.g. evaporation, desiccation and consolidation. The evaporation of the deposited tailings controls their geotechnical engineering behaviour, which is necessary to characterise the physical properties. In this study, a constant temperature device was employed in evaporation tests to investigate two classes of deposited tailings, and the effects of the initial concentration, particle size, exposure area and deposited layer thickness on the evaporation processes were analysed. The test results showed four stages in the evaporation processes of deposited coarse and fine tailings. Dewatering of the deposited tailings occurred during the first two stages, which were keys to improving the desiccation efficiency of the tailings in the pond. The exposure area and deposited layer thickness also had a considerable influence on evaporation. The evaporation rate increased with the exposure area and layer thickness. Direct shear tests were performed to measure the shear strength of intact tailings during evaporation and used to determine the variation law of the mechanical properties of the test tailings.
Show more [+] Less [-]Enhanced activated persulfate oxidation of ciprofloxacin using a low-grade titanium ore under sunlight: influence of the irradiation source on its transformation products Full text
2021
Macías-Vargas, José-Alberto | Campos-Mañas, Marina Celia | Agüera, Ana | Sánchez Pérez, José Antonio | Ramírez-Zamora, Rosa-María
In this work, the activated persulfate oxidation of ciprofloxacin (CIP) using a low-grade titanium ore under sunlight or simulated sunlight were conducted to analyze the CIP degradation efficiency and to identify the transformation products (TPs) generated during oxidation under both types of irradiation sources by using liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). All advance oxidation process experiments were performed in a 2700-mL raceway reactor at a pH value of ~ 6.5 and an initial CIP concentration of 1 mg/L, during 90 min of reaction time. The control experiments carried out under simulated sunlight achieved a 97.7 ± 0.6% degradation efficiency, using 385 W/m² of irradiation with an average temperature increase of 11.7 ± 0.6 °C. While, the experiments under sunlight reached a 91.2 ± 1.3% degradation efficiency, under an average irradiation value of 19.2 ± 0.3 W/m² in October–November 2019 at hours between 11:00 am and 3:00 pm with an average temperature increase of 1.4 ± 0.8 °C. Mass spectrometry results indicated that 14 of the 108 possible TPs reported in the literature were detected. The calculated exact mass, measured accurate mass, and its characteristic diagnostic fragment ions were listed, and two new TPs were tentative identified. The TP generation analysis showed that some specific compounds were detected in different time intervals with kinetic variations depending on the irradiation used. Consequently, two CIP degradation pathways were proposed, since the type of irradiation determines the CIP degradation mechanism. Graphical abstract
Show more [+] Less [-]Integrated risk prioritization and action selection for cold chain Full text
2021
Dagsuyu, Cansu | Derse, Onur | Oturakci, Murat
Cold chain, which affects human health and quality of life, is applied for temperature-sensitive and perishable products. Any problems occurring in the cold chain can cause deterioration in products, causing poisoning, death, or various diseases. There are many stages in the cold chain itself and the risk significance level of each stage is different. Therefore, the risks that occur depending on the weight of the stages in the cold chain should be defined and minimized and action plans are needed to be formed. Every action in the action plan cannot be implemented simultaneously since each action requires a different amount of budget and time resources of the companies are finite. Hence, the risks occurring in the cold chain should be minimized with the maximum use of limited company resources. In this study, an integrated mathematical model with analytical hierarchy method and failure mode and effect analysis is proposed that will maximize the weighted risk reduction amount by considering the budget and time constraints of the companies at the same time. The proposed approach has been applied in the 3PL service provider and the results are discussed. According to the results of the study where maximum benefit is aimed with the actions taken against the dangers, the maximum objective function value was obtained at the second and third levels of the workforce and budget values by evaluating the different situations with scenario analyses. In this solution, it is foreseen that by taking 5 actions, improvement will be made in 14 hazards.
Show more [+] Less [-]Comprehensive assessment of water quality and associated health risk by using physicochemical quality indices and multivariate analysis in Terme River, Turkey Full text
2021
Ustaoğlu, Fikret | Taş, Beyhan | Tepe, Yalçın | Topaldemir, Halim
The ecosystem and water quality of Terme River, an essential drinking and irrigation water source in the region, are at risk due to anthropogenic pressures. Therefore, the present study aim to present a comprehensive overview of the water quality state and pollution sources of the river. Some physicochemical water quality parameters were analyzed by standard methods along the surface water of river spatiotemporally. The concentrations of major elements and heavy metals (Na, Mg, K, Ca, Al, Cr, Fe, Co, Mn, Ni, Zn, Cd, Cu, Pb, As) were measured in water samples. Relationships between physicochemical data were assessed by using multivariate statistical analysis (MSA) methods. The order of the mean values of cations were as follow: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ > NH₄⁺ (32.66, 26.82, 13.29, 6.45, 0.305; mg/L), and order of anions: SO₄²⁻ > NO₃– >F⁻ > NO₂– (7.88, 3.988, 1.01, 0.0316; mg/L). Increases in ion concentrations in the downstream zone have been monitored in the summer and autumn months. Average water quality index (WQI) 22, heavy metal pollution index (HPI) 15.61, heavy metal evaluation index (HEI) 0.78, and nutrient pollution index (NPI) 0.404 values indicated that the general water quality of Terme River was fine. All hazard quotient (HQ) and hazard index (HI) values in this study were calculated below the risk threshold (<1). HI-total values (2.48E-01) in children were higher than in adults (2.14E-01). This suggests that children’s health is at higher risk than adults. Principal component analysis (PCA) data formed four principal components (PCs) explaining 85.22% of the total variance. These PCs revealed that the significant changes in water quality occurred from point and diffuse sources, including rock types of the basin, soil erosion, domestic wastewater discharges, and agricultural flow of inorganic fertilizers.
Show more [+] Less [-]Transcriptomic analysis reveals ligninolytic enzymes of white-rot fungus Phanerochaete sordida YK-624 participating in bisphenol F biodegradation under ligninolytic conditions Full text
2021
Wang, Jianqiao | Yin, Ru | Zhang, Xue | Wang, Nana | Xiao, Pengfei | Hirai, Hirofumi | Xiao, Tangfu
Bisphenol F (BPF) is widely used in the plastic manufacturing industry as a replacement for bisphenol A (BPA) because BPF and BPA have similar structures and comparable properties. However, BPF is ubiquitously present in the environment and has higher toxicity to humans. This study is the first to report BPF degradation using the white-rot fungus Phanerochaete sordida YK-624 under ligninolytic conditions (pH=4.5, 30 °C). P. sordida YK-624 almost completely degraded BPF within 4 days. Moreover, functional genes involved in BPF degradation were detected by RNA-Seq. Metabolic processes and peroxidases were enriched by GO analysis, and the metabolic pathway was enriched according to the KEGG pathway analysis. These results suggested that P. sordida YK-624 could secrete higher levels of ligninolytic enzymes lignin peroxidase (LiP) and manganese peroxidase (MnP) for BPF degradation. The results indicated that LiPs and MnPs are important for BPF degradation and cytochrome P450s play a small role. Furthermore, reliability of the RNA-Seq results was validated by qRT-PCR.
Show more [+] Less [-]Assessing changes and driving factors of energy consumption in China over 2000–2014: a perspective of final demand Full text
2021
Liu, Liwen | Wang, Daoping | Bai, Caiquan
As the economy enters the new normal in China, more and more intellectuals are concerned about the energy consumption in the economic green transformation and development process; this article computes the energy consumption embodied in various final demand types by the utilization of the environmentally extended input-output (EEIO) model during 2000–2014. Then, the structural decomposition analysis is adopted for exploring energy consumption changes’ driving factors considering various final demand categories. Furthermore, the decoupling between economic growth and energy consumption embodied in various final demand categories is revealed by the application of the Tapio model in China. The results indicate as below: (1) the energy consumption embodied in various final demand categories increased significantly during the study period; (2) the gross fixed capital formation (GFCF) was most conducive to the growth of energy consumption, while the construction department emerged as the greatest energy user in GFCF; (3) coal and oil were two main energy sources consumed regardless of any final demand categories; (4) in the three drivers, the scale effect had a primary contribution to increasing energy consumption. The intensity effect made a crucial contribution to mitigating energy consumption. The structural effect had a mild contribution to the energy consumption changes; (5) the five final demand categories were roughly characterized by the weak decoupling over the period 2000–2014. GFCF determined the decoupling index between economy growth and energy consumption largely. Finally, this article put forward implied policies concerning the reduction of energy utilization in China.
Show more [+] Less [-]Numerical analysis of economic and environmental benefits of marine fuel conversion from diesel oil to natural gas for container ships Full text
2021
Elkafas, Ahmed G. | Elgohary, Mohamed M. | Shouman, Mohamed R.
Shipping is a significant contributor to global greenhouse gas (GHG) and air pollutant emissions. These emissions mainly come from using diesel fuel for power generation. In this paper, the natural gas is proposed as an alternative marine fuel to be used instead of conventional marine diesel oil. Numerical analysis of environmental and economic benefits of the natural gas-diesel dual-fuel engine is carried out. As a case study, a container ship of class A7 owned by Hapag-Lloyd has been investigated. The results show that the proposed dual-fuel engine achieves environmental benefits for reducing carbon dioxide (CO₂), nitrogen oxides (NOx), sulfur oxides (SOx), particulate matter (PM), and carbon monoxide (CO) emissions by 20.1%, 85.5%, 98%, 99%, and 55.7% with cost effectiveness of 109, 840, 9864, 27761, and 4307 US$/ton, respectively. The results show that the conversion process to the dual-fuel engine will comply with the current and future IMO regulations regarding air pollutant emissions. On the other hand, using the proposed dual-fuel engine on the container ship will improve the ship energy efficiency index by 29.6 % with annual fuel cost saving of 4.77 million US dollars.
Show more [+] Less [-]A multi-stage fuzzy decision-making framework to evaluate the appropriate wastewater treatment system: a case study Full text
2021
Büyüközkan, Gülçin | Tüfekçi, Gizem
Selection of appropriate treatment processes for wastewater treatment (WWT) plants at the design stage involves a careful examination of different economic, environmental, and social parameters. Designers and decision-makers seek a compromise among such conflicting elements, which can be facilitated by decision support tools that are adapted for the ambiguity of individual opinions and decision parameters. This study aims to improve the qualification and efficiency of decision-making in WWT processes. A multi-stage framework is proposed to help select investments, technology, appropriate technology-specific system, and companies that apply such systems. The framework combines the Analytic Hierarchy Process (AHP), Preference Ranking Organization Method for Enrichment Evaluation (PROMETHEE), cash flow analysis, and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) within fuzzy logic. The main contribution is the description and formation of an integrated framework to guide businesses and researchers for the evaluation of several WWT decision processes. To the best of the authors’ knowledge, no study in the literature fuses multiple stages of this WWT process with the proposed approaches.
Show more [+] Less [-]