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1.
PLoS One ; 15(10): e0237264, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33002034

RESUMO

The precise evaluation of the potential damage caused by large commercial aircraft crash into civil structures, especially nuclear power plants (NPPs), has become essential design consideration. In this study, impact of Boeing 767 against rigid wall and outer containment building (reinforced concrete) of an NPP are simulated in ANSYS/LS-DYNA by using both force time history and missile target interaction methods with impact velocities ranging from 100 m/s to 150 m/s. The results show that impact loads, displacements, stresses for concrete and steel reinforcement, and damaged elements are higher in case of force time history method than missile target interaction method, making the former relatively conservative. It is observed that no perforation or scabbing takes place in case of 100 m/s impact speed, thus preventing any potential leakage. With full mass of Boeing 767 and impact velocity slightly above 100 m/s, the outer containment building can prevent local failure modes. At impact velocity higher than 120 m/s, scabbing and perforations are dominant. This concludes that in design and assessment of NPP structures against aircraft loadings, sufficient thickness or consideration of steel plates are essential to account for local failure modes and overall structural integrity. Furthermore, validation and application of detail 3D finite element and material models to full-scale impact analysis have been carried out to expand the existing database. In rigid wall impact analysis, the impact forces and impulses from FE analysis and Riera's method correspond well, which satisfies the recommendations of relevant standards and further ensure the accuracy of results in full-scale impact analysis. The methodology presented in this paper is extremely effective in simulating structural evaluation of full-scale aircraft impact on important facilities such as NPPs.


Assuntos
Acidentes Aeronáuticos , Aeronaves , Liberação Nociva de Radioativos , Acidentes Aeronáuticos/estatística & dados numéricos , Códigos de Obras , Simulação por Computador , Materiais de Construção/estatística & dados numéricos , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Fenômenos Mecânicos , Modelos Teóricos , Centrais Nucleares , Fenômenos Físicos , Liberação Nociva de Radioativos/prevenção & controle , Liberação Nociva de Radioativos/estatística & dados numéricos , Aço , Colapso Estrutural/prevenção & controle , Colapso Estrutural/estatística & dados numéricos
2.
Artigo em Chinês | MEDLINE | ID: mdl-33036529

RESUMO

Objective: To analyze the relationship between cumulative high temperature exposure and hypertension among steel workers. Methods: We conducted a survey among 7 660 production workers (7 023 males and 637 females) in a large steel mill during February-June 2017 and March-July 2018. Basic information, blood pressure, occupational history and high temperature data in workplace were collected through questionnaire survey, physical measurement and occupational exposure detection. Restrictive cubic spline model was used to analyze the dose-response relationship between cumulative high temperature exposure and hypertension, and the correlation between cumulative high temperature exposure and workers' hypertension was analyzed by logistic regression. Results: The median number of cumulative high temperature exposure was 626.56 ℃·year and 49.20% of workers were exposed to high temperature. The hypertension prevalence rate was 25.60% among the workers. According to the results of the spline model, the cumulative high temperature exposure was divided into three sections: <292.61, 292.61~<720.13, ≥720.13 ℃·year. Taking the exposure <292.61 ℃·year group as a reference, the risk of steel workers' hypertension in the 292.61~<720.13 ℃·year group and ≥720.13 ℃·year group is 1.44 and 2.17 times that of the reference group (P<0.05) . Conclusion: There was a nonlinear dose-response relationship between cumulative high temperature exposure and steelworkers' hypertension. With the increase of cumulative high temperature exposure, the risk of steelworkers' hypertension increases.


Assuntos
Hipertensão , Exposição Ocupacional , Pressão Sanguínea , Feminino , Humanos , Hipertensão/epidemiologia , Masculino , Aço , Temperatura
3.
PLoS One ; 15(9): e0238505, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32915839

RESUMO

Previous research has indicated that many European buildings are vulnerable to moderate-magnitude earthquakes. For example, during the L´Aquila (Italia, Mw 6.3, 2009) and Lorca (Spain, Mw 5.9, 2011) earthquakes, many old buildings were severely damaged and some of them collapsed. In specific, significant damage has been found in several school buildings after past earthquakes in Europe. This is due to the fact that many of them were constructed prior to the current seismic codes, thus considering only gravitational loads and with no seismic design whatsoever. Primary schools are even more vulnerable than other typologies because of their low adult/child ratio. The seismic activity of the Iberian Peninsula is low-moderate. However, the Algarve and Huelva regions, which are situated in the south-west, are influenced by large faults which have caused major earthquakes of long-return periods. The European project PERSISTAH (Projetos de Escolas Resilientes aos SISmos no Território do Algarve e de Huelva, in Portuguese) aims to cooperatively evaluate the seismic vulnerability of primary schools in the Algarve (Portugal) and Huelva (Spain) regions. The present work is framed under this project. The objective of this paper is to determine the most effective retrofitting scheme for a typical primary school building in this area, considering structural, architectural and constructive parameters. The scheme could be applied to several buildings of the same typology, decreasing costs and time. An existing reinforced concrete frame building has been selected for the study. This is one of the most commonly used typologies for primary schools in this area. A nonlinear static analysis has been carried out in order to study its seismic behaviour. The performance point of the building has been obtained through the capacity-demand spectrum method. The preliminary results have confirmed the poor seismic behaviour of this building. Specifically, soft-story behaviour has been identified in the ground floor and short columns have been observed in the upper floors. Therefore, specific seismic retrofitting solutions have been proposed and evaluated in order to identify the one that is the most efficient. The combination of reinforcements has been done considering the structural and architectural impact and constructive parameters. The calculations have shown that steel X-bracings are the best solution for preventing the formation of a soft-storey in the ground floor. Unfortunately, this scheme increases the deformation in the upper floor columns. The best solution for the upper floors' short columns has been the use of steel jackets. The results have also shown that this combination produces an important reduction of the expected general damage level. The resulting retrofitting scheme can be extrapolated to other buildings with a similar typology.


Assuntos
Materiais de Construção , Terremotos , Instituições Acadêmicas , Aço , Itália , Modelos Teóricos , Software
4.
Artigo em Chinês | MEDLINE | ID: mdl-32892584

RESUMO

Objective: To investigate the effect of sound insulation improvement on the noise exposure of workers in the operation room of hot rolling line for wide and heavy plate. Methods: From September 2019 to September 2017, based on the occupational health Survey, the data of 25 fixed operation rooms and workers in operation rooms of a steel rolling production line were collected retrospectively, the noise exposure levels before and after the improvement of sound insulation were statistically analyzed. Results: The noise exposure value of the workers, the qualified rate of 0 Grade 8 hours equivalent noise (L(EX, 8 h)) ≤85 dB (A) and the qualified rate of the design limit value of the operation room were all higher than those before the modification, the difference was statistically significant (P<0.01) , after the renovation, the Class II and above noise hazards were eliminated, the equivalent continuous a sound level (L(Aeq, 8 h)) >75 dB (A) of the workers in the operation room was 8h, and the noise level in the operation room still did not meet the Ergonomics limit standard. Conclusion: The improvement of sound insulation can effectively improve the working environment of noise workplace operating room and reduce the workers'noise exposure level.


Assuntos
Metalurgia , Ruído Ocupacional , Exposição Ocupacional/análise , Saúde do Trabalhador , Humanos , Estudos Retrospectivos , Aço , Local de Trabalho
5.
Sci Total Environ ; 740: 140403, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32927559

RESUMO

Waste amendments, such as steel slag and biochar, have been reported as a strategy for improving soil fertility, crop productivity, and carbon (C) sequestration in agricultural lands. However, information regarding the subsequent effects of steel slag and biochar on C cycling and the underlying microbial mechanisms in paddy soils remains limited. Hence, this study aimed to examine the effect of these waste amendments (applied in 2015-2017) on total soil CO2 emissions, total and active soil organic C (SOC) contents, and microbial communities in the early and late seasons in a subtropical paddy field. The results showed that despite the exogenous C input from these waste amendments (steel slag, biochar and slag + biochar), they significantly (P < 0.05) decreased total CO2 emissions (e.g., by 41.9-59.6% at the early season), compared to the control soil. These amendments also significantly (P < 0.001) increased soil salinity and pH. The increased soil pH had a negative effect (r = -0.37, P < 0.05) on microbial biomass C (MBC). The biochar and slag + biochar treatments (cf. control) significantly (P < 0.001) increased SOC contents in the both seasons. The amendments altered the soil microbial community structure that associated with soil C cycling: (1) all three amendments increased the relative abundance of Agromyces and Streptomyces, which was associated with higher soil pH (cf. control); and (2) biochar and slag + biochar treatments caused a higher relative abundance of Sphingomonas, which was supported by high SOC contents under those amendments. Overall, this study demonstrated that the steel slag and biochar amendments altered microbial community composition due to changes in key soil properties, such as salinity, pH and SOC contents, with implications for increasing soil C stocks while mitigating CO2 emissions in the paddy field.


Assuntos
Oryza , Solo , Dióxido de Carbono/análise , Carvão Vegetal , Microbiologia do Solo , Aço
6.
Water Sci Technol ; 82(3): 565-576, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32960800

RESUMO

The heterogeneous electro-Fenton process degradation of Yellow 2G from wastewater was studied using a batch reactor. The COD of the wastewater used in treatment experiments was 163 mg O2·L-1 and the BOD5 was 17 mg O2·L-1 (hardly biodegradable). The treatment of the wastewater at different current densities (2.5 mA·cm-2-12.5 mA·cm-2), solution pH (3 and 6.6), reaction times (5-25 min), electrolyte nature (NaCl, Na2SO4) and electrolyte concentrations (0.15 g·L-1-1 g·L-1) was investigated. According to the results, the heterogeneous electro-Fenton process was suitable for the decolorization of wastewater containing Yellow 2G. The optimum conditions were current density of 12.5 mA·cm-2, initial pH of the wastewater neutral, 25 min of electrolysis treatment using an additive steel electrode as a source of catalysis and in the presence of 1 g NaCl·L-1. We obtained easily biodegradable water with a mineralization rate equal to 85% and non-toxicity confirmed by the pea grain germination test.


Assuntos
Aço , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Catálise , Eletrodos , Peróxido de Hidrogênio , Oxirredução , Pirazóis
7.
Environ Sci Pollut Res Int ; 27(36): 45076-45094, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32776289

RESUMO

This study reports the results of a comparison made using life cycle assessment (LCA) analysis of the environmental impact of nine different sandwich material models (SMs). The objective is to reveal whether the candidate materials considered for a railway passenger vehicle (conventional or high-speed train) are green/environmentally friendly or not. For this aim, life cycle approach enables to take into account the light weighting gain without disregarding the environmental impact of manufacturing process. These SMs are designed as combinations of existing traditional and candidate materials, such as steel, aluminium, carbon/glass fibre-reinforced plastics (CFRP/GFRP), aluminium honeycomb, and polymer foam core. The environmental performance of these nine different models has been calculated via the LCA analysis with CML-IA v.3.0 impact assessment methodology in a SimaPro 8.5.0. The system boundaries in the LCA analysis include "cradle to grave" process of sandwich composite materials in the railway passenger vehicle. The functional unit was selected as "one product of SM" for each configuration; besides, this panel has a lifetime span of 25 years at 400,000 vehicle-km per year in the vehicle operation. The results show that the use-phase, which dominates the environmental impact of the SMs of the railway passenger vehicle car body, is itself largely affected by electricity generation. In particular, the mass reduction in the models also achieved a reduction in environmental impact over its lifetime, mainly owing to decreased energy consumption. Another important finding regarding the manufacture of certain models (such as CFRP and GFRP) for lightweight design, is that assessment, based solely on mass reduction, may not always have better environmental performance or be reliable due to the manufacturing impact.


Assuntos
Meio Ambiente , Aço , Eletricidade
8.
PLoS One ; 15(8): e0237039, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32776956

RESUMO

The deformation law for axisymmetric deformation during the drawing of a core filled tube (CORFT) has been studied. However, the results of such studies could not be used in the flat rolling process of the CORFT, which is a plan deformation condition. In this paper, the inner core material and outer steel tube were successively analyzed based on the slab method during the flat rolling process (plan deformation) of the CORFT, and equations for wall thickness, core density, and roll force have been developed. The theoretical results solved by the developed equations were compared with the experimental results, revealing adequate accuracy for engineering requirements. The influences of rolling parameters on the roll force and the ultimate value of the relative density of the core material were studied, and the limiting condition for a larger roll force or higher value for relative density was obtained.


Assuntos
Aço/química , Força Compressiva , Simulação por Computador , Materiais de Construção , Manufaturas , Fenômenos Mecânicos , Resistência à Tração
9.
PLoS One ; 15(8): e0238074, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853254

RESUMO

To reduce the incidence of safety accidents during the construction of all-steel-type attached lifting scaffolds and address the research gaps in related fields, in this study a theoretical model of trajectory crossing accidents was coupled with an analysis of similar safety accidents to determine the causes of accidents in the construction of high-rise buildings using steel-type attached lifting scaffolds. To do so, a safety evaluation index system covering all steel-type attached lifting scaffolds that comprises five first-level indicators and 17 second-level indicators was established. The first-level indicators cover three risk dimensions: unsafe human behavior (personal operations), unsafe conditions (material performance, structural calculation, components and connections), and lack of management (safety management). A combined multi-agent-based modeling (MABM) method and structural entropy weight were used to calculate a comprehensive weight for better alignment of the weight calculation results with objective laws. A safety assessment model for an all-steel-type attached lifting scaffolding was constructed using grey relative Euclidean weighted correlation theory to enable the calculation of a grey-to-Euclidean weighted correlation degree that directly correlates with the degree of security. Using the established assessment model, four projects were subjected to a safety evaluation, with the results validating the model by revealing that its output was consistent with the actual security situation.


Assuntos
Materiais de Construção , Modelos Teóricos , Segurança , Aço , Fenômenos Mecânicos
10.
J Environ Manage ; 272: 111080, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32854886

RESUMO

Reclaiming water for cooling systems in oil refineries has been strongly encouraged over the past years for decreasing the large consumption of fresh water, thus contributing to the efficient use of this valuable resource. In a recent study [Journal of Environmental Management 261 (2020) 110229], some of the authors studied the retention of phenols in refinery wastewater through reverse osmosis (RO) and found rejections of up to 98% of phenols and 99% of both chemical oxygen demand (COD) and total organic carbon (TOC). The permeates complied with the quality standards for make-up water in cooling processes. A missing aspect, important for the water to be used in the oil and gas industry, was the level of corrosivity of the new permeates. In this work the corrosion of mild carbon steel in the permeates and in the original cooling tower make-up water was studied by electrochemical techniques. The corrosion rate of steel in the permeates in aerated conditions was lower (between 0.053 ± 0.006 and 0.123 ± 0.011 mm year-1) than in the make-up water (0.167 ± 0.030 mm year-1), confirming their suitability for replacing make-up water in the cooling towers. The low corrosion of carbon steel was attributed to the low conductivity and absence of oxidizing species in the fluids, compared to fresh water.


Assuntos
Carbono , Aço , Corrosão , Eliminação de Resíduos Líquidos , Água
11.
J Environ Manage ; 271: 111035, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778315

RESUMO

Human-made material stocks promote the economic prosperity, while the consumption, maintenance, and operation of them have led to adverse environmental impacts. Decoupling materials stocks from economic growth is a key strategy for relieving environmental pressures and achieving sustainable development. China's unprecedented development offers a unique opportunity for uncovering the relationship between in-use stocks and economic growth. In this study, we analyzed the regional disparity of in-use steel stocks estimated by bottom-up accounting method during 1978-2018 in 31 provinces in mainland China, explored the stocks productivity on provincial and regional scale, and conducted a decoupling analysis of in-use steel stocks with economic growth. The results showed that there was a huge disparity among the provincial total steel stocks, per-capita steel stocks, and stocks density. Some provinces, e.g. Beijing, Tianjin, and Shanghai, that had the highest stocks density had comparatively lower per-capita steel stocks and total steel stocks, indicating higher share of in-use steel stocks and lower material intensive economic structure. In-use steel stocks in China showed no clear signs of saturation or flatten off pattern although their growth rate declined recently. An increase in steel stocks productivity was found during 1978-2018, which means relative decoupling of in-use steel stocks from economic growth, but still far away from absolute decoupling. The dematerialization pattern revealed in this study deepens our understanding of material-economy interactions. Policy implications for dematerialization transition should focus on developing compact cities, prolonging the lifespan of products, and advancing technological development.


Assuntos
Desenvolvimento Econômico , Aço , Pequim , China , Cidades , Humanos
12.
Waste Manag ; 117: 179-187, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32861080

RESUMO

Steel slags are generally alkaline with a high calcium content and are viewed as a potential feedstock for carbon dioxide sequestration and utilization, mostly through aqueous mineral carbonation routes. For recovery of multiple metals such as Ca, Fe, Mg, and Si, and generation of value-added products by dissolution and precipitation reactions in aqueous media, enhancing the metal selectivity and extraction efficiency are important. However, there is limited understanding of independent parameters that influence these important characteristics. In this work, a systematic attempt was made to correlate these key dissolution characteristics of basic oxygen furnace slag in acidic media with its mineralogical and physical characteristics, the changes in aqueous chemistry, and the role of potential secondary precipitates. The findings from this study substantiate that steel slag is a potential feedstock because of the calcium being mainly present as orthosilicates, which were found to leach congruently without forming a leached layer that might hinder calcium extraction. The leaching of Fe(II) from the slag is the main source of impurity and its slow oxidation-precipitation leads to a pH plateau at the end of the dissolution step. Oxidation-precipitation of Fe(II) is controlled by hydroxyl concentration in the aqueous solution, which necessitates a pH-swing step by addition of a base after dissolution. Use of surface complexing agents, such as sodium molybdate, can significantly reduce iron impurity in the leachate and obtain an iron-rich slag residue for recycle to iron and steel industry.


Assuntos
Resíduos Industriais/análise , Aço , Dióxido de Carbono , Metais , Solubilidade
13.
J Environ Manage ; 274: 111220, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32823086

RESUMO

China is experiencing unprecedented industrialization and urbanization which promotes the rapid growth of iron resource consumption and in-use stock. The material flow analysis (MFA) model and the average use life method were applied to analyze China's iron in-use stock (IIUS), and the IIUS reached 7.07 billion tons in 2016 in the reference scenario. Three driving factors of the intensity of IIUS were analyzed. Among them, the per capita IIUS was rising, and it was 5.11 t/cap in 2016 in the reference scenario. In addition, the per capita crude steel output has stabilized, which was 0.58 t/cap in 2016. The intensity of crude steel use was declining and showed the inverted U-shape. The decoupling indicator was applied to analyze the relationship between IIUS and economic growth. The decoupling of IIUS from economic growth was later than that of actual iron consumption, and the IIUS did not decoupling from economic growth in recent years. The actual iron consumption has continued to decoupling from economic growth since 2010, and the decoupling indicator peaked at 1.76 in 2015. The future per capita IIUS was predicted in different scenario and the relationship between future IIUS and GDP was analyzed. The per capita IIUS will reach saturation in 2030-2040, and the intensity of IIUS also conforms to the inverted U-shape.


Assuntos
Desenvolvimento Econômico , Ferro , China , Aço , Urbanização
14.
Environ Sci Pollut Res Int ; 27(34): 43186-43201, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32734541

RESUMO

In recent years, off-site volumetric construction has been promoted as a viable strategy for improving the sustainability of the construction industry. Most prefabricated prefinished volumetric construction (PPVC) structures are composed of either steel or concrete; thus, it is imperative to carry out life cycle assessments (LCAs) for both types of structures. PPVC is a method by which free-standing volumetric modules-complete with finishes for walls, floors, and ceilings-are prefabricated and then transferred and erected on-site. Although many studies have examined these structures, few have combined economic and environmental life cycle analyses, particularly for prefinished volumetric construction buildings. The purpose of this study is to utilize LCA and life cycle cost (LCC) methods to compare the environmental impacts and costs of steel and concrete PPVCs "from cradle to grave." The results show that steel necessitates higher electricity usage than concrete in all environmental categories, while concrete has a higher emission rate. Steel outperforms concrete by approximately 37% in non-renewable energy measures, 38% in respiratory inorganics, 43% in land occupation, and 40% in mineral extraction. Concrete, on the other hand, performs 54% better on average in terms of measures adopted for greenhouse gas (GHG) emissions. Steel incurs a higher cost in the construction stage but is ultimately the more economical choice, costing 4% less than concrete PPVC owing to the recovery, recycling, and reuse of materials. In general, steel PPVC exhibits better performance, both in terms of cost and environmental factors (excluding GHG emissions). This study endeavors to improve the implementation and general understanding of PPVC.


Assuntos
Indústria da Construção , Aço , Materiais de Construção , Meio Ambiente , Malásia , Reciclagem
15.
Water Res ; 182: 115961, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32622125

RESUMO

Concrete corrosion, as a major issue in sewer management, has attracted considerable research. In comparison, the corrosion of reinforcing steel bar (rebar) is not well understood. Particularly, fundamental knowledge of rebar corrosion and its interactions with concrete corrosion/cracking is largely lacking. This study investigated rebar corrosion and concrete degradation using reinforced concrete coupons exposed in a pilot sewer system. The physical-chemical corrosion characteristics were investigated in local regions; the nature of rebar rusts was analyzed using the advanced mineral analytical techniques, including Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD); further, the interactions between rebar corrosion and concrete corrosion/cracking were elucidated by characterizing the microstructure and element distribution in interfacial areas using Mineral Liberation Analysis (MLA). The rebar corrosion products were found to be iron oxides, oxyhydroxides, chlorides, sulfides and sulfates. The predominant rebar corrosion reactions varied with exposure time and the development of concrete corrosion. When concrete corrosion reached rebar surface, the cracking of the concrete cover was influenced by multiple effects, including the macro-cracking induced by the corrosion products expansion, and the micro-cracking accelerated by the dissolution, diffusion and deposition of Fe derived from rebar rusts at the concrete corrosion front. A conceptual model elucidating rebar corrosion and the complex interactions between rebar corrosion and concrete degradation is proposed to support the development of corrosion prevention and refurbishment strategies for reinforced concrete sewers.


Assuntos
Esgotos , Sulfetos , Corrosão , Modelos Teóricos , Aço
17.
Wei Sheng Yan Jiu ; 49(3): 403-408, 2020 May.
Artigo em Chinês | MEDLINE | ID: mdl-32693888

RESUMO

OBJECTIVE: To analyze the effect of occupational noise exposure on hypertension in male steel workers. METHODS: The general information, noise exposure and blood pressure were collected through questionnaires and physical examinations. Chi-square test was used to investigate the prevalence of hypertension under different cumulative noise exposure, and the effect of noise exposure and other factors on hypertension was analyzed by the restrictive cubic spline(RCS) combined with multivariatenon-condition Logistic regression model. RESULTS: The prevalence of hypertension in noise exposure group was higher than that in noise non-exposure group(P<0. 001). After adjusting for multiple factors, the restricted cubic spline model showed a dose-response relationship between cumulative noise exposure(CNE) and hypertension(overall correlation χ~2=75. 76, P<0. 001, and nonlinear χ~2=24. 17, P<0. 001). Compared with the steel workers exposure to lowest dose, the risk of hypertension of steel workers exposure to 82-94 and 95-107 dB(A) in group was 1. 81(95%CI 1. 31-2. 52) times and 2. 60(95%CI 1. 84-3. 68) times. CONCLUSION: There is a non-linear dose-response relationship between cumulative noise exposure and hypertension.


Assuntos
Perda Auditiva Provocada por Ruído , Hipertensão , Ruído Ocupacional , Doenças Profissionais , Exposição Ocupacional , Humanos , Masculino , Aço
18.
Environ Sci Pollut Res Int ; 27(32): 40001-40008, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32651791

RESUMO

Paddy soil contamination by cadmium (Cd) and arsenic (As) is a great concern. Field experiments were conducted to study the effects of steel slag (SS, 2.0 and 4.0 t ha-1) on the solubility of Cd and As in soil and their accumulation by rice plants grown in a historically co-contaminated paddy field with Cd and As. The results showed that SS amendment (4.0 t ha-1) significantly decreased soluble concentrations of Cd in pore-water but increased that of As, related to markedly elevated soil pH and soluble silicon, phosphorus of pore-water in rice rhizosphere at both heading and mature stages. The amendments also evidently decreased Cd but enhanced As in iron plaque on root surfaces, while the formation of iron plaque was not significantly increased. Further, SS amendment (4.0 t ha-1) markedly reduced Cd concentrations in rice tissues (roots, straw, and brown rice) by 48-78% at both stages, though increased As by 13-38%. Cadmium translocation from roots to aerial parts decreased significantly after the amendments, but not for As. Besides, SS application increased the biomass of roots, straw and grains, and root antioxidant enzyme activities. Collectively, steel slag decreased Cd accumulation in rice tissues and in iron plaque but increased those of As, likely due to steel slag decreasing soluble Cd and enhancing soluble As in pore-water, related to soil pH and soluble nutrients (Si, P), and restraining Cd translocation within rice. Our results indicate that steel slag represents a favorable potential for Cd-contaminated paddy soils, though it seems undesirable for Cd and As co-contamination.


Assuntos
Arsênico , Oryza , Poluentes do Solo , Cádmio/análise , Solo , Poluentes do Solo/análise , Aço
19.
Environ Sci Pollut Res Int ; 27(32): 40135-40147, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32661969

RESUMO

In this study, a new reuse process of the coarse fraction of basic oxygen furnace (BOF) sludge based on iron recovery by the ferrous sulfate production was proposed. This study was based on three main steps: (i) characterization of the steel waste, (ii) evaluation and optimization of the recycling process, and (iii) characterization of ferrous sulfate produced. Acid leaching was used to solubilize the iron for obtaining ferrous sulfate heptahydrate. The ferrous sulfate crystallization was performed by adding anhydrous ethanol (EtOH). A multivariate optimization for iron leaching and ferrous sulfate precipitation in the same solution was employed. This optimization consisted of screening steps using a full factorial design followed by optimization. The coarse fraction of BOF sludge was predominantly composed of iron in metallic form (82.5%, dry weight). The sulfuric acid concentration and leaching time had significant effects on Fe(II) solubilization. The desirability function predicted the following optimized conditions: 20% (v/v) sulfuric acid solution, 200 min of leaching time, 7.00 g of waste, and 110 mL of anhydrous EtOH, producing 19.60 g of ferrous sulfate heptahydrate (yield of 70.8%). The characterization of ferrous sulfate was performed by X-ray diffraction, scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The characterization of the ferrous sulfate produced evidenced the effectiveness of the optimized process condition. Graphical abstract.


Assuntos
Ferro , Esgotos , Oxigênio , Aço , Difração de Raios X
20.
Environ Sci Pollut Res Int ; 27(32): 40537-40551, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32666463

RESUMO

Recently, nanomaterials have been introduced as a new generation of inhibitors to control the microbiologically influenced corrosion (MIC). In this study, copper nanoparticles doped carbon quantum dots (Cu/CQDs) nanohybrid was used as an inhibitor to reduce the MIC. FESEM, EDS, FTIR, and XRD were used to characterize the nanohybrid. The dose-response test was performed to evaluate the inhibitory effect of Cu/CQDs against SRB. Design-Expert software was used to design the matrix of experiment and analyze the result. Cu/CQDs showed significant inhibitory effect against SRB compared to the copper nanoparticles (CuNPs) and carbon quantum dots (CQDs), at 50 ppm. Moreover, corrosion behavior of X60 steel was evaluated via electrochemical impedance spectroscopy (EIS) and Tafel polarization techniques in the presence of SRB and Cu/CQDs. The fitted result of EIS showed that the charge transfer resistance (Rct) value increased in the presence of Cu/CQDs owing to the enhancement in the thickness of the electrical double layer, indicating that Cu/CQDs is able to provide significant corrosion protection to X60 steel in the presence of SRB. In addition, FESEM, EDS, and XRD were used to study the formed corrosion products and biofilm on the surface of X60 steel. Corrosion test results indicated that the addition of the Cu/CQDs reduced the surface damage of X60 steel in the presence of SRB. It is attributed to the carbon dots adsorption film formation, which possessed a significant protective ability to inhibit the corrosion of steel in the presence of SRB.


Assuntos
Cobre , Pontos Quânticos , Carbono , Corrosão , Aço
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