排序方式: 共有62条查询结果,搜索用时 31 毫秒
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Romário J. da Silv Lizeth Carolina Mojica-Sánchez Filipe D.S. Gorz Graciela C. Pedro Bruna G. Maciel Gabriela P. Ratkovski Hérica D. da Roch Kamila T.O. do Nascimento Juan C. Medina-Llamas Alicia E. Chávez-Guajardo José J. Alcaraz-Espinoz Celso P. de Melo 《环境科学学报(英文版)》2021,33(2):62-73
We report the preparation of poly(3,4-ethylene dioxythiophene) (PEDOT)-modified polyvinylidene fluoride electrospun fibers and their use as a novel adsorbent material for the removal of the anionic dye Methyl Orange (MO) from aqueous media. This novel adsorbent material can be used to selectively remove MO on a wide pH range (3.0–10.0), with a maximum capacity of 143.8 mg/g at pH 3.0. When used in a recirculating filtration system, the maximum absorption capacity was reached in a shorter time (20 min) than that observed for batch mode experiments (360 min). Based on the analyses of the kinetics and adsorption isotherm data, one can conclude that the predominant mechanism of interaction between the membrane and the dissolved dye molecules is electrostatic. Besides, considering the estimated values for the Gibbs energy, and entropy and enthalpy changes, it was established that the adsorption process is spontaneous and occurs in an endothermic manner. The good mechanical and environmental stability of these membranes allowed their use in at least 20 consecutive adsorption/desorption cycles, without significant loss of their characteristics. We suggest that the physical-chemical characteristics of PEDOT make these hybrid mats a promising adsorbent material for use in water remediation protocols and effluent treatment systems. 相似文献
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Brondi SH De Macedo AN de Souza GB Nogueira AR 《Journal of environmental science and health. Part. B》2011,46(8):671-677
Analytical methods for the isolation and determination of cypermethrin in milk, based on the solid-phase microextraction (SPME) and QuEChERS methods (Quick, Easy, Cheap, Effective, Rugged, and Safe) are presented. The SPME technique was not appropriate to analyse cypermethrin in milk, even establishing the best extraction conditions, polydimethylsiloxane fiber, 60 min time extraction, 60 °C temperature extraction, addition of salt (NaCl) and stirring rate. The extraction efficiency was low probably because of the matrix constituents. The QuEChERS method involves the extraction of the analyte with acetonitrile and simultaneous liquid-liquid partitioning formed by adding anhydrous MgSO(4) plus NaCl, followed by the removal of residual water and cleanup using a procedure called dispersive solid-phase extraction, in which anhydrous MgSO(4) plus PSA and C18 are mixed with 1 mL of acetonitrile extract. The detection and quantification limits were 0.01 and 0.04 mg kg(-1), respectively, and the percentage recovery obtained ranged from 92 to 105% with relative standard deviations below 7%. 相似文献
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Jeremias Pakulski Panizzon Vera Regina Mussoi Macedo Vilmar Machado Lidia Mariana Fiuza 《Environmental monitoring and assessment》2013,185(3):2767-2775
In this study, we evaluate spatial and temporal variations of the water’s quality used in rice fields. Every 15 days during the different phases of cultivation of the rice—vegetative, reproductive, and maturity—samples were collected from the main irrigation channel, from the surface water in the field, and from the excess-water drainage channel. The differences in the values of 13 variables were analyzed by the analysis of variance system and by the Principal Component Analysis (PCA) technique. The results demonstrate that the values observed for the presence of total coliforms, heat-tolerant coliforms, and pH were higher in the irrigation water and that the calcium and magnesium components were greater in the drainage water. The PCA results indicate that three groups of variance exist and that these three account for 77 % of the observed variances. The first principal component, (39 % of the variances), includes the variables pH, phosphorus, potassium, carbon, and turbidity; the second (28.1 %), calcium, magnesium, and conductivity; while the third accounts for only 9.9 % of the variation and incorporates the variable biological thermotolerant coliforms. The spatial pattern resulting from the distribution of the sampling locations as regards the first two principal components indicates a difference between the irrigation and drainage waters. The variables of the first and third items (except for the turbidity in the second component) reach higher values in the irrigation water, while the variables associated with the second component have higher values in the drainage water. The information provided is important for the analysis of the influence exercised by plantation management decisions on the microbiological, physical, and chemical quality of the water. The results confirm the ability of paddy rice field to filter out some of the chemicals and coliforms from the irrigation water as it passes through the agro ecosystem. 相似文献
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Moura FC Araujo MH Costa RC Fabris JD Ardisson JD Macedo WA Lago RM 《Chemosphere》2005,60(8):1118-1123
In this work a novel heterogeneous Fenton system based on Fe(0)/Fe3O4 composites is described. The composites with several Fe(0)/Fe3O4 ratios were prepared by two different methods, i.e. mechanical alloying of Fe(0) and Fe3O4 powders and controlled reduction of Fe3O4 with H2. Reaction studies and detailed Conversion Electron M?ssbauer surface characterization of the composites Fe(0)/Fe3O4, Fe(0), Fe3O4, alpha-Fe2O3 and gamma-Fe2O3 suggested that Fe2+surf species are essential to produce an active Fenton system. Kinetic studies for the oxidation of the dye methylene blue, used as an organic model molecule, and for the peroxide decomposition suggest that the reactions proceed via HO* radicals generated from Fe2+surf species and H2O2 in a Fenton like mechanism. The increase in activity caused by the addition of Fe(0) is discussed in terms of a creation of Fe2+surf species during the preparation of the composite and by an electron transfer mechanism from Fe(0) to Fe3+surf during the Fenton reaction to regenerate the Fe2+surf active species. 相似文献
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Ivan Viegas Sónia Cotrim Marques Filipa Bessa Ana Lígia Primo Filipe Martinho Ulisses Miranda Azeiteiro Miguel ?ngelo Pardal 《Marine Biology》2012,159(1):33-43
This study provides a comprehensive examination of the life cycle dynamics of the brown shrimp (Crangon crangon L.) in the Mondego estuary, Portugal, a habitat located near the southern edge of the range of this species in European waters.
The phenology of all life stages was documented (from the occurrence of ovigerous females, developing embryos, planktonic
larvae and benthic post-larvae), and migration patterns of larvae into and out of the estuary were examined. Temperature-dependent
functions of egg and larval development were combined with data on field abundance to predict the timing and magnitude of
occurrence of larvae and recruits. Compared to brown shrimp at higher latitudes, southern conspecifics grow slower, mature
earlier and have smaller brood sizes, and larvae have a more protracted settlement period. The Mondego estuary, besides acting
as nursery area, is a dynamic platform for C. crangon to use in different stages, sizes and seasons. 相似文献
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Sophie Quérouil Luís Freitas Irma Cascão Filipe Alves Ana Dinis Joana R. Almeida Rui Prieto Silvia Borràs José A. Matos Diogo Mendonça Ricardo S. Santos 《Marine Biology》2010,157(11):2567-2580
Several cetacean species exhibit fine-scale population structure despite their high dispersal capacities and the apparent continuity of the marine environment. In dolphins, most studies have focused on coastal areas and continental margins, and they revealed differentiated populations within relatively small geographic areas, sometimes in conjunction with a specialisation for different habitats (ecotypes). We analysed the population genetic structure of short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) in the Azores and Madeira, the two most isolated archipelagos of the North Atlantic. The archipelago of the Azores is divided into three groups of islands and stands 900 km away from Madeira. It is not known whether individuals migrate between groups of islands and archipelagos, nor whether distinct ecotypes are present. These questions were investigated by genetic analyses of 343 biopsy samples collected on free-ranging dolphins. The analyses consisted in sequencing part of the mitochondrial hyper-variable region, screening up to 14 microsatellite loci, and molecular sexing. Results did not unravel any population structure at the scale of the study area. Lack of differentiation matches expectations for spotted dolphins, which are transient in both archipelagos, but not for common dolphins, which are present year-round in the Azores and potentially resident. Absence of genetic structure over hundreds and even thousands of kilometres implies the existence of gene flow over much larger distances than usually documented in small delphinids, which could be achieved through individual movements. This finding indicates that population structure in oceanic habitat differs from that observed in coastal habitat. 相似文献
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Moretto Cristiane Castellane Tereza Cristina Luque Leonel Tatiane Fernanda Campanharo Joao Carlos de Macedo Lemos Eliana Gertrudes 《Environmental science and pollution research international》2022,29(31):46953-46967
Environmental Science and Pollution Research - Rhizosphere bacteria, for example, rhizobia, can play several roles, and one of the most important, the protection of plant roots against toxic... 相似文献