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Registros recuperados: 18
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Adsorption of p-cresol on Granular Activated Carbon CIGR Journal
Lalitendu Das; North Carolina State University Biological and Agricultural Engineering; Praveen Kolar; North Carolina State University; Jason Osborne; North Carolina State University Department of Statistics; John Classen; North Carolina State University Biological and Agricultural Engineering.
Swine farming emit several odorous volatile organic compounds, one of which is p-cresol. Considering the layout of a swine barn, adsorption is one of the most suitable technologies for mitigating organic pollutants. In this study, commercial granular activated carbon (GAC) was tested as an adsorbent for removing p-cresol from aqueous solution. The objectives were to: 1) determine the combined effect of temperature, pH, and adsorbent dose on adsorption, (2) investigate the effect of volatile fatty acids and aldehydes on adsorption of p-cresol, (3) determine adsorption kinetics and isotherms, (4) study the effect of solvent on adsorption, (5) propose a possible mechanism of adsorption, and (6) discuss practical implications and design calculations for...
Palavras-chave: Agricultural Engineering Adsorption; P-cresol; Activated carbon; Kinetics; Isotherms; RSM.
Ano: 2012 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/2171
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Applicability of Moringa oleifera Lam. pie as an adsorbent for removal of heavy metals from waters AGRIAMBI
Gonçalves Junior,Affonso C.; Meneghel,Ana P.; Rubio,Fernanda; Strey,Leonardo; Dragunski,Douglas C.; Coelho,Gustavo F..
This study evaluated the efficacy of moringa seeds (Moringa oleifera Lam.) as an adsorbent material for removing toxic heavy metals such as cadmium, lead, and chromium from contaminated solutions. The effect of the adsorbent mass was investigated at two pH conditions (5.0 and 7.0). The optimized conditions were 0.300 g of adsorbent at pH 5.0, used for the isotherms construction, and linearized according to Langmuir and Freundlich models. Results showed that cadmium adsorption was similar in both the models used. For lead, the Freundlich model had the best adjustment and chromium was better adjusted by the Langmuir model. It was concluded that the adsorbent was effective in the remediation of solutions containing cadmium, lead and chromium, thus, its use as...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Adsorption; Isotherms; Remediation.
Ano: 2013 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662013000100013
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Application of mathematical models for the prediction of adsorption isotherms in solid mixture for mango powder refreshment Ciênc. Tecnol. Aliment.
Clemente,Edmar; Afonso,Marcos Rodrigues Amorim; Souza,Ana Paula; Correia,José Maria; Pires,Raquel Gomes; Maia,Geraldo Arraes.
Solid mixtures for refreshment are already totally integrated to the Brazilian consumers' daily routine, because of their quick preparation method, yield and reasonable price - quite lower if compared to 'ready-to-drink' products or products for prompt consumption, what makes them economically more accessible to low-income populations. Within such a context, the aim of this work was to evaluate the physicochemical and mineral composition, as well as the hygroscopic behavior of four different brands of solid mixture for mango refreshment. The BET, GAB, Oswim and Henderson mathematical models were built through the adjustment of experimental data to the isotherms of adsorption. Results from the physiochemical evaluation showed that the solid mixtures for...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Adsorption; Isotherms; Mathematical models; Nutritious powders; Refreshment; Mango.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-20612011000300010
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Biosorption of chromium (VI) from aqueous solutions by the husk of Bengal gram (Cicer arientinum) Electron. J. Biotechnol.
Ahalya,N; Kanamadi,R.D; Ramachandra,T.V.
The potential to remove Cr (VI) from aqueous solutions through biosorption using the husk of Bengal gram (Cicer arientinum), was investigated in batch experiments. The results showed removal of 99.9% of chromium in the 10 mgl-1 chromium solution, the biomass required at saturation was 1 g mg-1. Kinetic experiments revealed that the dilute chromium solutions reached equilibrium within 180 min. The biosorptive capacity of the (bgh) was dependent on the pH of the chromium solution, with pH 2 being optimal. The adsorption data fit well with the Langmuir and Freundlich isotherm models. The adsorption capacity calculated from the Langmuir isotherm was 91.64 mg Cr (VI)/g at pH 2. The adsorption capacity increased with increase in agitation speed and an optimum...
Tipo: Journal article Palavras-chave: Agro-wastes; Bengal gram husk (bgh); Cicer arientinum; Chromium biosorption; Isotherms; Fourier transform infrared spectroscopy (FTIR).
Ano: 2005 URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-34582005000300005
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Cadmium and copper adsorption on bentonite: effects of pH and particle size Rev. Ciênc. Agron.
Chaves,Lúcia Helena Garófalo; Tit,Gilvanise Alves.
Reactions of heavy metals with clay minerals are important in determining metal fates in the environment. However, the adsorption process of these metals by the bentonite has been extensively investigated. The objectives of this work were to assess the ability of bentonite clay to adsorb cadmium and copper and to study the effects of pH and particle size upon these metals adsorption. Adsorption isotherms were obtained from batch adsorption experiments, with increasing cadmium and copper concentrations (5-200 mg L-1). To find out the effects of pH and particle size on adsorption, the experiments were conducted at pH 4; 5 and 6 using particles sizes of < 0.5 mm and 0.5 to 2.0 mm . The difference between initial and final cadmium and copper concentrations...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Clay mineral; Heavy metals; Isotherms; Langmuir.
Ano: 2011 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902011000200004
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Copper adsorption in tropical oxisols BABT
Silveira,Maria Lucia Azevedo; Alleoni,Luís Reynaldo Ferracciú.
Cu adsorption, at concentrations between 0 to 800 mg L-1, was evaluated in surface and subsurface samples of three Brazilian soils: a heavy clayey-textured Rhodic Hapludalf (RH), a heavy clayey-textured Anionic ''Rhodic'' Acrudox (RA) and a medium-textured Anionic ''Xanthic'' Acrudox (XA). After adsorption, two consecutive extractions were performed to the samples which received 100 mg L-1 copper. Surface samples adsorbed higher amounts of Cu than the subsurface, and exhibited lower Cu removed after the extractions, reinforcing the influence of the organic matter in the reactions. Cu adsorption was significant in the subsurface horizons of the Oxisols, despite the positive balance of charge, demonstrating the existence of mechanisms for specific...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Adsorption; Isotherms; Desorption; Tropical soil.
Ano: 2003 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132003000400006
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Development of moisture isotherms for Momordica charantia and Carica papaya CIGR Journal
Rupasinghe, chintha Priyangani; Jayasinghe, Udara; Sugathapala, Thusitha.
Safe moisture of a product is important in drying of agricultural products to prevent it from deterioration. The equilibrium moisture content (EMC) is an important parameter in modeling and simulation of drying process. The objectives of the research are development of an EMC curve for Agricultural Products; bitter gourd (Momordica charantia) and papaya (Carica papaya) and to test the suitability of mathematical models of modified Henderson’s equations. The study is performed on the basis of adsorption of moisture content, at three temperatures (30, 40 & 50°C) and four relative humidity (Rh) (10, 30, 50 and 80%). Salt solutions with concentrations were used to maintain Rh. The statistical analysis was done to find the best model and the significant...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Post harvest technology Equilibrium moisture content; Adsorption; Isotherms; Mathematical model.
Ano: 2019 URL: http://www.cigrjournal.org/index.php/Ejounral/article/view/5114
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Drying kinetics of fermented grape pomace: Determination of moisture effective diffusivity AGRIAMBI
Deamici,Kricelle M.; Oliveira,Lucas C. de; Rosa,Gabriela S. da; Oliveira,Elizangela G. de.
ABSTRACT The aim of this study was to obtain the equilibrium moisture content of grape (variety ‘Tannat’) pomace through desorption isotherms, to evaluate the drying kinetics, determine the coefficient of effective diffusivity and physico-chemically characterize the grape pomace and the product obtained after drying. The desorption isotherms were determined at 50, 60 and 70 ºC and the experimental data were fitted using the GAB model (Gugghenheim, Anderson and de Boer). Drying was evaluated using a 22 factorial experimental design with three center points and effective diffusivity was obtained through the diffusion model of Fick’s second law. The grape pomace was characterized regarding the contents of moisture, protein, carbohydrates, lipids, ash and...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Byproducts; Isotherms; Proteins; Fibers.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662016000800763
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El Niño 1982-83, su formación, su desarrollo y sus manifestaciones en aguas ecuatorianas OceanDocs
Zambrano, E.; Moreano, H.R.; Trejos de Suescum, R.; Paredes, N..
"El Niño" 1982-83 respondió a un patrón de formación diferente a aquel que había sido característico para los fenómenos anteriores, a tal punto que sobrevino en forma sorpresiva y como una consecuencia de las fluctuaciones climáticas relacionadas con la oscilación Sur. Su desarrollo se inició en Junio de 1982 y no llegó a la costa ecuatoriana sino hasta Octubre, aunque en agosto ya se sentían sus primeras manifestaciones como la tendencia del Frente Ecuatorial a desplazarse hacia el sur y la profundización de las isotermas y la termoclina. En Noviembre el fenómeno estaba en pleno desarrollo en las aguas nacionales y en enero llegaba a la máxima intensidad, para posteriormente notarse un ascenso paulatino de las isotermas y termoclina, aunque las...
Tipo: Journal Contribution Palavras-chave: El Nino phenomena; Coastal upwelling; Biota; Isotherms; Biota.
Ano: 1986 URL: http://hdl.handle.net/1834/2122
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El Niño 1982-83, su formación, su desarrollo y sus manifestaciones en aguas ecuatorianas OceanDocs
Moreano, H.R.; Zambrano, E.; Trejos de Suescum, R.; Paredes, N..
"El Niño" 1982-83 respondió a un patrón de formación diferente a aquel que había sido característico para los fenómenos anteriores, a tal punto que sobrevino en forma sorpresiva y como una consecuencia de las fluctuaciones climáticas relacionadas con la oscilación Sur. Su desarrollo se inició en Junio de 1982 y no llegó a la costa ecuatoriana sino hasta Octubre, aunque en agosto ya se sentían sus primeras manifestaciones como la tendencia del Frente Ecuatorial a desplazarse hacia el sur y la profundización de las isotermas y la termoclina. En Noviembre el fenómeno estaba en pleno desarrollo en las aguas nacionales y en enero llegaba a la máxima intensidad, para posteriormente notarse un ascenso paulatino de las isotermas y termoclina, aunque las...
Tipo: Journal Contribution Palavras-chave: El Nino phenomena; Coastal upwelling; Biota; Isotherms; Biota.
Ano: 1986 URL: http://hdl.handle.net/1834/2122
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Estudios de algunas características físicas y biológicas de la columna de agua en Bahía Chile-Isla Greenwich OceanDocs
Cornejo, María P.; Arcos, F..
Se determinaron algunas características físicas y biológicas de la columna de agua en Bahía Chile, Isla Greenwich, por medio de la distribución espacial de temperatura, salinidad y clorofila "a", durante el verano austral (febrero de 1990). Las distribuciones verticales de las isotermas, isohalinas, isopicnas e isolíneas de clorfila "a" muestran que la circulación predominante es termohalina, influenciada por la topografía de la bahía, con un flujo subsuperficial que entra por el lado noroccidental de la misma y se dirige hacia el centro (siguiendo la topografía), aflora en el extremo interior y sale superficialmente por el lado oriental.
Tipo: Journal Contribution Palavras-chave: Chemical oceanography; Marine ecology; Salinity; Isotherms; Isopycnics; Thermohaline circulation; Chlorophylls; Chemical oceanography; Marine ecology; Salinity; Chlorophylls; Http://aims.fao.org/aos/agrovoc/c_1516; Http://aims.fao.org/aos/agrovoc/c_4609; Http://aims.fao.org/aos/agrovoc/c_6751; Http://aims.fao.org/aos/agrovoc/c_1577.
Ano: 1990 URL: http://hdl.handle.net/1834/3728
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Hygroscopicity of ‘sucupira-branca’ (Pterodon emarginatus Vogel) fruits AGRIAMBI
Oliveira,Daniel E. C. de; Resende,Osvaldo; Costa,Lílian M.; Silva,Glicélia P.; Sales,Juliana de F..
ABSTRACT ‘Sucupira-branca’ (Pterodon emarginatus Vogel) is a tree from ‘Cerrado’ and stands out mainly for its pharmacological properties; however, there are no technological information about its post-harvest operations. Thus, the aim of this study was to determine the sorption isotherms of ‘sucupira-branca’ fruits for different air conditions and obtain the values of desorption isosteric heat, depending on the equilibrium moisture content of the product. The equilibrium moisture content of ‘sucupira-branca’ fruits was determined by dynamic method for temperatures of 25, 30, 35 and 40 °C and water activities for each temperature between 0.270 and 0.775. The models Chung-Pfost, Copace, Modified Halsey, Oswin Modified and Sigma Copace obtained high...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Equilibrium moisture content; Isotherms; Water activity; Isosteric heat; Copace.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1415-43662017000400285
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Kinetic and isotherm studies of copper (II) removal from wastewater using various adsorbents OceanDocs
Abdel Wahab, O..
The present investigation deals with the utilization of marine green algae (GA), Ulva lactuca, and an activated carbon prepared from green algae (CGA) as adsorbents for the removal of copper from wastewater. A series of experiments were conducted in a batch system to evaluate the effect of system variables. The effect of pH, initial copper concentration, dose of adsorbents were considered. The optimal pH value of copper (II) adsorption onto GA and CGA was found to be pH 5.0. The maximum uptake capacities were 24.5 and 32.3 mg copper (II) per gram of GA and CGA, respectively. The efficiency of removal was slightly changed by replacing an aqueous solution by saline water or wastewater containing the same copper concentration. Adsorption kinetic data were...
Tipo: Journal Contribution Palavras-chave: Laboratory Study; Adsorption; Kinetics; Isotherms; Waste water; Adsorption; Http://aims.fao.org/aos/agrovoc/c_137.
Ano: 2007 URL: http://hdl.handle.net/1834/1910
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Removal of copper in cachaças using clays Ciência e Agrotecnologia
Duarte,Felipe Cimino; Cardoso,Maria das Graças; Magriotis,Zuy Maria; Santiago,Wilder Douglas; Mendonça,João Guilherme Pereira; Rodrigues,Leonardo Milani Avelar.
Increased production and cachaça consumption has stimulated research regarding its quality. It is known that copper can be harmful to human health when it is in concentrated form in the beverage and is ingested in large amounts. Thus, there is a great concern among researchers and producers about the use of adsorbent substances for the removal of excess copper. The kinetic parameters and the adsorption isotherms for copper on kaolinite were studied to evaluate the physical-chemical quality of the cachaça before and after adsorption. K01, K03 and K04 kaolinites presented a maximum adsorption capacity of 97, 95 and 90%, respectively. The kinetic rates followed the pseudo-first-order model, and the adsorption isotherm was best adjusted to the Freundlich...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Beverage; Kinetic parameters; Isotherms; Adsorption.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542014000400009
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Sorption and desorption of Suflafenacil in two soils in the state of São Paulo with different physical and chemical attributes Planta Daninha
Matallo,M.B.; Franco,D.A.S.; Almeida,S.D.B.; Cerdeira,A.L..
A study was conducted to evaluate the sorption and desorption of 14C herbicide saflufenacil (pyrimidinedione) in two soils in the State of São Paulo, classified as Red Yellow Latosol with clayey texture (LVA-1) and medium texture (LVA-2), using the batch method through isotherms. The soils were air dried and sieved a 2 mm mesh. The radioactivity was determined by liquid scintillation spectrometry in acclimatized room (25 ± 2 °C). Sorption isotherms were conducted for 5 concentrations of saflufenacil (5.0; 2.5; 1.0; 0.5 and 0.05 μg mL-1) and the results were adjusted to the Freundlich equation, thus obtaining the parameters of sorption followed by two extractions with 0.01 M CaCl2 to determine desorption parameters similarly to sorption. The results showed...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Isotherms; Hysteresis; Herbicides.
Ano: 2014 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582014000200017
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The effect of encapsulants on the heat of sorption in vacuum-dried cajá powder Rev. Ciênc. Agron.
Gomes,Maron Stanley Silva Oliveira; Polachini,Tiago Carregari; Lopes Filho,José Francisco; Romero,Javier Telis.
ABSTRACT Equilibrium moisture data from the powdered pulp of Spondias mombin, L., both with and without additives - 58% maltodextrin (MD) or 58% gum arabic (GA) - were determined at 20, 30, 40 and 50 °C, using the static gravimetric method for a water activity range of 0.06 to 0.90. The resulting isotherms were sigmoidal and typical Type III, with the Guggenheim-Anderson-de-Boer model (GAB) adjusted to the experimental data for equilibrium moisture vs water activity. The addition of additives was shown to affect the isotherms in such a way that, for the same water activity, samples of CP+GA and CP+MD showed a lower equilibrium moisture content and were not affected by the variations in temperature. The isosteric heat of sorption for the cajá powder with...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Isotherms; Maltodextrin; Gum arabic Water activity.
Ano: 2019 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1806-66902019000400584
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Un análisis de la estructura termal de la estación costera "La Libertad" y su relación con los eventos ENOS OceanDocs
Zambrano, E..
El Instituto Oceanográfico de la Armada (INOCAR) mantiene desde 1990 hasta la fecha una estación costera a 10 millas náuticas frente a las costas del puerto de La Libertad (Península de Santa Elena), en la que se efectúa un muestreo de toda la columna de agua desde la superficie hasta los 100 m de profundidad, cada 20 días. Del análisis preliminar se ha podido observar que la distribución de las isotermas responde a la presencia de los eventos ENOS; como se conoce durante un episodio ENOS la costa del Ecuador es visitada por ondas ecuatoriales, las cuales a su paso producen una elevación del medio del mar y una profundización de las isotermas. Por lo que se considera que esta distribución de las isotermas guarda relación con la ocurrencia de los eventos...
Tipo: Journal Contribution Palavras-chave: Isotherms; Equatorial waves; Sea level; El Nino phenomena; Water temperature; Oceanographic stations; Water temperature; Sea level; Http://aims.fao.org/aos/agrovoc/c_16063; Http://aims.fao.org/aos/agrovoc/c_34115.
Ano: 1998 URL: http://hdl.handle.net/1834/2197
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Variabilidad oceanográfica en Ecuador asociada con el evento ENSO 1997-98 OceanDocs
Martínez, R.; Zambrano, E.; Garcés Vargas, J..
El objetivo de este artículo es documentar científicamente la evolución del evento "El Niño" en Ecuador, desde el punto de vista oceanográfico, sugiriendo posibles mecanismos involucrados en este proceso, vinculados a ondas interestacionales Kelvin en el océano (Kessler et al., 1995) que actúan como contraparte a las oscilaciones de 60 a 75 días en la atmósfera (Maden - Julian, 1995) y más específicamente de ondas encontradas en los espectros de nivel medio del mar y TSM en el mar ecuatoriano- colombiano con estas mismas características (Martínez, 1998).
Tipo: Journal Contribution Palavras-chave: Variability; Isotherms; Thermohaline circulation; El Nino phenomena; Surface temperature; Cruises; Kelvin waves; Air temperature; Mean sea level; Salinity charts; Air temperature.
Ano: 2000 URL: http://hdl.handle.net/1834/2245
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