Efeito da força iônica da solução de equilíbrio na adsorção de cádmio em Latossolos brasileiros

Pierangeli, Maria Aparecida Pereira; Guilherme, Luiz Roberto Guimarães; Oliveira, Leyser Rodrigues; Curi, Nilton; Silva, Marx Leandro Naves

doi:10.1590/s0100-204x2003000600010

Cited by 19 publications

(9 citation statements)

References 14 publications

(12 reference statements)

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“…In the topsoil samples, the ∆G max decreased with increase in ionic strength, and the greatest values were between -6,640 (Rhodic Hapludalf) and -8,470 J mol -1 (Anionic "Rhodic" Acrudox) (Table 2), at ionic strength 0.01 mol L -1 Ca(NO 3 ) 2 . These results corroborated reports by Pierangeli et al (2003), who attributed the reduction in adsorption with the increase in ionic strength to competition among ions for exchange sites. In contrast, large increases in ∆G max would be observed, when ionic strength increased on the subsoil samples.…”

Section: Resultssupporting

confidence: 92%

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Zinc adsorption in highly weathered soils

Casagrande

Soares

Mouta

2008

Pesq. agropec. bras.

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-The objective of this work was to assess the effects of pH and ionic strength upon zinc adsorption, in three highly weathered variable charge soils. Adsorption isotherms were elaborated from batch adsorption experiments, with increasing Zn concentrations (0-80 mg L -1 ), and adsorption envelopes were constructed through soil samples reactions with 0.01, 0.1 and 1 mol L -1 Ca(NO 3 ) 2 solutions containing 5 mg L -1 of Zn, with an increasing pH value from 3 to 8. Driving force of reaction was quantified by Gibbs free energy and separation factor. Isotherms were C-, H-and L-type and experimental results were fitted to nonlinear Langmuir model. Maximum adsorption ranged from 59-810 mg kg ). Zinc adsorption was favorable and spontaneous, and showed sharply increase (20-90%) in the 4-6 pH range. No effect of ionic strength was observed at pH values below 5, because specific adsorption mechanisms predominated in the 3-5 pH range. Above pH 5, and in subsoil samples, Zn was adsorbed by electrostatic mechanisms, since ionic strength effect was observed. Despite depth and ionic strength effects, Zn adsorption depends mainly on the pH.Index terms: pH, adsorption envelope, adsorption isotherm, ionic strength, trace element. Adsorção de zinco em solos altamente intemperizadosResumo -O objetivo deste trabalho foi avaliar o efeito do pH e da força iônica sobre a adsorção de zinco, em três solos altamente intemperizados, com predomínio de cargas variáveis. A partir de experimentos tipo "batch", foram elaboradas isotermas de adsorção, com quantidades crescentes de Zn (0-80 mg L ).A adsorção de Zn foi favorável e espontânea, e mostrou nítido aumento (20-90%) no intervalo de pH entre 4 e 6. Não houve efeito da força iônica nos valores de pH abaixo de 5, o que indica o predomínio de mecanismos de adsorção específica na faixa de pH 3-5. Acima de pH 5 e no subsolo, o Zn foi adsorvido por mecanismos eletrostáticos, já que foi observado efeito da força iônica. Apesar dos efeitos da profundidade e da força iônica, a adsorção de Zn depende principalmente do pH.Termos para indexação: pH, envelope de adsorção, isoterma de adsorção, força iônica, elemento-traço.

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Section: Resultssupporting

confidence: 92%

“…Studies related to the ionic strength are appropriate to understand the stability, nature and intensity of the metal adsorption phenomenon, because they allow the distinction between specific and electrostatic mechanisms (Shuman, 1986;Naidu et al, 1994;Pierangeli et al, 2003), which are not yet fully understood for Zn.…”

Section: Introductionmentioning

confidence: 99%

Zinc adsorption in highly weathered soils

Casagrande

Soares

Mouta

2008

Pesq. agropec. bras.

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“…Cadmium adsorption by iron oxides and the correlation between Cd and Fe in soils are reported in the literature (King, 1998;Pierangeli et al, 2003;Alleoni et al, 2005b). In the soil, the Cd adsorption first occurs with a fast adsorption on iron oxide surfaces, and after a slow reaction that change the matrix ion for Cd, that undergoes a recrystalization.…”

Section: Resultsmentioning

confidence: 98%

Assessment of heavy metals in soils of a vineyard region with the use of principal component analysis

Valladares¹,

Camargo

Carvalho

et al. 2009

Sci. agric. (Piracicaba, Braz.)

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Agricultural management with chemicals may contaminate the soil with heavy metals. The objective of this study was to apply Principal Component Analysis and geoprocessing techniques to identify the origin of the metals Cu, Fe, Mn, Zn, Ni, Pb, Cr and Cd as potential contaminants of agricultural soils. The study was developed in an area of vineyard cultivation in the State of São Paulo, Brazil. Soil samples were collected and GPS located under different uses and coverings. The metal concentrations in the soils were determined using the DTPA method. The Cu and Zn content was considered high in most of the samples, and was larger in the areas cultivated with vineyards that had been under the application of fungicides for several decades. The concentrations of Cu and Zn were correlated. The geoprocessing techniques and the Principal Component Analysis confirmed the enrichment of the soil with Cu and Zn because of the use and management of the vineyards with chemicals in the preceding decades.

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“…Correlation coefficients between Cd adsorption and many soil properties for 17 Oxisols were inconclusive at pH 4.5, but highly significant at pH values of 5.5 and 6.5. Properties such as surface area, CEC, clay, kaolinite, and hematite contents were highly correlated (Pierangeli et al, 2003), emphasizing the importance of pH, surface area, and charge for Cd adsorption in these soils. Understanding mechanisms of metal adsorption in soils is important as these reactions control the strength of the metal-soil surface interactions (He et al, 2005).…”

Section: Introductionmentioning

confidence: 94%

Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption

Marchi

Vilar

O’Connor

et al. 2015

Rev. Bras. Ciênc. Solo

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intrinsic equilibrium constants for 22 representative brazilian oxisols were estimated from a cadmium adsorption experiment. Equilibrium constants were fitted to two surface complexation models: diffuse layer and constant capacitance. intrinsic equilibrium constants were optimized by fiteQl and by hand calculation using Visual minteQ in sweep mode, and excel spreadsheets. data from both models were incorporated into Visual minteQ. constants estimated by fiteQl and incorporated in Visual minteQ software failed to predict observed data accurately. however, fiteQl raw output data rendered good results when predicted values were directly compared with observed values, instead of incorporating the estimated constants into Visual minteQ. intrinsic equilibrium constants optimized by hand calculation and incorporated in Visual minteQ reliably predicted cd adsorption reactions on soil surfaces under changing environmental conditions.

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Efeito da força iônica da solução de equilíbrio na adsorção de cádmio em Latossolos brasileiros

Cited by 19 publications

References 14 publications

Zinc adsorption in highly weathered soils

Zinc adsorption in highly weathered soils

Assessment of heavy metals in soils of a vineyard region with the use of principal component analysis

Surface Complexation Modeling in Variable Charge Soils: Prediction of Cadmium Adsorption

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