Utilização de eletrodos potenciométricos de amálgama em estudos de complexação de substâncias húmicas

Abate, Gilberto; Masini, Jorge C.

doi:10.1590/s0100-40421999000500006

Cited by 10 publications

(7 citation statements)

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“…For complexometric titrations both pH-meters were used; one of them was used for monitoring the pH, that was kept at pH 6.00 ± 0.05 with the aid of the above mentionated combination glass electrode. The other pHmeter was used with an ion selective electrode (ISE-Orion 9429) for Cu(II), or with a hanging mercury drop electrode (HMDE -Metrohm 6.0335-000) filled with Pb, Cd or Zn amalgams, prepared according previous papers 8,9 , and using a double junction Ag/AgCl reference electrode (Mettler 373-90WTEISE-S7/105).…”

Section: Apparatus and Reagentsmentioning

confidence: 99%

“…The preparation of the standard solutions of metallic cations and sodium hidroxide solutions has already been described in the literature 9,[16][17][18] .…”

Section: Apparatus and Reagentsmentioning

confidence: 99%

“…For studies with Pb 2+ , Cd 2+ and Zn 2+ , potentiometric amalgam electrodes were prepared according to a previous paper 9 with the aid of a Metrohm Hanging Mercury Drop Electrode. For these experiments, all solutions were previously degassed with ultrapure N 2 (O 2 < 1 ppm) for 10 minutes.…”

Section: Complexometric Titrationsmentioning

confidence: 99%

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Acid-basic and complexation properties of a sedimentary humic acid. A study on the Barra Bonita reservoir of Tietê river, São Paulo State, Brazil

Abate

Masini

2001

J. Braz. Chem. Soc.

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Estudaram-se as propriedades ácido-base e de complexação de ácido húmico (AH) isolado de sedimento de rio por titulação potenciométrica, adotando-se o modelo de distribuição de sítios discretos e funções de Gran modificadas para tratamento dos dados. Foram caracterizadas seis classes de grupos tituláveis, com valores de pK entre 2,4 e 10,2. Grupos carboxílicos contribuiram com 66% do total de sítios ionizáveis. Estudaram-se as propriedades complexométricas com os íons Cu 2+ , Pb 2+ , Cd 2+ e Zn 2+ através de titulações potenciométricas com eletrodo íon-seletivo para Cu ou eletrodos de amálgama (Pb, Cd e Zn). O tratamento dos dados pelo método de Scatchard revelou a existência de duas classes de sítios complexantes para cobre e chumbo e uma classe para cádmio e zinco. As constantes de estabilidade médias seguiram a ordem: log KAH-Cu > log KAH-Pb > log KAH-Cd ≅ log KAH-Zn, e a ordem da capacidade complexante, C c , foi: Pb > Cu > Cd ≅ Zn.Acid-base and complexation properties of humic acid (HA) isolated from a river sediment were studied by potentiometric titration, adopting the discrete site distribution model and the modified Gran functions for data fitting. Six classes of titratable groups were characterized, with pKa values between 2.4 and 10.2. Carboxylic groups accounted for 66% of the total of ionizable sites. The complexing properties were studied with regard to Cu 2+ , Pb 2+ , Cd 2+ and Zn 2+ ions by potentiometric titration using Cu ion selective electrode, or amalgam electrodes (Pb, Cd and Zn). The data treatment by the Scatchard method revealed two binding sites for copper and lead and one binding site for cadmium and zinc. The average stability constants were in the following order: log KHA-Cu > log KHA-Pb > log KHA-Cd ≅ log KHA-Zn, while the complexing capacity order, C c , was: Pb > Cu > Cd ≅ Zn.

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Section: Apparatus and Reagentsmentioning

confidence: 99%

“…The preparation of the standard solutions of metallic cations and sodium hidroxide solutions has already been described in the literature 9,[16][17][18] .…”

Section: Apparatus and Reagentsmentioning

confidence: 99%

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Acid-basic and complexation properties of a sedimentary humic acid. A study on the Barra Bonita reservoir of Tietê river, São Paulo State, Brazil

Abate

Masini

2001

J. Braz. Chem. Soc.

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“…No caso das titulações de complexação, os tratamentos de dados para calibração do eletrodo íon seletivo a Cu(II), cálculo de concentração de Cu(II) livre, [Cu(II)], e complexado, [CuL], também podem ser encontrados em publicações anteriores 11,15,16 . No presente trabalho adotou-se que os dados experimentais de complexação podem ser descritos pela equação da isoterma de Langmuir, que assume que os complexos formados têm estequiometria 1:1 e que o experimento é conduzido em força iônica e temperatura constantes, de modo que a carga elétrica sobre a superfície mantém-se constante, assim como sua conformação espacial.…”

Section: Métodos De Cálculounclassified

Propriedades ácido-base e de complexação de ácidos húmico e fúlvico isolados de vermicomposto

Colombo¹,

Santos²,

Masini³

et al. 2007

Quím. Nova

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“…A Radelkis OP 936 microburette supporting a 10-mL glass syringe was used to dispense copper titrant. The dissolved oxygen was previously removed by bubbling ultrapure nitrogen (99.99%) through the solution for 15 min and a nitrogen atmosphere was maintained above the solution during the experiments [12]. Almost all experiments were performed at 25.0±0.1°C and ionic strength adjustment of 0.1 mol L -1 NaNO 3 .…”

Section: Ion Selective Electrode (Ise) Proceduresmentioning

confidence: 99%

Tangential-flow ultrafiltration: a versatile methodology for determination of complexation parameters in refractory organic matter from Brazilian water and soil samples

et al. 2003

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In this work the copper(II) complexation parameters of aquatic organic matter, aquatic and soil humic substances from Brazilian were determined using a new versatile approach based on a single-stage tangential-flow ultrafiltration (TF-UF) technique (cut-off 1 kDa) and sensitive atomic spectrometry methods. The results regarding the copper(II) complexation capacity and conditional stability constants obtained for humic materials were compared with those obtained using direct potentiometry with a copper-ion-selective electrode. The analytical procedure based on ultrafiltration is a good alternative to determine the complexation parameters in natural organic material from aquatic and soil systems. This approach presents additional advantages such as better sensibility, applicability for multi-element capability, and its possible to be used under natural conditions when compared with the traditional ion-selective electrode.

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Utilização de eletrodos potenciométricos de amálgama em estudos de complexação de substâncias húmicas

Cited by 10 publications

References 0 publications

Acid-basic and complexation properties of a sedimentary humic acid. A study on the Barra Bonita reservoir of Tietê river, São Paulo State, Brazil

Acid-basic and complexation properties of a sedimentary humic acid. A study on the Barra Bonita reservoir of Tietê river, São Paulo State, Brazil

Propriedades ácido-base e de complexação de ácidos húmico e fúlvico isolados de vermicomposto

Tangential-flow ultrafiltration: a versatile methodology for determination of complexation parameters in refractory organic matter from Brazilian water and soil samples

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