Estudo espectro eletroquímico de sistemas estruturados argila-corante

Souza, Gisele Aparecida; Fertonani, Fernando Luís; Pastre, Iêda Aparecida

doi:10.1590/s0100-46702003000100010

Cited by 13 publications

(2 citation statements)

References 26 publications

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“…Accordingly, studies [13][14][15][16][17] have suggested a simple and affordable method that can be used for the determination of trace amounts of Fe(III) ions in solution by an electrochemical method. Several studies have shown the application of modified electrodes for metal ions determination in aqueous solutions, some of them using a modification process with clays and organoclays [18][19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Thermal and electrochemical studies of Fe(III) organophilic montmorillonite

Franzin¹,

Lupi²,

Martins³

et al. 2017

J Therm Anal Calorim

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This study aimed at investigating the thermal and electrochemical behavior of montmorillonite clay-8hydroxyquinoline (8-HQ) film in the absence and presence of aqueous Fe(III) ions. The solid film characterization by means of UV spectroscopy, thermal (TG/DTG and TG-DTA, simultaneous) studies, SEM and optical images, and XRD suggested the formation of the ternary complex type: {Pt/[[Si-O] n [Fe(III)(OH 2) 3 (8-HQ) k ]} 3-n-k , with thermal stability up to 300°C. The electrochemical study was carried out on a platinum electrode modified by mechanical deposition of a thin solid film of the binary composite (SWy-1:8-HQ) from an aqueous suspension. The mechanical stability of the film was followed by performing 80 cyclic voltammograms. The electrochemical behavior of the modified electrode was investigated using cyclic voltammetry (CV) at different ferric ions concentration (C Fe(III)), followed by a study of the effect of the scan rate (v) with a fixed C Fe(III) ions. In the CVs, two independent pairs of current peaks, A/D and C/B, were observed. For Fe(III) ions in solution, log i p versus log v relationship shows a process controlled first by adsorption (pair of peaks A/D) and then by diffusion control (pair of peaks C/B). The current function i p /v 1/2 versus v and i p a /i p c versus v allowed a suggestion of two homogeneous coupled chemical reactions associated with CE and EC mechanisms, respectively, both with fast reversible chemical reactions. The first investigation of a modified electrode showed good sensitivity (S = 25.1 lA/lmol L-1) to low concentrations of ferric ions and detection limit [LOD = (2.4 ± 0.01) lmol L-1 ] and high sensitivity to traces of O 2 , showing that this system has great analytical potentials.

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Section: Introductionmentioning

confidence: 99%

Thermal and electrochemical studies of Fe(III) organophilic montmorillonite

Franzin¹,

Lupi²,

Martins³

et al. 2017

J Therm Anal Calorim

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“…Employment of modified electrodes, specifically clays, as proposed in the present study, is a field in constant development, and increasingly new methods of preparation are reported in literature for various matrices [21,[27][28][29][30][31][32][33]. Several studies showed the application of modified electrodes for metal ion determination in aqueous solutions, some of them employing a modification process with clays and organoclays [34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Thermal and electrochemical studies of Cu(II) 8-hydroxyquinoline organophilic montmorillonite

Lupi

Franzin

Pereira

et al. 2017

J Therm Anal Calorim

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The thermal and electrochemical behavior of montmorillonite clay-8-hydroxyquinoline (8-HQ) film was studied in the absence and presence of aqueous Cu(II) ions. The suggested formation of the ternary complex type: {Pt/ [[ Si-O] n [Cu(II)(OH 2) n (8-HQ) k ]} 3-n-k , with thermal stability up to 350°C, was studied, based on UV-spectroscopy, thermal (DTG-DSC, molecular fluorescence and XRD. The Pt/binary composite film (SWy-1:8-HQ) interphase composed of montmorillonite (SWy-1) with 8-hydroxyquinoline (8-HQ) was investigated by electrochemical techniques analyzing the cyclic voltammograms (CVs) obtained at different scan rates (v) and copper(II) ion concentrations. The mechanical stability of the thin films was demonstrated by performing 80 successive voltammetric cycles. Two pairs of redox peaks, indicated by peaks A/D and C/B were observed. For Cu(II) ions in solution, the log i p 9 log v relationships showed processes controlled by adsorption, peaks A/D, and by diffusion, peaks C/B. The analysis of i p / v 1/2 and i pa /i pc versus v suggested two homogeneous coupled reactions, being both reversible and fast kinetic chemical reactions, associated to the mechanisms chemical-electrochemical (CE) and electrochemical-chemical (EC), respectively. The modified electrode showed a good sensitivity to low concentrations of Cu(II) ions, which opens the possibility of being used in chemical analysis. Keywords Organic montmorillonite composites Á TG-DTA simultaneous, Cu(II) ions Á Reversible coupled reactions Á Cu(I)/Cu(II) redox species Electronic supplementary material The online version of this article (

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Hybrids with Functional Dyes

Bujdák

2017

Nanostructure Science and Technology

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Estudo espectro eletroquímico de sistemas estruturados argila-corante

Cited by 13 publications

References 26 publications

Thermal and electrochemical studies of Fe(III) organophilic montmorillonite

Thermal and electrochemical studies of Fe(III) organophilic montmorillonite

Thermal and electrochemical studies of Cu(II) 8-hydroxyquinoline organophilic montmorillonite

Hybrids with Functional Dyes

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