The adsorption of thiourea on the mercury from neutral and acidic solutions of perchlorates

Nosal‐Wiercińska, Agnieszka; Fekner, Zygmunt; Dalmata, Grażyna

doi:10.1016/j.jelechem.2005.01.044

Cited by 21 publications

(17 citation statements)

References 35 publications

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“…At potentials higher than -1400 mV the differential capacity curves are joined with the differential capacity curve of the supporting electrolyte, in the presence of all studied concentrations of TU and its derivatives, which proves that TU and its derivatives are not adsorbed on mercury in this range of potentials [33][34][35].…”

Section: Adsorption Measurementsmentioning

confidence: 92%

“…The differencial capacity curves of double layer interface Hg/1 mol dm -3 NaClO 4 (•) and Hg/1 mol dm -3 NaClO 4 in the presence of 3×10 -3 mol dm -3 TU (◊) [33], MTU (♦), ATU (Δ) [35] and DMTU (▲) [34] The zero charge potential E Z values and the surface tension values at zero charge potential g z on the interface Hg/1 mol dm -3 NaClO 4 and Hg/1 mol dm -3 NaClO 4 in the presents of studied TU derivatives are presented in Table 1. As Table 1 indicates, together with the increase of TU and its derivatives concentration of zero charge potential E Z values are shifted towards the more negative potentials, which is characteristic of anion adsorption.…”

Section: Figurementioning

confidence: 99%

“…The relative surface excesses increases together with the increase of TU and its derivatives concentration [33][34][35]. The changes of relative surface excesses in the function of electrode charge for concentration…”

Section: Figurementioning

confidence: 99%

“…Thiourea and its allyl derivatives have free electron pairs at sulphur and nitrogen atoms, therefore they show similar tendency for formation of complex compounds. Moreover these substances are adsorbed on mercury electrode surfaces [33][34][35], fulfilling the conditions of the cap-pair rule. The choice of chlorates(VII) as the supporting electrolyte is connected to the fact that ClO 4 -ions show weak complexing properties and is adsorbed on mercury to a lower degree, which allows for omission of their competitiveness in adsorption with organic substances.…”

Section: Introductionmentioning

confidence: 99%

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Catalytic activity of thiourea and its selected derivatives on electroreduction of In(III) in chlorates(VII)

Nosal‐Wiercińska

2010

Open Chemistry

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It was found that thiourea, N-methylthiourea, N,N'-dimethylthiourea and N-allylthiourea accelerate the electroreduction process of In(III) ions in chlorates(VII). These substances are adsorbed on mercury from chlorates(VII). The relative surface excesses of thiourea and its derivatives increase with the increase of their concentrations and electrode charge. After adding thiourea, N-methylthiourea, N,N'-dimethylthiourea and N-allylthiourea to the solution an acceleration of the electroreduction process of In(III) ions occurs. This process depends on two factors: the adsorption of an accelerating substance on mercury and on the formation of complexes between a depolarizer and an accelerating substance on the electrode surface. The equilibrium of this complexing reaction determines the magnitude of the catalytic effect.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Section: Adsorption Measurementsmentioning

confidence: 92%

Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Catalytic activity of thiourea and its selected derivatives on electroreduction of In(III) in chlorates(VII)

Nosal‐Wiercińska

2010

Open Chemistry

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“…The results of differential capacity curves studies and changes of the values of potentials of zero charge (E z ) together with the increase of the compounds concentration point to the adsorption of GTAMITU or GTA molecules on the mercury surface directly by the guanidine group. It is especially interesting taking into account isothiourea, as thiourea adsorbs at the mercury itself [27]. It can suggest a bigger connection of the guanidine group to mercury than sulphur from isothiourea.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical Studies and Square Wave Voltammetric Determination of S‐[(2‐Guanidino‐thiazol‐4‐yl)methyl]isothiourea hydrochloride and 2‐Guanidino‐1,3‐thiazole

Skrzypek

Lewkowski

2011

Electroanalysis

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S-[(2-Guanidino-thiazol-4-yl)methyl]isothiourea hydrochloride (GTAMITU) and 2-guanidino-1,3-thiazole (GTA) were studied at hanging mercury drop electrode under conditions of square-wave voltammetry and in the function of the electrode potential for different adsorbate concentrations. The experimental data of adsorption were obtained from the measurement of differential capacity of the double layer, the measurement of zero charge potential and surface tension at the zero charge potential. The received results point to the adsorption of molecules directly with the guanidine group to the mercury surface and suggest that the molecules are not placed flatly on the mercury surface. This kind of arrangement of molecules enables electron transfer, which is the basis of their electroactivity and causes the compounds to act as electrocatalysts. New adsorptive catalytic methods for voltammetric (SW AdSV) determination of GTAMITU and GTA were developed. The dependence of the peak current on pH, buffer concentration, and nature of the buffer were studied. The best results according to the shape and sensitivity of the peak were recorded in citrate buffer at pH 2.0 for GTAMITU and in phosphate-citrate buffer at pH 2.96 for GTA. This electroanalytical procedure enabled to determine GTAMITU and GTA in the concentration range 5 10 À8 -4 10 À7 mol L À1 and 8 10 À7-8 10 À6 mol L À1 respectively. Precision, repeatability and accuracy of the method were checked. The detection and quantification limits were found to be 1.3 10 À8 and 4.4 10 À8 mol L À1 for GTAMITU and 2.6 10 À7 and 8.0 10 À7 mol L À1 for GTA respectively.

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Heterogeneous Kinetics of Thiourea Electro‐Catalytic Oxidation Reactions on Palladium Surface in Aqueous Medium

Shabik

Begum

Rahman

et al. 2020

Chemistry An Asian Journal

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The electrochemical behaviors of thiourea (TU) oxidation have been studied at Palladium (Pd) electrode in the acidic medium by recording cyclic voltammograms (CVs). The influence of pH was investigated in the pH range of 1.0 to 9.0. Facilitated adsorption of TU on electrode surface results in enhanced catalytic response in acidic medium and maximum electro‐catalytic response was found at pH∼3.0. Chronoamperometric (CA) experiment determined this oxidation as 1e‐ transfer process and the variation of TU concentration reveals a 1st order kinetics. In the CV responses, the large value of peak separation (▵Ep >380 mV) calculated by the variation of scan rate indicates that oxidation of TU is an irreversible process. With the aid of convolution potential sweep voltammetry (CPSV), the standard rate constant (k°) for the reaction was found to be 7.1×10−4cm/s and the formal potential constant (E°′ ) was evaluated to be ∼0.37 V vs Ag/AgCl (sat. KCl). The value of transfer coefficient (α) was found to vary from 0.74 to 0.40 with applied potential (E). From the potential dependent variation of transfer coefficient (α) and activation energy (▵G≠), it was concluded that the overall electrochemical oxidation of TU follows a stepwise mechanism at lower potential (<0.40) V and a concerted one at relatively higher potential (>0.40) V. The FTIR analysis of the product after oxidation of TU molecules confirmed the appearance of a new sharp band near 530 cm−1 due to the formation of S−S bonds suggesting formation of formamidine disulfide (FD) ions.

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The adsorption of thiourea on the mercury from neutral and acidic solutions of perchlorates

Cited by 21 publications

References 35 publications

Catalytic activity of thiourea and its selected derivatives on electroreduction of In(III) in chlorates(VII)

Catalytic activity of thiourea and its selected derivatives on electroreduction of In(III) in chlorates(VII)

Electrochemical Studies and Square Wave Voltammetric Determination of S‐[(2‐Guanidino‐thiazol‐4‐yl)methyl]isothiourea hydrochloride and 2‐Guanidino‐1,3‐thiazole

Heterogeneous Kinetics of Thiourea Electro‐Catalytic Oxidation Reactions on Palladium Surface in Aqueous Medium

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