Direct measurement of the adsorption kinetics of 2-Mercaptobenzothiazole on a microcrystalline copper surface

Abstract

ABSTRACT:The adsorption on copper of 2-Mercaptobenzothiazole (2-MBT), a heterocyclic compound member of the tiazole family, has been investigated at different concentrations (1×10 −1 to 1×10 −6 M) in water, employing the Electrochemical Quartz Crystal Microbalance (EQCM). The frequency response over time was obtained for each concentration, showing a defined exponential behavior at higher concentrations (1×10 RESUMEN: Medición directa de la cinética de adsorción del 2-Mercaptobenzotiazol en una superficie micro cristalina de cobre.En el presente trabajo se ha investigado la adsorción del 2-Mercaptobenzotiazol (2-MBT) en cobre, un compuesto heterocíclico miembro de la familia de los tiazoles, en solución acuosa a diferentes concentraciones (1×10 −1 a 1×10 −6 M), empleando la Balanza Electroquímica de Cristal de Cuarzo (BECC). Se midió y analizó el cambio de frecuencia con respecto al tiempo para cada concentración, mostrando un comportamiento exponencial definido en el rango de concentraciones altas (1×10 −1 , 1×10 −2 y 1×10 −3 M), los cambios de frecuencia registrados se ajustaron usando la isoterma de adsorción de Langmuir obteniendo buenos coeficientes de correlación (R 2 =0,91 a 0,98). Se calculó también la fracción de superficie recubierta y se halló que se encuentra en el orden de 0,50 a 0,01 para las concentraciones altas de 2-MBT. La energía libre de adsorción calculada fue de ΔG ads =−5,59 kJ mol −1 , lo cual corresponde a un proceso de fisisorción.

Investigating metal‐inhibitor interaction with EQCM and SVET: 3‐amino‐1,2,4‐triazole on Au, Cu and Au–Cu galvanic coupling

“…Once the frequency shifts are recorded, they are fitted to the Langmuir isotherm according to Eqs. and , where ( θ ) represents the coated area; ( t ) is time; ( t 0 ) is the diffusion time and ( k m ) is the obstruction constant. …”

“…The electrochemical quartz crystal microbalance (EQCM) is another valuable electrochemical technique that allows the acquisition of relevant data about the adsorption of molecules on metallic surfaces with micro‐scale resolution enabling the characterisation of their adsorption kinetics . The technique works by applying an oscillatory electrical field to a quartz resonator placed between two electrodes made of the metal of interest; this makes the resonator to vibrate at its fundamental frequency.…”

SVET study of the interaction of 2-mercaptobenzothiazole corrosion inhibitor with Au, Cu and Au–Cu galvanic pair

“…The adsorption energy and frequency variation of 2MBT on Cu [17] is lower than 2MBT on Au [16] as it was expected since thiazole compounds have high affinity for gold. Therefore, 2MBT molecules will find more suitable adsorption sites on Au than on Cu, giving place to a denser and thicker film.…”

“…So, the sudden drop of electrochemical activity observed over Cu, could be due to 2MBT molecules being desorbed and resuming their tautomeric equilibrium in a very similar fashion to what is observed in the case of Au treated with 2MBT. The presence of 2MBT makes the FCP of the Au-Cu pair more negative ( Table 1), given that the adsorption of this compound corresponds to a physisorption process [17].…”

“…Most reports indicate that applied in very small concentrations, the organic inhibitors are capable of protecting metals from aggressive environments by adsorbing on the metal surface and creating a physical barrier [10][11][12][13][14][15][16][17][18][19]. Their adsorption takes place through heteroatoms like nitrogen, oxygen, sulphur, etc.…”