Electrochemical characterization of cationic surfactants? adsorption on a disturbed n-alkanethiolate self-assembled monolayer-modified polycrystalline gold electrode

Single-chain surfactant monolayer on carbon paste electrode and its application for the studies on the direct electron transfer of hemoglobin

“…The similar value of charge (Q) involved in the direct electron transfer of Hb indicates that the different surfactants on the surface of CPE should adsorb nearly the same amount of Hb. Whereas, the different direct electron-transfer behaviors of Hb in these cationic surfactant films should mainly arise from the different interactions of Hb with these surfactants, which were influenced by the structure properties of surfactant films like film density, chain length and orientation [27]. Surfactants with a longer hydrophobic tail could interact more strongly with Hb and make it more stable on the electrode surface with a more suitable orientation, producing a faster k s and a more positive E°′.…”

Intercalation of methylene blue in n-alkanethiolated self-assembled monolayers: Versatile electrochemical platforms for characterizing surfactant adsorption on hydrophobic surfaces

“…The addition of 1 × 10 −5 M CTAB exerts obvious influences on the response of MB at Au, reflected by the decrease of the reduction current as well as the narrowing and the positive shift of the oxidation potential (curve c). The formation of possible CTAB monolayer at the electrode interface at this concentration [26,27] might repress the reduction of positively charged MB by electrostatic repulsion and regulate the oxidation of the neutral product in the surfactant monolayer through reorientation. At the hexanethiolated selfassembled monolayers modified gold electrode (SAMs/Au), a pair of reduction and oxidation peaks appears at about −0.243 and −0.217 V both with (curve e) and without (curve d) the nitrogen purge treatment.…”

“…Similar to other electrochemical methods [26,27], this method had some overwhelming advantages for characterizing surfactant adsorption at hydrophobic surfaces compared with the nonelectrochemical methods, such as high sensitivity, wide concentration range, easy fabrication and operation, and low cost. In contrast to previous electrochemical methods for characterizing surfactant adsorption at hydrophobic surfaces [26,27], the replacement of the disturbed SAMs of dodecanethiol or a carbon paste electrode surface by the regular SAMs of hexanethiol provided a more ideal hydrophobic surface mode, the replacement of the negatively charged electrochemical probe K 3 Fe(CN) 6 by positively charged MB completely overcame the deficiency of the coprecipitation of K 3 Fe(CN) 6 with positive charged surfactants at high concentrations, and the avoidance of using equivalent circuits significantly simplified the operating procedure in electrochemical impedance spectroscopy (EIS). As a versatile platform, this electrochemical system can be used to monitor the adsorption of various neutral and positively charged surfactants on hydrophobic surfaces.…”

“…Although these techniques were powerful tools for characterizing the adsorption of surfactants on solid surfaces, the apparatuses employed were expensive and the operations were complicated. Recently, we reported two electrochemical systems for characterizing the adsorption of cationic surfactants on hydrophobic surfaces of a carbon paste electrode [26] and a disturbed n-alkanethiolated self-assembled monolayers modified gold electrode [27] using potassium ferricyanide (K 3 Fe(CN) 6 ) as the probe. Although these systems had their roles in characterizing the influences of surfactant adsorption on the interfacial properties of electrode|solution interface and the electrochemical behaviors of the substrates, they suffered from some inevitable disadvantages as the electrochemical platforms for characterizing surfactant adsorption on hydrophobic surfaces, such as the employment of irregular hydrophobic surfaces and the coprecipitation of K 3 Fe(CN) 6 and the positively charged surfactants at high concentrations.…”

Composite of Indium and Polysorbate 20 as Inhibitor for Zinc Corrosion in Alkaline Solution

“…The surfactants inhibit zinc corrosion by their adsorption on zinc. [17][18][19] The polar groups of surfactants are adsorbed on while the non-polar groups escape from the surface of zinc to form a protective layer that inhibits the corrosion of zinc. It has been found that the surfactants containing polyoxyethylene group are more effective than other surfactants as zinc corrosion inhibitors.…”