Portugaliae
Electrochimica Acta

In the present work, an EC used for steel corrosion protection was characterized by Ec techniques. This study aimed to describe the effect of the steel roughness surface on the performance of EC, through EIS and other methods. The studied metal was a low-strength CS immersed in a 3.5% NaCl solution. The CS surface was obtained by polishing it (metal electrodes) with an abrasive paper of 120, 600 and 1200 mesh. Then, the electrodes were painted with an anti-corrosive EC, which contained Zn3 (PO4)2 as an anti-corrosion agent. The study of the influence of the CS surface Ra and its corrosion behaviour and of the evolution of the protective capacity systems on the EC performance was made by stationary (Ecorr and Tafel plot) and no-stationary Ec techniques (EIS and CA). In order to confirm the detachment and blistering on the coating, the coated CS samples were analyzed by a salt spray in a 7.69 % NaCl solution, with an IT of 15 days. The obtained results showed that the CS surface state directly influenced the coating performance and the Ec parameter values variation, as a function of IT in the NaCl solution. EIS was the most valid Ec method for the studied coatings. Keywords: corrosion; CA; EIS; EC; surface roughness; Tafel plot.

Al and its alloys have a low atomic weight and high strength to density ratio. These properties make them very useful for the construction of parts in automotive industry, such as engine blocks or pistons. Al is prone to corrosion, due to its negative standard E of 1.66 V vs. NHE. In addition, Al corrosion resistance strongly depends on pH. Therefore, it is important to undertake a general study of Al corrosion behavior. Keywords: Al; CI; corrosion; electrochemical behavior; oxides.

A novel p(THFA-co-HEMA) membrane based on acrylate CP was successfully synthesized through PP technique, and applied into Pb-ISE (Pb-ISE). THFA optimum composition was HEMA 9:1 (TH91), with a Tg of -6.5 oC. The structure of p(THFA-co-HEMA) was characterized using FTIR. The Pb-ISE sensor showed remarkable calibration measurement in the range from 0.1 to 10-6 M, with a LOD of 7.59 x 10-7 M, and it has obeyed a Nernstian number of 30.5 mV/dec. In addition, the fabricated Pb-ISE sensors showed fairly good selectivity coefficients of several types of ions, such as K+ (-6.53 ± 0.11), Na+ (-6.35 ± 0.16), NH4+ (- 6.76 ± 0.11), Mg2+ (-12.15 ± 0.13), Ca2+(12.12 ± 0.14), Cu2+ (-4.33 ± 0.11) and Cd2+ (-6.43 ± 0.17), and an effective function in the pH range from 3 to 8. The resulting response time was quite good, 6.7 sec, with a change of 27.5 mV for a decade. The Pb-ISE sensor also showed validation results equivalent to AAS standard method, where the corresponding data with real samples produced values of 9.3 ± 1.9 and 9.2 ± 2.0 ppm and 275.5 ± 10.3 and 277.7 ± 4.0 g/g, for CREW and CRMS, respectively. Keywords: acrylate membrane; ISE; p(THFA-co-HEMA); Pb(II); PP.

MS corrosion behavior was herein studied via green azo methane, i.e., BDTT, in a 0.5 M H2SO4 solution. CI mechanisms were investigated by Ec techniques (PDP, EIS and WL). Experimental studies results were supplemented with theoretical calculations, DFT and various Td adsorption and activation parameters. BDTT molecule mechanism of adsorption onto the MS surface followed Langmuir’s isotherm. In this study, an eco-friendly and cost-effective strategy to hinder corrosion was proposed. Keywords: BDTT; CI; DFT; EIS; PDP; WL.

PA is a gram-negative pathogen that is highly aggressive and known to cause several nosocomial infections, leading to significant morbidity and mortality levels. Individuals with compromised immunity are especially vulnerable to life-threatening infections caused by this bacterium. PA importance as a pathogen is further underscored by its virulence, increasing resistance to antibiotics, and its ability to adapt to diverse environmental conditions. In this study, MO extract antibacterial activity was evaluated using Ec methods, such as CV, EIS and polarization curves (Tafel’s law), against pathogenic bacteria, including PA. The performance of the developed CPE modified by MO was herein tested with C6H12O6, by CV technique. The CV recorded at the CPE-MO surface showed a well-defined peak, which was due to C₆H₁₂O₆ Ec oxidation. PA addition to the electrolyte solution containing C₆H₁₂O₆ caused its oxidation peak to disappear. The hypothesis that PA would adhere to the CPE-MO surface, blocking the active sites and, subsequently, C₆H₁₂O₆ oxidation, was proposed. To verify this hypothesis, polarization curves and EIS, which revealed the presence of a non-conductive film on the CPE-MO surface, were employed. The morphology of the elaborated electrodes surfaces was characterized by SEM. Keywords: CPE; CV; EIS; inhibition; MO; PA; pathogenic bacteria; polarization curve (Tafel’s law); SEM; SR.