Portugaliae
Electrochimica Acta

There is a growing trend in utilizing pharmaceutical compounds and plant extracts as CI. Therefore, in this study, the inhibitive performance of Citrus x aurantiifolia extract (CAE) and expired CPM on MS corrosion in 0.5 M HCl solutions was studied using Ec measurements. Furthermore, MS samples without and with inhibitors were characterized by SEM/EDX spectroscopy. Results confirmed that CAE and CPM effectively acted as CI in HCl. IE(%) increased with inhibitors higher Ct. PDP studies confirmed that the system followed a mixed mode of inhibition. Investigations by SEM/EDX established the formation of a protective film on the MS surface. CAE adsorption performance was also studied, which suggested Langmuir’s isotherm was the most suitable model. Keywords: adsorption; CAE; CI; CPM; Ec measurements; EDX; MS; PDP; SEM.

This study focuses on evaluating the analytical performance and chelation capabilities of SV, using specialized NPM-CPE sensors designed for Ca2+ ion detection. The research context centres on addressing analytical and therapeutic challenges in conditions like gout, where CaC2O4 dissolution plays a critical role. The findings demonstrate that SV exhibits a remarkable ability to chelate Ca2+ ions in a solution, resulting in the formation of stable complexes. A combination of electrochemical techniques, including SWV, CV and EIS, to characterize SV's chelation capacity, and the presence of Ca2+ metals, was employed. Through these electrochemical methods, valuable insights on the efficacy of SV in chelating Ca2+ ions were gained, which offered significant implications for conditions associated with CaC2O4 deposition, such as gout. This study addresses the need to tackle analytical and therapeutic challenges posed by gout and related disorders, and proves a novel approach to understanding and potentially treating these conditions. Detailed results of the research, which include the successful chelation of Ca2+ ions by SV, can be found in the main body of the paper, offering a comprehensive account of the findings. Keywords: chelation; electrochemical methods; gout; SV.

This paper investigated Corchorus olitorius leaves extract efficiency in preventing MS corrosion, when immersed in a KOH solution. This will be the first report on the application of this plant extract in an alkaline medium of any kind, for mitigating metals corrosion. Pc analysis was employed along with PDP and FITR spectroscopy. Pc compounds, such as steroids, saponins, flavonoids, tannins, alkaloids and phenols, were found in the extract, which produced maximum IE(%) of 99.93%. Highest CR of 5.644e+003 mm/year was obtained, while theoretical fittings of various adsorption models for the extract found that it obeyed Langmuir’s isotherm. Kads was 0.9729 g/L, with R2 of 0.9616. 〖∆G〗_ads^° calculated at room temperature was -9.882 kJ/mol. As a result, COLE adsorption onto the MS surface was found to follow physical adsorption mechanism. Keywords: COLE; inhibition; isotherm model; MS; Pcs; PDP.

SAA as novel green inhibitor of MFe corrosion studied by EIS, DFT, PDP and SEM was investigated. It was observed that the increase in SAA various Ct triggered the rise in corrosion IE(%) up to 90.6, 97.6, 98.3 and 98.7%, as shown by EIS, PDP, WL and geometric techniques, respectively. This was due to high Rct during electrochemical processes, which reduced Icorr, and to SAA molecules strong adsorption onto the MFe surface. DFT results revealed short ∆E between SAA and MFe bands, which gave rise to faster inhibitor molecular transfer, stronger adsorption and increased inhibition. Thermodynamic assessment showed that SAA caused an exothermic reaction, creating a stable and spontaneous adsorption reaction. A physical adsorption mechanism was proposed from Langmuir’s isotherm results. Keywords: alkaloids; corrosion; electrochemistry studies; inhibition; quantum chemical calculations; SAA.

1-Methyl-N-((1R,3r,5S)-9-methyl-9-azabicyclo[3.3.1]nonan-3-yl)-1H-indazole-3-carboxamide (C18H24N4O: EGS) is used to prevent nausea and vomiting caused by cancer chemotherapy and radiation therapy. It works by blocking serotonin, a natural substance in the body that causes nausea and vomiting. After expiry, it can be used as additive or CI. IE% of EGS on MS corrosion in a 1 M HCl medium was herein evaluated by WL method. WL measurements showed that corrosion IE% increased with higher Ct of EGS, and its maximum value was obtained with 0.001 M. T affects CR. At high T, corrosion IE% decreased, and CR increased. The mechanistic aspects of corrosion resistance have been studied by PDP and EIS. PDP technique revealed that EGS system functioned as an inhibitor of cathodic type, controlling cathodic reactions. It was noted that, with EGS, icorr decreased and LPR increased. EIS studies revealed that a protective film (blanket effect) was formed on the MS surface, since, with EGS, Rct increased and Cdl decreased. MS surface morphology with EGS was analyzed by SEM. The constituent elements on the MS surface were characterized by EDX. Ra of MS polished, without and with EGS, was characterized by AFM. The results clearly showed that EGS has high IE% for MS corrosion in HCl. Keywords: acidic solutions; AFM; CI; EDX, EIS; EGS; IE(%); MS; PDP; SEM.

Along its 4 decades, the Portuguese Electrochemical Society (Sociedade Portuguesa de Eletroquímica, SPE) has been fostering the Electrochemical Sciences through a diversity of perspectives and pathways, which are illustrated in this talk, within the celebrations of the 40th anniversary of this Society. They include: (i) the publication of Portugaliae Electrochimica Acta (PEA), the only journal on original research in chemical sciences currently being published in Portugal; (ii) the organization of conferences of the SPE and of the Iberic Meetings of Electrochemistry (IME), the latter jointly with the Specialized Group of Electrochemistry of the Royal Spanish Chemical Society (Grupo Especializado de Electroquímica de la Real Sociedad Española de Química, GEE-RSEQ), apart from sponsoring other international conferences; (iii) the award of prizes for senior scientists and for young researchers; (iv) the coinage of celebratory medals; (v) the surveys of the Research on Electrochemistry in Portugal; (vi) the establishment of a Library; (vii) the cooperation with other scientific societies; (viii) other initiatives; and (ix) prospects. All the above-mentioned topics should contribute to the assignment of the role of the SPE within the national panorama of science and education in Portugal. Keywords: IME; PEA; RSEQ; GEE-RSEQ; SPE; SPQ; meetings; medals; prizes; research survey.

One of the most frequently produced agricultural wastes is biomass from which Lc is obtained. It contains a high concentration of Ln, Cs and Hcs. It is one of the main sources of energy in the globe, but is underutilized. To extract Ln from plants using acid pretreatment and alkali, the current research employed a Bm resource that is easily accessible. Ln was extracted from four different Bm: AS, BTB, NTB and WS. The proximate and final analyses were utilized to describe Ln after the pretreatment procedure. NTB had the lowest S content. Analysis of TGA test for Bm from Lc was performed. BTB had the highest projected Ct of Ln recovery, at 100 ºC. NTB produced a minimum Ln amount of 6%, compared to 8% yield from BTB, after 5 h. Ln yield at 160 ºC was lower. WS and AS had the same Ln yield (7%), after 5 h. The extracted Ln, which has a higher phenolic content than that from the commercial one, can be used in future applications. Keywords: Bm from Lcs; Cs; environmentally friendly; green biotechnology; renewable resource; TGA.

EC is an emerging technique used for various applications, due to its benefits, such as coagulation, flocculation and Ec treatment. Emerging pollutants are a real concern, and many researchers have focused on their removal, using EC, due to its several advantages, such as easiness of operation, less space requirements, versatile pollutants removal, lower sludge production, cost effectiveness, lower energy consumption and environment friendliness. Literature has also determined that EC technology is a proven efficient technology for treating various nature industrial effluents. However, those emerging pollutants, such as pesticides, Polyfluoroalkyl substances, cyproflyxin, amoxicillin and surfactants are not efficiently treated by simple EC technology, and their separation is not the solution, since they require degradation and safe disposal. Therefore, waste disposal from this process is a major concern, and the choice of advanced EC-degradation technology depends upon the nature and strength of the pollutant. To address these issues, various processes coupled with EC have been used, such as EF, PDS, EO, ozonation, photochemical degradation, PC, aeration and sonication. Thus, this paper focuses on the basics of EC technology, several degradation systems and application of combined degradation-EC technologies, for treating various WW. Keywords: di-sulfate oxidation; Fenton process; ozonation; PC; per-sulfate.

DAD was investigated as CI for SS corrosion in a 3.5% NaCl solution, using WL, thermometric and RSM techniques. The analyses results show that IE(%) of DAD was dependent on its Ct and T. The highest IE(%) values were recorded on 5.0 g/L, at 303 K, by thermometric and WL methods (90.0 and 98%, respectively). DAD adsorption onto the SS surface was found to be spontaneous, obeyed Langmuir’s isotherm, and its mechanism appeared to be partly physical, partly chemical. The results of RSM techniques supported experimental data. Finally, SEM was used to examine SS surfaces morphology without and with DAD, and its results confirmed the CI process. Keywords: adsorption; corrosion; DAD; NaCl; RSM; SEM; SS; WL.

In this study, to determine chemical elements and stable isotopes in 30 GW samples collected from SS Moroccan L-D region, various analytical techniques were used. Thus, the goal was to identify and understand different geochemical processes contributing to water mineralization in the study area. In fact, statistical results for major cations and anions indicated that they obeyed the following trend: Na+ > Ca2+ > Mg2+ > K+, and Cl- > SO42- > HCO3- > NO3-, respectively. Additionally, it was found that water EC values varied from 1290 to 6895 µs/cm. Indeed, pH values of investigated GW was from 6.88 to 7.75. Studied GW had HG facies with 86.66% Na-Cl and 13.33% Ca-SO4. This finding is explained by the dissolution of evaporative formations that characterizes Saharan sections. Additionally, ionic ratios analysis revealed that GW chemical evolution was influenced by processes such as rock weathering, mineral compounds dissolution and evaporation. Therefore, a better relationship between Ca and SO4 suggested gypsum and anhydrite leaching. It was found that stable isotopes (δ18O and δ2H) values differed from -6.96 to -8.93‰ and from -51.5 to 65.56‰, respectively. These findings strongly suggest that waters in the region undergo significant evaporation before reaching the aquifer. In addition, the aquifer's recharge height was also predicted to be no higher than 300 m, with a latitudinal gradient of δ18O, including 0.52 per 100 m. These results can serve as valuable guidance for decision makers in optimizing exploitation and assessment processes in Moroccan SS area. Keywords: AAS; GW; HG; mineralization; Moroccan SS; stable isotopic.

In this study, a composite material containing PY and CTS, as functional material, and dopamine, as template, was electrodeposited onto a GCE surface modified with NP from TiO2. The prepared MIP sensor was characterized by CV, SEM, FTIR and UV-vis techniques. The developed MIP matrix was used for dopamine detection, using DPV method. Diverse analytical parameters were optimized, such as: monomer, template, SE concentrations, electropolymerization cycles, pH medium, incubation time and scan rate. In the best conditions, the sensor response to dopamine was linear, in the concentration range from 1 x 10-6 to 1 x 10-5 mol/L-1. LOD was about 2.81.10-7 mol/L-1, and sensitivity was 3.202 μA/L/mol-1/cm-2. Furthermore, the proposed MIP sensor showed good selectivity, repeatability, reproducibility and stability. Also, it was successfully applied for dopamine determination in urine samples. Keywords: CV; dopamine; DVP; FTIR; MIP; PPY-CTS composite; SEM; TiO2; urine samples; UV-vis.

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.

MS surface deterioration is one of the most challenging problems, since it can be exacerbated by several industrial processes, such as descaling and pickling. In the proposed investigation, chemical and electrochemical techniques determined COLE IE(%) on MS corrosion in a 1 M HCl medium. COLE contains many Pc responsible for an excellent IE(%), since it forms a coating that adsorbs onto the metal surface and shields it from corrosion. Tafel polarization curves outcomes demonstrated that COLE is a mixed kind of CI. According to EIS measurements, Rct rose as Ct of COLE was increased. The relationship between T and MS corrosion behaviour in 1 M HCl with COLE addition was investigated from 300 to 320±1 K. G, which was determined from Langmuir’s isotherm model, revealed that COLE molecules predominantly blocked HCl attack by mixed physisorption and chemisorption mechanisms. Surface morphology studies validated electrochemical and chemical findings by FT-IR, SEM and WCA techniques. Furthermore, DFT computations demonstrated COLE effective interfacial adsorption onto the MS surface. Keywords: 1 M HCl; CI; COLE; DFT; EIS; FT-IR; MS; SEM; WCA.

This work presents a set of electrochemical techniques applied to investigate the effect of Zn baths with additives on steel surfaces coating by EP. The form and intensity of the reduction in I were analyzed as a function of the applied E, using LSV. In this way, different stages of the EP process involved in Zn deposition on steel surfaces, and the effect of each additive, were identified. First, commercial additives produced by a local company, with highly complex compositions, were studied to understand their Ct effects on the different stages of steel coating in Zn baths by the EP process. Based on the ability to replicate those results, C7H6O2 and Triton X-100, previously reported as brightener and leveler, respectively, were proposed as a simple additive mix. Very strong synergetic effects were present, even in this simplified bath. The effect of different additives Ct on the steel coatings grain size or morphology was also evaluated using SEM images, in the final stage. A correspondence between optimal Ct of the commercial additives (1 x 10-2 M Triton X-100 and 3 x 10-9 M C7H6O2) and the proposed bath was found. Finally, EIS experiments were carried out for the different bath compositions, with this simplified additive mix. The results were interpreted through an equivalent electrical circuit represented by Rct, with two parallel CPE, which evidenced Zn deposits inhomogeneities. Keywords: additives in ED; C7H6O2 commercial mix; chemical speciation; EIS; EP process; LSV; SEM; Triton X-100; Zn coating.

The present study demonstrated that, when a Cu-Ti electrode pair was polarized in an aqueous SO42- electrolyte, Cu was oxidized to a divalent state, under AC. In the solution volume, Cu2+ interacted with OH¯, to produce Cu(OH)2. Depending on the electrolysis conditions, Cu(OH)2 underwent a dehydration reaction, which produced CuO. Under industrial AC, each electrode was alternately polarized, firstly towards the anode, then to the cathode. CuE passivation did not occur. With a change in j on TiE, in the range from 0 to 75 kA/m2, CuE dissolution CE increased, reaching 96.5%. When j on CuE was increased to 1000 A/m2, Cu dissolution CE was above 90%. The most favourable conditions for CuE dissolution were a Na2SO4 Ct from 65 to 75 g/L, experiment duration of 1 h, room T, and I frequency of 50 Hz. The obtained CuO (II) composition was identified by XRD and EDXRF analyses. Keywords: AC; Cu; CV; dissolution; electrolysis; Ti.

BM is a renewable organic material obtained from plants and animals. The inability to characterize BM samples prior to the Py process reduces B-O yield quality. This study performed woody (IS and MB) and non-woody (CS and EG) BM samples preliminary characterization, to evaluate their energy potential in Py processing, for improving B-O yield quality. BM samples were sourced from Omu-Aran, Kwara State, Nigeria (latitude 8°08ʹ18.85ʺN and longitude 5°06ʹ9.36ʺE), and were subjected to Pc, structural compositional and thermal analyses. Results showed that all BM samples had good energy potential performance for B-O yield good quality. However, CS had the lowest AC (3.36%) and MC (0.4%), which are favorable properties that enhanced B-O yield quality. The highest AC (5.90%) recorded for EG shows that it had the lowest calorific value, which enabled the release of harmful substances into the reactor, during Py experimentation. Keywords: BM; characterization; proximate analysis; RE; TGA; ultimate analysis.