Portugaliae
Electrochimica Acta

Corona gas discharge (CGD) is a physical process that occurs when a gas is ionized. It is observed as a bluish glow at high breakdown voltages from 5 to 30 kV. In laboratory conditions, [1] has objectively studied CGD, in the former USSR, in the late 1940s. The method was classified as electrophotography, for recording information. Based on an electrophotographic information recording, Carlson developed xerography in the 1960s. [3] has conducted experiments using electrophotographic CGD methods, to record data. Antonov and co-authors proved that CGD primarily depends on the object’s dielectric permeability rather than on conductivity. [15, 16] have measured photon emission in different types of water. The method is called color coronal spectral analysis. Since 2012, [12] have developed a method for analyzing CGD image, assessing brightness for various water types. The authors consider that, with CGD, information is connected with water dielectric permeability and, thus, with H2O molecules restructuring. The developed method of water classification allows for an integral assessment of H2O characteristics. The experimental sample was classified based on brightness histogram (BH) analysis of CGD radiation images. Keywords: BH; CGD; discharge image; H2O.

EMD was herein applied as a glucose-oxidizing electrode catalyst. ZnO electrode showed considerable electro-catalytic activity for glucose oxidation. The effect of glucose Ct was studied by CV and SWV. The j increased with glucose Ct. Bacteria presence in the reaction environment showed that they tended to adhere to the Zn surface. The biofilm developed on the ZnO electrode surface did not promote glucose oxidation. Keywords: bacteria; CV; EIS; EMD; glucose; oxidation; SEM; SWV; ZnO.

Nano-sized PANI/Mn2CoO4 hybrid was successfully synthesized by diluted polymerization method, for high power SC. The metal oxide incorporation significantly increased the polymer’s crystallinity and electrochemical efficiency. PANI/Mn2CoO4 electrochemical evaluation showed enhanced energy, power density (2.28 and 762.6 W/kg-1, respectively), specific capacitance (470 Fg-1) and columbic efficiency of 87.1%, with long cycling stability up to 1000 cycles. NHP improved capacitive nature and power characteristics were achieved by the synergistic effect between PANI and Mn2CoO4. Keywords: charge-discharge; energy storage; PANI/Mn2CoO4; SC.

MSW or manufacturing WM must be sustainable, to achieve SDG and address health, environmental and economic disposal concerns caused by large amounts of artificial garbage. Locals are put at risk, due to improper MSW management. In Pakistan, MSW output is increasing daily. Urban settlements and other organisations generate a large amount of garbage in various forms, which typically degrades and makes the surroundings unappealing. The soil state in the metropolitan area has decreased, due to irresponsible debris dumping. The dumping of contaminated litter and mixed fluids outside of waste disposal borders raises serious environmental issues on soil and water pollution. This review focused primarily on the impacts of MSW collection on soil and water quality at open waste disposal facilities, as assessed by a mixed soil-WQI. Improper waste disposal techniques, which include open dumping, uncontrolled landfilling and illegal disposal, can lead to contamination that negatively effects soil and water quality. One must also look for sustainable WM options. The consequences related to these gaseous emissions have been widely investigated. Keywords: landfills; MSW; pollution; soil quality.

In this study, gravimetric analysis was used to determine corrosion properties, i.e., WL and CR of welded and tempered UNS G10400 CS exposed to Sw. In order to determine optimal WL and CR, RSM approach was utilized to develop a prediction model. 20 runs of the experiment were used for statistical ANOVA. As response variables, the experimental design matrix included WL and CR. To optimize the results of GC method and develop a predictive regression model, CCD was utilized. By ANOVA, the generated models for WL and CR indicated a significant p-value (which is probability, under the null hypothesis assumption, of obtaining a result equal to or higher than the one observed) of < 0.0001. F-values and R2 showed good statistical correlation between experimental and predicted values. Optimal conditions for WL and CR occurred at 25 °C(as-welded), with an ET of 17 days, and their optimum values were 0.744 g and 0.769 mm/year, respectively. Validation of optimized predicted results showed an UE of 1.6 and 2.9%, for WL and CR, respectively, which was below 5%. This revealed that the generated model adequately predicted CP of welded and tempered UNS G10400 CS in a Sw environment. Keywords: as-welded; GT; optimal conditions; predictive modeling; RSM; UNSG10400 CS.

Lignin generated from biomass is the most promising fuel for industrial civilizations. It is the most common aromatic polymer on the planet and one of the most challenging substances to commercialise. Among the various compounds released by LcB during pretreatment are reducing sugars, which may be utilised to generate biofuels and other merchandises. LcB are readily available, renewable, recyclable and abundant. As a result of climate change and environmental damage, sustainability has gained popularity. Many researchers are focusing on renewable biofuel derived from sustainable sources, due to the need for a flexible approach to address expanding global energy demands. Industrial biorefineries that use LcB as feedstock for biofuel and other bioproducts have been created. Biochemical conversion of LcB into fuels and chemicals is dependent on cellulose and hemicellulose extraction. To generate sustainable energy, LcB must be pretreated to increase fragmentation and decrease lignin concentration. T, duration, particle size and solid loading are all controlling factors in lignin extraction. Effective lignin recovery and valorisation solutions have been identified by sustainable lignocellulose biorefineries. Keywords: AC; biofuels; delignification; LcB; pretreatment; sustainable.

Accelerated corrosion is closely associated with the inclusion of secondary reinforcement particulates in metal matrices, where they are usually present as cathodic sites. This hinders full utilization of composite products for engineering applications. In this study, chemical CC were used to improve MMC corrosion in atmospheric and simulated seawater environments. Comparison between CCC and PPCC performance was done to find a substitute for the former, which contains carcinogenic Cr VI ions. Japanese industrial testing method was used to determine the composite LC/CC samples adhesion characteristics, after a series of exposure regimens. CCC specimens displayed marginal corrosion resistance superiority over their PPCC counterparts. There was little to no pits on the CC substrate compared to the non-coated samples. The CC applied on the substrates prevented the coating delamination. The lacquer remained unpeeled on the substrate, during Japanese industrial testing. This indicates reduced corrosion activities on the substrates. Keywords: adhesion; AMC; CCC; corrosion; LC; PKSA; PPCC.

The present work studied SR of electroless Ni-W-P ternary alloy coatings on a Cu substrate. There is very little specific research conducted on the importance of reducing materials SR through Ni-W-P electroless coating, which further improves their mechanical properties. In this study, it was attempted to reduce the as-coated Ni-W-P Cu substrate surface SR by adopting DoE and optimizing the process parameters using CCD. The aim was to optimize the desired response controlled by multiple input parameters. ANOVA and regression analysis were implemented to indicate the significance of as-coated substrates parameters and their impact on the measured SR responses. From CCD optimization, optimal SR parameters were found to occur at low values. Furthermore, FL approach was employed to predict Ni-W-P electroless coating SR, as compared to experimental and CCD approaches. It was found that fuzzy measured values were in good agreement with experimental and CCD values. There was a small difference among all values, and response optimization predicted optimal conditions comparatively well. Therefore, the developed models can be effectively used to predict SR. Moreover, confirmation tests were performed to validate that CCD optimized levels and developed fuzzy models effectively represented SR. Optimized parameters characterization was done with the help of SEM and EDX. It was seen that globular shaped atoms were scattered all over the sample, while granular grains were more clear. From EDX, appropriate deposition of Ni-W-P substrate in Cu was found. Thus, it was concluded that Ni-W-P incorporation in the Cu substrate made a major contribution to the film morphology, enhancing the metal properties and reducing SR. Keywords: CCD; contour plot; Cu substrate; EDX; electroless coating; FL; MF; microstructure; Ni-W-P coatings; SEM; SR.

Lignin (Ln) is an intricate byproduct that is present in all vascular plants. It is essential in the formation of cell walls, particularly in wood and bark, and the development of connective tissues, since it gives stiffness, strength and resistance against external stimuli like infections. Ln has a variety of economic uses, and its extraction might lead to the development of several novel applications. This study examined several ways of extracting Ln from Bm of RH and WH. TGA, SEM, PA, UA and other detailed characterization methods gave unexpected insights. Notably, WH yield 16% Ln, after 5 h, but RH yielded 13% after 4 h. Similarly, RH and WH yielded 10% and 12% Ln, after 3 h, respectively. WH had higher Ln yield than other Bm. These findings illustrate variability in Ln concentrations among Bm, when the alkaline method was used for giving more yield. Keywords: biofuel production; Bm; Ln extraction; pretreatment; RH; SEM; TGA; WH.

This report focused on understanding the effect of various SS and pH on MS in a mine water, using a RCE. The use of this type of apparatus in lab testing provides accurate SS, and generates electrochemical signatures that deliver repeatable and accurate data. The data obtained from the RCE were correlated with a modified model predictor with comparable CR monitoring, in order to provide more insight into MS corrosion mechanism in a simulated mine water. Keywords: CR; MS; RCE; simulated mine water; solution pH.

In this study, employing an accurate and simple method of CvV and DV, combined with numerical simulation, FeCl3 was electrochemically examined in a 1 M HCl aqueous solution using Au working electrode. It was discovered that electrons exchange between Fe (III) and Fe (II) was a quasi-reversible process. CV was used to determine the electrochemical parameters of Fe (III)/Fe (II), such as D, Eo, ks and α values, which were then confirmed using a numerical simulation method. The nature of K3[Fe(CN)6] electrode reaction, in selected media at Au electrodes, was studied. It was determined that its mechanism occurred through moderately fast electrons transfer. Keywords: DV; CvV; CV; FeCl3; numerical simulation.

Herein, electrodeposition of Zn-Ni alloy thin films on CS substrates under various conditions, from sulfate baths containing Na3C6H5O7, C7H5NO3S, and 2-butyne-1,4diol, was studied. So as to have the best bath composition, a mixture design application was examined. The best obtained composition was: 0.3 M Na3C6H5O7-, 0.1 g/L C7H5NO3S and 0.1 g/L 2-butyne-1,4-diol, for theoretical and experimental responses of 215.22 and 221.60 HV, respectively. Zn-Ni coating morphological properties and composition were examined by SEM and EDS. It was found that, on optimal conditions, a significant decrease in the grain size occurred. The deposits were homogeneous, uniform, compact and fine-grained, without any pores at the surface. Keywords: 2-butyne-1,4-diol; C7H5NO3S; mixture design; Na3C6H5O7-; sulfate acid bath; Zn-Ni electrocoatings.

In 2007, a study was done using color corona spectral analysis [39]. The method was applied in laboratory conditions with the coronal glow of biological objects and liquids. A high voltage of 12 kV and a frequency of 15 kHz have been applied during the research. In 1995, Antonov created the apparatus for the study, with registration in black and white photographic films. The scientist called the method selective high-frequency discharge. It has been categorized as silverless photography. In the presence of electrical conditions, electrography is at the heart of the photocopier invention. Herein, CaCO3 in a distilled H2O solution was tested. Comparative analysis was performed with distilled H2O. Physical and chemical processes under high-frequency corona gas discharge conditions were analyzed. CaCO3 was in dynamic interaction with CO₂ and H2O at the boundary of different environments. Keywords: CaCO3; color coronal discharge; FTIR; H2O.

In order to improve the corrosion resistance of Pb anodes in 4 M Pb-H2SO4 batteries, the electrochemical and metallurgical effect of Ag addition in small quantities on Pb corrosion in 4 M H2SO4, as well as its microcrystalline morphology, were herein studied. Different techniques, such as PDP, EIS and OM, were employed. The results showed that Ag addition up to 1 wt% led to a significant decrease in Icorr and Ipass rates, and also to a reduction in sulfation phenomena, by facilitating PbSO4 and PbO conversion into PbO2. All of these improvements led to an increase in the lifetime of the conventional Pb-acid battery up to 87.24%. Therefore, the new improved battery is more resistant, durable and environment friendly. T effect on the new casting alloys CR was also studied, and found to be inexistent. Keywords: battery; CR; EIS; electrochemistry; metallurgy; OM; Pb-Ag alloy; PDP.

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.