Portugaliae
Electrochimica Acta

The present study conducted investigations on Bd generated from palm WCO. In TE reaction, alkaline bases for catalysts are often employed. However, since WCO contains high Ct of free fatty acids, its direct use is not feasible, due to layer separation and saponification issues. A two-step process of esterification and TE was herein carried out. GC made from biomass was used. With lower Ct of WCO, maximum Bd yield was achieved using 5 wt.% from GC, CH₃OH:oil ratio of 12:1, reaction time of 70 min, T of 150 ºC and stirring speed of 600 rpm. TE’s second stage employed NaOH, T of 70 ºC and Ct of 1.0 wt.%, for 70 min. Final yield was 95.65 wt.%. Most important variables determining economic feasibility were plant capacity and pricing of feedstock oil and Bd. Keywords: Bd; catalyst; esterification; GC; TE; WCO.

subsequent calcination (HNS/MWCNT). Then, they were employed as an electrochemical sensor for SFA. The synthesized CuO/ZnO was characterized using various techniques, including TEM, SEM, FT-IR, EDX, DPV and CV. Electrochemical studies revealed that HNS from CuO/ZnO/MWCNT modified electrode exhibited high A, more reactive sites and excellent electrochemical catalytic activity towards SFA oxidation, compared to GCE. The pH, modifier amount, SR and analyte Ct effects on oxidation ip were investigated, to optimize experimental conditions. LoD of 0.089 µM and linear calibration range from 0.1 to 1000 µM were obtained for SFA determination on HNS from CuO/ZnO/MWCNT/GCE. The modified electrode was successfully applied for SFA determination in WW, pharmaceutical and biological samples. Keywords: complex-directed hybridization; CV; DPV; HNS; MWCNT; SFA; ZnO/CuO.

This research was conducted through color coronal spectral analysis (Ignatov, 2007). This method was employed under laboratory conditions, utilizing corona glow emitted by liquids and biological objects. The studies were performed with a high voltage of 12 kV and a high frequency of 15 kHz. In 1995, Antonov devised an apparatus with a transparent electrode for research with black-white photographic films. He named this method SHFD. In 2007, the device was improved by Ignatov and Stoyanov, for color Kodak films. Under specific electrical conditions, it is known as electrography. Notably, electrography forms the basis for the invention of the photocopier and the development of Xerox technology. EVOdrop water is a device authors use to transmit electromagnetic waves from 350 to 600 Hz, 20 to 40 kHz, and 7 Schumann frequencies under Color Corona Gas Discharge (CCGD) conditions. A comparative analysis of EVOdrop and tap water corona images was made. Furthermore, this analysis investigated physical and chemical processes occurring under high-frequency CCGD conditions. Keywords: CCGD; EVOdrop water.

such as PDP technique, AC impedance spectra and EIS. The study revealed that, in the presence of excess of Cl ions in AS, CR of Cu decreased. This implies that people wearing ornaments or watches made of Cu must be careful about NaCl level in their sweat. Keywords: AS; CR; Cu; electrochemical studies; NaCl influence.

Environmental and health issues have created the urgent need to transition from CrO₄²- legacy to more environment-friendly CC. The various international protocols on CrO₄²- have restricted its usage, thus opening a floodgate of research activities on its urgent replacements. The current study which examines HSCE and V salt takes a cue from earlier outcomes in which a hybrid HSCE and M2MoO4 coating outperformed CrO₄²- coating. The relatively faster diffusion rate of the chelated Mo (VI) complex of hybrid HSCE over Cr (VI) inhibited corrosion and provided a better barrier on the substrate. Thus, this study examined HC from HSCE in combination with V salt, a V salt-based CC and untreated Al 6061. From PDP measurements and EIS studies in a 3.5% NaCl solution, CC from VO4 outperformed HC, and both outclassed untreated 6061 Al. Rct values from EIS studies were 116 (lowest), 1825 and 3434 ohm/cm2 (highest) for uncoated 6061 Al, HSCE/VO4 coating and VO4, respectively. From PDP studies, icorr values were 24.934 x 10-6 (VO4), 33.275 x 10-6 (HSCE/VO4) and 36.64 x 10-6 A/cm2 (6061 Al), respectively, compared to 1.6 x 10-6 A/cm2, for CC from CrO₄², in a similar study. These primary findings might support new opportunities for producing environment-friendly smart hybrid and mono CC based on V compounds for corrosion control on Al in the metal finishing industries. Keywords: 6061 Al; CC; corrosion control; EIS; HC; HSCE from VO4; Rp.

Bm has the best role in the economy of a country. Ln is an essential structural component that is present in all vascular plants’ cell walls. It is essential for the development of connective tissues, since it gives stiffness, strength and resistance to external threats like infections. Ln has numerous economic uses, and its extraction might lead to the development of several novel applications. Therefore, it is of the utmost significance to develop efficient and long-lasting solutions for Ln extraction from Bm. For this reason, one of the goals of the current study was to examine optimized Ln extraction from Bm, SB, rice and WS, by chemical methods. Further, Ln chemical extraction process characterization, optimization, and its applications in resins have herein been carried out. Keywords: Bf; Bm; chemical; greenhouse gas; Ln; LnC; resin.

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.