Portugaliae
Electrochimica Acta

MS is a very versatile and useful alloy in metal industry, since it is available and affordable, but it is prone to corrosion. This study investigated MS corrosion inhibition by modifying Zn₃(PO₄)2 bath with MgO and, then, with combined MgO and CaO additives. Different phosphating times (40, 60 and 80 min) and T (65 and 80 °C) were considered. Ct from 0 to 1.8 g/L MgO and combined MgO/CaO additives were added to Zn₃(PO₄)2 bath. SEM analysis of the coated samples was carried out. The specimens were also immersed in 3.5 wt% NaCl, for WL testing. Obtained results showed that the highest IE(%) of 56% was obtained for the MS sample at a phosphating T of 65 °C and Ct of 1.8 g/L MgO additive. For combined MgO and CaO additive, an IE(%) of 32% was obtained, at 65 °C, with a Ct of 0.9 g/L. MgO and CaO adsorption process (separately and combined) onto MS followed Freundlich’s adsorption model. ΔG indicated a physical adsorption process, and ΔH indicated an exothermic adsorption process, while ΔS during coating revealed a decrease in the process randomness degree. Keywords: Ca additive; corrosion; Mg additive; MS; Zn phosphating.

This study investigated a method for sustainable energy production which involved extracting lignin from waste Bm (AS, BTB, NTB and WnS), to use it as an energy source. The main goal was to advance alternative resources for producing transportation fuels and commodity chemicals, paving the way for a carbon-emission-free future. A pretreatment procedure was conducted, using methods such as EDX, SEM, TGA, proximate and ultimate analyses, to examine extracted lignin. Herein, WnS displayed the highest Bm-derived lignin Ct. BTB and NTB exhibited highest Ct from S, while, remarkably, AS showed the lowest one. NTB extraction process investigation revealed that minimum and maximum yields, at 2 and 3 h, produced lignin Ct of 6 and 8%, respectively. Similarly, BTB yielded 12 and 13% lignin, after 1 and 2 h, respectively. The study indicated that WnS possessed the highest lignin Ct. Furthermore, it was seen that varying certain parameters increased lignin yield. Keywords: biofuel; Bm; chemical treatment; green energy; lignin cellulose; production; renewable energy.

Herein, accurate voltammetric techniques were used for investigating Aza compound at an Au electrode in an aqueous universal BRB solution with pH 4.0 and at room temperature. Employed voltammetric methods were CV, ConvV and DeconvV, at various SR in the range from 40 to 800 mV/s. DSM was used to confirm experimental electrochemical parameters, and to identify the nature of the electrode reaction mechanistic pathway. Recorded CV revealed an uni-directional irreversible sharp anodic peak (Ep = 0.541 mV) in a BRB with pH 4.0. It indicated that the oxidation process was moderately fast. Electrons consumed in the electrode reaction were two. ConvV and DeconvV supported the presence of a chemical step coupled with electron transfer, due to the absence of the cathodic peak coupled in the reverse scan. Oxidative peak sharpness indicated some Aza adsorption control at the Au electrode surface. Keywords: Aza; DSM; electrochemical parameters; electrode reaction; voltammetric techniques.

Electrochemical and AA study of a new heterocyclic Schiff base (L1) was herein carried out for the first time. Electrochemical results and AA tests were performed using PDP, in vitro, by ABTS, C40H56/C18H32O2, DPPH and FRAP, respectively. IE(%) of this compound against corrosion of MS, immersed in a KOH simulated concrete solution (pH of 13.5), with 0.8 M Cl-, was investigated. Electrochemical results showed that L1 was a good CI, even at low Ct (from 10-3 to 10-6 M; τinhib > 98%), the best scavenger in DPPH and ABTS (IC50: 0.022 ± 0.00 and 0.003 ± 7.92E-05 μg/mL, respectively), and the most active in C40H56/C18H32O2 test, with a an IE(%) of 80.22 ± 1.58%. L1 exhibited a significant reducing capacity (A0.5: 0.008 ± 0.00 mg/mL) analogous to that obtained for Trolox (A0.5: 0.008 ± 9.14 05 mg/mL). This study demonstrated L1 good IE(%) and AA. Keywords: ABTS; AA; CI; DPPH; IE(%); L1

Abstract YSZ is a compound with an important role in electrochemistry applications, due to its high electrical conductivity. It is commonly used as electrolyte in solid-oxide fuel cells. Several studies have also suggested additional uses of this material as a proton conductor, when grown in Nc form. The present research reports combined theoretical and experimental results that examined the incorporation and properties of proton defect in YSZ. The calculations were based on DFT and NEB methods. MSS was also performed by studying muons evolution, a lighter hydrogen particle with non-zero spin. The results provided vital information on the formation energetics of proton defect, its migration behavior and electronic structure. Keywords: DFT; MSS; NEB; YSZ.

This work focused on developing prediction models using ANN, in order to forecast the long-term performance of reinforcements in concrete slabs containing pure Mg anodes, and subjected to Cl- ingress. The experimental set-up consisted of two built RCC slabs with 1000 x 1000 x 100 mm. Slab #1 was cast with 3.5% NaCl by cement weight. Slab #2 was cast without NaCl. Considered input parameters were the distance of the anode from the point under consideration in x and y-axes, T, RH and concrete age in days. HCP values concerning SCE were considered output. Experimental values consisted of 80 HCP per slab/day. These were collected for 270 days, in order to generate the prediction model. The learning heuristic used LM supervised learning in feed-forward. A two-layer feed-forward network, with ten hidden sigmoid neurons and trained linear output neurons, was employed. The network architecture [5-10-1] and ten neurons in the hidden layer were used for all prediction models. The accuracy level of results obtained with LM was above 97%. Keywords: ANN model; Cl-induced corrosion; HCP; SA from Mg.

Patients with fractures require internal fixations, since treatment options are limited to metallic implants and autologous bone grafts. These limitations include chances of infection transference, quantity restrictions and the need for additional surgery. Bone tissue engineering seeks to address these limitations through the development of biocompatible bone scaffolds. This study fabricated a PLA based scaffold that sought to address some of the challenges associated with currently available treatment options. The methodology involved acquiring raw eggshells, which were rinsed with water and calcined with concentrated H3PO4. Hitherto, HAp powder was extracted from eggshells, and its presence was confirmed using color test. PLA (60,000 molecular weight) was procured from Sigma Aldrich, which was used with HAp powder, to form the composite, employing sol gel technique. SEM morphology established PLA, which has polymeric binding properties, as the 3D scaffold with the highest Ct (PLA/HAp (45/55 wt.%). It had a more consistent crystal and pore formation and weaker grain boundaries. FTIR analysis showed PLA characterizing peaks, and that functional groups present in 3D scaffold are not toxic to the body. X-RD spectra confirmed PLA and HAp presence in 3D scaffolds. However, peaks intensities decreased with lower Ct of HAp, and those of PLA increased in the 3D scaffold. This indicates that PLA and HAp particles have semi-crystalline and crystalline structures, respectively. Thus, 3D scaffolds can be tailored for many biomedical applications. Keywords: bone fillers; characterizations; HAp; PLA; scaffold.

Different Ct of KBE from its leaves were used to study its effect on MS corrosion resistance. Electrochemical methods such as PDP, EIS and WL tests were herein used. Experimental results showed that, with higher Ct of KB, its IE(%) increased. The highest corrosion IE(%) of 98.41, at 1600 ppm KBE in a 0.5 M H2SO4 solution, was obtained. The inhibitor’s adsorption onto the MS surface was excellent, since it created a monolayer. KBE´s adsorption mechanism obeyed Langmuir’s isotherm. SEM analysis established the development of a protective layer on the MS surface. Keywords: CI; EIS; LPR; PDP;SEM; WL.

employing Lingane’s equation in a simple and extended form. Ionic strength was kept constant by using NaClO4 and KNO3 as SE. All measurements were performed at a constant T of 298±1 K. The approximation of all possible Lingane’s equations was established. According to obtained results, it was concluded that the equation should be used in its extended form. In KNO3 and in NaClO4, q was found to be 5 and 6, and  logarithms were found to be 21.20 and 24.47, respectively. Spectrophotometric study was also performed to determine stoichiometry and  of Cd(II)/Na-DDTC complex in the same SE. Data indicated that Na-DDTC should be combined with Cd in molar ratios of 1:5 (ML5), in KNO3, and of 1:6 (ML6), in NaClO4.  logarithms were calculated to be 22.26 and 23.94, in KNO3 and NaClO4, respectively. IE(%) of Na-DDTC as an ecofriendly CI for CS in 0.5 M H2SO4 medium was also investigated using WL measurements. Experimental results showed that IE(%) increased with higher inhibitor’s Ct. The inhibitor’s adsorption onto the CS surface obeyed Langmuir’s isotherm, and it proceeded by both physisorption and chemisorption modes. ΔGads was determined. The effect of Cd2+ addition, which formed a complex with Na-DDTC, was also studied. Keywords: B; CI; DPV; Job’s method; Na-DDTC.

In the present study, a thin film of NixSy was deposited on an ITO GP by SILAR method. This film was characterized by UV-vis reflectance and FTIR spectroscopy. UV-vis reflectance revealed that Eg from NixSy was 1.55 eV. After coating, ITO GP Eg decreased from 1.88 to 1.55 eV. This indicates that the film functioned as a semi conductor. UV-vis absorbance showed that the film absorbance occurred at 322.00, 388.80 and 396.25 nm, with peak intensity of 1.229, 0.934 and 0.916 AU, respectively. FTIR spectra confirmed NixSy formation on ITO GP by SILAR technique. Thus, it was encouraging to note that NixSy was successfully prepared by this method. Electrochemical studies, such as polarization technique and AC impedance spectra revealed that current flowing through ITO GP increased after NixSy coating by SILAR method. These findings may be useful for solar panel systems used in marine environments. Keywords: Eg; electrochemical studies; ITO GP; NixSy; SILAR method; thin film.

Bd was produced by transesterification of refined NSO with MeOH and CaO catalyst using batch mode. Physicochemical properties of NSO and Bd as an alternative diesel fuel were characterized using ASTM fuel test standards. The FA composition and functional groups of Bd were investigated using GC-MS and FT-IR, respectively. The effect of basic parameters such as reaction catalyst Ct, MeOH/oil molar ratio, reaction T and time, and SS were determined using batch mode. These process parameters were optimized using RSM and ANOVA. The importance of various process parameters and their combined effects on transesterification performance was determined through CCD. Statistical analyzes of the data led to the development of a second-order quadratic polynomial regression model that established the relationship between Bd yield and process variables. The model was able to adequately predict Bd yield with R2 value of 0.9942. The obtained results were in good agreement with published data for Bd from other vegetable oils, as well as with various international standards for this product. An optimal yield of 94% was achieved under optimal conditions of catalyst Ct (4 wt%), MeOH/oil molar ratio of 8:1, T of 55 °C, time of 60 min and SS of 400 rpm. The results show that Bd produced using alcohol in the transesterification process improved CP and CFPP properties. Keywords: ANOVA; Bd; NSO; oil transesterification; optimization; RSM.

Poultry meat is a high-protein source that is consumed all over the world. This source is tainted not only by viruses but also by environmental contaminants, including HM. This study aimed to detect HM in the tissues (liver, gizzard, muscles, heart and kidney) of BC and DC in Quetta city, Balochistan, Pakistan for the first time, using AAF. Samples were collected from different regions of the district, and prepared for analysis. The measured Ct (mg/L) of detected HM like Pb (0.30-0.83), Co (0.18-0.35), Mn (0.10-0.21), Fe (0.32-12.70) and Cu (3.79-4.51) varied across different organs in analyzed BC and DC samples. Cu, Mn, Co and Fe content was within the range of acceptable values established by WHO and ANZFA. However, Ct of Pb for BC and DC exceeded WHO’s (0.2 mg/L) and EU’s (0.1 mg/L) permissible limits. Therefore, more in depth research studies on poultry feed should be carried out, for its improvement and safety. Keywords: AAS; BC; DC; HM.

NH has the ability to control corrosion of various metals and alloys such as Al, CS, Cu, Cu Sn, MS, Sn and SS. It behaves as a CI in acidic, basic or neutral media. In the several studies herein reviewed, various techniques like WL, and electrochemical methods such as PDP and EIS, have been used to evaluate NH corrosion IE (%). Protective films have been analyzed by FT-IR, UV-vis spectroscopy, GC-MS, SEM and EDX methods. NH adsorption onto the metals and alloys surface has obeyed Langmuir’s isotherm. PDP studies have revealed that NH may function as an anodic, cathodic or mixed type of CI, depending on the metal nature and on the corrosive environment. Keywords: CI; EDX; EIS; FT-IR; GC-MS; NH; PDP; SEM; WL.

Modern predictive modeling techniques, such as regression, NN and decision trees can be used to build better and more useful models. JMP 17.2.0 was used in this study to develop a fitting model for microbial growth observed data from chicken manure and banana peels labelled as Sample A, and a single chicken manure substrate, identified as Sample B. Statistical metrics, including COD (R2), RASE, MAD, negative log-likelihood and SSE were used to determine best predictions for Ct (X) from biomass of 22 and 24 samples (A and B) on SC (S) and SGR of microorganisms (μ). Along with estimated Monod parameters, TanH function SAS codes for 3 declared hidden layers, also demonstrated by surface plots, portrayed Sample B predicted model as the best one, even though the 2 samples datasets R2 values for training (A: 0.9887916 and B: 1.0000) and validation (A: 0.9787637 and B: 0.9999999) pointed to a good fit. According to findings, optimal conditions for datasets were: A- biomass = 899868717 mg/L and SC = 4.62 x 109 mg/L, correspondent to high µ (0.010201 h-1); and B- biomass = 15351147 mg/L and SC = 9.2322 x 109 mg/L, consistent with µ of 0.007316 h-1. RMSE, which is the standard method of choice for evaluating the accuracy of predictive models, including those based on NN, should be activated in future studies. This research is both timely and relevant in the pursuit of sustainable waste management and renewable energy generation. Keywords: ANN; JMP; Monod; SAS code; SGR; SC; TanH function.

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.