Portugaliae
Electrochimica Acta

Enhancing techniques for obtaining fluted pumpkin seeds oil (PSO), technically known as Telfairia occidentalis, was the goal of this study. The main objective was to analyse chemical and physical properties of the extracted oil, expediting the process by using response surface methodology (RSM) and artificial neural networks (ANN). Fluted PS were purchased from a local market, carefully washed, sun-dried, sorted from chaff and crushed. Using a Soxhlet extractor and n-hexane as solvent, PSO was extracted. For optimisation, a three-level, three-factor Box-Behnken design with 17 iterations was used. The sample’s weight, solvent volume and extraction time were the main factors taken into account for optimisation. According to the study's findings, RSM optimisation produced a 41.58% (w/w) pumpkin seeds oil yield (PSOY). ANN approach, on the other hand, produced a greater PSOY of 41.66% (w/w), demonstrating its superior capacity to forecast the ideal oil output. Standard industrial procedures were used to determine PSO density, specific gravity, moisture content and acid, saponification, iodine and peroxide values, among other parameters. When ANN and RSM were compared, it was found that the former was more reliable in predicting PSOY, since it had better coeeficients of determination (R2) and R2 adj. values (0.9746 and 0.9893) and lower root mean square error values (0.9889 and 0.9965). In conclusion, this study highlights the potential uses of fluted PS across a range of sectors. It emphasises how using statistical analytical approaches can significantly improve production operations. Keywords: ANN; extraction; percentage PSOY; PS; RSM.

To discriminate the structures of two polymers, 1,4-transpolymyrcene (TPM) and 1,4-cis polymyrcene (CPM), at molecular level, nuclear magnetic resonance (NMR) was herein used as the main method. However, to enhance the reliability of findings, this method involves a longer ordering time, which results in higher costs. A simple electrochemical technique, based on the use of cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS), was incorporated into the approach of this study. CV provided information on the polymers’ electronic properties, while EIS enabled to assess electrochemical properties and conductivity. These techniques were utilized to identify distinctions between TPM and CPM, without resorting to NMR analysis, and they provided crucial data on the polymers’ structure and electrochemical behavior. By comparing results obtained by these two approaches, the validity of conclusions drawn from NMR analysis was confirmed. This hybrid approach, combining advanced NMR techniques with electrochemical methods, enabled a more comprehensive characterization of TPM and CPM. Thus, it offers an integrated and more reliable approach to molecular structure discrimination, enhancing the understanding of natural polymers in diverse applications. Keywords: CPM; CV; EIS; NMR analysis; SWV; TPM.

forming an oxide layer on their surface. This causes several undesirable effects such as corrosion and malfunction. CR of Thermo Active Super Elastic Alloy (TASEA) immersed in artificial sweat (AS) with 100 ppm NaCl and 100 ppm urea was herein investigated and compared by polarization study and AC impedance spectra. It was seen that CR of TASEA immersed in AS with 100 ppm NaCl/urea increased. When TASEA was immersed in AS with 100 ppm NaCl linear polarization resistance (LPR) increased from 1760283 to 9506106 Ohm/cm2, icorr decreased from 2.382 x 10-8 to 4.008 x 10-9 A/cm2, Rct increased from 4884 to 12210 Ohm/cm2, impedance increased from 4.367 to 4.8, Cdl decreased from 10.442 x 10-10 to 4.1769 x 10-10 F/cm2 and phase angle increased from 48.1 to 68°. When TASEA was immersed in AS with 100 ppm urea LPR increased from 1760283 to 2430930 Ohm/cm2, icorr decreased from 2.382 x 10-8 to 2.004 x 10-8 A/cm2, Rct increased from 4884 to 10740 Ohm/cm2, impedance increased from 4.367 to 4.777, Cdl decreased from 10.442 x 10-10 to 4.748 x 10-10 F/cm2 and phase angle increased from 48.1 to 66°. Keywords: AC impedance spectra; AS; CR; NaCl, polarization study; TASEA; urea.

Polyaniline (PANI) is the oldest conducting polymer which has drawn demanding attention, due to its unique conductive properties and versatile applications in various fields. Carbon Nanofiber (CNF) is another promising material, due to its high electrical, thermal conductivity and great mechanical qualities, with various uses, including electrode constituents for batteries and supercapacitors (SC). The experiment of this study involved PANI and PANI/CNF synthesis, as well as the fabrication of their thin films on Indium Tin Oxide (ITO), using DCT. The primary focus was to examine electrical conductivity as a significant factor. The electrical conductivity of the hybrid composite consisting of PANI/CNF thin film-coated ITO was predominantly influenced by its dispersion state and thickness. Electrical conductance of PANI/CNF thin film on ITO glass prepared by Dip Coating Technique (DCT) was 41.78990 µS, whereas for PANI on ITO, and for bare ITO glass, was 7.30465 and 1.05238 µS, respectively. So, this study introduced a novel avenue for research in the domain of conducting polymers and their thin films on ITO substrates. Keywords: CNF; conducting polymer; DCT; hybrid composites; ITO; PANI.

Biomass torrefaction into fuel pellets is deemed a sustainable energy solution, which could mitigate over-dependency on fossil fuels. This study examined the effects of pelletization and torrefaction on selected physical and thermal properties of corncob waste (CW). Corncob samples were collected, sorted and pulverized, before torrefaction pre-treatment. Raw corncob (RC) and torrefied corncob waste (TCW) were screened to 0.3, 0.5 and 1.0 mm. Using starch (5 wt.%) as binder, RC and TCW pellets were produced, at compaction pressures of 50, 75 and 100 MPa. They were characterized by proximate, ultimate, physical, thermogravimetric and thermal analyses. All samples exhibited good quality and thermal properties, but those from TCW were better. Relaxed density of RC and TCW pellets varied from 700 to 876 and 616 to 800 kg/m3, respectively. Maximum relaxation values for RC and TCW pellets were 1.43 and 1.07, respectively. TCW sample (1.0 mm) had higher heating value of 25.8 MJ/kg, which was 29% greater than those from lignite or brown coal. Thus, pellets produced from TCW are suitable for energy applications. Keywords: compaction pressures; pelletized particles; particle size; TCW; TGA.

The long-standing history of low corrosion resistance in E316 CS poses a persistent challenge for its industrial applications. Green CI are among the most widely adopted and cost-effective methods to protect metals and alloys against corrosion. In this study, a novel approach involving controlled block polymerization of myrcene, a biobased isoprene dimer, with styrene, using a Nd(BH4)3(THF)3/BEM-based catalytic system, resulted in the synthesis of poly(1,4-trans myrcene-co-styrene) - PMy- copolymer. This transparent and adhesive copolymer was developed as CI agent. Experiments were conducted using WL method and electrochemical techniques, at various polymer Ct and IT. According to the results obtained from WL and electrochemical analyses, increased IE(%) was observed using a polymer Ct of V3, corresponding to 1,5 g/L, suggesting higher corrosion IE(%) properties. Electrochemical analyses revealed that PMy exhibited a uniform CI effect, with a cathodic predominance. Additionally, Rct of CS electrode in an untreated solution increased from 71.25 to 668.3 Ω cm-2, in a solution with PMy, after 24 h of IT. Keywords: CI; E316 CS; HCl solution; PMy.

into the effects of permanent magnetic field (MF) on water. The water molecule is polar, with a bond angle of approximately 104.5°. Electrical charges at O and H atoms were unevenly distributed. The negative charge was drawn toward O atom, and positive charges were redistributed toward H atoms. Water is a polar solvent. The applied MF influenced the orientation of dynamics of H bonds between water molecules, of which process depended on MF parameters. Fourier Transform Infrared (FT-IR) spectroscopy was applied to research potassium carbonate (K2CO3). One indicator of magnets’ properties is magnetic induction. It was shown that MF and strength were essential for this effect, which was on a limescale, in a reversed scheme of arranging magnets. In a non-reversed scheme, the effects manifested in water. The authors researched the effects of a permanent MF on water with and without dissolved K2CO3. The potential application was for animal husbandry. Keywords: animal husbandry; FT-IR; K2CO3; magnetic field; water.

Recent research on capacitive deionization (CDI) materials indicates that salt removal efficiency of their cells can be increased by modifying one carbon electrode, with an electrode operating through a redox mechanism. A potential candidate is δ-MnO2, due to its diverse crystalline phase structure, low price and environmental friendliness. This study synthesized the layered phase of δ-MnO2 via sol-gel route, targeting a high-performance electrode for hybrid CDI (HCDI) technology. Analyzes results on δ-MnO2 composition and porosity were verified through BET, Raman, SEM and X-RD measurements. Electrochemical properties confirmed pseudo-capacitance charge-storage of δ-MnO2 and high durability, with specific capacitance (Csp) of 143 F/g, at a rate of 1 A/g, remaining stable after 1000 cycles. Efficiency of salt removal by optimal performance active material, at 1.4 V, with a moderate salt adsorption capacity (SAC) of 22.5 mg/g, was investigated. Keywords: δ-MnO2; HCDI; pseudo-capacitance; SAC; water desalination.

The corrosion rate of an orthodontic wire (OW) made of thermo active alloy (TAA) immersed in artificial saliva (AS), in the absence and presence of copper barrel brandy (CBB), was herein examined by potentiodynamic polarization study, and it was observed to decrease. When TAA was immersed in AS, in the presence of CBB, linear polarization resistance value decreased from 208.94 x 103 to 37.97 x 103 Ohm/cm2, and corrosion current increased from 2.192 x 10-9 to 12.99 x 10-9A/cm2. It was therefore determined that individuals using OW composed of TAA should refrain from orally ingesting CBB. The change in corrosion potential was observed to be within 50 mV, suggesting that CBB acted as a mixed-type additive. This implies that it enhanced both anodic and cathodic processes of corrosion. The results of this research could be utilized in the field of dentistry. TAA’s surface morphology was investigated by scanning electron microscope. Keywords: artificial saliva; copper barrel brandy; corrosion rate; dentistry; potentiodynamic polarization; scanning electron microscope; thermo active alloy.

Corrosion of rebars is a major problem faced by structures, especially in marine environments. Reinforcing bars are subjected to pitting corrosion from chloride attacks. Furthermore, structures are also susceptible to acid rain and attack from sulphate species. To overcome such challenges, surface engineering can be an effective option. Recent studies have shown rising focus of engineers and scientist on preventing corrosion from rebars and reinforcing steels, by applying a layer of coating. Such coatings include enamel, epoxy, duplex enamel and epoxy, galvanization, electroless Ni and self-healing coatings. They effectively shield the rebars by providing either barrier or passive protection. Therefore, the present work aimed to summarize different coating variants used for corrosion prevention of rebars, and present recent trends. Further research directions to make the coatings more cost-effective were also reviewed. Keywords: concrete; corrosion resistance; electrochemical corrosion; reinforcing steel; surface coating.

LcBm is gaining popularity as an alternative energy source, due to the depletion of petroleum derivatives and environmental concerns. Characterizing Lcbm intermediates and products is critical for turning it into Bf. LBm chemical composition is crutial in creating successful pretreatment methods that break down its stiff structure and convert sucrose to glucose via enzymes and microorganisms. The steps herein reviewed allow for C2H5OH synthesis and additional value-added green chemicals. This review examines various feedstock and pretreatment techniques for C2H5OH production, including Ln degradation, breakdown, hydrolysis and fermentation. While combined pretreatment improves chemical production and enzymatic hydrolysis of LBm, it has greater operating costs. Acids pretreatment procedures, steam explosion and hydrothermal treatments effectively remove Hc fractions. Alkali, oxidative or organosolve pretreatment is more successful in removing and degrading phenols. The aim of this study was to improve the understanding of current and future bio refinery processes, identify constraints and develop technologies to improve pretreatment procedures. Keywords: Bf; LcBm; pretreatment.

CI of MS in ground water by AEOBL and Zn was herein investigated by WL method and PDP. It was concluded that MS corrosion resistance strengthened with AEOBL and Zn presence, due to an increase in LPR and a decrease in Icorr. Therefore, AEOBL and Zn inhibited metal corrosion and acted as good CI. SP showed a SE between AEOBL active principles and Zn ion. FTIR spectral analysis revealed that a protective film was formed on the MS surface by coordination of Fe2+ ion with polar O atoms of phenolic and ether groups, pi electrons of the double bonds and O of methoxy group. Each functional group contributed to the protective film formation, which also contained Zn(OH)2. SEM images confirmed the formation of a protective film on the MS surface. PDP revealed that LPR increased from 760 to 4561 Ohm/cm2 and Icorr decreased from 5.941 x 10-5 to 1.006 x 10-5 A/cm2. The findings may be useful in water towers where ground water is used for cooling. Keywords: AEOBL; CI; FTIR; ground water; MS; PDP; SEM; SP; WL method; Zn(OH)2.

AMMC are notable for their extensive research and unique property profiles, surpassing those of traditional solid metals. Their remarkable strength sets them apart, making them highly sought-after and versatile across diverse industries. The integration of reinforcements into AMMC boosts their properties, including increased tensile and compressive strength, improved wear resistance, reduced thermal expansion and enhanced hardness, characteristics unattainable with conventional materials. However, the use of CMC, such as SiC and Al2O3, escalates the production cost of AMMC, thereby limiting their application in various industries. In recent times, researchers have increasingly turned to natural reinforcements derived from waste sources, such as bamboo leaves, rice and palm kernel shells. However, investigations into PV potential as reinforcements for AMMC have been limited, prompting the initiation of this study. This research aimed to examine mechanical, microstructural, electrochemical and optoelectronic properties of AMMC reinforced with PVP. The study demonstrated an increase in hardness values, from 28.1 to 38.5 HRB, with 25% PVP reinforcement, and a significant reduction in CR, from 12.06 to 6.13 mm/yr. Electrical resistivity and conductivity measurements showed variations across composite samples, while microstructural analysis confirmed uniform PVP dispersion and integration within the metal matrix, alongside additional crystalline formations. Keywords: Al; corrosion; HRB; optoelectrical; PV; PVP; reinforcement.

Due to its wide areas of applications, ready availability and affordability, mild steel has become a very versatile metal in the industry, but it is usually exposed to different environments that can corrode it, thereby affecting its properties and performance. Hence, effective metal corrosion control is required before or during mild steel application. Zn₃(PO₄)₂ coating is a preferred method for surface treatment and finishing of both ferrous and non-ferrous metals, being highly regarded for its efficiency, rapid operation and ability to provide outstanding corrosion and wear resistance, adhesion and lubricative properties. In this review, components of Zn₃(PO₄)₂ bath, its detailed process, adsorption mechanism on metal surfaces, applications, thermodynamic and kinetic properties, are considered. Keywords: coating; corrosion; metal; Zn₃(PO₄)₂.

Electrooxidation (EO) of glucose (Glu) on a stainless steel (SS) electrode surface was investigated under two conditions: in the absence and presence of Pseudomonas bacteria. In its absence, CV analysis revealed a redox system within potential (E) range from -0.5 to 0 V. However, when bacteria suspension was introduced into the electrolytic solution, significant changes were observed. CV showed the emergence of anodic and cathodic peaks, accompanied by a substantial increase in current density (j). This indicated strong interactions between electrode surface and bacteria. The presence of bacteria also caused the redox system to shift towards more anodic E values. Despite this shift, oxidation j decreased. These findings suggest that Pseudomonas played a critical role in modifying the electrochemical behavior of Glu on SS electrode surface, possibly through direct interactions or alterations in the local environment at the electrode-electrolyte interface. Keywords: bio-corrosion; CV; EO; Glu; pseudomonas; SS.

The purpose of this study was to provide recommendations for enhancing environmental awareness and education in the region of Quetta, Pakistan, by investigating the influence of Environmental Education and Awareness on the Effective Management of Solid Wastes in the region. This was achieved by examining existing awareness on environmental policies, and how these influence people’s attitudes towards SWM. This was accomplished by establishing a link between mindset and SWM strategies, and assessing the influence of individuals’ environmental knowledge on how they address SW. Using a standardized survey, data were collected from 400 respondents from four zones: Kuchlack, Siryab, Kharot Abad and Nawakili, employing a systematic random sampling technique. The information gathered from the questionnaire was scrutinized. The findings revealed the presence of an environmental awareness policy in Quetta, Balochistan, as well as its effects on people’s attitudes towards SWM. In addition, no association was found between attitudes and SWM practice. Also, environmental education did not influence Quetta people’s attitudes towards SWM. Based on these findings, a collection of suggestions has been developed to assist practitioners, policymakers and especially academics in dealing with SWM. Keywords: environmental awareness; SW; WM.

This review paper examines the potential of using NPNi/NPNiO and NC as CI for MS and other ferrous alloys in a variety of aggressive corrosive media. A survey of previous literature revealed that higher Ct of NPNi has significantly reduced CR and has increased corrosion IE(%) for different ferrous alloys in various corrosive media. These CI effectively protect the substrate, even at low Ct, by forming a dense passive film which adheres to the metal surface and inhibits anodic or cathodic reactions that cause metal corrosion. Their enhanced corrosion protection ability is due to the presence of more available active sites for adsorption of destructive ions, caused by their high surface area to volume ratio. NPNi are very stable, even at higher T and in aggressive salt environments, due to their large surface area, high hardness and excellent thermal stability. These CI have a unique advantage over other traditional organic and green inhibitors, because they are not easily washed away by corrosive fluids during industrial operations, and are chemically stable under harsh conditions and elevated T. Different methods for synthesis and characterization of NPNi, as well as environmental and safety considerations associated with the use of these CI, are also herein discussed. Keywords: corrosion; CI; ferrous alloys; Ni; NiO; NP.

This study involved the development of a multifaceted Zn barrier coating through ED technique, followed by a comprehensive characterization of its properties. A MS plate, Zn and CaO were all sourced and assessed, in accordance with ASTM standards. ED process was then employed to coat MS, resulting in Zn-12CaO identification as the formulation with the highest coating thickness, at 0.2304 mm. Electrochemical assessment highlighted exceptional corrosion performance of Zn-12CaO coating, which showed CR of 2.4117 mm/year and Pr of 34.41 Ω. This performance stood out in comparison to the as-received sample, which had a CR of 13.449 mm/year across all Zn-CaO formulations. Microstructural analysis through SEM images unveiled the presence of rough and irregularly shaped refined particles, with the Zn-12CaO coating showing a significant deposit of crystallites. Furthermore, it exhibited remarkable hardness, registering a value of 258.12 BHN. EDS analysis provided insights into the coating’s significant elements, contributing to its corrosion resistance and hardness properties. With its impressive hardness value of 258.12 BHN and low CR of 2.0618 mm/year, Zn-12CaO coating emerges as an excellent solution against potential failure in steel, for application in industries requiring durable protective barriers, such as automotive, construction and marine environments. Keywords: corrosion; ED of Zn; mechanical properties; microstructural analysis.

The study's aim was to create a brightness histogram based on the electrical effects of a 1% solution of lavender essential oil dissolved with 5% ethyl alcohol in distilled water compared to a control sample of 5% ethyl alcohol in distilled water. Corona gas discharge (CGD) is a glowing corona with a bluish color that appears because of a high concentration of ions and electrons. The corona discharge is connected to ionization processes in the gas phase, which depend on the electric field and gas composition. CGD occurs in laboratory conditions. Corona can have a positive or negative charge. Both types are used for wastewater cleaning, fruit juice sterilization, surface disinfecting, and medicine. A high-voltage electrode usually ranges from 3 to 30 kV. The frequency range was from 10 to 20 kHz. The electric current is commonly in mA. Ignatov et al. have studied signal power ranges from one to two-tenths of a watt. Antonov et al. have shown that CGD parameters depend on the object’s dielectric permittivity, underscoring the importance of this research. The work of Pesotskaya et al. is also of significance to this study. It indicates that BH can be created with black-white registration and that brightness is linked with dielectric permittivity. This finding is particularly relevant to this research about the effects of CGD on lavender oil (LO) from the Lavandula angustifolia mill., as it provided a method for quantifying observed changes in brightness. The formula is Y = Cε, where Y is brightness, C is coefficient and ε is dielectric permittivity. Keywords: brightness; CGD; histogram; LO.

The aim of this study was to shed light on the process of CH₃OH bacterial electrolytic oxidation, catalysed by a Zn-modified CPE, in the presence of PM polymer in a solution containing 0.3 g NaCl dissolved in 20 mL distilled water. Electrodes were fabricated by depositing Zn on a CPE using potentiostat and galvanostatic techniques. Optical morphology analysis and microscopy techniques revealed Zn efficient dispersion on C, forming well-structured and connected clusters. The study of electrode behavior using CV techniques revealed catalytic effects that improved CH₃OH oxidation results. Keywords: CH₃OH; CV, electrodeposition; oxidation; PM Zn.