Optimising the parameters of leaching while assessing the dynamics of the process kinetics requires an investigation of the effects of different variables. A neural network (NN) and a fuzzy inference system (FIS) were used to evaluate and examine the leaching process. The results showed that increasing the acid concentration and stirring speed, while decreasing the solid-to-solution ratio and pH, enhanced copper (II) leaching. The optimum values obtained from the leaching process for pH 3 were found to be a solid-to-liquid ratio of 1g/100 mL, an agitation speed of 300 rpm, and an acid concentration of 1 M, with a 97% recovery of copper (II). Diffusion throughout the product layer controlled the leaching rate, and the experimental results suggested that a diffusion-controlled model would provide the best fit. The diffusion-controlled mechanism was indicated by an activation energy of 16.01 kJ/mol. To optimise the parameters of the leaching process, the algorithm training for neural networks (NNs) included the Levenberg–Marquardt method with a membership structure of 7-7-7-7, using the backpropagation (BP) technique for learning. The neural network (NN) method was trained using four input variables, representing leaching parameters, fifteen hidden layers, and one output representing copper (II) leaching recovery. R² values of 0.996, 0.997, and 0.997, respectively, show the validation, testing, and training phases of the ideal trained neural network. An R² value of 0.999 for FIS indicates that the study data can be precisely predicted. ANFIS had a Pearson's chi-squared value of 0.225, surpassing the ANN's score of 0.658.

India aims to produce five million tonnes of green hydrogen annually by 2030, which has ignited significant research into developing efficient and cost-effective production methods. Electrolysis, a critical environmentally friendly method for producing green hydrogen, faces challenges due to its reliance on costly precious metal electrodes, making it both expensive and inefficient. To reduce hydrogen production costs, this study investigates using wire arc additive manufacturing (WAAM) to create a Ni-induced Fe-Ni bimetallic structure (BS) as a cost-effective, alternative, and sustainable catalyst for efficient green hydrogen production. WAAM is an emerging technique that enables the deposition of multiple materials, such as stainless steel (SS) and nickel (Ni), layer by layer to create a BS with tailored properties.

The research focuses on the design and optimization of a BS by depositing different compositions of Ni (10% to 40%) in SS316L. The mechanical, metallurgical, and corrosion properties with oxygen evolution reaction (OER) activities were evaluated using corrosion, electrolysis, X-ray diffraction, and scanning electron microscopy.

This study revealed that increasing Ni content reduces micro-hardness by up to 38.14% due to higher L10-FCC phase formation. Similarly, increasing Ni content reduced the OER and corrosion activity, except for the 40% Ni content sample due to intermetallic formation (IMC) and lower polarization resistance. Further quenching heat treatment of the 40% Ni sample exhibited more remarkable performance than all other samples.

Finally, we have come to understand the effectiveness of WAAM in fabricating Ni-doped SS316L electrodes in an affordable way. IMC formation enhanced the activity of 40% Ni, and heat treatment plays a critical role in OER performance. Future work will explore other composition variations to understand the electrochemical behavior further, aiming to develop a scalable, cost-effective method for manufacturing green hydrogen-energy fuel-cell electrodes.

In this work, we extended an existing version of the Flow-Line Model (FLM) to the symmetric cold rolling of technically pure aluminum sheets. Through the modifications, the rolling process can be described with improved precision even in special conditions. The FLM aims to approximate the velocity values at each point of the rollgap using the new analytical function. The difficulty of the FLM models is in finding the correct value of the parameters based on the geometrical dimensions and frictional conditions. Besides the theoretical changes to the model, a set of empirical parameters were introduced, and the equations to determine the value of these empirical parameters were built up based on numerical results of Finite Element Model (FEM) simulations for a wide range of geometrical parameters.

The main theoretical challenge is to approximate the rollgap using a proper function. The distribution of the shear strain rates along the sheet’s thickness was approximated by a power function. The newly introduced empirical parameters were determined by using three non-dimensional factors: (i) the ratio of the actual to minimal coefficient of friction, (ii) the relative reduction in the sheet’s thickness, and (iii) a geometrical ratio expressing the ratio of the rollgap’s length to the sheet’s thickness.

The model was tested for the following regimes of the non-dimensional factors: the thickness reduction was changed from 0.01 to 0.38; the ratio of the pressed arc to the radius was varied between 0.0082 and 0.31; and the ratio of the real to minimal coefficient of friction was changed from 1.05 to 2.5.

The model’s precision determined from the three measured distortion lines (generated by Vickers indentations) was compared to their simulated version.

Introduction: Sunlight-induced photocatalytic oxidation of organic matter is significant for a number of reasons, including (i) its low cost, (ii) its ability to purify air and water [1], and (iii) its role as an alternative to the selective synthesis of high-value oxygenated compounds [2].

Methods: Materials used: ethanol, TiO_2, and Pt/TiO₂ powders (obtained by sol–gel method). The reaction products of gas-phase oxidation processes were analyzed by gas-phase chromatography (GC-TCD and GC-FID).

Results: Considering light-induced ethanol oxidation on a noble metal (Pt) loaded with TiO₂, both the support and noble metals are crucial for light absorption, charge separation, and carbon dioxide generation. Platinum nanoparticles on TiO₂ can primarily cause the separation of photogenerated charges and a red shift in the light absorption edge.

Figure 1. Oxidative conversion of ethanol driven by solar light.

Conclusions: The light-initiated photo-oxidative routes ofan organic substrate over TiO₂ charged with noble metals are revealed in this study. The production of carbon dioxide, the separation of the light-generated charges by platinum addition, and the mechanism of the oxidative conversion reaction of ethanol are the main topics of this analysis of the intricate phenomena connected to the photocatalytic processes.

References:

• Paz, Application of TiO₂ photocatalysis for air treatment: Patents overview, Appl. Catal. B 2010, 99, 448-460.
• Kou et all, Selectivity enhancement in heterogeneous photocatalytic transformation, Chem. Rev. 2017, 117, 1445-1514.

The increasing demand for advanced food packaging technologies has prompted the exploration of functional coatings that can extend the shelf life of food products while maintaining safety and quality. In this study, polypyrrole coatings were synthesized on aluminum can metals using various electroanalytical techniques across different electrolytic media, namely oxalic acid, sodium salicylate, and acetonitrile. The resulting films were subjected to extensive characterization through spectroscopic and microscopic techniques to assess their structural and compositional properties. The primary objective of this work was to evaluate the effectiveness of these polypyrrole (PPy) coatings in providing corrosion protection to aluminum cans, a critical factor for maintaining the integrity of food containers. Additionally, the films' ability to detect volatile organic compounds (VOCs) was investigated, aiming to incorporate sensory functionalities into the packaging system. The results demonstrated that the polypyrrole coatings significantly enhanced the corrosion resistance of aluminum in various aggressive environmental conditions. Moreover, the films exhibited promising sensitivity to VOCs, paving the way for the development of intelligent packaging systems capable of the real-time monitoring of food freshness. This research underscores the potential of polypyrrole-based coatings as multifunctional materials for smart food packaging applications, combining protective and sensory capabilities to improve food safety and quality.

Introduction: Surface topography plays a critical role in optimizing titanium implants for enhanced osseointegration—a phenomenon first described by Prof. Brånemark in 1952. His pioneering discovery led to dental implants with a surface roughness (Ra) of approximately 0.15 µm achieved through electropolishing. Advances in bone fixation have since introduced various surface treatments to improve implant roughness favouring cell adhesion. This study investigates the roughness of commercially pure (CP) titanium treated with electrochemical oxidation coatings to assess their suitability for dental applications.

Methods: CP titanium specimens (n=6) underwent surface coating via a proprietary electrochemical oxidation (ECO) of Biocera Medical (WO 2020/049299) in phosphate–zirconate electrolyte with four different concentrations of zinc (Zn) additive: Type 1 (Zr-P), Type 2 (Zr-P-Zn (L)), Type 3 (Zr-P-Zn (M)), and Type 4 (Zr-P-Zn (H)). Surface roughness of applied zirconia–Titania ceramic enriched with P and Zn was measured using a Keyence digital microscope (4 readings per sample) and three-dimensional parameters (Sa, Sq, Sz) following ISO 25178.

Results: Coated titanium surfaces demonstrated increased roughness compared to uncoated titanium (Sa = 0.45 ±0.07 µm). Coating Type 1 had a minimal impact on roughness (Sa = 0.49±0.09 µm), while Types 2, 3, and 4 increased the mean Sa values to 0.63±0.07 µm, 0.66±0.05 µm, and 0.72±0.10 µm, respectively. The roughness is not homogeneous, following lines for uncoated Ti while it is more spotted for coated samples, as observed on 3D Sa maps.

Conclusions: Electrochemical oxidation coatings enriched with Zn increased the roughness of CP Ti surfaces. The higher roughness of Types 2–4 may enhance osseointegration by promoting cell attachment and therefore would improve titanium’s surface properties for dental implants. Further research will expand the analysis of coating properties with SEM/EDS imaging, nano-indentation, and biological performance.

One of the main environmental problems is related to the generation of micro- and nanoplastics. This study aims to analyze the viability of an innovative method consisting of the adsorption of microplastics using hydrophobic metal particles, which require their functionalization. A laboratory protocol (of the adsorption process) and analysis (of the particles and the adsorption efficiency) were designed. For the production of the metal particles (of micrometric size), the ball milling technique was used. Also, milling equipment operating with liquid nitrogen was used to generate the microplastics. For morphological characterization, electron microscopy was used; for structural X-ray diffraction to analyze the composition, X-ray dispersion spectroscopy was used; and to monitor the functionalization, Fourier transform infrared spectroscopy was used. The functionalization was carried out in a 1M solution of lauric acid. The metallic particles are nanocrystalline (crystallite size range of 12-44 nm) and the crystallographic phase is the bcc-Fe. It was found that the adsorption of microplastics is more efficient when the size of the metal particles is smaller. The correct functionalization of the metal particles prevents their oxidation in aqueous media. Regarding the efficiency in the capture of microplastics, the highest value found is close to 90%, depending on the metallic particle production conditions. Additional studies are needed to optimize the efficiency of microplastic capture, probably by increasing the surface/volume ratio of metal particles.

Introduction: Corrosion resistance is one of the most important requirements for medical devices, as it determines the service life of the material. The aim of this work is to study the corrosion resistance of new biocompatible porous monolithic materials based on titanium nickelide (TiNi), with a different ratio of the reaction additive in the powder system (TiNi:(Ti-Ni)).
Materials and methods: Porous monolithic samples consisting of a monolithic TiNi plate with a porous powder surface were used as the studied material. The surface was powder mixture A–B, where mixture A was (5%Ti+0.5%Ni+TiNi), with exothermic additive B (Ti+Ni) in various ratios: TiNi (1-1), TiNi (1-0.75), TiNi (1-0.5). Sintering was carried out at a temperature of 1100 ℃ and was held for 15 minutes in an electric vacuum furnace. To homogenize the surface, the studied samples were subjected to electron beam treatment. The determination of corrosion resistance was carried out using voltammetry, with a linear potential sweep in a physiological solution.
Results: According to the data obtained from the electrochemical studies, it was established that the rate of corrosion is influenced by the amount of an exothermic additive. The lowest corrosion rate was observed in the TiNi with the highest content: the value of the corrosion rate of the TiNi sample (1-1) was about 2.5 times less than in TiNi (1-0.5). Microscopic analysis showed the presence of local fractures on the surface of the material after electrochemical tests, including cracks and pitting. The porous areas of the material were mainly corroded; therefore, the corrosion rate increases with a decrease in the amount of the exothermic additive.
Conclusions: As a result of the work performed, it is shown that an increase in the proportion of exothermic additives leads to an increase in the corrosion resistance parameters of porous monolithic materials based on TiNi.

CW722R and CW617N brasses are well known for their good formability at elevated temperatures; hence, both alloys find application in forging applications. In practice, it has been observed that CW722R alloy requires a slightly higher forging temperature than CW617N. Studies on other alloys have shown that the response to manufacturing is related to the characteristics of the oxide formed in the surface. However, no studies have been performed to show the effect of surface oxidation on brass during forging. Therefore, the surface oxidation behavior of a CW722R and CW617N alloy was investigated during manufacturing, and its effect on forging was explored. For this purpose, SEM–EDS analysis was performed on the surface of the samples in order to measure the depth of the oxide layer and identify the composition of the oxide. In addition, thermodynamic and Pilling–Bedworth ratio calculations were employed to determine the chemical composition of the oxide layers and explain their mechanical response. The results show that the oxide layer consists of Cu2O/ZnO/PbO with an average width of 0.81μm to 4.1μm according to SEM–EDS analysis and thermodynamic simulation. The Pilling–Bedworth ratio was assessed, showing that the oxide layer is cohesive and protects the surface from further oxidation. In addition, the oxide layer has lower thermal conductivity than the alloy; therefore, during hot forging, the lower thermal conductivity of oxide layer helps to maintain the temperature at higher degrees and thus reduces the forging load.

Background: Today, researchers are focusing on preparing photoactive semiconductor materials doped with non-metals; such semiconductors may be considered a prospective route to resolving the worldwide water crisis by degrading organic dyes present in wastewater from the textile industry.

Methodology, results, and conclusions: Herein, we report a facile route to synthesise S-doped graphitic carbon nitride (S-GCN) from thiourea via thermal polymerisation methods. The crystalline nature of the synthesised photocatalyst was examined by utilising X-ray diffraction (XRD), with the peak positions at Bragg angles (2θ) of 13.07° and 27.42°, which correspond to Miller indices of (100) and (002), respectively; however, their functional group purity was evaluated through Fourier transform spectroscopy (FT-IR), and the presence of three distinct bands appearing at 3153 and 1636-1240 indicates the presence of N-H and O-H stretching modes of heterocyclic S-doped g-C-N, whereas the region between 805 and 812 cm⁻¹ represents the tri-s-triazine unit of S-GCN. All these results indicated that the synthesised photocatalyst exhibited good crystallinity and purity. To examine the photocatalytic activity, 0.2 g/L of synthesised S-GCN was immersed in 100 mL of 10 ppm Congo red dye solution, stirred for 25 minutes, and kept in the dark to establish adsorption–desorption equilibrium followed by open sunlight irradiation. During irradiation, a 3 mL suspension was taken out at intervals of 25 minutes; absorbance was measured, which decreased with time. Moreover, the S-doped GCN displayed good photocatalytic activity in 150 min of sunlight exposure. The degradation of dyes followed pseudo-first-order kinetics.