Search Results (43)

Hydrogen production is increasingly vital for global decarbonization but remains a water- and energy-intensive process, especially in arid regions. Despite growing attention to its climate benefits, limited research has addressed the environmental impacts of water sourcing. This study employs a life cycle assessment (LCA) approach to evaluate three water supply strategies for hydrogen production: (1) seawater desalination without brine treatment (BT), (2) desalination with partial BT, and (3) freshwater purification. Scenarios are modeled for the United Arab Emirates (UAE), Australia, and Spain, representing diverse electricity mixes and water stress conditions. Both electrolysis and steam methane reforming (SMR) are evaluated as hydrogen production methods. Results show that desalination scenarios contribute substantially to human health and ecosystem impacts due to high energy use and brine discharge. Although partial BT aims to reduce direct marine discharge impacts, its substantial energy demand can offset these benefits by increasing other environmental burdens, such as marine eutrophication, especially in regions reliant on carbon-intensive electricity grids. Freshwater scenarios offer lower environmental impact overall but raise water availability concerns. Across all regions, feedwater for SMR shows nearly 50% lower impacts than for electrolysis. This study focuses solely on the environmental impacts associated with water sourcing and treatment for hydrogen production, excluding the downstream impacts of the hydrogen generation process itself. This study highlights the trade-offs between water sourcing, brine treatment, and freshwater purification for hydrogen production, offering insights for optimizing sustainable hydrogen systems in water-stressed regions. Full article

Iron–carbon micro-electrolysis and combined processes were used to treat simulated dyeing wastewater containing direct Big Red 4BE dye (concentration of 1500 mg/L, chromaticity of 80,000 times, and salt content of 20 g/L). Through single-factor experiments, the optimal reaction conditions were determined as follows: reaction time of 110 min, initial pH of 5, and iron and carbon mass ratio of 1:2. Under the optimal conditions, the concentration was reduced to 14.51 mg/L, the chromaticity was reduced to 3000 times, and the decolorization rate reached 99.03%. In order to further decrease the wastewater chromaticity, coagulation and Fenton oxidation were respectively employed for in-depth treatment after iron–carbon micro-electrolysis. The total decolorization rate of the dye wastewater exceeded 99.7%, with the treated effluent meeting the specified chromaticity discharge standard (80-fold). The integrated processes of iron–carbon micro-electrolysis combined with either coagulation sedimentation or Fenton oxidation demonstrated superior performance in treating direct Big Red 4BE dye wastewater. Full article

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

The miniaturization of smart materials has become a new trend in the modern manufacturing industry due to its enormous application in the aerospace, biomedical, and automobile sectors. Nickel–titanium (NiTi)-based binary shape memory alloys (SMAs) are one of the smart materials with certain supreme features like shape memory effect, pseudo-elasticity, high ductility, strong corrosion-resistance, and elevated wear resistance. For this, several micro-machining processes have been developed to machine NiTi SMAs. This paper summarizes all of the conventional and non-conventional micro-machining processes employed to machine NiTi SMAs. In this review process, the surface integrity, dimensional accuracy of the machined surface, cutting force and tool wear analysis during conventional and non-conventional micro-machining of NiTi SMA are evaluated mostly with the aid of input process variables like cutting speed, depth of cut, width of cut, types of coolants, tool coating, discharge voltage, capacitance, laser fluence, pulse duration, scan speed, electrolysis concentration and gap voltage. The optimization of process parameters using different methods during conventional and non-conventional micro-machining of NiTi SMAs is also analyzed. The problems faced during conventional micro-machining of NiTi SMAs are overcome by non-conventional micro-machining processes as discussed. The present study aims to recognize potential developments in the improvement of the micro-machinability of NiTi SMAs. Full article

Iron phosphate (FePO₄·2H₂O) was synthesized via anodic oxidation using nickel–iron alloy composition simulates from laterite nickel ore as the anode and graphite electrodes as the cathode, with phosphoric acid serving as the electrolyte. A uniform experimental design was employed to systematically optimize the synthesis parameters including voltage, electrolyte concentration, electrolysis time, and degree of acidity or alkalinity (pH). The results indicate that the addition of cetyltrimethylammonium bromide (CTAB) surfactant effectively modulated the morphology of the anodic oxidation products. The optimized conditions were determined to be an electrolyte concentration of 1.2 mol/L, a voltage of 16 V, a pH of 1.6, an electrolysis time of 8 h, and a 3% CTAB addition. Under these conditions, the synthesized FePO₄·2H₂O exhibited enhanced performance as a lithium-ion battery precursor. Specifically, the corresponding LiFePO₄/C cathode delivered an initial discharge capacity of 157 mA h g⁻¹ at 0.2 C, retaining 99.36% capacity after 100 cycles. These findings provide valuable insights and theoretical foundations for the efficient preparation of iron phosphate precursors, highlighting the significant impact of optimized synthesis conditions on the electrochemical performance of lithium iron phosphate. Full article

Flooded lead–acid batteries start producing oxygen and hydrogen during the final stages of charge and subsequent overcharge. The collection of the hydrogen produced allows for an increase in overall energy efficiency and transforms the system into a hybrid device typically referred to as a “Battolyzer” (battery electrolyzer). The present work explores the feasibility of the above approach through a detailed study of the long-term ageing process of flooded tubular lead–acid cells subjected to various rates of discharge and overcharge, emulating four different scenarios of Battolyzer use, starting from 70% depth of discharge cycling to nearly continuous water electrolysis. The combined results from the electrochemical and corrosion studies showed that the Battolyzer cells’ degradation was driven by the corrosion of the positive current collectors. The progress of the corrosion process was strongly correlated with the amount of hydrogen produced. The increase in the depth of discharge resulted in minor decreases in the corrosion current, indicating that the battery functionality of the Battolyzer was more advantageous than the continuous water electrolysis. Full article

Electrochemical technology presents a promising approach for phosphorus recovery from wastewater. Nevertheless, its application in industry is hindered by relatively low phosphorus recovery efficiency, high energy consumption and complex reactor configurations. In this study, a coupled electrolysis and microfiltration system was designed for phosphorus recovery in the shape of iron phosphate compounds with the use of steel pickling wastewater as the iron source. In the electrolysis unit, the anode diffusion layer was extracted from the porous anode surface with the production of an acid effluent and an alkaline effluent. The alkaline effluent was mixed with the stainless steel acid washing wastewater generated from the steel pickling process and then introduced into the microfiltration unit to intercept the iron phosphate crystals. The filtered effluent was finally introduced into the air aeration unit to further reduce the phosphorus content in the water. And the extracted acid solution could be reused in the pickling step of the iron and steel manufacturing process. The experimental results show that the coupled system achieved phosphorus recovery of 42~80% at a current density of 5~20 mA cm⁻², accompanying energy consumption of 5.78~9.15 kWh (kg P)⁻¹ and current efficiency of 79~43%, when the phosphorus concentration was 3 mM and the iron–phosphorus molar ratio was 1.5. After the microfiltration treatment, the residual phosphorus could be further reduced to 0.5 mg L⁻¹ within 30 min at an aeration rate of 80 mL min⁻¹, which met the discharge standard. The presence of interfering ions (HCO₃⁻ and SiO₄²⁻) posed inhibited effects on phosphorus recovery. Generally, this study provides a green and environmentally friendly way to efficiently recover phosphorus resources from wastewater. Full article

Perchlorate is a highly mobile and persistent toxic contaminant, with the potassium perchlorate manufacturing industry being a significant anthropogenic source. This study addresses the Energy Conservation and Perchlorate Discharge Reduction (ECPDR) challenges in China’s potassium perchlorate manufacturing industry through a multi-objective optimization model under uncertainty. The objectives encompass energy conservation, perchlorate discharge reduction, and economic cost control, with uncertainty parameters simulated via Latin Hypercube Sampling (LHS). The optimization was performed using both the Non-Dominated Sorting Genetic Algorithm II (NSGA-II) and the Generalized Differential Evolution 3 (GDE3) algorithm, enabling a comparative analysis. Three types of decision-maker preferences were then evaluated using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to generate optimal decision strategies. Results revealed: (1) The comprehensive perchlorate discharge intensity in China’s potassium perchlorate industry is approximately 23.86 kg/t KClO₄. (2) Compared to NSGA-II, GDE3 offers a more robust and efficient approach to finding optimal solutions within a limited number of iterations. (3) Implementing the optimal solution under PERP can reduce perchlorate discharge intensity to 0.0032 kg/t. (4) Processes lacking primary electrolysis should be phased out, while those with MVR technology should be promoted. This study provides critical policy recommendations for controlling perchlorate pollution and guiding the industry toward cleaner and more sustainable production practices. Full article

Cathodic plasma electrolytic treatment (CPET) is an emerging surface modification and coating preparation technology. By utilizing plasma discharge induced through electrolysis and the cooling impact of electrolyte, metal cleaning, saturation, and coating preparation are efficiently achieved. In this review, the principle, application, and development of the CPET process are briefly summarized based on the past literature. Detailed insights are provided into the influence of electrolyte parameters (pH, metal salt concentration, and temperature), electrical parameters (voltage, duty cycle, and frequency), and process parameters (electrode area ratio, material, roughness, and deposition time) on plasma discharge and coating formation for metal coatings. The interaction mechanism between plasma and material surfaces is also investigated. Recommendations and future research avenues are suggested to propel CPET and its practical implementations. This review is expected to provide assistance and inspiration for researchers engaged in CPET. Full article

The escalating levels of atmospheric CO₂, primarily attributed to human activities, underscore the urgent need for innovative solutions to mitigate environmental challenges. This study delves into the electrochemical reduction of CO₂ as a promising avenue for sustainable carbon capture and utilization. Focused on the formation of formate (HCOO⁻/HCOOH), a high-value product, the research explores the integration of nonthermal plasma (NTP) with electrochemical processes—an approach rarely studied in existing literature. A comprehensive investigation involves varying parameters such as plasma discharging voltage, carrier gas, discharging mode, electrolysis voltage, polarity, and plasma type. The electrochemical tests employ a 10 wt.% Pd/C catalyst, and formate production is quantitatively analyzed using NMR. Results reveal that NTP significantly enhances CO₂ reduction, with key factors influencing formate yield elucidated. The study reveals the complexity of CO₂ electrochemical reduction, providing novel insights into the synergistic effects of NTP. These findings contribute to advancing sustainable technologies for CO₂ utilization, paving the way for more efficient and environmentally friendly processes in the pursuit of a carbon-neutral future. Full article

Thermal events in lead-acid batteries during their operation play an important role; they affect not only the reaction rate of ongoing electrochemical reactions, but also the rate of discharge and self-discharge, length of service life and, in critical cases, can even cause a fatal failure of the battery, known as “thermal runaway.” This contribution discusses the parameters affecting the thermal state of the lead-acid battery. It was found by calculations and measurements that there is a cooling component in the lead-acid battery system which is caused by the endothermic discharge reactions and electrolysis of water during charging, related to entropy change contribution. Thus, under certain circumstances, it is possible to lower the temperature of the lead-acid battery during its discharging. The Joule heat generated on the internal resistance of the cell due to current flow, the exothermic charging reaction, and above all, the gradual increase in polarization as the cell voltage increases during charging all contribute to the heating of the cell, overtaking the cooling effect. Of these three sources of thermal energy, Joule heating in polarization resistance contributes the most to the temperature rise in the lead-acid battery. Thus, the maximum voltage reached determines the slope of the temperature rise in the lead-acid battery cell, and by a suitably chosen limiting voltage, it is possible to limit the danger of the “thermal runaway” effect. The overall thermal conditions of the experimental cell are significantly affected by the ambient temperature of the external environment and the rate of heat transfer through the walls of the calorimeter. A series of experiments with direct temperature measurement of individual locations within a lead-acid battery uses a calorimeter made of expanded polystyrene to minimize external influences. A hitherto unpublished phenomenon is discussed whereby the temperature of the positive electrode was lower than that of the negative electrode throughout the discharge, while during charging, the order was reversed and the temperature of the positive electrode was higher than that of the negative electrode throughout the charge. The authors relate this phenomenon to the higher reaction entropy change of the active mass of the positive electrode than that of the negative electrode. Full article

The possibility of using Si-based anodes in lithium-ion batteries is actively investigated due to the increased lithium capacity of silicon. The paper reports the preparation of submicron silicon fibers on glassy carbon in the KI–KF–KCl–K₂SiF₆ melt at 720 °C. For this purpose, the parameters of silicon electrodeposition in the form of fibers were determined using cyclic voltammetry, and experimental samples of ordered silicon fibers with an average diameter from 0.1 to 0.3 μm were obtained under galvanostatic electrolysis conditions. Using the obtained silicon fibers, anode half-cells of a lithium-ion battery were fabricated, and its electrochemical performance under multiple lithiations and delithiations was studied. By means of voltametric studies, it is observed that charging and discharging the anode based on the obtained silicon fibers occurs at potentials from 0.2 to 0.05 V and from 0.2 to 0.5 V, respectively. A change in discharge capacity from 520 to 200 mAh g⁻¹ during the first 50 charge/discharge cycles at a charge current of 0.1 C and a Coulombic efficiency of 98–100% was shown. The possibility of charging silicon-based anode samples at charging currents up to 2 C was also noted; the discharge capacity ranged from 25 to 250 mAh g⁻¹. Full article

Drawing development plans requires evaluating the available resources and assessing their sustainable and subsequent utilization-driven environmental impacts. The current work is concerned with evaluating the sustainability of the halite harvesting process from Al-Qasab Playa, Shaqra, Central Saudi Arabia. The authors integrated, conceptually and quantitatively, ArcGIS-processed SRTM-DEM (Shuttle Radar Topography Mission-Digital Elevation Model) data, hydrogeochemical and thermodynamic-based geochemical modelling, and graphical approaches to achieve the ultimate aims of the study. The watershed is identified as a nonmarine closed basin with a drainage area of 1290 km², with the slope controlling recharge to the Playa. The Chadha plot including the rainwater exhibits linear regression, with an R² value of 0.9947, confirming the rainwater origin of the Playa water. The hardness-forming ions are primarily removed in pond 3, eliminating the need for costly and power-consuming steps of softening with ion exchange resins or nanofiltration as it can be used directly as a readily available feed for the chlor-alkali process for producing NaOH, Cl₂, and H₂ gases through electrolysis. XRD (X-ray diffraction) analysis and the SEM-EDS (Scanning electron microscopy-energy dispersive X-ray spectroscopy) of the harvested halite confirmed its purity. An improved design of the current folkloric harvesting process has been proposed based on the saturation indices calculated thermodynamically to provide a readily available feed intake for the electrolysis chlor-alkali process with or without minimal pretreatment to produce higher value chemicals. The methodological aspects presented here are deemed robust and valid for applications in other study areas, including the assessment of the exploitation of the rejected brine from the desalination plants to achieve the zero liquid discharge approach, as well as other types of sabkhas, regardless of their geographical location. Full article

Recent advancements in energy conversion and storage systems have placed a spotlight on the role of multi-functional electrodes employing conductive substrates. These substrates, however, often face obstacles due to intricate and expensive production methods, as well as limitations in thickness. This research introduces a novel, economical approach using graphite felt as a versatile electrode. A method to enhance the typically low conductivity of graphite felt was devised, incorporating interfacial chemical tuning and the electrodeposition of a highly conductive nickel layer. This technique facilitates the integration of diverse transition metal-based active sites, aiming to refine the catalytic activity for specific electrochemical reactions. A key finding is that a combination of a nickel-rich cathode and an iron-rich anode can effectively optimize alkaline water electrolysis for hydrogen production at the ampere scale. Furthermore, the addition of sulfur improves the bi-functional oxygen-related redox reactions, rendering it ideal for air cathodes in solid-state zinc–air batteries. The assembled battery exhibits impressive performance, including a peak power density of 62.9 mW cm⁻², a minimal voltage gap in discharge–charge polarization, and a lifecycle surpassing 70 h. This advancement in electrode technology signifies a significant leap in energy storage and conversion, offering a sustainable and efficient solution for future energy systems. Full article

A promising method of energy storage is the combination of hydrogen and compressed-air energy storage (CAES) systems. CAES systems are divided into diabatic, adiabatic, and isothermal cycles. In the diabatic cycle, thermal energy after air compression is discharged into the environment, and the scheme implies the use of organic fuel. Taking into account the prospects of the decarbonization of the energy industry, it is advisable to replace natural gas in the diabatic CAES scheme with hydrogen obtained by electrolysis using power-to-gas technology. In this article, the SENECA-1A project is considered as a high-power hybrid unit, using hydrogen instead of natural gas. The results show that while keeping the 214 MW turbines powered, the transition to hydrogen reduces carbon dioxide emissions from 8.8 to 0.0 kg/s, while the formation of water vapor will increase from 17.6 to 27.4 kg/s. It is shown that the adiabatic CAES SENECA-1A mode, compared to the diabatic, has 0.0 carbon dioxide and water vapor emission with relatively higher efficiency (71.5 vs. 62.1%). At the same time, the main advantage of the diabatic CAES is the possibility to produce more power in the turbine block (214 vs. 131.6 MW), having fewer capital costs. Thus, choosing the technology is a subject of complex technical, economic, and ecological study. Full article