Search Results (118)

Electrokinetic remediation (EKR) was evaluated in naturally contaminated vineyard soils to assess copper redistribution, treatment redistribution efficiency, and changes in copper fractions across contrasting soil pH conditions. Ten vineyard soils (five acidic, five alkaline) were subjected to a 30-day ex situ EKR experiment under a constant electric field. Total copper content was measured in the anode, cathode, and inter-electrode zones, while copper fractions were quantified only in electrode zones exhibiting the most pronounced post-remediation decrease in total copper. The findings demonstrate that the EKR process generated distinct, soil-type-dependent gradients in copper mobility. In acidic soils, copper exhibited pronounced central-zone accumulation with notable depletion toward the anode, whereas in alkaline soils, the lowest concentrations consistently occurred near the cathode and increased toward the anode. Notably, one slightly alkaline soil displayed the highest redistribution efficiency (43.0%), underscoring the strong influence of soil chemistry on EKR performance. Redistribution efficiencies averaged 29.5% in acidic soils and 12.8% in alkaline soils, although localized acidification enabled notably higher redistribution in highly contaminated samples. These trends reflected on copper fractions: acidic soils showed enhanced release from Fe/Mn oxides and carbonates, while alkaline soils experienced stronger short-term mobilization driven by cation competition and dissolution of less stable oxide phases. Fractionation results indicated that the Fe/Mn oxide-bound fraction was the most susceptible to electromigration, while both acidic and alkaline soils ultimately shifted copper toward less extractable operational fractions. Full article

Traditional lithium-ion battery recycling relies mainly on pyrolysis or chemical leaching to separate current collectors from electrode materials, inevitably resulting in secondary pollution. In contrast, eddy current separation (ECS) applied to crushed lithium-ion battery residues can substantially reduce the introduction of contaminants while minimizing material losses. However, the heterogeneous composition and diverse surface characteristics of crushed battery products, together with the conductivity degradation of electrode materials after long-term use, make conventional empirical particle–trajectory correlations inadequate for accurate optimization of ECS operating parameters. In addition, the coupling between process parameters and the resultant forces acting on conductive particles, as well as the associated separation trajectories, remain insufficiently understood, which severely limits process controllability. A force–trajectory model was therefore developed for spent current collectors and conductivity-degraded LiFePO₄ to describe their particle dynamics in an alternating magnetic field. The results demonstrate that the trajectory of LiFePO₄ is very similar to that of non-conductive materials, thereby facilitating its effective separation from metallic components in battery scrap. Eddy current separation experiments further confirm the accuracy of the model predictions with respect to separation trajectories and the influence of key process parameters. On this basis, optimization of the operating parameters increased the separation efficiency of the cathode material to above 95.1%. The clarified ECS mechanism for current collectors and electrode materials provides new insights into the mechanical pre-sorting and mechanistic understanding of lithium-ion battery fragments, thereby contributing to reductions in contaminant introduction during battery material recycling. Full article

The current work examines the impact of isopropanol (IPA) on the electrochemical characteristics of nickel foam and Pd-modified Ni foam electrodes in a 0.1 M NaOH medium, with respect to the kinetics of the hydrogen evolution reaction (HER) over the temperature range of 20–40 °C. Comparative HER/IPA examinations are presented for a highly catalytic polycrystalline Pt electrode. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and cathodic Tafel polarization experiments were carried out in this work, where the IPA concentrations ranged from 1.0 × 10⁻⁵ to 1.0 × 10⁻³ M. The introduction of small amounts of isopropyl alcohol into the working electrolyte noticeably facilitated the catalytic efficiency of the hydrogen evolution reaction on the surface of Ni foam electrodes. This is most likely related to the fact that IPA molecules undergo partial electrooxidation to acetone (qualitatively confirmed by GC-MS analysis) during initial CV cycling, which is believed to significantly diminish the surface tension phenomenon during the HER, thus promoting hydrogen bubble separation from the electrode surface. It should also be noted that acetone will continuously be produced at the Pt anode, making it essential to consider further migration of (CH₃)₂CO molecules to the working cell compartment. Most importantly, isopropanol was found not to undergo significant surface electrosorption on the nickel foam-based catalysts, which could otherwise significantly inhibit the hydrogen evolution reaction On the contrary, the presence of IPA in the electrolyte solution seems to have a detrimental effect on the kinetics of both the HER and the UPDH (underpotential deposition of H) processes on the surface of the polycrystalline Pt electrode, which is a superior electrochemical catalyst for HER, but highly susceptible to surface contamination. Full article

The enhanced performance of electrokinetics (EK) on the cadmium (Cd) dissociation, redistribution, and phytoremediation of Cd-contaminated agricultural soil has been investigated based on the application of an electric field in different dimensions (1D, 2D, 3D). In electrokinetic–assisted phytoremediation (EKPR), unlike the uniform pH change observed in 1D treatment, more soil points (P1–P9) under 2D/3D electric fields were exposed to the influence of the anode (or cathode during polarity switching). Sedum plumbizincicola mitigates EK-induced soil acidification and alkalization, particularly anode acidification under high voltage (10–20 V). Studies reveal that EK promotes Cd dissolution into soil pore water, with a 227.82% maximum increase in the anode region under EK2 treatment of 10 V voltage, facilitating Cd phytoextraction. Periodically reversed DC electric fields enhanced Sedum plumbizincicola height more significantly than biomass, with no conspicuous regional differences. Overall, EKPR (voltage of 5–10 V) can effectively promote soil Cd phytoremediation due to the synergistic effect of direct interface action and indirect influence of the electric field to improve the Cd speciation evolution, dissociation, and bioavailability at the soil–water interface. The appropriate electric field arrangement and voltage were 2D treatment (EKPR2) and 5 V for S. plumbizincicola, respectively. In this case, the average Cd removal rate was as high as 50.23%, and the biomass and Cd accumulation increased by 16.59% and 29.31%. This suggests that plant growth constitutes the pivotal stage driving Cd accumulation and ultimately achieving Cd removal from soil, which is the key to enhancing remediation efficiency. Meanwhile, the configuration and intensity regulation of electric fields, as core elements ensuring the enhanced efficacy of electrokinetic–assisted phytoremediation (EKPR), can indirectly affect plant growth and Cd accumulation processes by modulating intermediate variables such as soil pH, nutrient status, and heavy metal speciation evolution. Full article

Electrochemical advanced oxidation processes based on peroxymonosulfate (PMS-EAOPs) have shown great promise for eliminating organic pollutants from water. However, earlier research primarily concentrated on pollutant degradation at the cathode, with little attention given to the anode’s role in PMS-EAOPs. In this work, we developed a PMS-EAOP system using nitrogen-doped carbon nanotubes (N-CNTs) as the electrocatalyst and examined the degradation of pollutants (acetamiprid (ATP) and sulfamethoxazole (SMX)) at both the cathode and anode. Our findings indicate that SMX was rapidly degraded at both electrodes, while ATP was effectively broken down only at the cathode, demonstrating the selective nature of PMS-EAOP. At a voltage of −2 V and 2.5 mM PMS, the pseudo-first-order rate constant (k_obs) for ATP at the cathode reached 0.122 min⁻¹, with over 92% removal within 30 min. In contrast, the anode exhibited high selectivity, removing ~75% of SMX (k_obs = 0.041 min⁻¹) while less than 20% of ATP was degraded. Analysis of reactive oxygen species showed that hydroxyl and sulfate radicals were produced and contributed to pollutant degradation at the cathode. In contrast, selective oxidation occurred at the anode, likely driven by direct electrolysis-induced nonradical oxidation responsible for the selective degradation. Phosphates and bicarbonates significantly inhibited the degradation of pollutants in the PMS-EAOP process (31.7–76.4%). In contrast, chloride ions exhibited an electrode-dependent effect, with the anode being less susceptible to interference from common water anions. Overall, this study highlights that while PMS-EAOP can selectively remove contaminants, the influence of water matrix components must be taken into account when treating real wastewater. Full article

Chlorinated solvents such as vinyl chloride (VC) and trichloroethylene (TCE) represent a persistent threat to groundwater-derived drinking-water supplies, including riverbank filtration well fields in alluvial aquifers. This work presents a laboratory-scale evaluation of an electrochemical barrier concept for targeted VC and TCE removal performed using synthetic groundwater representative of a riverbank filtration setting in the Danube River basin. Experiments were conducted in a covered batch reactor equipped with Ti/IrO₂–RuO₂ mixed-metal-oxide anodes and Ti cathodes, systematically varying current intensity (10–60 mA), treatment time (0–60 min), active anode surface area (12–48 cm²), and inter-electrode distance (0.5–2.5 cm). At 60 mA, VC and TCE removals of 97% and 95%, respectively, were achieved within 20 min, while prolonged treatment to 60 min increased removal to about 99% for VC and 98.5% for TCE. Multivariate analysis (PCA) and correlation assessment identified applied current as the dominant control parameter, particularly for TCE removal, whereas electrode configuration and spacing played secondary roles within the investigated range. For the most cost-effective treatments meeting Serbian drinking-water criteria, estimated electricity costs were 0.39 €/m³ for VC and 0.10 €/m³ for TCE. Overall, the results demonstrate the technical feasibility and promising cost-effectiveness of electrochemical barriers as a proactive measure to protect riverbank filtration systems from future VC and TCE contamination n urban environments, while highlighting the need for follow-up studies on by-product formation and long-term performance. Full article

Electrolyte degradation and trace water contamination critically affect the lifetime and safety of lithium-ion batteries. In organic-based electrolytes such as acetonitrile (MeCN), even small amounts of water can trigger ${\mathrm{PF}}_6^{-}$ hydrolysis, producing HF, POF₃, and related species that contribute to electrolyte ageing and alter interfacial reactions. This study explores the electrochemical signatures of ageing and moisture contamination in Bu₄NPF₆- and LiPF₆-based MeCN electrolytes through a systematic cyclic voltammetry protocol. Platinum electrodes with different surface morphologies—flat, Nafion-coated, and nanostructured—were compared to assess their sensitivity to water-induced degradation. Cathodic Faradaic currents appearing around −0.7 to −1.0 V vs. Ag/AgCl were attributed to the protonic species generated by ${\mathrm{PF}}_6^{-}$-induced hydrolysis. The presence of LiPF₆, commonly used in battery electrolytes, further increases the concentration of anions responsible for the protonic species, therefore contributing to the acceleration of the electrolyte degradation. Experiments using a Nafion proton-conductive membrane assess the protonic origin of these peaks. Meanwhile, nanostructured platinum exhibits approximately four times higher current responses and enhanced sensitivity to water additions, reflecting the influence of surface roughness and active area. Overall, the findings indicate that electrode morphology significantly influences the detectability of ageing- and water-driven reactions, supporting the potential of nanostructured Pt as a diagnostic material for in situ monitoring. Full article

This study presents a statistically robust quality-engineering evaluation of an industrial cathodic electrodeposition (CED) process applied to large electric-charging station components. In contrast to predominantly laboratory-scale studies, the analysis is based on 1250 thickness measurements, enabling reliable assessment of process uniformity, positional effects, and long-term stability under real production conditions. The mean coating thickness was specified at 21.84 µm with a standard deviation of 3.14 µm, fully within the specified tolerance window of 15–30 µm. One-way ANOVA revealed statistically significant but technologically small inter-station differences (F(49, 1200) = 3.49, p < 0.001), with an effect size of η² ≈ 12.5%, indicating that most variability originates from inherent within-station common causes. Shewhart X^¯–R–S control charts confirmed process stability, with all subgroup means and dispersions well inside the control limits and no evidence of special-cause variation. Distribution tests (χ², Kolmogorov–Smirnov, Shapiro–Wilk, Anderson–Darling) detected deviations from perfect normality, primarily in the tails, attributable to the superposition of slightly heterogeneous station-specific distributions rather than fundamental non-Gaussian behaviour. Capability and performance indices were evaluated using Statistica and PalstatCAQ according to ISO 22514; the results (Cp = 0.878, Cpk = 0.808, Pp = 0.797, Ppk = 0.726) classify the process as conditionally capable, with improvement potential mainly linked to reducing positional effects and centering the mean closer to the target thickness. To complement the statistical findings, an AIAG–VDA FMEA was conducted across the entire value stream. The highest-risk failure modes—surface contamination, incorrect bath chemistry, and improper hanging—corresponded to the same mechanisms identified by SPC and ANOVA as contributors to thickness variability. Proposed corrective actions reduced RPN values by 50–62.5%, demonstrating strong potential for capability improvement. A predictive machine-learning model was implemented to estimate layer thickness and successfully reproduced the global trend while filtering process-related noise, offering a practical tool for future predictive quality control. Full article

Pharmaceutical contamination poses growing environmental risks, yet industrial adoption of advanced oxidation processes (AOPs) remains limited by high costs and the environmental impacts associated with specialized electrodes. This study demonstrates that unmodified aluminum electrodes achieve pharmaceutical degradation performance comparable to precious metal systems at dramatically reduced cost and carbon footprint. An aluminum-based electro-Fenton (EF) system was optimized for amlodipine (AML) removal through systematic evaluation of operational parameters. Under optimized conditions (pH 2.7, 35 mg L⁻¹ FeCl₃, 1.3 mM NaCl, 5 V), the system achieved 97% AML degradation within 15 min, following pseudo-first-order kinetics ($k=0.15$ min⁻¹). The mechanism combines hydroxyl radical oxidation with synergistic electrocoagulation resulting from anodic Al³⁺ release and cathodic Fe²⁺ regeneration. Sustainability assessment revealed exceptional performance: an energy consumption of 0.32 kWh m⁻³, a carbon footprint of 0.53 kg CO₂-eq m⁻³ (60–75% lower than conventional AOPs), and operational costs of $0.71–1.05 m⁻³. Aluminum electrodes cost 100× less than platinum alternatives, with the generated Al(OH)₃ sludge offering valorization potential. This work demonstrates that high-performance electrochemical remediation is achievable using Earth-abundant materials, providing a scalable and cost-effective alternative for pharmaceutical wastewater treatment in resource-constrained settings. Full article

This study investigates the atmospheric corrosion behavior of zinc in tropical marine environments affected by hydrogen sulfide (H₂S), particularly from the decomposition of stranded Sargassum algae. Four exposure sites in Martinique with varying levels of H₂S and marine chlorides were selected. Gravimetric analysis showed that zinc thickness loss reached up to 45 µm after one year at the most impacted site (Frégate Est), compared to only 3–10 µm at less contaminated locations. This degradation level classifies the site as “extremely corrosive” according to ISO 9223. Electrochemical impedance spectroscopy (EIS) and linear polarization measurements revealed distinct corrosion behaviors. After 12 months of exposure, the polarization resistance and corrosion current density reached R_p = 916 Ω·cm² and I_corr = 28 µA·cm² at the Frégate Est site and R_p = 1835 Ω·cm² and I_corr = 6 µA·cm² at the Vauclin site. In H₂S-poor environments (Diamant, Vert-Pré, Vauclin), corrosion resistance increased over time due to the formation of protective layers such as hydrozincite and simonkolleite. In contrast, H₂S-rich environments favored the formation of sulfur-based compounds like elemental sulfur and zinc sulfide (ZnS), which exhibit poor protective properties and result in lower polarization resistance and higher corrosion current densities. Polarization curves confirmed a general decrease in anodic and cathodic currents over time, with less significant improvements in passivation at H₂S-impacted sites. The corrosion mechanism is influenced by both pollutant type and exposure duration. Overall, this study highlights the synergistic effect of H₂S and chlorides on accelerating zinc corrosion and underscores the need for adapted protection strategies in tropical coastal zones affected by Sargassum proliferation. Full article

In the current industry standard of batch processing electrode slurry, manual cleaning processes pose significant challenges due to their labor intensive nature. The long-term objective is to expand the existing mixing process to create an intelligent, autonomous, and continuous slurry production process. This will result in a reduction in downtime and setup times, as well as an increase in the degree of automation. Additionally, the implementation of complex parameter selection in the mixing process is intended to make it manageable for variable recipes, ensuring efficient, resource-saving process control. This study aims to address this issue by investigating the continuous production of anode slurry and its subsequent cleaning in a laboratory extruder, with a focus on optimizing the cleaning conditions and analyzing the residual slurry. Several samples were taken during the cleaning of the process area and analyzed by UV-Vis spectroscopy, while also quantifying the residual slurry on the screw elements. The effectiveness of the cleaning was evaluated using Sinner’s Circle parameters, i.e., the effects of time, mechanical, chemical and thermal treatment on the effectiveness of the cleaning process are evaluated and discussed. Several detergents were tested, including deionized water, alcohol, and industrial detergents. Deionized water proved to be the most effective in terms of cleaning rate and residual slurry. In addition, higher screw speeds and flow rates improved cleaning efficiency. The effect of temperature was significant, with better cleaning rate results at higher temperatures. This indicates that mechanical and thermal factors play a critical role in improving cleaning kinetics. For a more in-depth knowledge of the resulting cell chemistry, successive cross-contamination of cathode materials in anode half-cells was examined. As a result, an indicator was identified in the first cycle that displays a voltage increase during delithiation with regard to electrochemical properties. Full article

The electrochemical production of silicon from SiO₂ in molten salts can reduce energy consumption and mitigate carbon emissions associated with the conventional carbothermic process. In this study, we compare the anodic behaviour of platinum, graphite, and tin oxide electrodes in molten CaCl₂-NaCl-CaO-SiO₂ at 850 °C using electrochemical methods including cyclic voltammetry, linear sweep voltammetry, and chronoamperometry. Pt exhibited low oxygen evolution overpotentials and no significant currents before OER, compared to SnO₂. An eight-hour potentiostatic electrolysis with a SnO₂ anode and a graphite cathode yielded a Si-Sn deposit, indicating partial dissolution of the SnO₂ anode during the electrolysis process. These results highlight the kinetic trade-off of SnO₂ relative to Pt, and the risk of Sn contamination with extended electrolysis times. While SnO₂ is unsuitable for production of high-purity Si, it remains a promising anode candidate for Si-Sn alloy formation. Full article

Conventional energy resources have been constrained by their inefficient utilization and present a severe impact on the human living environment, and there is an urgent need to develop energy technologies with high efficiency, low carbon emissions, and environmental cleanliness. Solid oxide fuel cells (SOFCs) have been recognized as a highly efficient and clean energy conversion device that directly converts chemical energy in fuels into electricity, holding promising prospects for addressing the issues of low efficiency and environmental concerns associated with conventional energy resources. However, under practical operation conditions, the cathodes of SOFCs are often exposed to various contaminations including working environment-induced degradation, cathode poisoning, and corrosion. This review summarizes the severe performance degradation of SOFC cathodes caused by CO₂ poisoning, analyzes recent research findings on cathode durability under CO₂-containing atmospheres, and provides an overview of the reported strategies for enhancing CO₂ tolerance. Full article

Hydrogen-rich water (HRW) has attracted significant attention for its physiological and therapeutic potential, driving efforts to develop a green and direct production approach. In particular, if solar energy could be utilized to power the process and the power-generation and water-production modules could be integrated into a single device, it would greatly enhance portability and user convenience, making it an ideal solution for personalized healthcare and outdoor applications. We demonstrate solar-assisted proton exchange membrane (PEM) electrolysis using symmetric IrO₂ electrodes at both cathode and anode to directly generate HRW. The symmetric design simplifies manufacturing, mitigates lifetime mismatch and metal-ion cross-contamination. IrO₂ films were electrodeposited on stainless steel substrates and annealed at 400–700 °C. When coupled with a 100 cm² Si solar cell, the electrode annealed at 550 °C—featuring ~6 nm IrO₂ nanocrystals embedded in an amorphous matrix—exhibited the highest hydrogen production rate. At an applied voltage of 4 V, this 550 °C-annealed IrO₂ electrode produced approximately 1800 μmol h⁻¹ of H₂, corresponding to about 44 mL h⁻¹ of H₂ at 25 °C and 1 atm. Corrosion tests show the HRW is less aggressive to iron than DI, RO, and tap water, suggesting better compatibility with metallic components. During water splitting, the oxidation–reduction potential (ORP) rapidly decreases to <−300 mV within 0–10 min and then stabilizes, with the 550 °C–annealed electrode exhibiting the lowest ORP. Upon air exposure, the ORP increases by ~200 mV over 45–70 min yet remains reductive for >120 min, indicating persistent dissolved H₂ and sustained performance. Overall, the symmetric IrO₂ architecture provides a green, stable, and direct route to HRW production. Full article

Mining activities in the study area have led to the formation of irregular depressions where rainwater accumulates, creating acidic mine ponds. The water in these ponds becomes contaminated through contact with mine wastes and bottom sediments, leading to the dispersion of toxic metals and metalloids into the surrounding environment and food chain. This study investigates electrokinetic remediation (EKR) of highly contaminated acidic mine pond sediments and evaluates the role of citric acid (CA) as a biodegradable and environmentally friendly chelating agent. The sediment was highly acidic (pH 3.35) and contained elevated concentrations of Al, Fe, Mn, and As. Laboratory-scale EKR experiments were conducted for 27 days under a constant potential gradient of 1 V/cm, using 0.1 M CA as the electrolyte. The results obtained from this study were compared with those obtained using deionised water (DIW) as the electrolyte. The results demonstrated that CA significantly enhanced metal mobility, leading to higher removal efficiencies for Al (82.4%), As (51.1%), Mn (32.9%), and Fe (29.5%) compared to DIW. The pH near the cathode remained more balanced, and metal precipitation was minimised. Furthermore, total energy consumption decreased by about 53% (from 551 to 262 kWh/m³), indicating improved process efficiency. These results reveal that CA-assisted EKR can be an effective and sustainable method for the remediation of highly acidic mine pond sediments. Full article