Search Results (971)

Landfill leachate, a byproduct of municipal solid waste treatment, typically contains hazardous substances such as toxic metals (e.g., lead) and eutrophication agents (e.g., phosphate). This study addresses the pressing challenge of polishing complex wastewater, such as landfill leachate, through the development of a novel ternary layered double hydroxide (LDH). As CaFe-LDHs are known to have an affinity for anions, and CoFe-LDHs have shown an affinity for toxic metal cations, CoCaFe-LDH was proposed to integrate both functionalities. The LDH was anchored on activated biochar to synthetize the novel composite adsorbent CoCaFe-LAB. Key operational parameters (including initial pH, adsorbent dosage, contact time, initial adsorbate concentration, presence of coexisting ions, and regeneration capability) were systematically evaluated. Kinetic and equilibrium analyses revealed that Elovich and Sips models, respectively, best described the adsorption behavior of Pb²⁺ and PO₄³⁻, indicating a heterogeneous adsorption system. Maximum adsorption capacities in synthetic solutions reached 140.81 mg Pb²⁺ g⁻¹ and 25.19 mg PO₄³⁻ g⁻¹ at 45 °C. The CoCaFe-LAB composite proved highly effective, particularly for lead removal. In real effluent tests, the adsorbent achieved complete phosphate removal (100%) from electro-oxidized landfill leachate at a dosage of 2.0 g L⁻¹, confirming its practical applicability and efficiency. Full article

The electro-oxidation of eugenol (EUG) natural antioxidant was studied by cyclic voltammetry in phosphate buffer solutions (PBS) of different pH at electrochemically partially reduced graphene oxide (GCE/ePRGO). The voltammetric responses were mainly controlled by adsorption at this modified electrode. Current values were higher at pH 2.0 PBS, therefore, this pH was chosen to perform all experiments. DFT calculations of pKa’s and standard potentials defined the possible pathways of eugenol and its oxidation products. These pathways were evaluated through the comparison of voltammetric simulations of adsorbed species with experiments at pH 2.0, which also allowed for the estimation of the values of the kinetic parameters involved in electrochemistry. Our findings suggest a multi-step redox process in which Eugenol is first oxidized to the radical species and then to a cationic product. At this stage, the pathways branch into to methylenquinone and a 4-allyl-1,2-diquinone molecules. 4-allyl-1,2-diquinone is finally reduced in single or double reversible electrochemical step to the hydroquinone species. The present physicochemical work allows for a deeper understanding of the eugenol oxidation mechanism, which was only partially proposed in previous studies. Full article

Coffee silverskin (CSS), the major by-product of coffee roasting, is reported to contain bioactive compounds, including xanthines and polyphenols, showing promising potential for food and nutraceutical applications. This study investigated the beneficial effects of CSS hydroalcoholic extracts, which were chemically characterized by Attenuated Total Reflectance–Fourier-Transform Infrared Spectroscopy and ElectroSpray Ionization tandem Mass Spectrometry, on Caenorhabditis elegans physiology. CSS supplementation improved healthspan-related parameters and delayed aging-associated functional decline, without significantly extending lifespan in wild-type nematodes. Treated worms exhibited a 57% reduction in reactive oxygen species (ROS) levels and upregulation of antioxidant genes (gst-4 and sod-3), suggesting that CSS mitigates oxidative stress through the DAF-2/DAF-16 pathway. Under high-glucose diet conditions, CSS reduced lipid droplet accumulation and modulated the expression of metabolic genes, including upregulation of nhr-49 which is a key regulator of fatty acid oxidation. CSS restored lipid homeostasis and rescued the shortened lifespan of obese nhr-49 mutant worms, suggesting enhanced β-oxidation. Moreover, CSS modulated serotonergic signaling by increasing tph-1 and ser-6 expression, linking its effects to serotonin-mediated regulation of fat metabolism. Finally, CSS promoted the growth of probiotic strains, suggesting potential prebiotic properties. Overall, these findings identify CSS as a metabolic modulator capable of alleviating oxidative and metabolic stress, supporting its sustainable application in the development of functional foods and nutraceuticals. Full article

Ethanol is widely used as an additive in fuels, so its effect on the electrochemical oxidation of triethanolamine was investigated on a 25 μm platinum microelectrode. Ethyl acetate was applied as a cosolvent to increase the permittivity of the medium. A hydrocarbon n-heptane, typically present in gasohol samples as the main component, was studied, and its solutions prepared with ethanol in the entire concentration range (between 0 and 100 v/v% ethanol contents) were mixed with ethyl acetate. The as-prepared liquid mixtures were prepared separately, and they were mixed with ethyl acetate in uniform ratios. Triethanolamine, the selected redox-active compound, exhibited a sharp peak in ethyl acetate at the 15 mM concentration. The changes in the voltammograms served as a good template for quantitative analysis of ethanol content. The most suitable analytical signal used for it was the current minimum after the anodic peak, and this parameter proved more sensitive and reproducible than the anodic peak height itself. The scatterings of the current minimum values were typically within some nanoamperes. MTBE (methyl tert-butyl ether) was added to the apolar mixtures of ethanol, and this ether had a negligible interfering effect on the estimation of ethanol content. Full article

Herein, (Nafion-treated) (30 wt%) NiO_x/graphene (GP) were prepared at 250 °C and 450 °C and investigated as materials for dopamine electrochemical detection. Initially, characterization of the samples was performed using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. Subsequently, they underwent electrochemical evaluation using cyclic voltammetry, linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoamperometry (CA) techniques. All electrochemical measurements of the dopamine oxidation reaction (DOR) were performed in a 0.1 M phosphate buffer solution (PBS) at pH of 7.00 and at temperature of 36.6 °C. It was found that Nafion addition to the electrocatalysts surface facilitates access of the cationic dopamine molecule to their active centers being attributed to Nafion cation permeability. Nafion-NiO₂₅₀/GP exhibited higher activity towards the DOR reaction. The limit of detection (LOD) for the lower linear range of 0.5–10 μM was calculated to be 0.8 μM, with a sensitivity of 3.086 μA μM⁻¹cm⁻². Furthermore, the Nafion NiO₂₅₀/GP/GC electrode exhibited high selectivity towards DA, as well as good repeatability and reproducibility with an acceptable level of deviation, and excellent storage stability. The six electrodes produced from the Nafion-NiO₂₅₀/GP showed 8.28% reproducibility (RSD), indicating adequate behavior, while the same electrode after six measurements over a 30-day period showed an RSD of 5.50%, indicating a reliable electrode. Full article

This study assessed the performance of five anode materials (Fe, stainless steel (SS), Al, Zn, and Ti/RuO₂–IrO₂) in terms of the removal of ammonia, phosphorus, and turbidity from anaerobic digestate using a single-cell hybrid electrocoagulation (EC)–electrooxidation (EO) system, which enabled the simultaneous evaluation of EC and EO processes under identical conditions. Experiments were conducted at a current density of 25 mA cm⁻² and 0.5–1% NaCl. Al anodes showed the highest phosphorus (92%) and turbidity (85%) removal, through electrocoagulation, while ammonia removal remained limited (24%). In contrast, Ti/RuO₂–IrO₂ anodes achieved high ammonia removal (up to 86% at 1% NaCl) via EO, but lower phosphorus and turbidity removal (≤61%). SS and Fe anodes provided moderate and comparable nutrient removal (≈52% P, 68% turbidity, and 32–37% ammonia), whereas Zn anodes were less effective, with selective removal (70%) in P in1 h but limited ammonia and turbidity removal. Ti/RuO₂–IrO₂ demonstrated high durability with minimal weight loss. These results highlight the critical role of anode material on the balance between EC and EO pathways, offering practical guidance for selecting electrode material for efficient electrochemical treatment of nutrient-rich effluents. Full article

The electro-Fenton (EF) process is a promising advanced oxidation technology for the removal of micropollutants (MPs) from wastewater. This study aimed to identify energy-efficient operating conditions for H₂O₂ electro-production and EF degradation of the neutral micropollutant carbamazepine (CBZ). The effects of current density, residence time (RT), Reynolds number, pH, and temperature were evaluated, and non-EF removal pathways and flow-configuration effects were quantified. H₂O₂ production was maximized under conditions that sustained current efficiencies ≥ 50%, corresponding to specific energy consumption of 4.0–6.4 kWh/kg H₂O₂. Non-EF removal mechanisms intrinsic to the divided electrolytic cell accounted for approximately 35% of total CBZ removal at an RT of 5 min. Under energy-efficient EF conditions (25:1 H₂O₂:Fe²⁺ and 5 min RT), CBZ removal efficiency reached 95%. Asymmetric flow configurations reduced apparent removal through dilution. In contrast, directing the cathode effluent through the anode enhanced oxidation and reduced treated water volume without additional energy input. Total electrical energy per order of CBZ removal from secondary effluent for EF (73.8–94.4 kWh/m³) was comparable to that of Fenton oxidation (61.1–100.0 kWh/m³). In both processes, H₂O₂ production dominated the energy demand. The results highlight EF as a feasible, energy-competitive option for removing persistent MPs from wastewater effluents. Full article

Bromine, as a strategic fundamental chemical raw material, is crucial for modern industry, but the traditional chlorine displacement method poses safety risks in oilfield brine development and faces challenges like resource depletion and inefficient utilization. Addressing the need for high-concentration bromine brine development in underground oilfields, this study developed an electrochemical oxidation-based chlorine-free bromine extraction technology. Leveraging the standard redox potential difference between Br⁻ and Cl⁻ (0.271 V), the effective potential window for selective Br⁻ oxidation was determined as 1.0–1.52 V (vs. SHE) via linear sweep voltammetry (LSV). Within this window, efficient and preferential oxidation of Br⁻ over Cl⁻ and OH⁻ was achieved. In simulated brine with high chloride and low bromide concentrations, a Br⁻ conversion rate of 92.3% was attained with no Cl₂ generation. The self-designed zero-gap electrolyzer with carbon cloth as the anode reduced the reaction time by over 75% compared to a traditional H-type cell, oxidizing over 90% of Br⁻ within 12 min. Kinetic studies revealed that the reaction follows first-order kinetics, with current intensity positively correlated with Br⁻ concentration. Investigation of coexisting ions revealed that low concentrations of Cl⁻ promote the reaction, while high concentrations exert inhibitory effects. CO₃²⁻ exhibits a weak promoting effect, and Ca²⁺/Mg²⁺ show negligible impact. Notably, organic matter (e.g., ethylene glycol) concentrations exceeding 80 mg/L substantially compromise bromine recovery efficiency. This technology provides a feasible solution for the safe and green development of high-concentration bromine resources and holds significant importance for the upgrading of the bromine chemical industry. Full article

Porous silicon (PSi), characterized by its high specific surface area and highly tunable morphology, presents significant potential across optoelectronics, energy storage, and biomedical applications. This review provides a systematic analysis of the synthesis methodologies, interfacial chemical engineering, and diverse applications of PSi. Initially, fabrication techniques are examined, contrasting the pore formation mechanisms of electrochemical anodization, metal-assisted chemical etching (MACE), and emerging vapor-phase etching methods, while elucidating the control of geometric parameters from microporous to macroporous scales. To address the thermodynamic instability of the hydride-terminated surface, this review systematically evaluates modification strategies such as thermal oxidation, hydrosilylation, carbonization, and atomic layer deposition (ALD). We critically analyze their efficacy in mitigating oxidative drift and enabling specific functionalization. Subsequently, the review summarizes current applications in sensing (refractive index and photoluminescence modulation), energy storage (lithium-ion battery anodes and supercapacitors), and microsystem technologies (radio frequency (RF) isolation, gettering, and micro-electro-mechanical systems (MEMS) sacrificial layers), emphasizing the critical role of structure–property relationships. Finally, an objective assessment is provided regarding the challenges in translating PSi technology to industrial scales, specifically addressing the trade-offs between biodegradability and stability, wafer-scale process uniformity, and the compatibility of wet-chemical processing with standard complementary metal–oxide–semiconductor (CMOS) integration flows. Full article

Paired electrolysis represents a more environmentally sustainable and efficient approach for converting agroforestry biomass-derived 5-hydroxymethylfurfural (HMF) and furfural (FUR) into valuable fine chemicals and fuel additives. A critical challenge in developing paired electrolysis systems for furanal compounds is finding the optimal potential matching between the anode and the cathode. One solution is to reduce the potential sensitivity of the anode so that the paired electrolysis system can be regulated only by the cathode potential. In this study, we employed the homogeneous catalyst 4-acetamido-TEMPO (ACT) to facilitate oxidation reaction at the anode, enabling the potential sensitivity of the anode to be reduced. The results displayed the furanal substrates oxidation proceeds through a non-electrochemical chemical reaction with the active oxoammonium cation (ACT⁺), rather than being directly governed by the anode potential. The paired electrolysis system exhibited enhanced catalytic performance, with a total faradaic efficiency of 190.69% and 189.11% in the FUR and HMF paired electrolysis setup, respectively. Furthermore, this system demonstrated excellent stability, maintaining a total faradaic efficiency of over 167.64% after multiple successive cycles. Additionally, the solar-driven paired electrolysis system showed commendable substrate conversion capabilities, achieving a total faradaic efficiency of 187.89%, comparable to that of the electrically driven system. The mechanisms of the ACT electro-oxidation of furanal compounds and the construction of paired electrolysis systems for furanal compounds were proposed and discussed. This work aims to enhance electrical energy efficiency and underscore the potential of paired electrochemical catalysis for sustainable biomass conversion in the green economy. Full article

Bismuth-based semiconductors have emerged as a promising class of visible-light-responsive photo(electro)catalysts for environmental remediation owing to their tunable electronic structures, moderate band gaps, and relatively low toxicity. The stereochemically active Bi³⁺ 6s² lone pair and strong Bi–O orbital hybridization tailor valence-band states, enabling enhanced utilization of the solar spectrum and favorable charge-carrier dynamics. In addition, layered, perovskite-like, and aurivillius-type crystal frameworks generate internal electric fields that are advantageous for photoelectrochemical (PEC) operation. This review critically examines advances from 2015 to 2025 in the design, synthesis, modification, and environmental applications of bismuth-based photo(electro)catalysts, with particular emphasis on PEC systems for pollutant degradation. Major material families, including bismuth oxides, oxyhalides, oxychalcogenides, chalcogenides, perovskite-like oxides, and complex metal oxides, are discussed in relation to their structure–property–performance relationships. Key synthesis strategies, such as solid-state, sol–gel, hydro/solvothermal, microwave-assisted, spray pyrolysis, and electrodeposition methods, are compared with respect to morphology control, defect chemistry, and electrode integration. Performance-enhancing approaches, including elemental doping, oxygen-vacancy engineering, and the rational design of type-II, p–n, Z-scheme, and S-scheme heterojunctions, are critically assessed. Practical considerations related to stability, scalability, and techno-economic constraints are highlighted. Finally, current challenges and future directions toward durable and application-ready bismuth-based PEC technologies are outlined. Full article

The present study addresses the development and characterization of an in-chip laser-induced graphene (LIG)-based sensor that combines optical and electrochemical transduction techniques as a proof of concept for the advancement of novel point-of-care (POC) devices. In recent years, LIG has emerged as a suitable material for next-generation diagnostic devices due to the increasing need for effective and easily accessible biosensing platforms. In this context, the presented sensors were fabricated and tested with an increasing number of laser exposures to understand how the resulting morphology, degree of graphitization, defects, and electrical resistance of LIG electrodes affect the electrochemical and optical sensing performance. To validate the dual sensor, ferrocyanide ([Fe(CN)₆]⁴⁻) was used as a redox probe and [(4-Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran] (DCM) was used as model dye to explore the electrochemical and optical sensing capabilities. Finally, we showcase the sensor’s ability to perform simultaneous optical and electrochemical on-time detection and analysis of the ferrocyanide electro-oxidation process, underscoring its potential to be used as a dual optical/electrochemical POC device. Full article

Reduced graphene oxide (rGO) has attracted interest as a potential, cost-effective alternative to graphene layers produced by single-crystal thin-film growth techniques. Its solubility in various solvents, the ability to tune its optical and electrical properties, the ability to manipulate the optoelectronic properties of rGO-based heterojunctions, and the possibility of depositing it on flexible substrates broaden its potential applications, from electro-optical communications to environmental monitoring. In this work, we present a characterization of reduced graphene oxide (rGO) deposited on p-type Si₃N₄/Si substrate using different techniques such as Raman spectroscopy, optical transmittance, and current-voltage measurements under dark and illuminated conditions in the 400–700 nm range. Furthermore, the temperature dependence of the photocurrent of the rGO-based photoconductive device was studied in the temperature range from 300 K to 77 K. It has been shown that the electron transport mechanism through the p-type rGO/SiN/Si heterojunction at low voltage involves mainly a hopping process at 77 K and a thermionic mechanism at room temperature. Furthermore, the Fowler–Nordheim tunneling and trap-limiting mechanisms allow the presence of charge carriers in the device at both temperatures. Estimation of the main figures of merit, responsivity, detectivity, and NEP, shows an improvement in photodetection performance at low temperatures. 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 continuous emission of persistent and bioaccumulative pollutants into aquatic environments has become a critical global issue. Among these, per- and polyfluoroalkyl substances (PFASs) are of particular concern due to their exceptional stability, extensive industrial use, and adverse impacts on ecosystems and human health. Their resistance to conventional physical, chemical, and biological treatments stems from the strength of the carbon–fluorine bond, which prevents efficient degradation under standard conditions. This review provides a concise and updated assessment of emerging advanced oxidation processes (AOPs) for PFAS remediation, with emphasis on heterogeneous photocatalysis and electrochemical oxidation. Photocatalytic systems based on In₂O₃, Bi-based oxyhalides, and Ga₂O₃ exhibit high PFAS degradation under UV light, while heterojunctions and MOF-derived catalysts improve defluorination under solar irradiation. Electrochemical oxidation—particularly using Ti₄O₇ reactive electrochemical membranes and BDD anodes—achieves near-complete mineralization with comparatively low specific energy demand. Energy consumption (E_EO) was calculated from literature data for UV- and simulated-solar-driven photocatalytic systems, enabling a direct comparison of their energy performance. Although solar-driven processes offer clear environmental advantages, they generally exhibit higher E_EO values, mainly due to lower apparent quantum yields and less efficient utilization of the incident solar photons compared to UV-driven systems. Hybrid systems coupling photocatalysis and electro-oxidation emerge as promising strategies to enhance degradation efficiency and reduce energy requirements. Overall, the review highlights key advances and future research directions toward scalable, energy-efficient, and environmentally sustainable AOP-based technologies for PFAS removal. Full article