Oxidation Technology Research Articles

Enhanced wear resistance, corrosion behavior, and thermal management in magnesium alloys with PEO coatings

The harsh conditions encountered in aerospace applications, such as high operational temperatures, abrasive wear, and corrosive substances, present significant challenges to the performance and longevity of magnesium alloy components. To create a coating with superior wear resistance, corrosion resistance, and high emissivity, this study employs plasma electrolytic oxidation (PEO) technology to develop a nanocomposite coating doped with carbon nanotubes (CNTs) and hexagonal boron nitride (h-BN). The results demonstrate that the MgO-BN/CNTs coating with an emissivity of 0.82 reduces the equilibrium temperature of the 5 W LED junction by nearly 10 °C compared to the magnesium alloy substrate, showing improved radiative heat dissipation performance. Due to the ability of the porous structure to accommodate abrasive particles, coupled with the lubricating effect of h-BN and CNTs, the friction coefficient of the MgO-BN/CNTs coating is 0.57, which is 21 % lower than that of the MgO coating. Additionally, the coating exhibits excellent corrosion protection, attributed to the dense microstructure and chemical inertness of h-BN. The findings demonstrate that the strategic incorporation of h-BN and CNTs into PEO coatings effectively improves the wear resistance, corrosion resistance, and thermal management performance of magnesium alloys.

Anti-cytoplasmic performance of Zn/g-C3N4 photocatalysts in the battle against microcystis aeruginosa

Cyanobacterial blooms pose a serious challenge to ecosystems and human health. Photocatalysis, as an advanced green oxidation technology, has potential applications in cyanobacteria removal. In this paper, Zn/g-C3N4 photocatalysts with different mass ratios were prepared for algal inactivation. In 3 h, the best performance comes from the experiment using 10 % Zn/g-C3N4 photocatalyst, which inactivated 80 % of microcystis aeruginosa (9×106 ∼ 10×106 cells/mL) when exposed to visible light. Secondly, the potential mechanism of the photocatalytic inactivation of microcystis aeruginosa was proposed in combination with the generation of reactive oxygen species and the leakage of the algal cell contents. The photocatalyst first covered the surface of the algal cells to stop their movement; then the catalyst was excited under light and destroyed the outer protective structures of the cells (cell membrane, cell wall, and organic membrane, etc.) through the action of reactive oxygen species (1O2 and •OH) generated by Zn/g-C3N4, leading to structural changes in the outer layer of the cells. And then photocatalytic oxidation of the intracellular cytoplasm led to the loss of its physiological functions (via losing of inorganic ions and non-electrolytes, etc.). Finally the cell is inactivated or decomposed. This understanding may provide theoretical and practical implications for the prospects of harmful algal control.

Highly efficient MIL-53(Al)@Biomass hybrid for oxytetracycline elimination: Adsorption, LED-induced photocatalysis and pyrolytic recycling

The presence of antibiotics in water discharges represents a hazard for the ecosystems, as it could affect the biota equilibrium at the micro and macroscales. Consequently, it is crucial to develop effective adsorption and oxidation technologies to remove antibiotics from water. Herein, we assessed the effectivity and stability of a metal organic framework-biomass hybrid (MIL-53(Al)@RH) for the removal of oxytetracycline (OTC) via adsorption and photocatalytic degradation. Under equilibrated conditions, the hybrid retained 165mgg−1 OTC. When adsorption and photocatalytic degradation were arranged in tandem, the system removed 99% of OTC with a dose of 2.83mg H2O2/mg OTC. The thermo-kinetic interpretation of the adsorption measurements was well described by Sip´s isotherm and pseudo-second kinetic models, which along with the heat of adsorption (−104.8kJmol−1) suggest a chemical interaction between the OTC and MIL-53(Al)@Rice Husk hybrid active centres. The MIL-53(Al)@RH hybrid demonstrated a remarkable stability with an OTC removal above 90% after 10 operational cycles. Moreover, pyrolysis of OTC-saturated hybrid led to a carbonaceous structure which demonstrated an outstanding OTC adsorption capacity (221mgg−1 OTC). The results demonstrate that the MIL-53(Al)@RH hybrid presents a significant prospect for combined adsorption-photocatalytic treatment of water bodies contaminated with antibiotics.

PROSPECTS FOR THE USE OF MICROARC OXIDATION IN THE PRODUCTION OF AVIATION AND AUTOMOTIVE COMPONENTS

This article discusses the prospects for the application of microarc oxidation (MAO) technology in the aviation and automotive industries. The MAO process allows the creation of durable, wear-resistant and corrosion-resistant coatings on the surface of metal parts, which significantly increases their durability and performance characteristics. Technological aspects of MAO are discussed, including surface preparation features, selection of electrolytes and control of process parameters. Examples of successful application of MAO in the production of aviation and automotive components are given. Also, directions for further research and development of the technology are explored, including the creation of new materials, combined coatings and the study of the durability of coatings under real operating conditions. The article emphasizes the importance of MAO as a promising technology for improving the reliability and efficiency of vehicles and equipment.

Plasma‐Generated Luminescent Coatings: Innovations in Thermal Sensitivity and Corrosion Resistance

AbstractThe strategic design of traditional coating materials has long been pivotal in broadening their range of applications. In this work, europium‐doped TiO2 coatings are grown in situ on the surface of titanium substrate using plasma electrolytic oxidation technology. The core reaction took no more than five minutes. Incorporating europium into the coating preserved the inherent corrosion resistance of PEO coatings while imparting anticipated thermal‐sensitive luminescence capabilities. The intrinsic emission of TiO2 and the characteristic emission of Eu3+ (5D0 → 7F2) are employed as the self‐reference for the LIR thermometry. The absolute and relative temperature sensitivity of the coating reached 0.0087 K−1 and 0.739% K−1, respectively. Notably, the coating exhibited a signal discriminability of up to 5100 cm−1 and a temperature uncertainty of only 0.18 K, which is comparable to some TiO2: Eu nanoparticles. The ingenious fusion of corrosion resistance and thermal‐sensitive luminescence of the coating not only makes it a classic protective structure but also facilitates its applicability to diverse scenarios, including optical thermometry in extreme environments.

PTFE composite membrane with peroxymonosulfate activation self-cleaning for highly-efficient oil-water emulsion separation and dye degradation

Combining membrane separation with advanced oxidation technology can make the membrane self-cleaning, extending its service life. However, the preparation of composite membranes with excellent catalytic ability, self-cleaning performance, and stability remains a key research direction. In this study, a PTFE composite membrane with peroxymonosulfate activation self-cleaning ability was successfully prepared by in-situ growth of CoOOH and ZIF-67 on the surface of a l-DOPA/PEI modified PTFE membrane. The as-prepared membrane is superhydrophilic and has significant superoleophobic surfaces underwater, the separation efficiency of the as-prepared membrane for multiple oil-water emulsions exceeded 98.4 %. Meanwhile, the effective degradation of several organic dyes under visible light was simulated, with still high degradation efficiency (>99 %) after 10 cycles. Overall, this study puts forward a approach towards self-cleaning membranes based on PTFE material; the resulting composite membrane's high separation efficiency, stability under repeated use conditions as well as its self-cleaning ability position it as an attractive candidate for long-term wastewater purification applications.

Role of quercetin in permanganate oxidation of bisphenol A: Kinetics and mechanism

Potassium permanganate (Mn (VII)) oxidation, a green advanced oxidation technology, is widely used as an in-situ remediation method for groundwater contamination. Based on the complexity of organic substances in aquatic environments, many novel organic components, whose processes and mechanisms affecting the oxidative efficacy of Mn (VII), remain unknown and need to be studied systematically. Therefore, using the reducing macromolecular quercetin as the organic matter, the efficiency and mechanism of quercetin-bound, low-valent Mn enhanced Mn (VII) oxidation of bisphenol A (BPA) were studied. The pH and concentration of quercetin strongly influenced its performance. Under pH 4.0–6.0, quercetin evidently promoted the BPA degradation rate in the Mn (VII)/quercetin (Mn (VII)/Q) system. However, the presence of quercetin had little effect on the degradation efficiency of Mn (VII) at pH ≥ 7.0. This study found that at pH 4.0–5.0, quercetin could act as both a reductant and complexing ligand in the process of BPA oxidation. As a complexing ligand, quercetin stabilized the intermediate states of Mn (III) to form complexes. These stable complexes could efficiently oxidize BPA. While low concentrations of quercetin were insufficient to complex and stabilize Mn (III), Mn (III) was reduced to Mn (II). Mn (II) then reacted with Mn (VII) to form MnO2, enhancing the degradation efficiency of the Mn (VII)/Q system for BPA through its catalytic and oxidative properties. This study provides a better understanding of the degradation of organic pollutants by KMnO4 in groundwater treatment.

Topographical hard protective coating for joint replacement implants

Joint replacement surgery, essential for managing joint diseases, requires improvements in tribocorrosion performance to ensure surgical success and longevity of joint implants. Transition-metal light-element (TMLE) compound coatings, known for their high hardness and chemical stability, have been extensively researched and applied for surface protection of joint implants. However, these coatings typically lack a lubrication phase, leading to high friction coefficients and severe corrosion wear, which makes long-term effective protection challenging. A promising approach is to utilize the natural lubricating proteins present in body fluids, which are continuously available and can thus address long-term service issues of TMLE coatings. In this work, we utilized micro-arc oxidation (MAO) technology to develop an underlying morphology, then conformally deposited a TiB2 layer, resulting in a cratered dual-layer TiB2/MAO coating. This unique cratered dual-layer structure not only preserves the high hardness and wear resistance of TiB2 but also aims to (1) absorb wear particles to prevent abrasive wear and (2) increase surface energy to optimize protein lubrication capacity. Consequently, the TiB2/MAO coating exhibits low friction coefficients and wear rates in protein-containing simulated body fluids. Furthermore, the dual-layer TiB2/MAO coating demonstrates excellent corrosion resistance and biocompatibility. This dual-layer coating design synergistically combines the superior intrinsic properties of material with unique structural construction, while also harnessing continuously available external proteins as lubricants to further optimize performance, thereby introducing an advanced strategy for developing protective coatings for implant materials.

Investigation on the performance of a solar multifunctional photovoltaic/thermal window combining photocatalytic oxidation technology

In response to the challenges of high energy consumption and poor indoor air quality, a novel solar multifunctional louver window has been proposed. This study developed a numerical model to examine the effects of environmental variables and louver angles on the thermal, electrical, and degradation performance of the system. Additionally, an exergy-based evaluative framework was introduced to account for the varying qualities of energy in assessing the performance of solar multifunctional windows. Finally, a comprehensive evaluation was conducted using this framework. The results demonstrate that the exergy efficiency of the solar multifunctional window can be maintained at 20 % or higher, even under reduced solar irradiation, delivering high-quality energy. Lower environmental temperatures and solar radiation intensities were found to negatively affect ventilation, thermal efficiency, and air purification capacity. The thermal, purification, and electrical efficiencies were influenced by the louver angle to varying extents. In terms of air purification, the window achieved the highest Clean Air Delivery Rate (CADR) at louver angles between 80° and 90°, thereby enhancing air purification performance.

A novel persulfate activation strategy by double Z-scheme Bi2O3/CuBi2O4/BiOBr heterojunction: Non-radical dominated pathway for levofloxacin degradation

Persulfate advanced oxidation technology (PS-AOPs) is known as a novel wastewater treatment method. Considering the poor self-stability of Bi2O3/CuBi2O4, we synthesized Bi2O3/CuBi2O4/BiOBr ternary composite material and established the non-radical pathway-dominated peroxymonosulfate (PMS) activation system. The study indicated that BiOBr promoted electron migration on the material surface. Bi2O3/CuBi2O4/BiOBr/Vis/PMS system exhibited excellent catalytic performance (86.83 % within 100 min), significantly higher than Bi2O3/CuBi2O4 (63.19 %) and BiOBr (60.35 %). Furthermore, it has strong catalytic activity and adaptability to various environmental conditions. By quenching experiments and EPR analysis, O2−∙ and 1O2 were the main active species. Finally, possible degradation pathways and intermediates were predicted through liquid mass spectrometer (LC-MS), and toxicity analysis was conducted on levofloxacin (Lev) and intermediates. The degradation mechanism may be attributed to the construction of double Z-scheme heterojunction, photogenerated electron transfer and ROS generation through the redox cycle of Cu2+/Cu+ and Bi5+/Bi3+.

Dyeing kinetics and thermodynamics of mono-chlorotriazine reactive dye in recycled wastewater

Purpose This study aims to elucidate the dyeing kinetics and thermodynamic relationships of CI Reactive Red 24 (RR24) on cotton fabrics, achieve the recycling of inorganic salts and water resources and obtain comprehensive data on color parameters, fastness and other characteristics of fabrics dyed with the recycled dyeing residual wastewater. Design/methodology/approach The dyeing wastewater obtained through advanced oxidation technology was used as a medium for dyeing cotton fabrics with RR24. The absorbance value of the dyeing residue served as an evaluation index, and the relevant kinetic and thermodynamic parameters were calculated based on this absorbance. The color parameters and fastness of the fabric samples were measured to compare the performance of different dyeing media. Findings Dyeing cotton with RR24 in both media follows pseudo-second-order kinetics. When dyeing with wastewater media, the dye adsorption in the first 45 min increased by 0.082–1.29 g/kg compared with conventional dyeing. Furthermore, the half-dyeing time was shortened by 4.19–11.99 min and the equilibrium adsorption amount was reduced by 0.277–0.302 g/kg. The adsorption of RR24 on cotton fabrics conformed to the Freundlich model. Fabrics dyed using recycled wastewater exhibit a deeper color, with reduced red light and enhanced blue light, resulting in an overall deeper apparent color. Originality/value These dyeing kinetics and thermodynamic properties are beneficial for comprehending and interpreting the dyeing performance and behavior of reactive dyes in dyeing wastewater. They lay a theoretical foundation for the treatment and recycling of dyeing wastewater.

Methane capture, utilization, and sequestration technology based on biological ectoine production using Methylotuvimicrobium alcaliphilum 20Z

Methanotroph-based CH4 conversion technology is a promising alternative to conventional CH4 utilization methods that rely on energy-intensive CO2 capture processes. In this study, we introduce a novel CH4 capture, utilization, and sequestration (MCUS) technology as a proof-of-concept for eco-friendly CH4 conversion that is applicable to various methanotroph strains. We validated this hypothesis by evaluating ectoine production in Methylotuvimicrobium alcaliphilum 20Z. Cultivation experiments were conducted using pure O2 pulse injection to facilitate the separation of the CO2 generated during CH4 oxidation by concentrating it. To verify the MCUS concept systematically, we performed a model-based process analysis. The operational strategies for the reactors were developed using experiment-based kinetics and reactor models, followed by the design of a rigorous process flow diagram. Economic and environmental impact analyses were conducted to compare MCUS with air-based cultures and existing oxidative CH4 conversion technologies. The key advantage of MCUS is its significantly lower CO2 emissions (0.71 kg-CO2 eq/kg-CH4) than oxidative CH4 utilization (>2.75 kg-CO2 eq/kg-CH4). Moreover, the net present value per CH4 molecule was estimated at 0.7 $/kg-CH4, substantially higher than existing oxidative conversion methods (0.03 $/kg-CH4). Additionally, compared with air-based cultivation, the MCUS process exhibits superior economic and environmental performances. We used methanotrophs for CH4 “capture” and “utilization,” effectively leveraging “sequestration” to convert emissions into pure CO2. The proposed MCUS technology holds promise for practical applications of methanotrophs in producing various high-value-added products, emphasizing eco-friendly approaches.

Trace the evolution path of pharmaceutical wastewater treatment technology based on a patent perspective

ABSTRACT This paper discusses the research hotspots and future development trends of pharmaceutical wastewater treatment technology, in order to provide valuable reference and guidance to promote the development of technology. First, the search path counting (SPC) algorithm is utilized to identify the global main path to perform a preliminary analysis of the technology evolution path from a macro perspective. Second, according to the life cycle, S-curve divides the time windows of the temporal themes and uses the Latent Dirichlet Allocation (LDA) modeling to identify the themes under each time window. Then, a visualized Sankey diagram is generated to determine the evolutionary relationship, which can be supplemented with the paths of technological evolution from the micro point of view. Finally, six research hotspots of pharmaceutical wastewater treatment technology were found, which are compounding agents, advanced oxidation technology, nanomaterials, artificial intelligence (AI) technology, membrane pollution prevention, and various combinations of wastewater treatment technology. The study also predicted its future development direction.

A Liquid Metal-Based Temperature-Responsive Low-Toxic Smart Coating for Anti-Biofouling Applications in Marine Engineering.

Titanium alloys have been widely used in marine engineering fields. However, because of high biocompatibility, they are vulnerable to biofouling. In this work, based on the micro-arc oxidation technology and spontaneous galvanic replacement reaction, a temperature-responsive low-toxic smart coating consisting of liquid metal particles is designed to control the release of Ga3+, Cu2+, and Cu1+ ions in different temperatures. This technology can ensure the full release of active ingredients within the target temperature range, intelligently maintaining the excellent anti-biofouling performance, while saving active ingredients. After being immersed in culture media with Sulfate-Reducing Bacteria (SRB) for 14 days at 10, 20, and 30°C, at the optimal activity temperature of 30°C for SRB, the best sample releases the highest amounts of Ga3+, Cu2+, and Cu1+ ions, demonstrating a 99.9% bactericidal rate. When the temperature decreases to 10°C, the activity level of SRB is very low, and the smart coating can also reduce the released ions correspondingly, still with a 97.3% bactericidal rate. The remarkable anti-biofouling performance is attributed to the physical damage and lethal ions interaction. Furthermore, the best sample exhibits good corrosion resistance. This work presents a design route for smart anti-biofouling coatings for temperature-responsive.

Advancements in Copper-Based Catalysts for Efficient Generation of Reactive Oxygen Species from Peroxymonosulfate

Over the past few decades, peroxymonosulfate (PMS)-driven advanced oxidation processes (AOPs) have garnered substantial interest in the field of organic decontamination. The copper (Cu)/PMS system is intriguing due to its diverse activation pathways and has been extensively employed for the clearance of refractory organic pollutants in water. This article is designed to offer a comprehensive overview of the latest trends in Cu-based catalysts such as single-metal and mixed-metal catalysts aimed at treating recalcitrant pollutants, highlighting PMS activation. Subsequently, investigative methodologies for assessing PMS activation with copper-based catalysts are reviewed and summarized. Then, the implications of pH, PMS and catalytic agent concentrations, anions, and natural organic matter are also addressed. The combination of Cu-based catalyst/PMS systems with other advanced oxidation technologies is also discussed. Following that, the degradation mechanisms in the Cu-based catalyst-activated PMS system are considered and synopsized. Lastly, potential future research avenues are proposed to enhance the technology and offer support for developing of economically viable materials based on copper for activating PMS.

Preparation and Wear Resistance of Porous TC4 Titanium Alloy Micro‐arc Oxidation Coating Produced by Selective Laser Melting

The porous TC4 titanium alloy prepared by selective laser melting (SLM) is modified by micro‐arc oxidation (MAO) technology. By introducing active elements such as calcium (Ca) and phosphorus (P) into the electrolyte, a wear‐resistant active coating is constructed on the surface of porous TC4. The effects of MAO process parameters on the surface morphology and wear resistance of the coating are discussed. The results show that the thickness and adhesion of the coating increase with the increase of the first‐stage oxidation time, and decrease with the increase of the second‐stage oxidation time. In all processes, the MAO‐2 coating has better surface morphology and performance, with a median pore size of 0.51 μm and a binding force of 18 N. XPS analysis confirms that the coating is mainly composed of TiO2, Ca2P2O7, and Ca(PO3)2 phases. The study of tribological behavior shows that the wear form of the substrate is abrasive wear, while the wear form of the coating is adhesive wear. The friction coefficient of the coating is significantly lower than that of the substrate, and the wear resistance is better. This study provides an effective way to optimize the surface properties of porous TC4 titanium alloy.

Novel approach to corrosion resistance and radiative cooling with biomimetic amorphous coatings

To address the application challenges of high-power-density electronic devices in harsh conditions, it is crucial to develop electric insulation materials that possess both corrosion resistance and excellent radiative cooling performance. In this study, inspired by the wrinkle morphology of the Camponotus ant with thermoregulation, a biomimetic amorphous coating composed of a hemispherical array was fabricated on aluminum alloy using plasma electrolytic oxidation (PEO) technology. This biomimetic microstructure is obtained by controlling the content of hexagonal boron nitride (h-BN) nanoparticles in the electrolyte, where the increase in current density at a later stage allows the transition of the porous coating to the hemispherical array. The effects of functional group vibration and rotation in combination with the hemispherical structure afford the biomimetic coating a high emissivity of 0.91 within the range of 3–14 μm, which reduces the LED temperature by 17.1 °C and achieves a cooling efficiency of 10.6 %. Meanwhile, with a resistivity of 5.15 × 1014 Ω∙cm and a dielectric strength of 29.9 V/μm, the coating can prevent current leakage, consequently improving the stability and reliability of electronic packaging materials. In addition, h-BN flakes in the biomimetic coating with almost defects free act as a protective barrier to enhance the corrosion resistance of the aluminum alloy. This approach offers a time-efficient and cost-effective route for the manufacture of multifunctional coatings with potential applications in electronic packaging.

Investigation of the sustainable production of ethylene oxide by electrochemical conversion: Techno-economic assessment and CO2 emissions

Ethylene oxide (EO) is a pivotal intermediate in the chemical industry owing to its versatility and high demand. Currently, direct oxidation is the most important technical process to produce EO. This conventional process, in which ethylene is partially oxidized with air or oxygen, has limited selectivity for EO of 65–90%, leading to significant CO2 emissions. This study explores an alternative method involving the electrochemical selective oxidation of ethylene powered by renewable electricity. The electrochemical oxidation technology is expected to reduce CO2 emitted during EO production. Process models were developed based on existing literature data. A techno-economic evaluation and sensitivity analysis focusing on the electrochemical cell variables were conducted. In this assessment, the investment and production costs of the electro-oxidation process for EO production were compared with those of the conventional process. This assessment also compared processes producing of mono-ethylene glycol and ethylene carbonate from EO. These analyses reveal that the separation energy has a significant impact on the carbon footprint. While current economic and environmental benefits are not favorable, this study identifies key descriptors of the technology for further reducing the carbon footprint. Based on the evaluation results, this study demonstrates the potential to cut CO2 emissions in half compared to conventional plants by utilizing the electro-oxidation of ethylene via a direct route.

Influence of ultrasonic power modulation on the optimisation of aluminium alloy micro-arc oxidation coating properties

Conventional micro-arc oxidation (MAO) technology, due to the randomness and transient nature of arc discharge, produces coatings with numerous defects, poor abrasion resistance, and inadequate ability to effectively block the intrusion of corrosive media. In this paper, ultrasonic-assisted technology was used to study the effect of different ultrasonic power regulation on the performance optimization of MAO coating on 6061 aluminum alloy. The coating microstructure and elemental composition were characterized by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer, and its hardness, wear resistance, corrosion resistance and other properties were tested. The results show that the prepared coating has the characteristics of high hardness, good wear resistance and excellent corrosion resistance under the assistance of ultrasonic power of 50 W. This is mainly attributed to the cavitation effect, mechanical effect and thermal effect generated by the corresponding ultrasonic power, which effectively enhances the surface quality, performance and service life of the coating. This study provides valuable insights into the interaction between ultrasound power and the resulting MAO coatings, and has important implications for optimizing ultrasound-assisted processes and improving coating properties.

Electro-nitrification coupled with biological denitrification achieves efficient nitrogen removal from rare earth mine ammonia-nitrate wastewater

Nowadays, ammonia-nitrate wastewater has been posed serious environmental hazards. Electrochemical ammonia oxidation (AOR) technology with environmentally friendly and easy-to-operate features has attracted much attention. In this work, a novel anode catalytic electrode (Ni1Cu1Fe0.5-S/Ti) is prepared by a one-step electrodeposition method for electro-nitrification, and coupled a biological denitrification device for the treatment of real ammonia-nitrate wastewater. The unique three-dimensional layered spherical structure of Ni1Cu1Fe0.5-S/Ti electrode has been verified through physical characterization, and electrochemical tests demonstrated that Ni1Cu1Fe0.5-S/Ti electrode gained an excellent current density of 54.48 mA·cm−2 toward to AOR at 0.65 V vs. Hg/HgO as well as good stability for four times repeated electro-nitrification experiments. The optimal experimental operating conditions were obtained by changing electrode spacing, initial NH4+-N concentration, current density and flow rate. Consequently, 97.7 % total nitrogen (TN) removal efficiency of real wastewater is achieved through electro-nitrification coupled with biological denitrification, providing a new perspective technology for ammonia-nitrate wastewater treatment.