Green Oxidant Research Articles

Endowing viscose fabric ultraviolet and antibacterial activities using zinc oxide nanoparticles

To enhance the bioactive functionality of viscose fabrics via a new eco-friendly approach; novel green zinc oxide nanoparticles were biosynthesized and incorporated as functional additives in the finishing formulations encompassing citric acid as a green crosslinking agent and sodium hypophosphite as a potential catalyst using pad-dry-cure method. For this purpose, ZnO-NPs were biosynthesized using zinc acetate as a processor and our formerly prepared and fully characterized starch nanoparticles (SNPs) having particle size ranged from 80-100 nm as a green reducing and stabilizing agent for substituting the traditionally used toxic reducing agents. The zeta sizer determined that the ZnO-NPs were approximately tailored at 18-20 nm in size, while the UV-visible spectra revealed highly symmetric single-band absorption with a maximum peak around 382 nm. In contrast, both FTIR and SEM of finished viscose fabric in the presence of ZnO-NPs-III confirm the presence of ZnO-NPs and the formation of agglomerated nanostructures on the fabric surface. The finished fabric had a UPF of 34.07 compared to 4.0 for untreated fabric, and the antibacterial activities had very good bacteriostatic activity against Staphylococcus aureus and Escherichia coli bacteria, compared to zero for untreated fabric. Furthermore, how the finishing bath ingredients interact with the fabric was projected.

Oxygen Vacancies and Lattice Distortion Synergistically Enhanced Piezocatalysis of CaZn2(BO3)2 for Nonantibiotic Pharmaceutical Degradation.

Piezocatalysis, an emerging green and advanced oxidation technology, has recently been widely researched in environmental treatment. However, the limited polarization efficiency of the piezocatalyst is a serious bottleneck for its practical application. The search for an excellent piezocatalyst with a high piezoelectric coefficient and abundant reactive sites remains an urgent task that needs to be developed. Herein, a piezocatalyst, CaZn2(BO3)2 (CZBO), obtained by quenching has an excellent piezocatalysis, which exhibited superior activity for ibuprofen (IBP) and carbamazepine (CBZ) removal with 100% and 83.8% efficiency under ultrasonic cavitation (120 W, 40 kHz) within 36 min, respectively. The outstanding piezocatalytic degradation was attributed to the strong polarization of the material under the synergistic effect of oxygen vacancies (OVs) and lattice distortion, which effectively facilitated the generation of a high concentration of reactive oxygen species (ROS). The lattice distortion induced by O-deficient [BO3] plane units can promote the e- and h+ pair separation and transportation, and the OVs with abundant electron-rich regions can significantly decrease O-O bond activation energy, thus collaboratively contributing to the high production of ROS for IBP and CBZ degradation. This work provides a simple avenue for enhancing piezoelectric polarization based on the OVs and lattice distortion and proposes insights into the reaction mechanisms for degrading nonantibiotic pharmaceuticals in wastewater.

Sustainable photocatalytic hydrogen peroxide production over octonary high-entropy oxide

The direct utilization of solar energy for the artificial photosynthesis of hydrogen peroxide (H2O2) provides a reliable approach for producing this high-value green oxidant. Here we report on the utility of high-entropy oxide (HEO) semiconductor as an all-in-one photocatalyst for visible light-driven H2O2 production directly from H2O and atmospheric O2 without the need of any additional cocatalysts or sacrificial agents. This high-entropy photocatalyst contains eight earth-abundant metal elements (Ti/V/Cr/Nb/Mo/W/Al/Cu) homogeneously arranged within a single rutile phase, and the intrinsic chemical complexity along with the presence of a high density of oxygen vacancies endow high-entropy photocatalyst with distinct broadband light harvesting capability. An efficient H2O2 production rate with an apparent quantum yield of 38.8% at 550 nm can be achieved. The high-entropy photocatalyst can be readily assembled into floating artificial leaves for sustained on-site production of H2O2 from open water resources under natural sunlight irradiation.

Growth, physiological responses, and meat quality of feedlot-finished Bonsmara steers offered unprocessed Mucuna pruriens utilis seed meal with or without conventional and green zinc oxide nanoparticles.

Feedlot finishing of beef cattle on commercial nutrient-dense diets based on expensive corn (maize), soybean meal (SBM) and other commonly used protein-rich ingredients is economically unsustainable, especially for smallholder farmers. Rich in energy and proteins, Mucuna pruriens utilis seed meal (MSM) could replace corn and protein-rich ingredients in beef cattle diets provided its problems of antinutritional factors (ANFs) and high fiber content that compromise animal growth performance are resolved. The objective of this study was, therefore, to investigate the effects of incorporation of conventional (C-Nano-ZnO) versus green (G-Nano-ZnO) zinc oxide (ZnO) nanoparticles in the diets of feedlot-finished Bonsmara steers supplemented with 20% MSM (dry matter basis). In a completely randomized design, 28 Bonsmara steers were randomly allocated to 4 experimental diets [i.e., Control diet without MSM (C); C with 20% MSM replacing corn (partially) and the common protein-rich ingredients (CM); CM with 25mg/kg C-Nano-ZnO (CM-C); and CM with 25mg/kg G-Nano-ZnO (CM-G)] each with seven replicates for 98 days. Performance variables, carcass traits, hemato-biochemistry, and meat quality were then measured. All data were analyzed with SAS using one-way ANOVA applying the GLM procedure, with diet as the independent variable, except for growth performance data that were analyzed as repeated measures. Results showed that while dietary MSM did not affect (P > 0.05) meat quality and serum biochemistry, it decreased body weight gain (BWG; P < 0.01), feed intake (FI; P = 0.001), feed conversion efficiency (FCE; P < 0.01), carcass fatness (P = 0.05), hot carcass weight (HCW; P < 0.05), cold carcass weight (CCW; P = 0.05), blood MCV (P < 0.05), MCH (P < 0.01), and neutrophils (P < 0.01) as it increased blood lymphocytes (P < 0.001). Interestingly, the harmful effects of MSM were attenuated by C-Nano-ZnO and worsened by G-Nano-ZnO. In conclusion, feeding of high dietary unprocessed MSM did not affect Bonsmara beef meat quality and serum biochemistry but compromised their growth performance, carcass traits, and some hematology responses, and these were alleviated by C-Nano-ZnO and deteriorated by G-Nano-ZnO incorporation. We recommend feeding commercial diets supplemented with 20% MSM, replacing corn and commonly used protein-rich ingredients, plus 25mg/kg of C-Nano-ZnO to feedlot-finishing beef cattle.

Performance improvements for green hydrogen-ammonia fueled SOFC hybrid system through dead-end anode recirculation and split transcritical CO2 power cycle

This paper proposes a novel green hydrogen-ammonia fueled solid oxide fuel cell (SOFC) hybrid power system by coupling dead-end anode recirculation with split transcritical CO2 power cycle (STCC). The STCC with dual-temperature heaters adopts split heat absorbing concept to recover cathode off-gas waste heat. The thermodynamic and economic performances of novel system are investigated and compared. Furthermore, the impacts of fuel ammonia mixing ratio, cell stack fuel utilization ratio, STCC CO2 split ratio, fuel price etc. on system performance are revealed. The results show that the introduction of STCC results in a 3.96% improvement in total system energy efficiency and a 0.6% reduction in total system levelized cost of electricity (LCOE) compared with standalone dead-end anode recirculated SOFC unit. The extremely high current density is not beneficial to enhance hybrid system thermo-economic performance. For every 0.1 increase in fuel ammonia mixing ratio, total system energy efficiency increases by 0.26∼0.85% and LCOE decreases by 4.6∼7.4%. The optimal STCC CO2 split ratio of recuperator declines with increasing fuel ammonia mixing ratio. Novel hydrogen-ammonia fueled hybrid system offers a high total energy efficiency of 0.7406, and its economic performance advantage over dead-end anode recirculated SOFC declines with decreasing fuel price.

Honey-Derived Hydrochar Containing 2,2,6,6-tetramethylpiperidine-1-oxyl Free Radical for Degradation of Aqueous Organic Pollutants

The increasing demand for greener technologies in environmental remediation makes carbon materials from biomass and its derivatives some of the most attractive resources for a sustainable future. However, integrating these materials with stable free radicals remains challenging. This study presents a straightforward one-pot hydrothermal route using raw honey as the carbon source and 4-amino 2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO) as the free radical. The addition of TEMPO derivative initiates Maillard reactions between its amino group and the carbonyl groups of the carbohydrates in honey, resulting in the formation of a functionalized hydrochar with a spherical morphology (~ 8 μm). The presence of free radicals within the carbonaceous matrix was confirmed by electron spin resonance spectroscopy, supported by infrared spectroscopy, elemental analysis, thermal analysis, scanning electron microscopy, and X-ray photoelectron spectroscopy. The free radical content was estimated at 0.4 mmol∙g-1. The material effectively removed methylene blue, fluorescein, and doxorubicin from water in the presence of green oxidants like hydrogen peroxide and sodium hypochlorite. After 24 h, removal efficiencies reached 92% for doxorubicin, 73% for methylene blue, and 23% for fluorescein. Moreover, the hydrochar demonstrated good regeneration capability, maintaining its dye removal efficiency over several cycles.

Toward Continuous Electrochemical Synthesis of Ferrate

AbstractFerrate (Fe(VI)) is of great interest in energy storage solutions, organic synthesis, and wastewater treatment due to its decent oxidation potential and non‐toxic end‐product formation, making it a green oxidizer. The electrochemical generation of ferrate in NaOH at current densities of j ≥ 100 mA cm−2 is presented using low‐cost sacrificial iron anodes, mild steel, and spheroidal graphite cast iron (ductile iron). Under optimized reaction parameters with 40 wt.% (14 m) NaOH and a ZrO2‐based diaphragm, spheroidal graphite cast iron shows no signs of passivation in 5 h experiments even at j = 150 mA cm−2. The results are used in a novel electrolysis cell with a combined geometric anode surface area of 230 cm2, incorporated in a mini‐plant suitable for continuous synthesis. This setup produces a peak ferrate concentration of 10.1 g L−1 (84 mm) after 5 h in 1.6 L anolyte volume, resulting in a total ferrate mass of 16.2 g. Optimal electrolysis temperatures are between 35 and 50 °C. The highest current efficiency is 63.0%, and the lowest specific energy consumption is 9.2 kWh kg−1 ferrate. The presented work is an essential step toward the continuous electrochemical synthesis of ferrate using sacrificial anodes under basic conditions.

Sodium Copper Chlorophyllin: A Sustainable Bioinspired Catalyst for the Aerobic Oxidative Synthesis of Nitrogen Heterocycles and the Oxidative Cyanation of Tertiary Amines

AbstractA remarkably simple and straightforward protocol has been reported showcasing sodium copper chlorophyllin (SCC) as an eco‐friendly, bioinspired catalyst for the aerobic oxidative synthesis of pharmaceutically prevalent nitrogen‐containing heterocycles, such as benzimidazoles and quinoxalines. This reaction was performed in green solvent water, using the green oxidant, molecular oxygen. SCC displayed exceptional efficiency, congruent with the prevailing metal/non‐metal‐based catalyst regime without requiring additives. The SCC catalyst exhibited excellent recyclability upto three cycles for the benzimidazole synthesis reaction. This benign strategy was successfully applied in synthesizing a bioactive quinoxaline i. e., Tyrphostin AG1296, a promising candidate for melanoma treatment. The catalytic activity of SCC was explored for the synthesis of another privileged moiety i. e., α‐aminonitriles, via the α‐cyanation of tertiary amines under oxidative conditions. This reaction progressed with a mild, easy‐to‐use, convenient cyanide source, such as ethyl cyanoformate, and a green and attractive solvent, such as methanol, precluding acidic media. SCC catalyst was efficiently recycled upto three cycles for the α‐aminonitriles synthesis. Overall, the utility of a biodegradable, robust catalyst such as SCC, eco‐friendly solvents such as water and methanol, green oxidants such as O2, and mild reaction conditions, devoid of acidic additives, renders the present work viable for academic and industrial research.

Well-Defined Microenvironment in Metal–Organic Frameworks Enable Green, Benign, and Isolation-Free Catalytic Oxidation Reaction

Well-Defined Microenvironment in Metal–Organic Frameworks Enable Green, Benign, and Isolation-Free Catalytic Oxidation Reaction

Development of Green Energetic Oxidizers for Solid Propellant Applications: Present Status

Development of Green Energetic Oxidizers for Solid Propellant Applications: Present Status

Toxicity optimization of green zinc oxide quantum dots in zebrafish using Box-Behnken design: a novel approach for safer nanoparticle synthesis

Zinc oxide quantum dots, also known as ZnO QDs, are highly desirable due to their numerous favorable characteristics, such as their beneficial photoluminescence, solubility in water, along with sunlight absorption. They are well-suited for use in biomedical applications, drugs, and bioimaging. However, study on the in-vivo toxicology of these QDs is needed before they can be used in humans. Zebrafish (Danio rerio) are cheap, fast-growing, and similar to humans, which makes them ideal as in vivo model for studying the toxicity of nanomaterials. The toxicity investigations involving zinc oxide QDs (ZnO QDs) and zinc oxide bionanocomposite (ZnO BC) in zebrafish that were concentration-dependent are evaluated, and the Box-Behnken design (BBD) was utilized to optimize the results. To determine the proper dosage, a study on cell line as well as hemocompatibility was carried out prior to testing the toxic effects of ZnO QDs along with ZnO BC upon zebrafish. When administered at 2.5 μg/l of ZnO BC and 2 μg/l of ZnO QDs, neither ZnO BC nor ZnO QDs appeared to be toxic to embryos during hatching and development. The testing of larval behavior in visible light revealed a dose-dependent decrease in both the total diving distance as well as speed. Nevertheless, at ZnO BC and ZnO QDs levels >250 μg/l and >200 μg/l, respectively, notable effects were seen in zebrafish embryos. Hence, ZnO QDs and BC at low concentrations were notably nontoxic. In order to guarantee the safety of nanomaterials in bio applications, this research supports upcoming in-vivo imaging investigations on their harmful effects.

Covalent attachment of Mn-porphyrin onto functionalized activated carbon for green oxidation of olefins

Covalent attachment of Mn-porphyrin onto functionalized activated carbon for green oxidation of olefins

Frustrated Lewis Pair-Promoted Organocatalytic Transformation of Hydrosilanes into Silanols with Water Oxidant.

Owing to their unique properties, the silanols have attracted intense attention but remain challenging to prepare from the organocatalytic oxidation of hydrosilanes using H2O as a green oxidant. Herein, we employ a frustrated Lewis pair (FLP) to successfully suppress the formation of undesired siloxanes and produce silanols in high to excellent yields in the presence of H2O. Mechanistic studies suggest that the reaction is initiated with the activation of FLP by H2O rather than by silanes and goes through a concerted SN2 mechanism. More importantly, the combination of the FLP-catalyzed oxidation of hydrosilanes with B(C6F5)3-catalyzed dehydrogenation enables us to realize the precise synthesis of sequence-controlled oligosiloxanes. This method exhibits a broad substrate scope and can be easily scaled up, thus exhibiting promising application potentials in the precision synthesis of silicon-containing polymer materials.

Access to Diverse Carbonyl Compounds by Catalyst-Free and Photoinduced Aerobic Cleavage of C=N Bonds.

Functional group interconversion is of great significance in organic synthesis. However, aerobic cleavage of C=N bonds to access carbonyl compounds still suffered from some limitations such as harsh reaction conditions, stoichiometric oxidants, poor substrate scope and use of toxic reagents. Herein, we report a catalyst-free and photo-induced aerobic cleavage of C=N bonds to afford diverse carbonyl compounds using oxygen from air as green oxidant. This mild methodology permits N-tosylhydrazones converted into the corresponding carbonyl compounds including ketones, aldehydes and carboxylic acids, showing broad functional group tolerance and compatibility. Moreover, the gram-scale reaction and post-modification of complicated molecules proved the applicability and efficiency of this strategy. Finally, a plausible mechanism was proposed based on spectroscopic investigations and detailed mechanistic studies.

Acid-Promoted Self-Photocatalyzed Regioselective Oxidation: A Novel Strategy for Accessing Quinoxaline-2,3-diones.

Disclosed here is an efficient approach for the preparation of quinoxaline-2,3-diones using air (O2) as a green oxidant via acid-promoted self-photocatalyzed regioselective oxidation of quinoxalin-2(1H)-ones at C-3 position. This protocol presents a novel synthetic route for the preparation of quinoxaline-2,3-dione derivatives, featuring mild reaction conditions, simple operation, and a wide range of substrates, without the need for external photocatalysts, metal reagents, and strong oxidants.

Oxidative halogenation enabled by 2-haloethanol and aqueous H2O2 under metal-free conditions

Electrophilic halogenation reactions have been recognized as robust approaches to accessing synthetically useful organohalides. Herein, we disclose an exclusive oxidative halogenation pathway, which highlights the use of 2-haloethanol (X ​= ​Cl, Br, I) as the halogenating reagent and aqueous H2O2 as the green oxidant. This method is applicable to various halogenative transformations including halogenation of olefins, alkynes and arenes, which were rarely realized by the previous oxidative halogenation systems. The obtained halogenated products can serve as versatile linchpins for further synthetic applications as demonstrated by the total synthesis of Bulgarein.

Efficient production of singlet oxygen via dioxygen activation on Cu0 decorated MoS2 facilitates the elimination of oxytetracycline

Molecular oxygen (O2), a green oxidant, is applied in advanced oxidation processes, which represents one of the current focal points in water treatment research. However, achieving efficient and economical activation of O2 remains a formidable challenge because of its spin-restricted nature. Herein, zero-valent copper (Cu0) modified molybdenum disulfide (MoS2) materials were applied as O2 activators to degrade organic pollutants. The results showed that Cu0-MoS2 could significantly enhance the activation of O2 and thus accelerate the removal of oxytetracycline (OTC). Notably, 90.0 % of OTC was eliminated within 20 min in the Cu0-F-MoS2 (Cu0-Flower-MoS2) /air system. Quenching experiments, XPS spectra, and DFT calculations confirmed •O2− and 1O2 were pivotal reactive species, with both Mo and Cu playing essential roles. Specially, O2 was activated by Cu0/Cu+ to generate •O2−, then •O2− was oxidized by Mo6+ of MoS2 into 1O2. This research offers an eco-friendly approach for eliminating organic substances by activating O2.

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.

Green synthesis of cobalt oxide nanoparticles (Co3O4NPs): Characterization and green light-driven photocatalytic aerobic oxidation of alkyl and aryl sulfides to the corresponding sulfoxides

In recent years, cobalt oxide nanoparticles (Co3O4NPs) have garnered significant attention due to their unique properties and wide range of applications, particularly in catalysis and environmental remediation. This study focuses on the green synthesis of Co3O4NPs using garlic extract as a bio-reducing and stabilizing agent, marking the first instance of employing this eco-friendly and cost-effective method. The synthesized nanoparticles were characterized using various techniques including SEM, EDX, FTIR, XRD, UV–Vis DRS, and BET analysis, revealing their spherical morphology, elemental composition, surface area, and optical properties. The primary application investigated was the photocatalytic aerobic oxidation of alkyl and aryl sulfides to sulfoxides under visible green light irradiation. The study meticulously optimized the reaction conditions, evaluating the effects of different solvents, light sources, and catalyst dosages. The optimal conditions were found to be a MeCN:H2O (5:1) solvent system, green LED light (535 nm), and 10 mg of Co3O4NPs catalyst with the highest TON of 12.5. Under these conditions, the catalyst demonstrated high efficiency, achieving up to 95% yield of sulfoxides with various substrates. Furthermore, the reusability of the Co3O4NPs was assessed through multiple catalytic cycles, showing excellent stability and consistent performance. Mechanistic studies indicated that the photocatalytic activity involves the generation of reactive oxygen species (ROS) such as superoxide anion radicals (O2.-) and singlet oxygen (1O2), with both holes and electrons playing crucial roles in the oxidation process. This research highlights the potential of green synthesized Co3O4NPs as effective and sustainable photocatalysts for selective oxidation reactions, offering a promising approach for environmentally benign chemical processes. The findings pave the way for further exploration of bio-derived catalysts in various industrial applications, promoting greener and more sustainable practices in chemical synthesis.

Hydroxylation of Phenol by an Azomethine Quinoxaline Schiff Base Copper (II) Complex

Introduction: A binuclear azomethine quinoxaline Schiff base copper (II) complex, [Cu2LCl2], having square-planar environment around each copper (II), has been synthesized. Method: The coordination of the azomethine quinoxaline Schiff base with copper (II) and its structure was studied by various physicochemical and spectroscopic measurements. Results: Catalytic activity of this complex in phenol hydroxylation reaction has been examined using H2O2 as a green oxidant. Conclusion: Catalytic reaction conditions were optimized and under these conditions, 18.32 % conversion of phenol has been obtained for this catalyst