Improvement In Oxidative Stability Research Articles

Evaluation of Cobalt, Nickel, and Palladium Complexes as Catalysts for the Hydrogenation and Improvement of Oxidative Stability of Biodiesel

Developing effective catalysts that can selectively hydrogenate C=C bonds in biodiesel samples is vital as it tackles the major problem of oxidative stability, which greatly limits the utilization of biodiesel as an alternative fuel. In this work, Co, Ni, and Pd catalysts stabilized with the bidentate nitrogen ligands N-(3-(triethoxysilyl)propyl)pyridin-2-ylmethylimine and N-(3-(triethoxysilyl)propyl)picolinamide were synthesized, characterized, and used as pre-catalysts in the transfer hydrogenation of C=C bonds in fatty acid methyl esters. The active catalysts from the Co, Ni, and Pd complexes sequentially hydrogenate the C18:2 chains to C18:1, which is further converted to C18:0 in the FAMEs of both methyl linoleate and jatropha biodiesel. The hydrogenation process was kinetically controlled, and after 3 h it yielded a biodiesel sample that contained 25.83% C16:0, 12.52% C18:2, 41.54% C18:1, 14.47% C18:0 and 3.0% C18:2 isomers. The un-hydrogenated jatropha diesel, hydrogenated jatropha diesel, and a B20 blend of jatropha were tested for susceptibility to oxidation reactions using the Rancimat method and FTIR spectroscopy, and the partial hydrogenation had improved the induction period by 3 h.

Microscopic insights into effects of sulfolane additive on Li–S battery electrolyte

Lithium–sulfur (Li–S) batteries, which have a high theoretical capacity and can be prepared using low-cost activation materials, are a promising alternative for realizing high-energy-density battery systems. However, the stability of the electrolyte and the shuttle effect caused by dissolved lithium polysulfides in the electrolyte prevent their practical application. Due to its non-flammability and high oxidation stability, sulfolane shows good promise for improving the oxidation stability and weakening the shuttle effect of Li–S electrolytes. In this work, the effects of a sulfolane additive on a Li–S battery electrolyte were revealed by density functional theory calculations and molecular dynamics simulations. The molecular orbitals, thermodynamics, and dynamics of the oxidation reaction were analyzed from the electron level. The addition of sulfolane lowers the HOMO energy level and the configuration energy difference, which leads to improved oxidation stability. Furthermore, sulfolane shows affinity to the S atoms close to Li, which correspond to low-order polysulfides. This affinity is confirmed by binding energy data and indicates that the addition of sulfolane inhibits the diffusion of Li2S4, Li2S6 and Li2S8. This work provides an analysis of the effects of sulfolane as an additive from the electron and molecular levels, which will promote a better understanding of Li–S battery systems and enable the design of improved electrolytes.

The Effects of a Natural Citrus Phenolic Extract on the Quality Attributes and Oxidative Stability of Pariza-Type Meat Emulsion Product

Several synthetic food additives that bear an E-number are used by the meat industry as antioxidants/preservatives of cured meat products, such as pariza-type meat emulsion products. However, these agents have been associated with health problems, namely cardiovascular disease, metabolic syndrome, and potential carcinogenic effects. As a result, natural alternatives are constantly under evaluation with the intention of replacing/minimizing their applications in the meat industry. The aim of the present study was therefore to evaluate the effects of a natural citrus phenolic complex extract on the quality characteristics of pariza-type meat emulsion products. The following three batches of pariza were produced based on the same raw material and recipe: a control group without natural antioxidants and two groups with the addition of the polyphenol complex at the levels of 500 and 1000 ppm. The pH, color, tenderness, and oxidative stability of the meat products were assessed immediately after pariza manufacture (day 0), and 30 and 72 days after the start of its refrigerated storage. As indicated, the oxidative stability of pariza was improved as a result of the natural polyphenol complex addition, since the values of malondialdehyde (MDA), an index of lipid peroxidation, were linearly decreased. Parameters such as pH, lightness (L), and yellowness (b*) were linearly increased, while redness (a*) was linearly decreased, and tenderness was not significantly influenced in the treatment groups compared to the control group. It can be concluded that the natural polyphenol complex under examination can be utilized for the improvement of oxidative stability in pariza.

Antioxidant efficacy of amino acids on vitamin A palmitate encapsulated in OSA-starch electrosprayed core-shell microcapsules

The encapsulation and the oxidative stability of vitamin retinyl palmitate (AP), a vitamin A derivative, within coaxial electrosprayed (AP) core – octenyl succinic anhydride (OSA-modified starch) shell microcapsules were investigated. The antioxidant efficiency of amino acids (AAs) (namely histidine, leucine, valine, tryptophan, tyrosine, cysteine and lysine) added to the core, on the oxidative stability of AP was evaluated using differential scanning calorimetry at the isothermal temperature of 140 °C. Confocal microscopy confirmed the location of the AP within the core with AAs microcapsules, surrounded by the shell layer of OSA starch. Scanning electron microscopy revealed that the microcapsules are uniform in size with an average diameter ranging from 2.06 ± 1.05 to 2.41 ± 1.42 μm. The AAs contributed substantially to enhance the oxidative stability of AP, with histidine being the most efficient with an improvement in oxidative stability of about 214 times, while lysine showed the lowest protection (about 3.9 times), compared to non-encapsulated AP. For the encapsulated AP, the presence of histidine or lysine enhanced the oxidative stability of the vitamin by about 70.6 or 1.3 times, respectively. The enhancement of the oxidative stability was mainly due to both the hydrophobic interactions formed between AP and AAs, and the adsorption of AP on the surface of AAs crystals (except lysine), assisted by the suspension of the AAs in ethanol antisolvent, as confirmed with attenuated total reflection–Fourier transform infrared (ATR–FTIR) and X-ray diffraction (XRD) analyses.

Spray drying the Pickering emulsions stabilized by chitosan/ovalbumin polyelectrolyte complexes for the production of oxidation stable tuna oil microcapsules

The microencapsulation of polysaturated fatty acids by spray drying remains a challenge due to their susceptibility to oxidation. In this work, antioxidant Pickering emulsions were attempted as feeds to produce oxidation stable tuna oil microcapsules. The results indicated that the association between chitosan (CS) and ovalbumin (OVA) was a feasible way to fabricate antioxidant and wettable complexes and a high CS percentage favored these properties. The particles could yield tuna oil Pickering emulsions with enhanced oxidation stability through high-pressure homogenization, which were successfully spray dried to produce microcapsules with surface oil content of 8.84 % and microencapsulation efficiency of 76.65 %. The microcapsules exhibited significantly improved oxidation stability and their optimum peroxide values after storage at 50 °C, 85 % relative humidity, or natural light for 15 d were 48.67 %, 60.07 %, and 39.69 % respectively lower than the powder derived from the OVA-stabilized emulsion. Hence, Pickering emulsions stabilized by the CS/OVA polyelectrolyte complexes are potential in the production of oxidation stable polyunsaturated fatty acid microcapsules by spray drying.

Stability, chromatic characteristics and chemical changes of sacha inchi (Plukenetia huayllabambana) oil enriched with aguaje oil (Mauritia flexuosa L.f.) rich in carotenoids

Sacha inchi (Plukenetia huayllabambana) oil is a food matrix that contains more than 80 % of polyunsaturated fatty acids, especially linoleic and α-linolenic acids. The objective of this study was to develop blends of sacha inchi oil (P. huayllabambana) enriched with aguaje oil (Mauritia flexuosa L.f.) and evaluate the induction period, total carotenoid content, nutritional quality indices and oxidative stability from the fatty acid composition. The analytical tests were conducted for oil blends that had the following proportions: sacha inchi oil enriched with aguaje oil at 5, 10 and 20 %. The results prove that the enrichment of sacha inchi oil with aguaje oil (SIO-PH-AO) leads to an improvement in oxidative stability and nutritional and physical properties. For example, the oxidative stability index (OSI) varied from 0.87 to 2.53 h. The content of total carotenoids produces an increase from 0.35 to 99.90 mg/kg, while total polyphenols from 47.45 to 126.90 mg GAE/g, and chroma from 39.91 to 69.02 units. Regarding the fatty acid profile, the oxidizability value improves with the addition of aguaje oil. Reduces levels of PUFA, PUFA/SFA, and hypo-and hypercholesterolemic ratio (h/H). Additionally, an increase in SFA and MUFA levels, while the ω6/ω3 ratio remained constant. Finally, it can be noted that the enrichment of sacha inchi oil with aguaje oil (rich in carotenoids) provides better stability and can be used for commercial applications as a mechanism to establish new vegetable oils with better properties.

Cross-Linked Polyolefins through Tandem ROMP/Hydrogenation.

Cross-linked polyolefins have important advantages over their thermoplastic analogues, particularly improved impact strength and abrasion resistance, as well as increased chemical and thermal stability; however, most strategies for their production involve postpolymerization cross-linking of polyolefin chains. Here, a tandem ring-opening metathesis polymerization (ROMP)/hydrogenation approach is presented. Cyclooctene (COE)-co-dicyclopentadiene (DCPD) networks are first synthesized using ROMP, after which the dispersed Ru metathesis catalyst is activated for hydrogenation through the addition of hydrogen gas. The reaction temperature for hydrogenation must be sufficiently high to allow mobility within the system, as dictated by thermal transitions (i.e., glass and melting transitions) of the polymeric matrix. COE-rich materials exhibit branched-polyethylene-like crystallinity (25% crystallinity) and melting points (Tm = 107 °C), as well as excellent ductility (>750% extension), while majority DCPD materials are glassy (Tg = 84 °C) and much stiffer (E = 710 MPa); all materials exhibit high tensile toughness. Importantly, hydrogenation of olefins in these cross-linked materials leads to notable improvements in oxidative stability, as saturated networks do not experience the same substantial degradation of mechanical performance as their unsaturated counterparts upon prolonged exposure to air.

Encapsulation and characterization of soy protein-based ω-3 medium- and long- chain triacylglycerols microencapsulated with diverse homogenization techniques for improving oxidation stability

Recently, MLCTs have attracted considerable attention as a potential alternative to traditional oils due to their suppressive effect on fat accumulation and insulin sensitivity. In this study, the microcapsules of MLCTs with superior performance were fabricated through different homogenization processes to overcome the limitations of ω-3 medium- and long- chain triacylglycerols (MLCTs), including poor stability and prone oxidation. Additionally, the impact of various homogenization techniques, namely, high-pressure, ultrasound, and cavitation jet, on the particle structure, encapsulation efficiency, and oxidation stability of microcapsules (MLCTs) was investigated. The MLCTs microcapsules fabricated through high-pressure homogenization had a smaller particle size of 295.12 nm, lower PDI of 0.24, and a higher zeta-potential absolute value of 32.65, which significantly improved their dispersion and encapsulation efficiency, reaching 94.56 % after the spray-drying process. Furthermore, the low moisture content and superior storage stability of MLCTs microcapsules have the potential to serve as carriers of liposoluble actives.

Binary Effect of Tertiary Butylhydroquinone and Butylated Hydroxytoluene Additives with The Addition of Glycerol Monostearate to Improve Oxidative Stability of Palm Oil-Based Biodiesel

Biodiesel is a renewable and environmentally friendly alternative to conventional diesel fuel. However, like any fuel, biodiesel is subject to oxidation, which can negatively impact its quality and performance when kept for long-term. The addition of binary antioxidants such as TBHQ:BHT had been proven to improve oxidation stability of biodiesel. Combining surfactant such as GMS into single antioxidant had been proven to solve its insolubility issue. However, the implementation of mixing binary antioxidants and surfactant has not been done yet. Therefore, this research analyzed the effect of single antioxidant, binary antioxidants, and binary antioxidants with GMS (100 ppm) addition into biodiesel and biodiesel blend B35. The effect was observed within 8 weeks storage period. The result showed that B35 did not have any significant impact. While in pure biodiesel samples, B100-bi and B100-bi+GMS had a slight difference in the results of oxidative parameters. B100-bi showed the best result in induction period and kinematic viscosity. Rancimat test showed 170 hours for B100-bi and 168 hours for B100-bi+GMS. While B100-bi+GMS indicated as the best additives in term of acid number, iodine value, and dispersion test. Hence, the addition of surfactant into binary antioxidants showed similar performance with B100-bi but with slightly better solubility.

Nonfluorinated Antisolvents for Ultrastable Potassium-Ion Batteries.

A robust interface between the electrode and electrolyte is essential for the long-term cyclability of potassium-ion batteries (PIBs). An effective strategy for achieving this objective is to enhance the formation of an anion-derived, robust, and stable solid-electrolyte interphase (SEI) via electrolyte structure engineering. Herein, inspired by the application of antisolvents in recrystallization, we propose a nonfluorinated antisolvent strategy to optimize the electrolyte solvation structure. In contrast to the conventional localized superconcentrated electrolyte introducing high-fluorinated ether solvent, the anion-cation interaction is considerably enhanced by introducing a certain amount of nonfluorinated antisolvent into a phosphate-based electrolyte, thereby promoting the formation of a thin and stable SEI to ensure excellent cycling performance of PIBs. Consequently, the nonfluorinated antisolvent electrolyte exhibits superior stability in the K||graphite cell (negligible capacity degradation after 1000 cycles) and long-term cycling in the K||K symmetric cell (>2200 h), as well as considerably improved oxidation stability. This study demonstrates the feasibility of optimized electrolyte engineering with a nonfluorinated antisolvent, providing an approach to realizing superior electrochemical energy storage systems in PIBs.

A novel oleogel based on porous microgel from egg white

In this study, oleogel was prepared by oil absorption using egg white microgel (EWM), and the EWM was obtained through microwave hydrothermal treatment, freeze-thawing, ethanol solvent replacement, atmospheric drying and ball milling pulverization. Compared with water bath and hydrothermal method, microwave hydrothermal treatment had higher heating efficiency to form egg white hydrogel (EWH). Ethanol solvent exchange reduced the surface tension from water evaporation, allowing the porous structure of EWH to be maintained during atmospheric pressure drying, while EWH structure collapsed without solvent exchange. Ball milling made EWM present smaller particle size and higher specific surface area than common pulverization, owing excellent oil holding ability (1.24 ± 0.04 g/g) and great ability to form networks in oil. Compared to control oleogel based on microgel without solvent exchange or by common pulverization, EWM oleogel showed higher viscosity and gelatinability, which was beneficial to the improvement of oxidation stability. This oleogel can be further used as the solid fat alternative or bioactive substance delivery carriers in food industry.

Can We Find an Optimal Fatty Acid Composition of Biodiesel in Order to Improve Oxidation Stability?

Air quality currently poses a major risk for human health. Currently, diesel is widely used as fuel and is a significant source of nitrogen oxides (NOx) and particulate matter (PM), both hazardous to human health. A good alternative for mineral diesel is biodiesel, not only for the improvement of hazardous components in the exhaust gases but also because it can be produced in view of a circular economy. Biodiesel consists of a mix of different fatty acid methyl esters, which can react with oxygen. As a consequence, the oxidation stability of biodiesel has to be studied, because the oxidation of biodiesel could affect the performance of the engine due to the wear of injectors and fuel pumps. The oxidation stability could also affect the quality of the exhaust gases due to increases in NOx and PM. The basic question we try to answer in this communication is: ‘Can we find an optimal fatty acid composition in order to have a maximal oxidation stability?’ In this article, we try to find the optimal fatty acid composition according to the five most common fatty acid methyl esters present in biodiesel in order to reach a maximal oxidation stability. The measurements and statistical analysis show, however, that there is no useful regression model because there are statistically significant two- and three-way interactions among the different fatty acids.

Improvement of Oxidation Stability and Cold Flow Properties of Biodiesel Using Mixed Oil Strategy

Improvement of Oxidation Stability and Cold Flow Properties of Biodiesel Using Mixed Oil Strategy

Synergy stabilization of vitamin E and D-sorbitol on crosslinked ultrahigh molecular weight polyethylene for artificial joint under in-vitro clinically relevant accelerated aging

Maintaining reliability remains a great challenge for ultrahigh molecular weight polyethylene (UHMWPE) bearings due to oxidation in biological environments. This work aimed at inspecting the efficacy of the hybrid antioxidant strategy in stabilizing crosslinked UHMWPE under an in vitro clinically relevant accelerated aging condition. The hybrid antioxidant system was composed of vitamin E (VE) and D-sorbitol (DS) as primary and secondary antioxidants, respectively. The already established in vitro clinically relevant accelerated aging was performed via squalene absorption and subsequent thermal oxidation treatment. Compared to the use of VE alone, the combination of VE and DS significantly protracted the oxidation induction time of UHMWPE with no apparent oxidation after aging, showing a notable synergistic effect on the oxidative stability of UHMWPE. The crosslink density was higher for VE/DS/UHMWPE than VE/UHMWPE at each aging period. It revealed that the hybrid antioxidant strategy settled the longstanding contradiction between oxidation stability and crosslinking of UHMWPE. Attributed to improved oxidation stability, there was a positive reversal in the tensile property between VE/DS/UHMWPE and VE/UHMWPE after aging, where comparable ultimate tensile strength and higher elongation at break were observed. These findings underline the high potential of the hybrid antioxidant strategy for developing artificial joint materials with desired ability to resist oxidation and balanced performance.

Effects of selenium addition in nanostructured tellurium/PEDOT:PSS thermoelectric composite materials on the improvement of oxidation stability

Recently, the development of a composite thermoelectric material including conducting polymer (PEDOT:PSS) and nanostructured tellurium (Te) offers both high thermoelectric performance and mechanical flexibility. But they are usually vulnerable to oxidation, which limits the material's ability to continuously harvest energy in any environment. To address this issue, this report presents a Se doping strategy to improve the oxidation stability of the composite material, and evaluates the material characteristics and thermoelectric properties of synthesized composites. Se-doped nanostructured Te/PEDOT:PSS composite materials have improved oxidation stability and thermoelectric properties, making them a promising candidate for the next-generation thermoelectric device application.

Improvement of Oxidative Stability of Fish Oil-in-Water Emulsions through Partitioning of Sesamol at the Interface

The susceptibility of polyunsaturated fatty acids to oxidation severely limits their application in functional emulsified foods. In this study, the effect of sesamol concentration on the physicochemical properties of WPI-stabilized fish oil emulsions was investigated, focusing on the relationship between sesamol-WPI interactions and interfacial behavior. The results relating to particle size, zeta-potential, microstructure, and appearance showed that 0.09% (w/v) sesamol promoted the formation of small oil droplets and inhibited oil droplet aggregation. Furthermore, the addition of sesamol significantly reduced the formation of hydrogen peroxide, generation of secondary reaction products during storage, and degree of protein oxidation in the emulsions. Molecular docking and isothermal titration calorimetry showed that the interaction between sesamol and β-LG was mainly mediated by hydrogen bonds and hydrophobic interactions. Our results show that sesamol binds to interfacial proteins mainly through hydrogen bonding, and increasing the interfacial sesamol content reduces the interfacial tension and improves the physical and oxidative stability of the emulsion.

Improvement in oxidative stability and quality characteristics of functional chicken meat product supplemented with aqueous coriander extract

ABSTRACT The aim of the current study was to explore the preservative effect of aqueous coriander extract and butylated hydroxytoluene (BHT) on the shelf life of refrigerated chicken patties for 9 days. For this purpose, BHT (100 ppm) and aqueous coriander extract (1%) was applied to improve the storage stability. The patties were evaluated for their physiochemical characterization including total phenolic content (TPC), thiobarbituric acid reactive substances (TBARS), peroxide value (PV), total carbonyl, metmyoglobin, and instrumental color, microbial analysis including (total plate count), and sensory attributes including (color and odor). The results showed that coriander extract has a significant (P < .05) effect in terms of delaying microbial growth, lipid and protein oxidation compared to BHT application. Likewise, higher phenolic contents were observed in patties treated with coriander extract. Conclusively, coriander extract did not impose any undesirable effect of physical attributes (instrumental color and color/odor) of cooked chicken patties. It is concluded that aqueous coriander extract is a plenteous source of various antioxidants and should be used as a functional food additive in meat products at 1% concentration without affecting the product’s quality attributes.

Stable Operation of Lithium Metal Batteries with Aggressive Cathode Chemistries at 4.9 V.

High-voltage lithium metal batteries (LMBs) pose severe challenges for the matching of electrolytes with aggressive electrodes, especially at low temperatures. Here, we report a rational modification of the Li+ solvation structure to extend the voltage and temperature operating ranges of conventional electrolytes. Ion-ion and ion-dipole interactions as well as the electrochemical window of solvents were tailored to improve oxidation stability and de-solvation kinetics of the electrolyte. Meanwhile, robust and elastic B and F-rich interphases are formed on both electrodes. Such optimization enables Li||LiNi0.5 Mn1.5 O4 cells (90.2 % retention after 400 cycles) and Li||LiNi0.6 Co0.2 Mn0.2 O2 (NCM622) cells (74.0 % retention after 200 cycles) to cycle stably at an ultra-high voltage of 4.9 V. Moreover, NCM622 cells deliver a considerable capacity of 143.5 mAh g-1 at -20 °C, showing great potential for practical uses. The proposed strategy sheds light on further optimization for high-voltage LMBs.

Stable Operation of Lithium Metal Batteries with Aggressive Cathode Chemistries at 4.9 V

AbstractHigh‐voltage lithium metal batteries (LMBs) pose severe challenges for the matching of electrolytes with aggressive electrodes, especially at low temperatures. Here, we report a rational modification of the Li+ solvation structure to extend the voltage and temperature operating ranges of conventional electrolytes. Ion‐ion and ion‐dipole interactions as well as the electrochemical window of solvents were tailored to improve oxidation stability and de‐solvation kinetics of the electrolyte. Meanwhile, robust and elastic B and F‐rich interphases are formed on both electrodes. Such optimization enables Li||LiNi0.5Mn1.5O4 cells (90.2 % retention after 400 cycles) and Li||LiNi0.6Co0.2Mn0.2O2 (NCM622) cells (74.0 % retention after 200 cycles) to cycle stably at an ultra‐high voltage of 4.9 V. Moreover, NCM622 cells deliver a considerable capacity of 143.5 mAh g−1 at −20 °C, showing great potential for practical uses. The proposed strategy sheds light on further optimization for high‐voltage LMBs.

Enhancing the Chemical Stability of MXene Through Synergy of Hydrogen Bond and Coordination Bond in Aqueous Solution.

MXenes with unique physicochemical properties have shown substantial potential in electromagnetic interference (EMI) shielding. However, the chemical instability and mechanical fragility of MXenes has become a major hurdle for their application. Abundant strategies have been dedicated to improving the oxidation stability of colloidal solution or mechanical properties of films, which always come at the expense of electrical conductivity and chemical compatibility. Here, hydrogen bond (H-bond) and coordination bond are employed to achieve chemical and colloidal stability of MXenes (0.1mg mL-1 ) by occupying the reaction sites of Ti3 C2 Tx attacking of water and oxygen molecules. Compared to the Ti3 C2 Tx , the Ti3 C2 Tx modified with alanine via H-bond shows significantly improved oxidation stability (at room temperature over 35 days), while the Ti3 C2 Tx modified with cysteine by synergy of H-bond and coordination bond can be maintained even after 120 days. Simulation and experimental results verify the formation of H-bond and Ti-S bond by a Lewis acid-base interaction between Ti3 C2 Tx and cysteine. Furthermore, the synergy strategy significantly improves the mechanical strength of the assembled film (up to 78.1 ± 7.9MPa), corresponding the increment of 203% compared to untreated one, almost without compromising the electrical conductivity and EMI shielding performance.