Degree Of Oxidation Research Articles

A novel method for determination of peroxide value and acid value of extra-virgin olive oil based on fluorescence internal filtering effect correction

Peroxide value (PV) and acid value (AV) are widely used indicators for evaluating oxidation degree of olive oils. Fluorescence spectroscopy has been extensively studied on the detection of oil oxidation, however, the detection accuracy is limited due to internal filtering effect (IFE). Due to the primary and secondary IFE, at least two wavelengths of absorption information are required. Least squares support vector regression (LSSVR) models for PV and AV were established based on two absorption coefficients (μa) at 375 nm and emission wavelength and one fluorescence intensity at corresponding wavelength. The regression results proved that the model based on 375 and 475 nm could reach the best performance, with the highest correlation coefficient for prediction (rp) of 0.889 and 0.960 for PV and AV respectively. Finally, the explicit formulations for PV and AV were determined by nonlinear least squares fitting, and the rp could reach above 0.94 for two indicators.

Oxidation-alkaline-enhanced abiotic humification valorizes lignin-rich biogas digestate into artificial humic acids

This study introduces a cost-effective, mild thermal abiotic humification method for producing highly humified artificial humic acids (AHAs) from lignin-rich biogas digestate. Derived from the anaerobic digestion of cattle manure, the digestate slurry undergoes an MnO2-KOH-urea-enhanced humification reaction. Key process variables, such as MnO2 dose (0–15 mg/L), KOH dose (0–1 mol/L), urea dose (0–1.2 mol/L), reaction time (30–150 min), and temperature (25–85 °C), were systematically explored to optimize AHA yield, carboxylic acid content, and lignin removal. Optimal conditions, employing 7.69 mg/L of MnO2, 0.57 mol/L of KOH, and 0.63 mol/L of urea at 85 °C for 106 min, resulted in an impressive AHA yield of 32.15%, featuring a significant carboxylic acid content of 3.325 mmol/g. Under these conditions, up to 65% of lignin was effectively removed, accompanied by the release of orthophosphate up to 258 mg/L. The produced AHAs exhibited reduced toxicity, as demonstrated by substantial reductions of 54.13%, 57.14%, and 42.50% in phenols, furfural, and hydroxymethylfurfural, respectively. Notably, the AHAs displayed favorable characteristics, including a lower molecular weight (760.49 g/mol), diminished aromaticity (66.25% reduction), higher humification degree (lower C/N ratio of 8.79), increased oxidation degree (higher O/C ratio of 0.6), and elevated spectral index of humification (higher E4/E6 of 4.58). Analytical techniques, such as FT-IR, XPS, and TGA-MS, revealed chemical resemblance and enhanced functionality of AHAs compared to natural counterparts. Differentiation between AHA, lignin, and humification residues was confirmed through SEM-EDX, ICP-OES, and organic/inorganic carbon analyses. The obtained AHAs exhibit promising characteristics suitable for diverse applications in sustainable agriculture and environmental management.

Effect of black spot infection on the chemical composition and comprehensive quality of pecan (Carya illinoinensis) kernel oil

Abstract Objectives The changes in the chemical composition of oil from pecan kernels following infection with black spot disease were evaluated to determine whether the disease affects the quality of the seed oil. The findings should provide theoretical support for developing the pecan industry and enhancing the risk resistance of the industry. Materials and Methods Oil samples from healthy and diseased pecan kernels were obtained using the squeezing method, and the bioactive substances and fatty acid composition of the two types of oil samples were compared. The degree of oxidation and deterioration of the diseased kernel oil was evaluated. Based on supervised orthogonal partial least squares–discriminant analysis, gray correlation analysis, and unsupervised factor analysis, a multivariate evaluation model was established to comprehensively score the quality of the two types of oils. Results The results showed that, compared with the healthy kernel oil, the contents of total polyphenols and flavonoids, as well as the peroxide and acid values, were significantly higher in the diseased kernel oil. The content of oleic acid, as well as the ratio of monounsaturated fatty acids to polyunsaturated acids, was also significantly higher in the diseased kernel oil. In addition, no aflatoxin was detected. Multivariate analysis revealed no significant difference in the quality of diseased kernel oil compared with that of healthy kernel oil. Conclusions Therefore, following infection, the pecan oil begins to oxidize, but this does not have a significant negative effect on the nutrients, suggesting that oil from diseased kernels has the potential to be further processed and sold as edible-grade vegetable oil.

In-depth understanding of the microscopic mechanism of biochar carbonaceous structures during thermochemical conversion: Pyrolysis, combustion and gasification

The thermochemical utilization of biomass char is vital for addressing environmental pollution and the energy crisis. The carbonaceous structure plays a crucial role in this process, and understanding the conversion mechanism aids in optimizing biomass reactors. This study performs a comprehensive analysis of high-temperature rice husk char using 13C NMR, XPS, and FTIR techniques. The carbonaceous structure is classified based on carbon bonding modes and the forms of O and N. The reaction mechanisms of thermochemical transformations under various atmospheres (N2, O2, CO2, H2O) are investigated using ReaxFF-MD. The reaction characteristics are determined, and the reaction activities are compared. The results indicate that the nitrogen-containing heterocycles remain in pyridine-type pyrolysis products under the N2 atmosphere (pyrolysis). Repolymerization occurs in the initial stages of pyrolysis, with the size of aromatic rings affecting the formation of heavy components. Under the O2 atmosphere (combustion), the degree of complete carbon oxidation is linked to the number of aromatic rings. The reactivity of aliphatic carbonaceous structures depends on the hydrogen content. Under the CO2 atmosphere (gasification), the pyrrole-type structure exhibits the highest gasification activity. Aromatic structures with oxygen functional groups are more susceptible to reacting with CO2, indicating higher sensitivity. Aliphatic H atoms tend to be oxidized into H2O. Under the H2O atmosphere (gasification), hydrogen in the gasification of aromatic carbon primarily originates from H at the aromatic boundary. In N2 and CO2 atmospheres, the CO bridge bond breaks first, followed by reactions. In H2O gasification, the breaking of bridge bonds connected to aliphatic carbon occurs simultaneously with gasification. Each reaction system's product distribution and elemental migration processes are also determined. The findings provide valuable theoretical insights into the application of biomass char.

Oil from Mullet Roe Byproducts: Effect of Oil Extraction Method on Human Erythrocytes and Platelets.

Background: The valorization of byproducts to obtain high nutritional value foods is of utmost importance for our planet where the population is booming. Among these products are oils rich in ω-3 fatty acids produced from fishery byproducts. Recently, mullet roe oil from roe byproducts was produced that was rich in the ω-3 fatty acids eicosatetraenoic acid (EPA) and docosahexaenoic acid (DHA). Oils are customarily characterized for their composition and degree of oxidation but little is known of their biological effects, especially the effect of the extraction method. Methods: The purpose of this study was to evaluate the effects of freshly extracted mullet roe oil from mullet roe byproducts and the effect of the extraction method on human red blood cells (hRBCs) and platelets. To this end, the hemocompatibility (cytotoxicity), oxidative effects, and erythrocyte membrane changes were examined after 1 and 24 h of incubation. Antiplatelet effects were also assessed in vitro. Results: The expeller press oil extraction method and alcalase-assisted extraction produced the most biocompatible oils, as shown by hemocompatibility measurements and the absence of erythrocyte membrane alterations. Solvent extracts and protease-assisted extraction oils resulted in the rupture of red blood cells at different examined dilutions, creating hemolysis. Conclusions: It seems that the proper functioning of oil-erythrocyte interactions cannot be explained solely by ROS. Further investigations combining chemical analysis with oil-cell interactions could be used as an input to design high nutritional value oils using green extraction technologies. All samples exhibited promising antiplatelet and antiblood clotting effects in vitro.

Silicon-Germanium on Insulator CMP Slurry Designed with Oxidant and Accelerator Heading an Amine Functional Group for Remarkably Enhancing Polishing Rate

High quality single crystal silicon-germanium-on-insulator (SGOI) has a potential to enable the next generationof photonic and electronic devices. However, to utilize an SGOI structure, a high SiGe-film polishing rate isnecessary (i.e., > 200 nm/min) for polishing the facet crystalline SiGe during the fabrication of SiGe on insulatorthrough epitaxial growth processes.In previous studies, amine-based chemicals as SiGe-film polishing rate accelerators have been reported, butthere were limitations in increasing the SiGe-film polishig rate by considering only the chemical reaction of SiGe-film surface. In this study, for the first time, both oxidant(i.e., H2O2) and accelerator with amine functional groups(i.e., triethanolamine) were designed, resulting in a surprising increase in the SiGe-film polishing rate of 270nm/min, as shown Fig. 1a.The SiGe chemical mechanical planarization (CMP) mechanism was clearly demonstrated by preciselyinvestigating both chemical properties(i.e., GeO2 spectra intensity via X-ray photoelectron spectroscopy) andmechanical properties(i.e., electrostatic repulsive force between colloidal silica abrasives and the SiGe-film viaelectrophoretic light scattering). The remarkable enhancement of the SiGe-film polishing rate for oxidant andtriethanolamine was the result of (i) minimizing the loss of degree of SiGe surface oxidation, as shown Fig. 2, (ii)enhancing degree of adsorption of the CMP slurry on the polished SiGe-film surface during CMP, and (iii)decreasing the electrostatic repulsive force between colloidal silica abrasives and the SiGe-film surface, as shownFig 1b. Finally, successful removal of the facets in SiGe on insulator wafers was achieved, securing excellentsurface roughness characteristics. SiGe-film polishing mechanism and the SiGe slurry characteristics will bepresented in detail. Figure 1

(Digital Presentation) In-Situ Spectroelectrochemistry to Unveil the Mechanism of Green Ammonia Production on the Ti2n Nitride Mxene

Electrochemical nitrogen reduction reaction (NRR) is used to convert nitrogen (N2) to ammonia (NH3) at ambient temperature and pressure. In general, acidic electrolytes are used to provide protons (H+) for the reduction process. However, this leads to a low NH3 selectivity because of H2 by-product formation via the hydrogen evolution reaction (HER). Recently, we showed that a Ti2N MXene is active and selective for NRR, and provided preliminary evidence that this catalyst works through a Mars-van Krevelen (MvK) mechanism rather than conventional associative/dissociative mechanisms. To improve the selectivity of the NRR process, the electrolyte was shifted from acidic to neutral pH values. From this, it was seen that NRR in 0.1M Na2SO4 was able to achieve a selectivity significantly greater than that of 0.1M HCl. We also observed that at more cathodic potentials, the material begins to irreversibly decompose into TiO2 as evidenced by cyclic voltammetry analysis before and after chronoamperometry experiments. To further understand the performance of this material, we use in-situ/operando techniques, including X-ray absorption spectroscopy (XAS) and Fourier-transform infrared (FTIR) spectroscopy, to deconvolute the mechanism of NH3 production. We use XAS to track the Ti oxidation state shift and degree of shift as a function of reaction time and applied potential. We also use XAS to track the change in the atomic bond lengths at the local coordination environment of the Ti atoms throughout time and voltage. Furthermore, we use FTIR to elucidate in real-time the adsorption of NRR reactive species and intermediates on the MXene surface. All findings are further corroborated with density functional theory (DFT) calculations to track the reaction energy pathway over each intermediate. We plan to expand these findings to other materials and systems, and use the knowledge obtained from these studies to design optimal electrolytic conditions to produce NH3 through NRR.

Solid-State Redox-Active Pseudocapacitor with Improved Performance at High Temperature

With the emergence of environmental issues such as global warming as well as our new demand for efficient energy storage systems (EES) that can power portable electronics; batteries and supercapacitors are gaining more attention in the latest literature. Batteries can provide high energy density and lower power densities (e.g. for LIB, 1kW.kg-1 vs. 150-200 Wh.kg-1), while supercapacitors are high power devices with low energy densities (e.g. for most commercial devices ⁓ 10 kW.kg-1 vs. 5-10 Wh.kg-1). In order to couple high energy and high power densities of both devices, pseudocapacitance was introduced in 1991 by Conway 1 using metal oxide. Pseudocapacitance is a fast and reversible surface faradaic process with performance similar to double layer capacitors but higher energy densities closer to that of batteries. Aside from metal oxides, conductive polymers also demonstrate pseudocapacitance. In this regards, the use of conductive polymers as nontoxic, abundant, low cost and sustainable organic material is on the rise. Nevertheless, the inherent issue related to instability of the conductive polymer especially at high degree of oxidation had restricted their application in EES. However, redox active polymers (RAPs) with non-conjugated backbone and redox active pendant group demonstrates improved performance and structural diversity with more distinct redox potentials. 2 Amongst them, quinone-containing polymers with their high theoretical capacities, facile kinetics and tunable redox potential are at the top of the list. Particularly, catechol, a bioinspired ortho-quinone based polymer has gain popularity following a work by Detrembleur et al. 3 However; the solubility of the organic materials in organic solvents hinders their application in EES. To this end, using solid-state electrolyte can help alleviate the issue. Nevertheless, solid-state design stimulate sluggish kinetics and reduce electrode/electrolyte interfacial area, a component required to achieve high pseudocapacitance. Consequently, nano-structuring the redox polymer can help improve the contact resistance as well as increasing the surface area. In addition, the nanoparticles structure will promote more distinct redox processes. 4 In this study, we demonstrate for the first time, a prototype pouch cell based on all-solid-state organic hybrid supercapacitor bearing catechol redox active moieties. Using emulsion polymerization, catechol based RAP nanoparticles of size ranging from 50 to 150 nm were synthesized 4 and together with activated carbon was used as working electrode. Block-co-polymers based solid electrolyte was employed as electrolyte as well as binder for both cathode and anode. Using this design, discharge capacities of ⁓ 10 and 60 mAh/g at room temperature and at 50 °C were obtained, respectively.

Molecular simulation study of microstructural evolution during low-temperature oxidation of coal

In this study, industrial analysis, 13C NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), and in-situ infrared spectroscopy were employed to determine the elemental composition and structure of Tingnan coal. The peak area, pore volume, and specific surface area were used as the main parameters to investigate the structural changes of coal molecules and pore evolution during low-temperature coal oxidation, using an automated surface area and pore size analyzer. The analysis revealed that with increasing oxidation degree, the CH groups in the aromatic structure gradually decreased, while the total content of oxygen-containing functional groups such as alcohols, phenols, carboxyls, and carbonyls remained relatively constant. However, the relative content of hydroxyl groups and ether linkages increased with increasing oxidation temperature. Additionally, coals with different oxidation degrees exhibited well-developed micropores, and the specific surface area gradually decreased while the pore size increased with temperature. Molecular models of Tingnan coal in its original state and oxidized at temperatures of 50 °C, 70 °C, and 110 °C were constructed using Materials Studio software. Based on these models, pores with diameters of 2.79 nm, 3.07 nm, 3.07 nm, and 3.11 nm and a length of 4.5 nm were constructed using the coal molecular structure as the pore walls.

A new insight into the mechanism of Ce enhancing high temperature oxidation resistance of hot-formed steel

In this paper, the effect of Ce addition on high temperature oxidation behavior of hot-formed steel was studied by high temperature oxidation experiment. The structure and phase composition of surface oxide layer of specimens with different Ce content were systematically analyzed by SEM, EDS, XPS. The results showed that the addition of Ce promoted the formation of a dense oxide layer during the initial oxidation stage, and effectively weaken the oxidation degree of the steel surface. Meanwhile, the Ce2O3 particles segregation in Si–Cr rich phase reduced the concentration of vacancy defects in oxide layer and enhanced the adhesion between oxide layer and substrate. After Ce addition, the surface oxidation resistance of hot-formed steel is significantly improved.

Spontaneous regeneration of active sites against catalyst deactivation

Catalyst deactivation is one of the long-standing challenges in heterogeneous catalysis. Here, we found that the Ni/MgAl2O4 catalyst shows an atmosphere-dependent deactivation behavior during dry reforming of methane (DRM) process, i.e., oxidation and redispersion of Ni near the inlet in an oxidizing atmosphere while coking and sintering of Ni near the outlet in a reducing atmosphere. These structural evolutions of the Ni species are revealed to be driven by the surface oxidation degree of the catalyst, such that it is reversible when the redox atmosphere changes. It inspired us to develop an alternating-feeding gas strategy that periodically changes the gas flow direction to balance the structural evolution of Ni species across catalyst bed through the spontaneous regeneration of deactivated sites, enabling a supra-stable DRM process. This study provides new insights into the catalyst deactivation for DRM process, while opens a new avenue to address catalyst deactivation in various redox-catalyzed processes.

Enhanced formation of methane hydrates via graphene oxide: Machine learning insights from molecular dynamics simulations

Gas hydrates, with their significant applications in energy and environment sectors, have emerged as promising technologies for gas separation, natural gas and energy storage. The formation of methane hydrates occurs in substrate-contact conditions, where the properties of the substrate surfaces play a crucial role in determining hydrate formation pathways. Herein, the influence of the hydroxyl group (-OH) content on the graphene surface on methane hydrate formation in confined systems using molecular dynamics (MD) simulations with machine learning (ML) technique. The MD results show that increasing the oxidation degree effectively enhances the formation of methane hydrate within the oxidation degree of 10 %–40 %. This enhancement is attributed to the hydrophilicity of the (GO) surfaces. When the oxidation degree reaches 50 %, however, the formation rate of methane hydrates slows down compared to the GO-40 system. This deceleration can be attributed to the formation of dense water layers that adhere to the GO surfaces, resulting in impeding the hydrate formation process. Markov State Model (MSM) is employed to analyze the induction time of GO on methane hydrate formation, highlighting the important role of GO in the formation of methane hydrates. Additionally, an eXtreme Gradient Boosting (XGboost) ML model is developed to predict the formation behaviors of methane hydrates. Ternary water-ring aggregations (TWRAs) are adopted as indicators to understand to the formation behaviors, and the XGboost ML model facilitate the identification of key TWRAs associated with the formation process. This work provides molecular-level insights into the influence of –OH group on formation of methane hydrates, and offers a predictive framework for understanding and characterizing the formation clathrate hydrates in confined systems.

Temperature Exposure of Single- and Double-Layer Coatings of Inconel 625 Reinforced with Ni3Al Intermetallics

Abstract The customization of metallic alloys offers the possibility of adding functionalities to a material. Customizing alloys with a dispersion of intermetallic compounds obtained by in situ synthesis does not compromise processing and allows for the addition of functionalities to less noble alloys. However, intermetallic materials present important challenges regarding their processability by welding and forming because of low toughness, ductility, and metallurgical stability at high temperatures. Graded multilayer coatings might offer a balanced solution to the aforementioned challenges by taking advantage of a ductile matrix while the fine dispersion of aluminides reinforces hardness and metallurgical stability. This investigation addressed this challenge by processing coatings of Inconel 625 superalloy with in situ formed Ni-Al based intermetallics to increase hardness and high temperature oxidation resistance while maintaining weldability. Powder mixtures of Inconel 625, Ni, and Al elementary powders were processed as single and double-layer coatings. Inconel 625 atomized alloy was modified with a powder mixture containing 75 wt. % Ni and 25 wt. % Al. Each deposited layer had a different amount of the Ni + Al powder mixtures added to the atomized Inconel 625 alloy. The single layer coating was processed with a mixture containing Inconel 625 and 80 wt. % (Ni + Al), while the double-layer coating of the first layer was deposited with the powder mixture Inconel 625 and 20 wt. % (Ni + Al), and the second layer deposited with Inconel 625 and 80 wt. % (Ni+Al). Monel 400 substrates were used for all deposits in the study. Powder mixtures were deposited by Plasma Transferred Arc allowing the in situ synthesis of Ni-Al intermetallics without compromising weldability. For both coatings, microstructural stability was sustained until 900 °C, and at 1,100°C exposure led to some degree of oxidation, but the increased hardness due to nickel aluminides intermetallics in situ formation was sustained.

Structural effects induced by dialysis-based purification of carbon nanomaterials

Dialysis plays a crucial role in the purification of nanomaterials but its impact on the structural properties of carbon nanomaterials was never investigated. Herein, a carbon-based nanomaterial generated electrochemically in potassium phosphate buffer, was characterized before and after dialysis against pure water. It is shown that dialysis affects the size of the carbon domains, structural organization, surface functionalization, oxidation degree of carbon, and grade of amorphicity. Accordingly, dialysis drives the nanomaterial organization from discrete roundish carbon domains, with sizes ranging from 70 to 160 nm, towards linear stacking structures of small nanoparticles (<15 ​nm). In parallel, alcohol and ether (epoxide) surface groups evolve into more oxidized carbon groups (e.g., ketone and ester groups). Investigation of the as-prepared nanomaterial by electron paramagnetic resonance (EPR) revealed a resonance signal consistent with carbon-oxygen centred radicals.Additionally, this study brings to light the selective affinity of the carbon nanomaterial under study to capture Na+ ions, a property greatly enhanced by the dialysis process, and its high ability to trap oxygen, particularly before dialysis. These findings open new perspectives for the application of carbon-based nanomaterials and raise awareness of the importance of structural changes that can occur during the purification of carbon-based nanomaterials.

The evaluation of mixed-layer emulsions stabilized by myofibrillar protein-chitosan complex for delivering astaxanthin: Fabrication, characterization, stability and in vitro digestibility

Muscle protein based functional foods have been attracted great interests in novel food designing. Herein, myofibrillar protein (MP)-chitosan (CH) electrostatic complexes were employed to fabricate mixed-layer emulsions to protect and deliver astaxanthin. The MP/CH complex fabricated mixed-layer emulsions displayed higher stability against pH and temperature changes, exhibiting smaller droplet and homogenous distributions. After UV-light irradiation for 8 h, the mixed-layer emulsions had higher astaxanthin retention (69.11 %, 1:1 group). During storage, a lower degree of lipid oxidation, protein oxidation and higher astaxanthin retention were obtained, indicating desirable protections of mixed-layer emulsions. The vitro digestion reveled the mixed-layer emulsions could decrease the release of free fatty acids. Meanwhile, the bioaccessibility of astaxanthin was higher (30.43 %, 2:1 group) than monolayer emulsion. In all, the MP/CH prepared mixed-layer emulsions could protect and deliver fat-soluble bioactive compounds, and contributed to develop muscle protein based functional foods to meet the needs of slow and controlled release.

Kinetics in low-temperature-isothermal oxidation of tungsten carbide under different humidity conditions

The isothermal oxidation experiments of tungsten carbides (WC) were carried out at levels of inequality in relative humidity (RH) levels and below 200 °C. Evaluated resistivity fluctuations and structural transformations during the low-temperature corrosion process were detected. In this paper, we present a detailed investigation into the resistivity behavior of WC under varying humidity conditions. Our innovative approach enabled us to witness a rapid decrease in resistivity under conditions of 85 % RH and 85 °C, from 0.00374 Ω-cm to 0.00177 Ω-cm, followed by a stable linear increase after 0.7 h at a constant rate of 0.000924 Ω-cm/h. Notably, a clear correlation between humidity levels and resistance change rates was found, where higher humidity led to faster resistivity changes. In sharp contrast, a resistivity change rate of less than 5 % under the conditions of water and oxygen independently was observed. The low-temperature oxidation mechanism of WC was described by XRD and XPS spectra. Moreover, the Nernst-Einstein equation and Wagner's model are used to establish the relationship between resistivity and oxidation degree for analyzing and predicting the reaction kinetics and oxidation behavior, indicating that the oxidation degree of WC increased logarithmically with oxidation time.

Cavitation resistance of FeMnCrSi coatings processed by different thermal spray processes

Cavitation-resistant FeMnCrSi coatings were developed in the past years as a cost-effective alternative to Co-containing alloys to increase the lifespan of hydraulic machinery. The effect of different chemical compositions, surface finishing, and post-processing treatments was investigated for various processing techniques, namely: Arc Spraying Process (ASP), High-Velocity Oxy-Fuel (HVOF), High-Velocity Air-Fuel (HVAF), Plasma Transferred Arc (PTA), and Cold Gas Spray (CGS). This works consists of a compilation and review of original and literature results, and discusses the microstructure changes imparted by each type of processing and their impact on the coating properties and cavitation resistance. Low heat input high-velocity processes (HVOF, HVAF, CGS) developed a reduced degree of oxidation and porosity, accounting for a cavitation resistance higher than that of the coatings that ASP processed. In addition, ASP coatings showed reduced cohesive strength, with the oxidized inter-splat interface being a preferential site for crack propagation.

Modifying improved-Hummer’s method to synthesize graphene derivatives from waste asphaltene

A method for synthesizing graphene derivatives from asphaltene is proposed in this work. The method is based on chemical treatment on which the asphaltene molecules are dispersed in liquid intercalating agents to remove the alkyl side chains, functionalize the aromatic core, and expand the inter-layer distance between the aromatic sheets to facilitate their exfoliation. In this intercalation process, the graphitic surface of asphaltene was oxidized to form asphaltene oxide and then graphene derivative. The results designate that the chemical treatment has caused considerable changes in aliphaticity, aromaticity, oxidation level, sulfonation range, and condensation degree. The novelty in the proposed method is envisaged by the fact that it has been tailored to selectively oxidize the asphaltene molecules and maintain its aromatic moiety. The results also confirmed that the conventional graphite oxidation treatments, such as Hummers’ Method and its subsequent improvements, are not suitable because asphaltene is far more susceptible to oxidation than graphite. The method proposed in this study, in comparison with graphite conventional oxidation methods, has less effluents of undesirable chemicals, less time, lower degree of oxidation, less weight losses, and subsequently higher yield.

Effect of plasma-activated water (PAW) soaking on the lipid oxidation of sardine (Sardina pilchardus) fillets

The efficacy of plasma-activated water (PAW) as a chemical-free and environmentally friendly preservative has been documented for a variety of foods, but the onset of lipid oxidation induced by plasma-reactive species has been less extensively studied. In this work, global indices (peroxide value, UV specific absorbance) and direct analytical determinations of volatile and non-volatile oxidation products were performed on sardine lipids extracted from fish fillets immersed in PAW (treatments) and distilled water (controls) for 10–30 min. Evidence of PAW-induced lipid oxidation was provided by higher UV specific absorbances and higher levels of C5-C9 secondary volatile oxidation products in the treated samples. However, the degree of fatty acid oxidation was not sufficient to cause a significant reduction in nutritionally valuable eicosapentaenoic acid and docosahexaenoic acid. Twelve cholesterol oxidation products (COPs) were identified in the sardine lipids, but no significant differences in total COPs content were found between PAW processed and control samples.

Development of controlled-release antioxidant poly (lactic acid) bilayer active film with different distributions of α-tocopherol and its application in corn oil preservation

The antioxidant poly (lactic acid) bilayer active films with a different distribution of α-tocopherol (TOC) in two layers (outer layer/inner layer: 0%/6%, 2%/4%, 3%/3%, 4%/2%, 6%/0%) were developed. The effects of TOC distribution on the structural, physicochemical, mechanical, antioxidant and release properties of the films and their application in corn oil packaging were investigated. The different distributions of TOC showed insignificant effects on the color, transparency, tensile strength and oxygen and water vapor barrier properties of the films, but it affected the release behavior of TOC from the films into 95% ethanol and the oxidation degree of corn oil. The film with higher TOC in outer layer showed a slower release rate. The corn oil packaged by the film containing 4% TOC in outer layer and 2% TOC in inner layer exhibited the best oxidative stability. This concept showed a great potential to develop controlled-release active films for food packaging.