Oxidation Process Research Articles

Improving the in-situ upgrading of extra heavy oil using metal-based oil-soluble catalysts through oxidation process for enhanced oil recovery

AbstractThe demand for fuel from unconventional sources is increasing all over the world, however, there are still special and strict regulations regarding the methods of enhanced oil recovery as well as the content of the oil produced, including the amount of sulfur. In-situ combustion (ISC) is an attractive thermal method to enhance oil recovery and in-situ upgrading process. In this work, copper (II) oleate and copper (II) stearate were used for the oxidation of extra heavy oil with high sulfur content in the ISC process using a self-designed porous medium thermo-effect cell (PMTEC) and visual combustion tube. Using PMTEC the catalytic performances of the synthesized oil-soluble copper (II) oleate and copper (II) stearate and kinetic parameters such as activation energy using Ozawa-Flynn-Wall method were studied. The X-ray diffraction (XRD) and high-resolution field emission scanning electron microscopy were used to examine the characteristics of in-situ synthesized CuO nanoparticles during oxidation. As shown, the presence of oil-soluble copper (II) stearate and copper (II) oleate reduced oil viscosity from 9964 to 8000 and 6090 mPa˙s, respectively. Following ISC process in porous media in the presence of copper (II) oleate, the high sulfur extra heavy oil upgraded, and its sulfur content decreased from 10.33 to 6.79%. Additionally, SARA analysis revealed that asphaltene and resin content decreased in the presence of oil-soluble catalysts. During the oxidation reaction, homogeneous catalyst decomposed into nanoparticles, and heterogeneous catalyst is distributed uniformly in porous media and played an active role in the catalytic process. It should be noticed that, these kind of oil-soluble catalysts can be novel and highly potential candidates for initiation and oxidation of extra heavy oil in order to decrease the viscosity, enhanced oil recovery and production of the upgraded oil. Graphical abstract

Gas–Liquid Microchemical Oxidation for Continuous Synthesis Processes: A Short Review

AbstractGas–liquid oxidation processes, despite their wide application in the chemical industry, still pose considerable safety concerns. Microchemical technology has received high recognition for its intrinsic safety performance and process-intensification capability in hazardous reactions. This Short Review offers a comprehensive summary on how microchemical technology can be employed to achieve gas–liquid oxidation processes for continuous synthesis of chemicals in a safe, efficient, and controlled manner. Herein, we discuss the key aspects of gas–liquid dispersion and hydrodynamics, as well as mass transfer characteristics on microscale, and present representative gas–liquid oxidation cases in microflow reactors. Finally, the current challenges in industrial applications and potential academic research directions are presented.1 Introduction2 Microbubble Generation Technology for Gas–Liquid Oxidation Reactions3 Hydrodynamic and Mass-Transfer Characteristics of Gas–Liquid Oxidation Microreactors4 Gas–Liquid Oxidation Reactions in Microreactors5 Conclusion and Outlook

Approaches for Enhancing Wastewater Treatment of Photocatalytic Fuel Cells: A Review.

Environmental pollution and energy crises have garnered global attention. The substantial discharge of organic waste into water bodies has led to profound environmental contamination. Photocatalytic fuel cells (PFCs) enabling the simultaneous removal of refractory contaminants and recovery of the chemical energy contained in organic pollutants provides a potential strategy to solve environmental issues and the energy crisis. This review will discuss the fundamentals, working principle, and configuration development of PFCs and photocatalytic microbial fuel cells (PMFCs). We particularly focus on the strategies for improving the wastewater treatment performance of PFCs/PMFCs in terms of coupled advanced oxidation processes, the rational design of high-efficiency electrodes, and the strengthening of the mass transfer process. The significant potential of PFCs/PMFCs in various fields is further discussed in detail. This review is intended to provide some guidance for the better implementation and widespread adoption of PFC wastewater treatment technologies.

Bioinspired axial S-coordinated single-atom cobalt catalyst to efficient activate peroxymonosulfate for selective high-valent Co-Oxo species generation

The efficient activation and selective high-valent metal-oxo (HVMO) species generation remain challenging for peroxymonosulfate (PMS)-based advanced oxidation processes (PMS-AOPs) in water purification. The underlying mechanism of the activation pathway is ambiguous, leading to a massive dilemma in the control and regulation of HVMO species generation. Herein, bioinspired by the bio-oxidase structure of cytochrome P450, the axial coordination strategy was adopted to tailor a single-atom cobalt catalyst (CoN4S-CB) with an axial S coordination. CoN4S-CB high-selectively generated high-valent Co-Oxo species (Co(IV)=O) via PMS activation. Co(IV)=O demonstrated an ingenious oxygen atom transfer (OAT) reaction to achieve the efficient degradation of sulfamethoxazole (SMX), and this allowed robust operation in various complex environments. The axial S coordination modulated the 3d orbital electron distribution of the Co atom. Density functional theory (DFT) calculation revealed that the axial S coordination decreased the energy barrier for PMS desorption and lowered the free energy change (ΔG) for Co(IV)=O generation. CoN4S-PMS* had a narrow d-band close to the Fermi level, which enhanced charge transfer to accelerate the cleavage of O-O and O-H bonds in PMS. This work provides a broader perspective on the activator design with natural enzyme structure-like active sites to efficient activate PMS for selective HVMO species generation.

Advanced oxidation processes (AOPs): Navigating from MOS to COS and X-COS systems - Unraveling strategies, tackling challenges, and pioneering advances

This article presents a significant advancement in the field of photocatalysis through the synthesis of a MSO(Metal oxide semiconductor), COS (coupled oxide semiconductor) and X-COS(doped coupled oxide semiconductor) nanocomposite systems with diverse morphologies, including nanoflowers, nanorods, nanosheets, nanotubes and spherical shapes. In this particular study, we propose a hybrid methodology that amalgamates the coupling of CuO and ZnO oxides and the doping of various elements resulting in a comprehensive study of the relationship between morphology and photocatalysis. The degradation efficiency for various pollutants, including Methylene Blue (MB), Methyl Orange (MO), Green Malachite (GM), and Rhodamine B (RhB), was systematically investigated, employing distinct degradation mechanisms. Our study reveals that X-COS materials exhibit superior surface area, heightened porosity, and elevated specific capacitance, higher light absorption while minimizing energy and surface losses (VELF and SELF), accompanied by a well-suited morphology. These distinctive structural features of X-COS contribute to its enhanced photocatalytic efficiency when compared to MOS and COS systems. Our research not only consolidates the fundamental principles governing the photocatalytic properties of materials but also unveils critical strategies for fabricating highly efficient catalysts. In conclusion, this work significantly contributes to the evolving landscape of photocatalysis, offering a nuanced understanding of the synergistic relationship between morphology and catalytic efficiency. The findings not only broaden the scope of fundamental principles but also pave the way for the development of highly effective catalytic materials with diverse morphologies for environmental remediation applications.

Thermodynamic analysis of energy coupling by determination of the Onsager phenomenological coefficients for a 3×3 system of coupled chemical reactions and transport in ATP synthesis and its mechanistic implications

The nonequilibrium coupled processes of oxidation and ATP synthesis in the fundamental process of oxidative phosphorylation (OXPHOS) are of vital importance in biosystems. These coupled chemical reaction and transport bioenergetic processes using the OXPHOS pathway meet >90% of the ATP demand in aerobic systems. On the basis of experimentally determined thermodynamic OXPHOS flux-force relationships and biochemical data for the ternary system of oxidation, ion transport, and ATP synthesis, the Onsager phenomenological coefficients have been computed, including an estimate of error. A new biothermokinetic theory of energy coupling has been formulated and on its basis the thermodynamic parameters, such as the overall degree of coupling, q and the phenomenological stoichiometry, Z of the coupled system have been evaluated. The amount of ATP produced per oxygen consumed, i.e. the actual, operating P/O ratio in the biosystem, the thermodynamic efficiency of the coupled reactions, η, and the Gibbs free energy dissipation, Φ have been calculated and shown to be in agreement with experimental data. At the concentration gradients of ADP and ATP prevailing under state 3 physiological conditions of OXPHOS that yield Vmax rates of ATP synthesis, a maximum in Φ of ∼0.5J(hmgprotein)−1, corresponding to a thermodynamic efficiency of ∼60% for oxidation on succinate, has been obtained. Novel mechanistic insights arising from the above have been discussed. This is the first report of a 3 × 3 system of coupled chemical reactions with transport in a biological context in which the phenomenological coefficients have been evaluated from experimental data.

Optimizing removal of antiretroviral drugs from tertiary wastewater using chlorination and AI-based prediction with response surface methodology

Chemical and pharmaceutical chemicals found in water sources create substantial risks to human health and the environment. The presence of pharmaceutical contaminants in water can cause antibiotic resistance development, toxicity to aquatic organisms, and endocrine disruption. Hence, the elimination of chemicals and other contaminants from wastewater prior to its release is a burgeoning concern in the domains of engineering and science. The use of treatment technologies in wastewater treatment plants can remove pharmaceutical contaminants through the oxidation process. However, many traditional wastewater treatment plants lack the advanced monitoring tools required to detect low concentrations of pharmaceuticals. Without the ability to detect these compounds, it's challenging to treat them effectively. The goal of this study was to use Response Surface Methodology (RSM) and Artificial Neural Networks (ANN) algorithms to model and improve how Nevirapine and Efavirenz break down in different chlorination conditions. The RSM analysis revealed statistically significant models (F-values: Nevirapine, pH-t: 108.15, T-t: 76.55, ICC-t: 110.84), indicating a strong correlation between operational parameters (pH, temperature, and initial chlorine concentration) and degradation behavior. The ANN model accurately predicted the degradation of both Nevirapine and Efavirenz under various chlorination conditions, as confirmed by analyzing actual-predicted graphs, residual plots, and Mean Squared Error (MSE) values. The ANN model using ICC-t achieved the highest MOD value of 31.31 % for Nevirapine. The ANN model based on ICC-t yielded a maximum MOD value of 16.06 % for Efavirenz. These findings provide valuable insights into optimizing chlorination processes for better removal of these pharmaceutical contaminants from water.

Enhanced detection of lysergic acid diethylamide using Ehrlich reagent and screen-printed electrodes: A hybrid method for application in forensic analysis

In forensic investigations, the presumptive identification of illicit substances, such as Lysergic Acid Diethylamide (LSD), is crucial. While the Ehrlich's colorimetric reagent (EHR) is commonly employed for LSD detection, producing a characteristic colour change, its lack of selectivity often leads to false-positive or misinterpreted results. Addressing this, we propose a novel method combining electrochemical detection with EHR, enhancing selectivity for LSD’s preliminary identification in forensic samples. This method utilizes a screen-printed carbon electrode (carbon-SPE) in a pH 12 phosphate buffer. We observed two irreversible oxidation processes for LSD at Epa= +0.35 V (Ox1) and + 0.65 V (Ox2), and for EHR at + 0.62 V and + 0.83 V (vs Ag/AgCl). The LSD + EHR combination displayed three distinct irreversible oxidation processes at + 0.35 V, +0.66 V, and + 0.86 V. This approach provides three analytical responses for LSD identification: (1) colour change post-EHR test; (2) voltammetric detection of LSD’s two oxidation processes on carbon-SPE; (3) decreased peak current of LSD at Ox1 post-reaction after EHR. Additionally, our method facilitates LSD quantification, exhibiting a low limit of detection (LOD) of 0.69 μmol/L, and consistent electrochemical responses (RSD < 3.0 %) using the same or different carbon-SPEs. Interference studies with other illicit drugs underscored the method’s reliability and selectivity in LSD detection. Moreover, addition-recovery studies on real seized samples approached 100 %, and LSD identification was corroborated by QTOF-LC/MS analyses. Therefore, combining voltammetry with carbon-SPE and EHR offers significant potential for a rapid, simple, and selective LSD screening test in forensic analysis.

Study on the evolutionary mechanism of the cavity inside aluminum nanoparticles while reacting with oxygen

Aluminum nanoparticles are often considered attractive choices for fuels in energetic materials. In this study, molecular dynamics simulation with the reactive force field (ReaxFF) was used to study the oxidation process of three different particle sizes (4 nm, 5 nm, 6 nm) of ANPs (aluminum nano-particles). The cavity formation mechanism was obtained during the ANPs oxidation process. The cavity size, the oxide layer thickness, and the active aluminum content of ANPs with time were obtained. The results indicated that the formation of cavities is highly dependent on particle size. Large particle size prevents the formation of cavities. In 0–100 ps, the average growth rate of the oxide layer is 0.33, 0.25, and 0.20 nm/ps, respectively. Within 100–250 ps, the average growth rate of the oxide layer is −0.017, 0.038, and 0.117 nm/ps, respectively. Our results emphasize the effect of particle size on cavity formation, which provides insights into the atomic-scale oxidation mechanism of metal nanoparticles.

Bi-ZFO/BMO-Vo Z-scheme heterojunction photocatalysis-PMS bidirectionally enhanced coupling system for environmental remediation

Given the urgency of organic pollutant removal and the low efficiency of advanced oxidation processes (AOPs), a novel Bi-ZFO/BMO-Vo photocatalyst was fabricated via the solvothermal method. A coupling system was constructed to combine photocatalysis with peroxymonosulfate (PMS) oxidation processes, which synergistically degrade organic pollutants. Bi-ZFO/BMO-Vo exhibited excellent photocatalytic performance, which could remove 100% RhB in 110 min and degrade 100% MG in 70 min, and 88% H-TC in 50 min. The excellent catalytic performance of Bi-ZFO/BMO-Vo was not only attributed to the synergistic effect of PMS activation and photocatalysis, but also attributed to the SPR effect of Bi nanoparticles, electron capture of oxygen vacancies, and intense contact of Bi-ZFO/BMO-Vo heterojunctions. The active species capture experiments and EPR tests indicated that 1O2, SO4–·, ·OH, and O2–· worked together for the RhB removal. The degradation intermediates of RhB were identified by LC-MS. Based on the experimental results, the band structure and Z-scheme charge transfer mechanism were proposed. Toxicity evaluation indicated that Bi-ZFO/BMO-Vo-Vis/PMS could significantly reduce RhB toxicity. This efficient and stable catalyst is expected to be used in organic wastewater degradation and practical applications.

Overcoming poisoning issues in hydrogen fuel cells with face-centered tetragonal FePt bimetallic catalysts

Hydrogen fuel cells are expected to play a central role in the next-generation energy paradigm. However, owing to practical limitations, hydrogen is supplied in the form of refined hydrocarbons or alcohols in industrial applications. Among them, methanol is widely used as a hydrogen source, and CO is inevitably generated during its oxidation process. Even a small amount of CO (∼20 ppm) strongly binds to Pt used as a catalyst, and deactivates it. In addition to CO, surface adsorption of organic cations by binder or ionomer use in alkaline fuel cells is also one of the poisoning issues to be overcome. Herein, we propose FePt bimetallic catalysts that can resist unavoidable CO and organic cation poisoning. Our synthetic strategy, including annealing and acid treatment, allows the catalysts to possess different alloying degrees and surface structures, which in turn induce different levels of resistance to CO and organic-cation poisonings. The correlation between the surface and bulk structures of the catalysts and poisoning resistance was elucidated through X-ray photoemission spectroscopy and electrochemical analysis. The results revealed that an FePt catalyst having an ordered atomic arrangement displayed a better poisoning resistance than that having a disordered arrangement.

Study of high-entropy oxide diffusion barrier and diffusion resistance mechanism in high-temperature protective coatings

In order to obtain high temperature protective coatings with low diffusivity, high entropy (HEA) as well as high entropy oxide (HEO) diffusion barriers were deposited between the NiCrAlY coating and the substrate by magnetron sputtering. These two coatings were subjected to constant temperature oxidation tests at 1050 °C. These results show that the two coatings containing diffusion barriers have better high-temperature oxidation properties compared to the NiCrAlY coating. Both HEA and HEO diffusion barriers have the desired performance in hindering the diffusion of elements between the coating and the substrate. The evolution of these two diffusion barriers and the mechanism of diffusion resistance during the oxidation process have been investigated.

Preparation and characterization on the eco-friendly corn starch based adhesive of with salient water resistance, mildew resistance

Starch adhesive is a commonly used bonding glue that is sustainable, formaldehyde-free and biodegradable. However, there are obviously some problems related to its high viscosity, poor water and mildew resistance. Hence, exploring a starch-based adhesive with good properties that satisfies the requirements of wood processing presents the context of the current research. Thus, corn starch was used as raw material to form oxidized starch (OCS) via oxidation using sodium periodate, it was reacted with a synthesis polyurea compound that prepared from hexanediamine-urea (HU) obtained by deamination to yield a oxidized starch-hexanediamine-urea adhesive (denoted hereafter as OCSHU). The oxidation process was optimized in terms of oxidant concentration, reaction time and temperature. Furthermore, the impact of HU addition on the mechanical properties of the adhesive was explored. Results indicate adhesive exhibited outstanding shear strength, when 13 % of NaIO4 was used as an oxidant to treat starch at 55 °C for 24 h, and involved in a subsequent reaction with 40 % of HU. The dry shear strength, 24 h cold water strength, 3 h hot water strength and 3 h boiling water strength are 1.84, 1.50, 1.32, and 1.31 MPa. Meantime, OCSHU adhesive solution revealed good storage stability whereas cured resin exhibited mildew resistance. The developed adhesive is a simple and green biomass wood adhesive.

Cu-optimized long-range interaction between Co nanoparticles and Co single atoms: Improved Fenton-like reaction activity

The interplay between multi-atom assembly configurations and single atoms (SAs) has been gaining attention in research. However, the effect of long-term range interactions between SAs and multi-atom assemblies on the orbital filling characteristics has yet to be investigated. In this context, we introduced copper (Cu) doping to strengthen the interaction between cobalt (Co) nanoparticles (NPs) and Co SAs by promoting the spontaneous formation of Co–Cu alloy NPs that tends toward aggregation owing to its negative cohesive energy (−0.06454), instead of forming Cu SAs. The incorporation of Cu within the Co–Cu alloy NPs, compared to the pure Co NPs, significantly expedites the kinetics of peroxymonosulfate (PMS) oxidation processes on Co SAs. Unlike Co NPs, Co–Cu NPs facilitate electron rearrangement in the d orbitals (especially dz2 and dxz) near the Fermi level in Co SAs, thereby optimizing the dz2–O (PMS) and dxz–O (SO5−) orbital interaction. Eventually, the Co–Cu alloy NPs embedded in nitrogen-doped carbon (CC@CNC) catalysts rapidly eliminated 80.67% of 20mg/L carbamazepine (CBZ) within 5min. This performance significantly surpasses that of catalysts consisting solely of Co NPs in a similar matrix (C@CNC), which achieved a 58.99% reduction in 5min. The quasi in situ characterization suggested that PMS acts as an electron donor and will transfer electrons to Co SAs, generating 1O2 for contaminant abatement. This study offers valuable insights into the mechanisms by which composite active sites formed through multi-atom assembly interact at the atomic orbital level to achieve high-efficiency PMS-based advanced oxidation processes at the atomic orbital level.

Post-macrocyclization strategy to octaphenoxy-substituted zinc pyrazinoporphyrazine, its photochemical and electrochemical properties

An efficient post-macrocyclization strategy to new octaphenoxy-substituted zinc pyrazinoporphyrazine has been developed. This approach allows avoiding the template synthesis of the target compound from the phenoxy-substituted dinitrile, during which oligomerization and phenol release occur. The possibility of obtaining the initial octachloropyrazinoporphyrazine using template synthesis activated thermally and using microwave irradiation has been shown. Octaphenoxy-substituted zinc pyrazinoporphyrazine demonstrates short but intense triplet signals in triplet absorption spectrum and substantial singlet oxygen quantum yield (ΦΔ = 0.34). The fluorescent properties and fluorescence decay kinetics of target porphyrazines were studied. In contrast to the initial poorly soluble chlorinated complex, cyclic voltammetric measurements show both reduction and oxidation processes. Two waves of reduction and one wave of oxidation were observed. The electron-donating nature of phenoxy groups compared to chlorine groups is shown.

Nano-roughness effect on the interfacial thermal oxidation and surface catalytical recombination characteristics for silicon carbide based materials under non-equilibrium flow

With the rapid development of high-speed aircraft, the demanding for light, strong, reliable and high temperature resistive thermal protection material (TPM) is becoming urgent. High temperature material interface, such as silicon carbide (SiC) ceramic matrix composite, has received strong interest recently due to its high mechanical and thermochemical stability. For reactive interface development with nano-roughness under extremely hyperthermal non-equilibrium flow conditions for TPM applications, however, has not been reported yet. This work performs a systematic reactive molecular dynamics (RMD) study of the SiC surface morphology effect withstanding hyperthermal atomic oxygen (AO) impact via a gas–solid interface reaction model. The results show that a self-healing trend of the defect-rich silicon carbide surface with original nano-roughness is revealed towards a flatter interface accompanying with the oxidation process. The surface catalytic recombination coefficient is more sensitivity to the surface defects when wall temperature Tw > 500 K. Nano-roughness structure can also vary the main thermochemical reaction path at the thermochemical reactive interface: For the nano-groove surface model, the thermal oxidation reaction becomes dominant, while more pronounced surface catalytic recombination characteristics are revealed for the flat surface model. The mechanisms of roughness effect, surface temperature and gas impacting angle on the surface catalytic recombination, surface oxidation, and interface evolution are revealed, which advance our microscopic understanding of SiC interfacial performance with nano-roughness under non-equilibrium flow conditions.

Fluorescence visualization of CO2-responsive phase transfer materials targeting at the heterogeneous interfacial reactions in advanced oxidation of naphthenic acid in wastewater

Treatment of naphthenic acids (NAs) in wastewater is necessary due to its high toxicity and difficult degradation. In the heterogeneous Fenton-like advanced oxidation of organic pollutant system, the insufficient accessibility of oxidizing agent and NAs greatly hamper the reaction efficiency. CO2-responsive phase transfer materials derived from polyethylene glycol (PEG)-based deep eutectic solvents were specific targeted at the immiscible-binary phase system. The NAs oxidative degradation process was optimized including the kinds of catalyst (Molecular weight of PEG, constitute of DESs, and dosage.), temperature, flow rate of CO2, et al. With the help of fluorescence properties of catalyst, the hydrophilic-hydrophobic interaction was visual-monitored and further studied. The amphipathic property of PEG-200/Sodium persulfate/Polyether amine 230 (PEA230) greatly reduced the aqueous/organic phase transfer barrier between sodium persulfate and NAs (up to 84 %), thus accreting oxidation rate. The surface tension decreased from 35.364 mN/m to 28.595 mN/m. To control the reaction rate, the CO2 respond structure of amido played an important role. In addition, the interfacial transfer intermediates and oxidation pathways were also explored by nuclear magnetic resonance, flourier transform infrared spectroscopy, surface tension, and radical inhibition experiments. The mechanism of advanced oxidation of NAs catalyzed by CO2-responsive phase transfer catalyst was proposed, which would made up for the deficiency of the system theory of heterogeneous chemical oxidation of organic pollutants.

The advances in the recovery process for precious metals from nickel slag, a review

The creation of nickel-smelting products including important metals like nickel, cobalt, and copper is a persistent issue in the nickel mining business. Another secondary source of precious metals is nickel slag. In addition, the massive amounts of nickel slag generated by the nickel smelter sector will pollute the environment, particularly the soil, since the smelting slag contains hazardous materials. This study examines techniques for recovering precious metals from nickel slag by reviewing publications from Springer Link, Google Scholar, MDPI, ScienceDirect, Membrane Journal, and other authors. The two types of metal recovery techniques from nickel slag that were examined were hydrometallurgical and pyrometallurgical techniques. This review article describes a pyrometallurgical method that involves roasting and selective reduction. In the meantime, the hydrometallurgical techniques were examined in the high-pressure oxidative acid leaching process, the atmospheric acid leaching method, and the bioleaching process. A roadmap for research designs that can be used to recover valuable metals from nickel slag sustainably has been created due to the completed literature evaluation.

Gelsenicine disrupted the intestinal barrier of Caenorhabditis elegans

Gelsemium elegans Benth. (G. elegans) is a traditional medicinal herb that has anti-inflammatory, analgesic, sedative, and detumescence effects. However, it can also cause intestinal side effects such as abdominal pain and diarrhea. The toxicological mechanisms of gelsenicine are still unclear. The objective of this study was to assess enterotoxicity induced by gelsenicine in the nematodes Caenorhabditis elegans (C. elegans). The nematodes were treated with gelsenicine, and subsequently their growth, development, and locomotion behavior were evaluated. The targets of gelsenicine were predicted using PharmMapper. mRNA-seq was performed to verify the predicted targets. Intestinal permeability, ROS generation, and lipofuscin accumulation were measured. Additionally, the fluorescence intensities of GFP-labeled proteins involved in oxidative stress and unfolded protein response in endoplasmic reticulum (UPRER) were quantified. As a result, the treatment of gelsenicine resulted in the inhibition of nematode lifespan, as well as reductions in body length, width, and locomotion behavior. A total of 221 targets were predicted by PharmMapper, and 731 differentially expressed genes were screened out by mRNA-seq. GO and KEGG enrichment analysis revealed involvement in redox process and transmembrane transport. The permeability assay showed leakage of blue dye from the intestinal lumen into the body cavity. Abnormal mRNAs expression of gem-4, hmp-1, fil-2, and pho-1, which regulated intestinal development, absorption and catabolism, transmembrane transport, and apical junctions, was observed. Intestinal lipofuscin and ROS were increased, while sod-2 and isp-1 expressions were decreased. Multiple proteins in SKN-1/DAF-16 pathway were found to bind stably with gelsenicine in a predictive model. There was an up-regulation in the expression of SKN-1:GFP, while the nuclear translocation of DAF-16:GFP exhibited abnormality. The UPRER biomarker HSP-4:GFP was down-regulated. In conclusion, the treatment of gelsenicine resulted in the increase of nematode intestinal permeability. The toxicological mechanisms underlying this effect involved the disruption of intestinal barrier integrity, an imbalance between oxidative and antioxidant processes mediated by the SKN-1/DAF-16 pathway, and abnormal unfolded protein reaction.

Plasma catalysis. A study of the influence of Oxysulfur, SOx• species through the degradation of sulfonated dyes by non-thermal plasma.

This work studied the degradation reaction of sulfonated dyes, indigo carmine, phenol red, and their mixtures by non-thermal plasma (NTP). Interestingly, the degradation rate constant showed a faster process and lower activation energy (Ea) for the dye mixtures than for the degradation reaction of the individual dyes. This unexpected result opened up new opportunities for understanding plasma chemistry and the interaction between reactive species formed by the plasma and the target molecule. As no catalyst or chemical additive was added to the reactor, the decrease in Ea came from a self-synergistic effect (SSE), through the dye molecules fragmentation, which resulted in plasma catalysis. The hypothesis proposed in this work is that oxysulfur (SOx) species are formed by the desulfonation reaction of dyes. The sulfonic groups (SO3) present in the chemical structures of dyes can function as precursors for forming several SOx•– species. Studies based on oxygenated sulfonated species such as SO3•–, SO4•– and SO5•– have been widely applied in advanced oxidative and reductive processes due to their satisfactory efficiency and low cost. Among them, SO4•– is the key reactive species with the best performance in the degradation of pollutants due to its high oxidation potential (E° = 2.60 V). In addition, it is an alternative source of HO• in aqueous media, improving the oxidation reaction. In order to elucidate the SSE, the kinetic process was followed by UV-Vis analysis, and the reactive species, such as alkyl, hydroxyl, and oxy-sulfur radicals were identified by Electron Paramagnetic Resonance. The by-products of the NTP degradation reaction were analyzed by ultrafast liquid chromatography coupled with a mass spectrometer, and a fragmentation route was proposed.