Formation Of Reactive Species Research Articles

Selective catalytic reduction of NOx with ethanol and other C1–4 oxygenates over Ag/Al2O3 catalysts: A review

Research results regarding selective catalytic reduction (SCR) of NOx with ethanol and other C1-4 oxygenates as reductants over silver-alumina catalysts are summarized. The aspects of the process mechanism, nature of active sites, role of alumina and silver (especially in the formation of bifunctional active sites), effects of reductants and reaction conditions are discussed. It has been determined that key stages of the process include formation of reactive enolic species, their interaction with NOx and formation of nitroorganic compounds which transform to NCOads species and further to N2. The results obtained over various silver-alumina catalysts demonstrate the perspectives of their application for reducing the level of nitrogen oxides in engine emissions, including in the presence of water vapor and sulfur oxides. Ways to improve the catalysts for the SCR of NOx with C1-4 oxygenates are outlined.

Aromatization of Ethylene – Main Intermediate for MDA?

AbstractMethane dehydroaromatization (MDA) over Mo/HZSM‐5 has been hypothesized in literature to proceed via a two‐step mechanism: methane is first converted to ethylene on the molybdenum (Mo) functionality and then ethylene is oligomerized, cyclized and dehydrogenated on the Brønsted acid sites (BAS) of the HZSM‐5 support. This hypothesis is tested by studying the conversion of ethylene at the same conditions as used for MDA, namely 700 °C, atmospheric pressure, and by co‐feeding experiments with H2 and CH4. Our results suggest that ethylene is not the main intermediate for MDA, because the aromatic selectivities obtained from methane conversion are higher than selectivities measured during ethylene conversion. Furthermore, carbonaceous deposits formed during MDA have a lower density, are more hydrogenated and more active than the ones formed during ethylene aromatization (EDA). Similarly as for MDA, an activation period in which Mo carburizes to its active phase and an induction period, in which aromatics formation rates increase to their maximum are observed for ethylene conversion. The induction period, which was explained by the buildup of a hydrocarbon pool (HCP) is much faster with methane than with ethylene. This period, is attributed to a slow buildup of hydrocarbons, strongly adsorbed on Mo sites, because it is only observed with catalysts containing Mo. Hydrogen co‐feeding with ethylene leads to the formation of more reactive coke species and a significantly prolonged lifetime of the catalyst, but not to a faster buildup of the HCP.

Formation and removal of disinfection by-products in a full scale drinking water treatment plant

In this case study, high sensitivity simple methods for the analysis of trihalomethanes (THM4), iodinated-trihalomethanes (I-THMs), haloacetic acids (HAAs), bromide, iodide and iodate have been developed. A one-step procedure for the analysis of haloacetic acids by head-space GC–MS provides good reproducibility and low limits of quantification (≤50 ng L−1). These methods were applied to characterize the formation of disinfection by-products (DBPs) in a full scale drinking water treatment plant. In this treatment plant, the incorporation of bromine into THMs increases throughout the water treatment line, due to the formation of bromine reactive species favored by the decrease of competition between dissolved organic carbon (DOC) and bromide towards chlorine. A linear correlation has been observed between the bromine incorporation factor and the Br-/DOC mass ratio. The conversion of iodine to iodate by chlorination occurs in this water due to the relatively high bromide concentration. Moreover, a higher formation of iodate compared to iodide levels in the raw water is observed indicating a degradation of organic iodinated compounds. The formation of I-THMs was constant in terms of quantity and speciation between campaigns despite fluctuating concentrations of DOC and total iodine in the raw water. A preferential removal of DBPs formed by the intermediate chlorination in the order I-DBPs > Br-DBPs > Cl-DBPs occurs during the subsequent activated carbon filtration. The removal rates range from 25 to 36% for the regulated THM4, from 82 to 93% for the ∑I-THMs and 95% for haloacetic acids. The assessment of the relative toxicity shows that despite a much lower concentration of HAAs (<10% of the total mass of measured DBPs) compared to THMs, these compounds are responsible for 75% of the relative cytotoxicity of the treated water. Bromoacetic acid on its own accounts for more than 60% of the overall toxicity of the 17 compounds included in this study.

Use of Nitrogen-Doped Carbon Nanodots for the Photocatalytic Fluoroalkylation of Organic Compounds.

The use of amine-rich N-doped carbon nanodots (NCNDs) for the photochemical radical perfluoroalkylation of organic compounds is reported. This operationally simple approach occurs under mild conditions producing valuable new C-C bonds. The chemistry is driven by the ability of NCNDs to directly reach an electronically excited state upon light absorption, thereby successively triggering the formation of reactive radical species from simple perfluoroalkyl iodides. Preliminary mechanistic studies are also reported.

The anticoagulant effect of Apis mellifera phospholipase A2 is inhibited by CORM-2 via a carbon monoxide-independent mechanism.

Bee venom phospholipase A2 (PLA2) has potential for significant morbidity. Ruthenium (Ru)-based carbon monoxide releasing molecules (CORM) inhibit snake venoms that are anticoagulant and contain PLA2. In addition to modulating heme-bearing proteins with carbon monoxide, these CORM generate reactive Ru species that form adducts with histamine residues resulting in changes in protein function. This study sought to identify anticoagulant properties of bee venom PLA2 via catalysis of plasma phospholipids required for thrombin generation. Another goal was to determine if Ru-based CORM inhibit bee venom PLA2 via carbon monoxide release or via potential binding of reactive Ru species to a key histidine residue in the catalytic site of the enzyme. Anticoagulant activity of bee venom PLA2 was assessed via thrombelastography with normal plasma. Bee venom PLA2 was then exposed to different CORM and a metheme forming agent and anticoagulant activity was reassessed. Using Ru, boron and manganese-based CORM and a metheme forming agent, it was demonstrated that it was unlikely that carbon monoxide interaction with a heme group attached to PLA2 was responsible for inhibition of anticoagulant activity by Ru-based CORM. Exposure of PLA2 to a Ru-based CORM in the presence of histidine-rich human albumin resulted in loss of inhibition of PLA2. Ru-based CORM likely inhibit bee venom PLA2 anticoagulant activity via formation of reactive Ru species that bind to histidine residues of the enzyme.

Generation of hydrogen peroxide in protein solutions under the influence of thermal and optical electromagnetic radiation

Using the method of induced chemiluminescence in solutions of bovine serum albumin (BSA) and bovine gamma globulin (BGG) under the influence of thermal and optical electromagnetic radiation, the formation of long-lived reactive protein species (LRPS) with a half-life of about 4-5 hours was registered. The oxygen effect was established, namely, the dependence of the chemiluminescence intensity of protein solutions on the concentration of dissolved oxygen. Using the enhanced chemiluminescence method in the luminol-p-iodophenol-peroxidase system, the ability of LRPS, induced by heat and laser radiation, to generate hydrogen peroxide in solution was studied. The dependence of the formation of H2O2 under the influence of LRPS at different times after exposure was established. Using the fluorescent probe coumarin-3-carboxylic acid, the formation of hydroxyl radicals in protein solutions after exposure to laser radiation and heat was detected. The obtained experimental data suggest that the generation of hydrogen peroxide by LRPS after exposure to thermal and optical electromagnetic radiation may be one of the mechanisms for activating protective cellular mechanisms that help overcome diseases, including those associated with oxidative stress.

Hyperoxia and oxidative stress in anesthesia and critical care medicine.

Oxygen administration is particularly relevant in patients undergoing surgery under general anesthesia and in those who suffer from acute or critical illness. Nevertheless, excess O2, or hyperoxia, is also known to be harmful. Toxicity arises from the enhanced formation of reactive oxygen species (ROS) that, exceeding the antioxidant defense, may generate oxidative stress. Oxidative stress markers are used to quantify ROS toxicity in clinical and non-clinical settings and represent a promising tool to assess the optimal FiO2 in anesthesia and critical care setting. Despite controversial, the guidelines for the regulation of FiO2 in such settings suggest the adoption of high perioperative oxygen levels. However, hyperoxia has also been shown to be an independent mortality risk factor in critically ill patients. In this literature review, we discuss the biochemical mechanisms behind oxidative stress and the available biomarkers for assessing the pro-oxidant vs antioxidant status. Then, we summarize recent knowledge on the hyperoxia-related consequences in the most common anesthesia and critical care settings, such as traumatic brain injury or cardiac arrest. To this purpose, we searched the PubMed database according to the following combination of key words: ("hyperoxia" OR "FiO2" OR "oxygen therapy") AND ("oxidative stress" OR "ROS" OR "RNS" OR "lipid peroxidation") AND ("anesthesia" OR "surgery" OR "intensive care"). We focused in the results from the past 20 years. Available evidence points toward a conservative monitoring and use of oxygen, unless there is solid proof of its efficacy.

Commentary: Ultraviolet radiation triggers “preparation for oxidative stress” antioxidant response in animals: Similarities and interplay with other stressors

Preparation for oxidative stress (POS), i.e., the upregulation of endogenous antioxidants, is a widespread response of animals exposed to extreme conditions. This response has been described for more than 80 animal species belonging to eight phyla during hypometabolism or situations that limit oxygen availability. The pattern of the typical POS-response, in which a mild redox imbalance triggers antioxidant adjustments that results in increased tolerance to subsequent oxidative insults, roughly follows the curve of hormetic phenomena. A similar pattern has been reported for various animal species exposed to ultraviolet radiation (UVR) – these studies, on animals from six phyla, are discussed herein. In the light of the similarities in the redox-response of animals exposed to either oxygen restriction or UVR, we argue in this essay that UVR elicits a type of response that fits the POS theory. Exposure to UVR induces both reactive species formation and antioxidant adaptation, which is the essence of typical POS-responses. Thus, antioxidant response to UVR in animals can be categorized as a POS-type mechanism. Moreover, considering that animals are exposed to multiple stressors simultaneously in nature, this would represent an ecologically relevant process, by which one stressor (e.g., UV or ionizing radiation) may enhance the tolerance to other. We also discuss a possible role of low doses of ionizing radiation as inductor of POS-like responses in animals.

Enhanced photocatalytic degradation of levofloxacin by Fe-doped BiOCl nanosheets under LED light irradiation

In this research, Fe-doped BiOCl nanosheets were successfully synthesized through controlled hydrothermal method and applied in the degradation of levofloxacin (LVX) by sulfate radical-based photo-Fenton process. The conduction band of Fe-doped BiOCl was calculated as 2.77 eV compared to BiOCl (3.24 eV), and showed remarkable visible-LED-light driven photocatalytic activity with the expanded visible light absorption. Certain parameters were studied, with the addition persulfate (1 mM) and catalyst dosage (0.5 g L−1) at natural pH, the LVX reached over 95% degradation efficiency in 60 min during at least five successive experiments which displayed excellent catalytic activity and stability. LVX degradation was confirmed to depend on the formation of free reactive oxidant species through radical scavenger reagents and EPR analysis. On the basis of the experimental results and density functional theory calculations, the role of photocatalytic degradation mechanism of LVX degradation by the Fe-BiOCl sample was investigated. Moreover, the LVX degradation pathway was induced according to the intermediates detected by LC-MS. The results of this research demonstrated the good feasibility of Fe-doped BiOCl nanosheets which would enhance the utilization of photocatalysts under visible light irradiation.

Evidence of oxygen defects mediated enhanced photocatalytic and antibacterial performance of ZnO nanorods

Defect engineered one-dimensional (1D) ZnO nanostructures have found great interest in diverse fields, including water detoxification and environmental remediation. In this article, we report a facile, low-temperature hydrothermal synthesis of defect enriched ZnO nanorods at different pH conditions. The dimension of all the synthesized ZnO nanostructures was restricted to 1D with changes only in their aspect ratios, unlike previous reports where change in morphology accompanies the effect of pH. With an increment in the pH value of the reaction mixture, oxygen defect concentration was controlled and confirmed using XPS and Raman spectroscopy. Considerable increase in optical light absorption and reduction in the bandgap, as inferred from the UV–vis study, corroborating the pH-dependent enrichment of defect states in 1D ZnO. Superior photosensitivity of oxygen defect rich ZnO nanorods was utilized to study their sunlight-induced photocatalytic and bactericidal activity towards its application in wastewater treatment. Within 4 h and 30 min of sunlight exposure (900 W/cm2), a 100% bacterial population (S.aureus, 106 cells/m) killing and complete degradation of methylene blue dye (10μM) were achieved. Enhanced reactive oxidative species (ROS) formation due to the presence of additional oxygen defect states is ascribed to be the prime factor facilitating improved degradation efficiency. Additionally, during the optimization study, ZnO nanorods were found to be active against bacterial cells even in the absence of light opening avenues in antimicrobial food packaging and protective surface coatings.

Photoelectrocatalytic degradation of organics and formation of disinfection byproducts in reverse osmosis concentrate

The high content of organics in municipal reverse osmosis concentrate (ROC) requires proper treatment. Here, this study applied the photoelectrocatalysis (PEC) to reduce the concentration of organics in ROC. Meanwhile, the formation of disinfection byproducts (DBPs) was investigated. Participation of primary oxidants in organics removal and DBPs formation was revealed at different anodic potentials and pHs. The results showed that PEC process effectively oxidized the organics in ROC, achieving the highest mineralization rate of 63%. Increasing anodic potential from 0 to 1.0 V enhanced the oxidations of bulk organics (i.e., dissolved organic carbons (DOC), UV254, fluorescence, large molecular weight compounds) and trace-level pharmaceuticals. Raising anodic potential to higher than 1.0 V slightly benefited the oxidations of bulk organics, owing to the relatively stable formation of hydroxyl radicals (OH•) and radical reactive chlorine species (r-RCS). The continuously rising concentration of free chlorine (FC) accelerated the decompositions of pharmaceuticals at ≥ 1.0 V. However, the generated FC raised the concentration of DBPs up to 10.36 μmol/L at 3.0 V. Lowering initial pH from 7-9 to 4-6 improved the mineralization rates by around 20% due to the higher formation of OH• at pH 4-6. Further decreasing initial pH from 6 to 4 enhanced the breakdown of large molecular weight compounds as well as the decomposition of pharmaceuticals. This came from the strengthened formation of FC and r-RCS at lower pHs. The intense participation of FC and r-RCS resulted in a higher total DBP concentration at pH 4-6 than that at pH 7-9. However, the individual species of DBPs changed differently toward the pH shift. The results of this study show that PEC could be an alternative for organics oxidation in ROC with proper control of DBPs formation.

Fast reaction of carbon free radicals with flavonoids and other aromatic compounds

Many theoretical and experimental studies have shown that the principal initial biological targets of free radicals are nucleic acids, lipids and proteins. The reaction normally generates carbon-centered radicals which can propagate molecular damage either directly or after formation of new reactive species following reaction with oxygen. Overall damage prevention is therefore best achieved by repair of the carbon radicals before they initiate further reactions. Recent studies have shown that the repair cannot be achieved by normal levels of the endogenous antioxidants glutathione, ascorbate or urate. Since their concentrations are well regulated and cannot be enhanced by oral intake, we have investigated the effectiveness of flavonoids and other polyphenols as potential carbon radical repair agents, because their levels in vivo can be significantly enhanced by diet. Pulse radiolysis measurements of the rate constants of repair of amino acid radicals by several polyphenols showed reversible formation of radical-polyphenol adducts 100–1000 times faster than previously reported for the bimolecular stoichiometric reactions of flavonoids i.e. with rate constants in the order of 1010 M−1s−1. Adduct formation depended only on the presence of a carbon-centered radical and an aromatic moiety in the reactants, without the involvement of redox reactions at the phenolic groups. Formation of adducts lowered the reactivity of the radicals. Our results suggest that flavonoids, polyphenols and many of their metabolites can effectively reduce the damaging potential of carbon radicals at concentrations achievable in vivo by diets rich in fruits and vegetables.

The effect of gas additives on reactive species and bacterial inactivation by a helium plasma jet

In this paper, the influences of gas doping (O2, N2, Air) on the concentrations of reactive species and bactericidal effects induced by a He plasma jet are studied. Firstly, results show that gas doping causes an increase in voltage and a decrease in current compared with the pure He discharge under the same discharge power, which might be attributed to the different chemical characteristics of O2 and N2 and verified by the changes in the gaseous reactive species shown in the optical emission spectroscopy (OES) and Fourier transform infrared (FTIR) spectroscopy. Secondly, the concentrations of aqueous reactive oxygen species (ROS) and reactive nitrogen species (RNS) are tightly related to the addition of O2 and N2 into the working gas. The concentrations of aqueous and significantly increase while the concentrations of aqueous ROS decrease with the admixture of N2. The addition of O2 has little effect on the concentrations of and and pH values; however, the addition of O2 increases the concentration of and deceases the concentrations of H2O2 and OH. Finally, the results of bactericidal experiments demonstrate that the inactivation efficiency of the four types of plasma jets is He + O2 > He + Air > He > He + N2, which is in accordance with the changing trend of the concentration of aqueous Simultaneously to the better understanding of the formation and removal mechanisms of reactive species in the plasma–liquid interaction, these results also prove the effectiveness of regulating the concentrations of aqueous reactive species and the bacteria inactivation effects by gas doping.

Sulfur- and chlorine-co-doped g-C3N4 nanosheets with enhanced active species generation for boosting visible-light photodegradation activity

Elemental doping is an important strategy for modifying the electronic properties of graphitic carbon nitride and tuning its visible-light photocatalytic activity. In this study, sulfur- and chlorine-co-doped g-C3N4 (S/Cl-CN) have been synthesized by a thermal condensation method. Among a series of samples, S/Cl-CN exhibited the best photocatalytic activities for the degradation of rhodamine B (RhB) and 4-nitrophenol (4-NP). The as-synthesized S/Cl-CN possessed a modified electronic structure and large specific surface area as well as more active sites. According to diffuse-reflectance spectroscopy (DRS), UPS (ultraviolet photoelectron spectrometer), and valence band (VB)-XPS investigations, S/Cl-CN displayed a narrowed band gap and positively shifted VB edge potential with enhanced oxidation ability. First-principles calculations implied that the narrower band gap and better charge-separation ability may be attributed to the Cl 3p orbital as the doping level. Moreover, the S/Cl-CN with narrowed band-gap and positively shifted VB potential could possess double channels to form OH by direct oxidation of h+ at VB and reduction of O2 at CB. Based on the strong oxidizing ability of the S/Cl-CN, the possible formation of reactive chlorine-based species in the photocatalysis process is proposed. This work provides a new perspective for tuning the band structure of a photocatalyst through a doping strategy and greater insight into the generation paths of active species involved in the photocatalytic process.

Evaluation and optimization of the process parameters for the photo-electrochemical treatment of urea using mixed metal oxide anodes

The present study investigates the electro-oxidation (EO) treatment of urea containing wastewater using mixed metal oxide (MMO) anodes. Box-Behnken design (BBD) was employed to analyze the effects of various operational process parameters like current density (j), NaCl dose (n), treatment time (t) and pH in an EO reactor in batch mode. The performance of the treatment process was evaluated in terms of % degradation and energy consumption. Under optimum conditions, the experimental results showed that more than 94.78% of degradation of urea was achieved. Electro-oxidation has effectively reduced the TOC (90%) under optimum conditions. Attempts were made to integrate the two process electro-oxidation and photocatalysis i.e. Photoelectrocatalysis within the same treatment unit for the enhanced degradation of target pollutant. The electro-oxidation process with mixed metal oxide anode has also attained a significant removal of nitrogen by transforming into the NO3− and NH4+ through the formation of OH and reactive chlorine species. Characterization techniques like SEM-EDX and XRD have confirmed the durability of mixed metal oxide anodes even after 90 recycles of the experimental run. The total operating cost for electro-oxidation treatment of urea under optimized conditions is found to be 0.78 $/m3.

Inhibitory effects of herbal decoction Ojeoksan on proliferation and migration in vascular smooth muscle cells.

The proliferation of vascular smooth muscle cells plays a crucial role in pathogenesis of cardiovascular disease. The principal objective of this study was to determine the effects of Ojeoksan (OJS) on human aortic smooth muscle cell (HASMC) proliferation induced by tumor necrosis factor α (TNF-aα). Thymidine incorporation after TNF-α treatment was increased and this effect was inhibited significantly by OJS treatment. HASMC proliferation and migration by kinetic live cell imaging were also reduced by treatment with OJS. TNF-α induced the expression of cyclins/cyclin-dependent kinases (CDKs) and reduced the expression of p21waf1/cip1/p27kip1. However, OJS also attenuated the expression of TNF-α-induced cell-cycle regulatory proteins. The results of Western blot analysis demonstrated that the TNF-α treated HASMC secreted gelatinases, probably including MMP-2/-9, which may be involved in the invasion and migration of HASMC. Additionally, OJS suppressed the mRNA expression levels of matrix metalloproteinase-2/-9 (MMP-2/-9) in a dose-dependent manner. OJS inhibited the production of TNF-α-induced hydrogen peroxide (H2O2) and the formation of DCF-sensitive intracellular reactive oxygen species (ROS). Further, OJS suppressed the nuclear translocation and phosphorylation of inhibitor of kappa B-α (IκB-α) of nuclear factor κB (NF-κB) under TNF-α conditions. Our results demonstrate that OJS exerts inhibitory effects on TNF-α-induced HASMC proliferation and migration, suggesting the involvement of the inhibition of both MMP-2 and MMP-9 expressions, and the downregulation of ROS/NF-κB signaling. Thus, herbal decoction OJS may be a possible therapeutic approach to the inhibition of cardiovascular disease including atherosclerosis.

Extraction of phospholipid-rich fractions from egg yolk and development of liposomes entrapping a dietary polyphenol with neuroactive potential

A new protocol to obtain egg yolk phospholipids in ethanol is presented. Rutin-phospholipids nanoliposomes were prepared and characterized. The procedure takes advantage of the different solubility of egg yolk lipids in ethanol and acetone at low temperature, to efficiently obtain a phospholipid-rich fraction of high purity degree. The phospholipid content in the final fraction is 208.65 ± 26.46 μmol/g fresh egg yolk (16%), accounting for ca. 96% of the extract's dry weight. The phospholipid-rich fraction contains cholesterol (0.069–0.082 cholesterol/phospholipid molar ratio), and vestigial amounts of lutein and zeaxanthin (89.24 ± 9.76 and 14.9 ± 2.16 ng/g of fresh egg yolk, respectively). Saturated fatty acids dominate the extracted phospholipids (50% of egg's total yolk phospholipids), the levels of monounsaturated ranging from 20 to 25%, and polyunsaturated up to 35%. Rutin-liposomes, prepared with phospholipid-rich fraction, presented mean diameter <140 nm, negative surface charge (Zeta potential ~ −13 mV), and entrapment efficiency of rutin up to 87%. In human neuroblastoma cell line SH-SY5Y, rutin-liposomes (lipid 25 μM + rutin 16.7 μM) attenuated glutamate-induced cytotoxicity, in part by reducing the formation of intracellular reactive species, pointing to their potential application as new functional neuroprotective agents.

Peel oils from three Citrus species: volatile constituents, antioxidant activities and related contributions of individual components.

In the present study, peel oils were extracted through hydrodistillation and cold pressing from three Citrus species (Valencia orange, Ponkan and Eureka lemon) to investigate their volatile constituents and antioxidant activities. A total of 47 volatile components were identified by GC-MS, and then grouped by principal component analysis. The extraction methods were found to have an obvious effect on the proportion of terpenes and oxygenated compounds in the six Citrus oils, especially for Eureka lemon oils. The major fractions in the Citrus oils were found to be monoterpenes (78.65-96.57%), with limonene occupying a dominant percentage (51.22-86.65%). Furthermore, γ-terpinene and terpinolene displayed strong DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging abilities and efficient inhibition of lipid peroxidation, while oxygenated compounds of α-terpineol and terpinen-4-ol showed poor DPPH radical-scavenging abilities. Therefore, hydrodistillated Eureka lemon oil with high levels of α-terpineol (9.11%) and terpinen-4-ol (4.69%) presented low radical scavenging capability. Citral displayed a high pro-oxidant ability against thiobarbituric acid reactive species formation, which might lead to the decreased ability of the Eureka lemon oils in inhibition of lipid peroxidation, since citral was significantly high in Eureka lemon oils. This study facilitated the understanding of volatile constituents and antioxidant activities in different Citrus peel oils.

Modeling study of reactive species formation from C1–C3 alkanes in an HCCI engine

The production of oxygenated hydrocarbons, hydrogen peroxide, and ethylene by low and intermediate temperature reactions of C1–C3 alkanes in a homogeneous charge compression ignition (HCCI) in an internal combustion engine was explored via single-zone modeling. For lean equivalence ratios, the main operating parameters were successively optimised with respect to intermediate species yield. A combination of 9–13 for compression ratio, 400 rpm for engine speed, and 0.05–0.25 for equivalence ratio was found for fixed intake temperature and pressure of 400 K and 1 bar, respectively. The optimum was sharply delineated in compression ratio, and widest in equivalence ratio. For these optimal parameters, 5–13.3% of the methane fuel was converted to formaldehyde and 1.6–3.4% to hydrogen peroxide, while more than 1% ethylene yield was found for ethane, and somewhat less for propane over that range. At this optimum, adding reactive species to methane as a fuel did not significantly improve yields, nor did varying intake temperature off the chosen 400 K, indicating that in fact the parameters combination is at least near-optimal. Operating conditions of an In-situ production unit of hydrogen peroxide and formaldehyde from methane partial oxidation have been explored to feed highly-efficient combustion and/or easy accessible/stabilised operating conditions of HCCI engine fuelled by low reactive fuel, the methane/natural gas.

Electricity generating & high efficiency advanced oxidation process including peroxymonosulfate activation in photocatalytic fuel cell

A novel system including peroxymonosulfate (PMS) activation process in a photocatalytic fuel cell (PFC) was established, promoting the degradation efficiency of berberine and enhancing the simultaneous electricity generation. The cathode is based on carbon-fiber cloth (CC) and loaded CoFe2O4 with carbon nano-fibers (CNFs), matching well with Ag NPs/ZnO NRs/NiF photo-anode to drive PFC work. The CNFs/CoFe2O4/CC cathode is multifunctional, it can activate PMS for sulfate radical (SO4-·) generation, and can simultaneously accept electrons from photo-anode for transform between Co3+and Co2+. The adding of PMS in PFC system boosts radical formation and cyclic reactions between related species. This PFC-PMS system showed a high antibiotic degradation efficiency and stable electricity generation (93.5% for berberine degradation, 9.18 h−1 for kinetic rate constant, ~0.50 V for cell-voltage at 2000 Ω). In addition, the pollutant removal capacity, influencing factors and the pollutant degradation mechanism in PFC-PMS system were illustrated. The feasible mechanism of berberine degradation was elucidated by the radical trapping and EPR test and these results confirmed that the formation of reactive species, including SO4-·, OH, O2-·, 1O2 radicals and holes. This study suggests that the established PFC-PMS system is more efficient in wastewater treatment and simultaneous energy recovery.