Conversion Of Radicals Research Articles

Boosting catalytic activity of Fe-based perovskite by compositing with Co oxyhydroxide for peroxymonosulfate activation and ofloxacin degradation

A novel Fe-based perovskite hybrid catalyst was designed by sol-gel preparation of Ni-substitution of LaFeO3 containing in-situ growth of metal oxyhydroxide (MeOOH, Me=Mn, Ni, Co). The performances of metal oxyhydroxide-perovskite composites (MeOOH/LaFe0.5Ni0.5O3) for peroxymonosulfate (PMS) activation and ofloxacin (OFL) degradation were investigated. CoOOH/LaFe0.5Ni0.5O3 exhibited the best OFL degradation efficiency of 91.84 % within 15 min. Compared with LaFe0.5Ni0.5O3, the specific surface area (from 21.391 to 100.216 m2·g−1) and pore volume (from 0.080 to 0.226 cm3·g−1) of CoOOH/LaFe0.5Ni0.5O3 increased drastically. Among the structures and properties, substitution of Ni into B-site of LaFeO3 accelerated the electron transfer and promoted the redox cycle between Fe3+/Fe2+ and Ni2+/Ni0. Besides, doping with CoOOH could provide more active sites for the catalyst and more electrons for the activation of PMS to generate reactive species. The higher redox potential of Co ions resulted in good thermodynamic cycling between Co3+/Co2+, Fe3+/Fe2+ and Ni2+/Ni0. Moreover, oxygen vacancies (Vo) on the material surface were involved in the activation of PMS. Quenching experiments and electron paramagnetic resonance (EPR) verified that the catalytic reaction was primarily driven by both ·O2- (radical way) and 1O2 (non-radical way), with electron transfer process (ETP) also had some effect on OFL degradation. In addition, the conversion of radicals to non-radicals was demonstrated. Finally, the degradation pathway of OFL and the ecotoxicity of the intermediates were proposed. The work provided scientific support and theoretical basis for the development of efficient heterogeneous PMS catalysts.

Electrochemically activated calcium sulfite for atrazine degradation: Performance, mechanism and kinetics

The conventional use of Na2SO3 in advanced oxidation processes leads to excessive dissolved SO32−, limiting the utilization of oxysulfur species. This study introduced an electrochemically activated CaSO3 (EC-CaSO3) process that exploited the slow-release property of CaSO3. The results showed that the removal ratios of several micropollutants were over 90 % within 10 min, with SO4•− as the primary oxidant. A mathematic model was further developed to simulate the radical conversion, analyze the degradation kinetics and optimize the operational parameters, using atrazine (ATZ) as the target pollutant. The continuous low concentration of SO32− promoted O2 evolution for oxysulfur species transformation and reduced SO4•− quenching. This resulted in 74 % of SO3•− converting to SO5•− and 84 % of SO32− contributing to SO4•− formation. In the initial 2 min, the matched electro-generation of SO3•− and O2 remarkably accelerated SO4•− generation, leading to 82 % removal of ATZ. As electrolysis continued, the reduced release rate of SO32− prevented excessive accumulation of SO32− and maintained high O2 evolution rate to drive SO4•− generation. Consequently, complete degradation of ATZ was achieved within 5 min, with the contribution of SO4•− exceeding 99 %. By investigating the influence of operational parameters on ATZ degradation and energy consumption, the cost-effective conditions (EE/O values < 2.2 kWh/m3/order) occurred at pH above 7, current densities of 60 to 90 A/m2 and initial CaSO3 dosages of 2 to 4 mM. Additionally, density functional calculation and LC-MS analysis confirmed the formation of less toxic intermediates through dealkylation and dechlorination-hydroxylation. These findings suggested that EC-CaSO3 process was a promising technology for oxidizing micropollutants.

Design of dual-defective polymeric carbon nitride with compact interlayer stacking for boosting photocatalytic H2O2 production: Insight of various configurations

Polymeric carbon nitride (PCN) is an environmentally friendly photocatalyst for solar-driven H2O2 production, but the activity of original PCN is still not satisfactory. The main limitation is the sluggish exciton dissociation leading to slow generation and conversion of superoxide radical (•O2−) intermediate. Herein, the PCN with dual defect sites and compact interlayer is rationally designed for H2O2 photosynthesis with an ultrahigh rate of 3930.9 μmol g−1h−1 and rapid •O2− yield rate of 1.92 min−1. The enhanced activity is attributed to effective exciton dissociation during interlayer and intralayer process. Moreover, nitrogen vacancies change the oxygen adsorption configuration (formation of C − O − O − C bridge mode), thus promoting O2 adsorption and activation. A well-matched linear relationship was established between the concentration of nitrogen vacancies and •O2−/H2O2 production. This work not only provides in-depth insights for the photocatalytic H2O2 generation mechanism, but also offers a new paradigm for designing efficient PCN-based photocatalysts for energy conversion.

Non-radical activation of peracetic acid by Fe-Co sulfide modified activated carbon for the degradation of refractory organic matter

Recently, the non radical activation system had attracted much attention due to its strong anti-interference ability. In this study, a novel FeCo2S4/activated carbon (AC) catalyst was prepared and used to construct a non radical dominated degradation system. Due to the electron-donating groups (C-OH) of AC and the conversion of free radicals generated from the activation of PAA by iron (Fe) and cobalt (Co) ions, a large amount of singlet oxygen (1O2) were produced, making the activation system possessed excellent universality and applicability for the removal of organic pollutants. Within 5 min, about 89.87 % of tetracycline hydrochloride (TCH) was removed in FeCo2S4 /AC + PAA. After only 20 min of reaction, the TCH removal efficiency reached 94.12 %, accompany with the reaction rate reached 0.099 min−1. Other organic pollutants including ibuprofen (IBU), sulfamethoxazole (SMX), ciprofloxacin (CIP), p-nitrophenol (PNP) and atrazine (ATZ) were also efficiently removed within 20 min, with the removal efficiencies were 92.0 %, 91.5 %, 89.4 %, 88.3 %, and 84.5 %, respectively. When the solution pH changed from 5.01 to 9.48, FeCo2S4 /AC also showed excellent catalytic performances, with the TCH removal rates were maintained at over 85.18 %. Moreover, the removal rate of TCH still reached 90.23 % after 5 recycles. This study offered an efficient non-radical peracetic acid (PAA) activation system, which can be effectively used to degrade refractory organic pollutants from complex water environment.

Revealing the vital role of sulfur site on the surface of pyrite in 1O2 formation for promoting ciprofloxacin degradation via peracetic acid activation

Pyrite has been widely utilized to activate oxidants for water treatment, yet the regulation of reactive oxygen species (ROS) by sulfur sites on its surface has been overlooked. In this study, the surface sulfur sites were regulated by thermal modification of natural pyrite in the N2 atmosphere (denoted as P-X, where X represented pyrolysis temperatures ranging from 400 to 700 °C), and these modified pyrites were employed to activate peracetic acid (PAA) for ciprofloxacin (CIP) degradation. The results revealed that the degradation rate of CIP increased as the reduced sulfur content increased, with the P600/PAA system achieving the highest apparent degradation rate (kobs = 0.0999 min−1). Quenching experiments and electron paramagnetic resonance (EPR) analysis identified various ROS involved in the P-X/PAA system, with hydroxyl radical (·OH) and singlet oxygen (1O2) identified as dominant reactive species responsible for CIP degradation. The reduced sulfur sites served as the primary active sites facilitating the conversion of organic radicals (·CH3C(O)OO) into superoxide radicals (·O2−) and 1O2. Furthermore, the P600/PAA system demonstrated robust adaptability under both acidic and neutral pH conditions, efficiently degrading CIP even in the presence of complex matrices such as Cl−, NO3−, SO42−, NH4+, or humic acid (HA) in water bodies, although HCO3− was found to inhibit CIP degradation. This study significantly enhances our understanding of the interaction between reduced sulfur sites and ROS in PAA-based advanced oxidation processes (AOPs), offering a promising technology for efficient antibiotic treatment in water purification.

SP3.1 - Could shorter length of stay and oncological non inferiority justify a radical paradigm shift towards RAS to be the gold standard for all rectal cancer resections

Abstract Aim Robotic-assisted surgery (RAS) has proven to be an effective alternative to open (OP) and laparoscopic-assisted (LAP) rectal cancer resections. We aim to evaluate pathological and peri-operative outcomes of patients in a single centre undergoing rectal cancer resections using all three surgical techniques to evaluate whether RAS should be the gold-standard. Methods We retrospectively identified all elective rectal cancer resection cases since 2019 at our centre offering OP, LAP, and RAS services. We audited length-of-stay (LoS), complications, readmission rates, margin clearance status, and lymph node yield. Results Since 2019, there were 28 OP, 77 LAP, and 35 RAS resections performed. The median LoS for OP resections was 11 days, for LAP was 8 days (p=0.02) and was lowest for RAS resections (3 days, p=0.005). Readmission rates were highest for OP resections (21.4%) and were identical for LAP and RAS resections (14.2% each). Complications (OP 25%, LAP 34%, RAS 37%; p&amp;gt;0.05) were categorized using Clavien-Dindo (CD) classification with LAP having highest proportions of CD-IV (7.7%) and CD-V (7.7%), whereas RAS and OP resections had no severe complications (CD-IVa/IVb/V). Conclusion Our analysis shows significantly superior outcomes for shorter LoS and clear non-inferiority of RAS in all other aspects as compared to conventional approaches. Efforts must be bolstered to introduce RAS for rectal cancer resections in the long run considering the need for increasing training opportunities and improved resources to allow for a stable transition to RAS led services, rather than a radical conversion. Further studies are warranted to substantiate our observation.

Synergistic enhancement of singlet oxygen generation in Au and oxygen vacancy co-modified Bi2MoO6 ultrathin nanosheets for efficient ciprofloxacin degradation

Solar-driven molecular oxygen activation (MOA) is crucial for generating reactive oxygen species (ROS) for pollutant degradation, while the low activation efficiency greatly weakens the degradation efficiency. Herein, oxygen vacancies (OVs) and Au nanoparticles are co-introduced into Bi2MoO6 (ABMOH) to enhance the photocatalytic activity of Bi2MoO6 (BMO), thereby promoting MOA efficiency. Density functional theory demonstrates that the introduction of OVs not only improves the molecular oxygen adsorption on BMO, and but also strengthens the O-O bond dissociation of molecular oxygen, which is beneficial to MOA. Meanwhile, the unique localized surface plasmon resonance effect of Au nanoparticles immensely increases the photo-absorption capacity. Crucially, both OVs and Au nanoparticles work as “electron traps” to capture photogenerated electrons, thereby accelerating charge transfer. Based on the advantage of OVs and Au nanoparticles, ABMOH displays excellent MOA efficiency, and the degradation rate constant of ciprofloxacin (CIPF) by ABMOH-4 is 3.62-fold higher than BMO. Free radical trapping experiment and electron spin resonance suggest that singlet oxygen (1O2) can be selectively formed in the ABMOH system for CIPF degradation, and superoxide radical (•O2–) conversion and energy transfer are two pathways for 1O2 formation. This investigation serves as a beacon for the strategic design of high-performance and stable photocatalysts for MOA activation, paving the way for advancements in environmental remediation.

Photoinduced C(sp3)-H Bicyclopentylation Enabled by an Electron Donor-Acceptor Complex-Mediated Chemoselective Three-Component Radical Relay.

The photoredox electron donor-acceptor (EDA) complex-mediated radical coupling reaction has gained prominence in the field of organic synthesis, finding widespread application in two-component coupling reactions. However, EDA complex-promoted multi-component reactions are not well developed with only a limited number of examples have been reported. Herein, we report a photoinduced and EDA complex-promoted highly chemoselective three-component radical arylalkylation of [1.1.1]propellane, which allows the direct functionalization of C(sp3)-H with bicyclo[1.1.1]pentanes (BCP)-aryl groups under mild conditions. A variety of unnatural α-amino acids, featuring structurally diversified 1,3-disubstituted BCP moieties, were synthesized in a single-step process. Notably, leveraging the high tension release of [1.1.1]propellane, the highly unstable transient aryl radical undergoes rapid conversion into a relatively stable tertiary alkyl transient radical, and consequently, the competing side-reaction of two-component coupling was entirely suppressed. The strategic use of this transient radical conversion approach would be useful for the design of diverse EDA complex-mediated multi-component reactions. It is noteworthy that the highly chemoselective late-stage incorporation of the 1,3-disubstituted BCP pharmacophores into peptides was achieved both in liquid-phase and solid-phase reactions. This advancement is anticipated to have significant application potential in the future development of peptide drugs.

Microwave-assisted PMS activation Ti3C2/LaFe0.5Cu0.5O3-P catalysts for efficient degradation of CIP: Enhancement of catalytic performance by phosphoric acid etching

The LaFe0.5Cu0.5O3 perovskite synthesised by MOFs template method was compounded with Mxene Ti3C2, and the novel catalyst M-Ti3C2/LFCO-P was subsequently prepared by phosphoric acid etching. This catalyst effectively induced microwave activation of peroxymonosulfate (PMS), and ciprofloxacin (CIP) was efficiently degraded with a degradation rate reaching 95.48 % within 14 min. Characterization results revealed that the MOFs template method and phosphoric acid etching increased specific surface area (from 25.91 m2/g to 142.41 m2/g) of catalyst and improved its pore size distribution. Phosphoric acid etching successfully introduced phosphorus functional groups and promoted the formation of more oxygen vacancies, thereby significantly enhancing the catalytic activity of the catalyst. The conversion of free radicals and the transformation of free radicals to non-free radicals were demonstrated. Additionally, the catalyst exhibited higher electron transfer efficiency. The catalytic reaction was primarily driven by O2– and 1O2, with OH, SO4−, and e- playing auxiliary roles. Furthermore, the degradation pathway and toxicity of CIP were also evaluated. This work provides a new perspective for improving the catalytic degradation activity of antibiotics by perovskite catalysts.

Photoinduced C(sp3)‐H Bicyclopentylation Enabled by an Electron Donor–Acceptor Complex‐Mediated Chemoselective Three‐Component Radical Relay

The photoredox electron donor–acceptor (EDA) complex‐mediated radical coupling reaction has gained prominence in the field of organic synthesis, finding widespread application in two‐component coupling reactions. However, EDA complex‐promoted multi‐component reactions are not well developed with only a limited number of examples have been reported. Herein, we report a photoinduced and EDA complex‐promoted highly chemoselective three‐component radical arylalkylation of [1.1.1]propellane, which allows the direct functionalization of C(sp3)–H with bicyclo[1.1.1]pentanes (BCP)‐aryl groups under mild conditions. A variety of unnatural α‐amino acids, featuring structurally diversified 1,3‐disubstituted BCP moieties, were synthesized in a single‐step process. Notably, leveraging the high tension release of [1.1.1]propellane, the highly unstable transient aryl radical undergoes rapid conversion into a relatively stable tertiary alkyl transient radical, and consequently, the competing side‐reaction of two‐component coupling was entirely suppressed. The strategic use of this transient radical conversion approach would be useful for the design of diverse EDA complex‐mediated multi‐component reactions. It is noteworthy that the highly chemoselective late‐stage incorporation of the 1,3‐disubstituted BCP pharmacophores into peptides was achieved both in liquid‐phase and solid‐phase reactions. This advancement is anticipated to have significant application potential in the future development of peptide drugs.

The level of blood neutrophils primary reactive oxygen species production in Graves’ disease patients undergoing conservative therapy with thiamazole.

Background. Conservative therapy with thiamazole in Graves’ disease helps to reduce the level of oxidative stress by restoring euthyroidism and the total reactive antioxidant potential of plasma. However, until now, in patients with Graves’ disease, the radical-producing ability of neutrophils remains unexplored at the initial stage of free radical conversion at different durations of drug-induced euthyroidism, which seems significant in revealing the mechanisms of disease recurrence. The aim is to study the level of production of primary reactive oxygen species in peripheral blood neutrophils depending on the duration of drug — induced euthyroidism in patients with Graves’ disease. Materials and methods. A single-center, prospective, controlled study was conducted with the participation of patients with laboratory-confirmed Graves’ disease. Subgroups of patients with Graves’ disease were formed depending on the duration of achieved drug-induced euthyroidism with continuous conservative therapy with thiamazole. The level of ROS production in peripheral blood neutrophils was determined by chemiluminescence. The assessment of spontaneous and zymosan-induced chemiluminescence was carried out for 90 minutes on a 36-channel chemiluminescence analyzer BLM-3607 (Medbiotech LLC, Krasnoyarsk). Results. The study included 102 Graves’ disease women with an average age of 47.54 ± 15.47 years. Of these, 75 (73.5 %) with relapse and 27 (26.47 %) with newly diagnosed disease. The total synthesis of (S) primary ROS increased statistically significantly relative to the control values in the examined patients with a duration of the euthyroid state of 5–8 and 9–12 months. It was found that in patients with Graves’ disease with stable drug-induced euthyroidism for 5–8 and 9–12 months, the S index of zymosan-induced lucigenin-dependent chemiluminescence of neutrophils increased statistically significantly, respectively, by 10.7 and 7.4 times relative to the control values. Conclusion. The restoration and maintenance of drug-induced euthyroidism for more than 12 months against the background of conservative thiamazole therapy in patients with Graves’ disease reduces the load of systemic oxidative stress on the immune system. However, the high total production of primary ROS in neutrophils of patients with Graves’ disease in a state of drug-induced euthyroidism with conservative thiamazole therapy may play a significant role in disconnecting the functioning of the NADPH oxidase complex and determine the functional capabilities of neutrophils in case of disease recurrence.

Insight into the activation mechanism of sulfite over amorphous Fe1-xCoxS: Key role of Fe3+/Fe2+ self-cycling and oxysulfur radicals generation

Sulfite activation has been considered as a promising advanced oxidation technique for treating organic pollutants in water. In this work, a series of cobalt-doped FeS (Fe1-xCoxS) samples were synthesized via ultrasonic-assisted precipitation route and applied them in sulfite activation and Rhodamine B (RhB) removal in water at the same time, and their physical properties were characterized by XRD, SEM, TEM, XPS and electrochemical analysis. Benefiting from its high electron density, low corrosion voltage and impedance that beneficial to accelerate the electron transfer rate in the Fe1-xCoxS/sulfite system and the reducing sulfur species rich in electrons which beneficial to promote the self-cycling of Fe3+/Fe2+, the activity of Fe1-xCoxS for sulfite activation on the RhB removal was better than that of FeS in both acidic and neutral conditions. The redox cycle of metal ions on the surface of Fe1-xCoxS efficiently triggered sulfite activation. The hydroxyl radical (·OH), resulting from the conversion of oxysulfur radicals, plays a crucial role in the degradation of RhB. Additionally, a non-radical activation pathway of sulfite has been proposed. The present study provided a new idea and effective strategy for sulfite activation to environmental removal of organic matter in water.

Activation of peroxymonosulfate with natural pyrite-biochar composite for sulfamethoxazole degradation in soil: Organic matter effects and free radical conversion

Peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) represent an effective method for the remediation of antibiotic-contaminated soils. In this study, a natural pyrite-biochar composite material (FBCx) was developed, demonstrating superior activation performance and achieving a 76% removal rate of SMX from soil within 120 min. There existed different degradation mechanisms for SMX in aqueous and soil solutions, respectively. The production of 1O2 and inherent active species produced by soil slurry played an important role in the degradation process. The combination of electron paramagnetic resonance (EPR) and free radical probe experiments confirmed the presence of free radical transformation processes in soil. Wherein, the·OH and SO4·− generated in soil slurry did not directly involve in the degradation process, but rather preferentially reacted with soil organic matter (SOM) to form alkyl-like radicals (R·), thereby maintaining a high concentration of reactive species in the system. Furthermore, germination and growth promotion of mung bean seeds observed in the toxicity test indicated the environmental compatibility of this remediation method. This study revealed the influence mechanism of SOM in the remediation process of contaminated soil comprehensively, which possessed enormous potential for application in practical environments.

Crystal Plane Regulation Promotes the Oriented Conversion of Radicals in Heterogeneous Persulfate Catalyzed Oxidation Process.

In heterogeneous persulfate-catalyzed oxidation systems, the mechanism underlying the crystal plane effects of the catalyst on the selective conversion of reactive oxygen species (ROS) remains ambiguous. In this study, nano-Co3O4 catalysts with varying crystallinity and exposure levels of (111) crystal planes are prepared via a hydrothermal method. Compared to low crystalline catalysts, high crystallinity catalysts predominantly expose (111) planes containing higher concentrations of Co2+ and oxygen vacancies (Ov), resulting in an increase degradation efficiency of p-nitrobenzaldehyde (4-NBA) from 74.5% to 100%. Radical quenching experiments and EPR characterization reveal that the degradation of 4-NBA occurs through a radical pathway, and quantification of radicals demonstrates that increasing exposure levels of (111) planes effectively promote radical yield (CSO4•- increase from 18.2 to 172.8 µm and C•OH increase from 1 to 58.9 µm). Furthermore, XPS and DFT calculations indicate that high crystallinity catalyst possesses more Ov active sites on (111) planes. The presence of Ov not only facilitates the adsorption of PMS molecules but also enhances electron transfer from Co2+ to PMS, leading to directed formation and efficient transformation of radicals. This study presents a novel strategy for promoting efficient radical formation in persulfate-activated systems.

Mn-Based Artificial Mitochondrial Complex "VI" Acts as an Electron and Free Radical Conversion Factory to Suppress Macrophage Inflammatory Response.

Disturbance in the mitochondrial electron transport chain (ETC) is a key factor in the emerging discovery of immune cell activation in inflammatory diseases, yet specific regulation of ETC homeostasis is extremely challenging. In this paper, a mitochondrial complex biomimetic nanozyme (MCBN), which plays the role of an artificial "VI" complex and acts as an electron and free radical conversion factory to regulate ETC homeostasis is creatively developed. MCBN is composed of bovine serum albumin (BSA), polyethylene glycol (PEG), and triphenylphosphine (TPP) hierarchically encapsulating MnO2 polycrystalline particles. It has nanoscale size and biological properties like natural complexes. In vivo and in vitro experiments confirm that MCBN can target the mitochondrial complexes of inflammatory macrophages, absorb excess electrons in ETC, and convert the electrons to decompose H2O2. By reducing the ROS and ATP bursts and converting existing free radicals, inhibiting NLRP3 inflammatory vesicle activation and NF-κB signaling pathway, MCBN effectively suppresses macrophage M1 activation and inflammatory factor secretion. It also demonstrates good inflammation control and significantly alleviates alveolar bone loss in a mouse model of ligation-induced periodontitis. This is the first nanozyme that mimics the mitochondrial complex and regulates ETC, demonstrating the potential application of MCBN in immune diseases.

DL‐malic acid for inhibiting the re‐ignition of long‐flame coal and its micro‐reaction mechanism

AbstractTo study the metal ion chelating agent (DL‐malic acid) inhibiting oxidation characteristics of residual coal in goaf, the microscopic thermal transformation characteristics of the treated coal samples were obtained using apparent morphology, infrared spectroscopy, free radical testing, and thermal analysis. The results demonstrate that after the addition of malic acid, the sphericity and roundness of the coal samples decrease, and the small fractured particles accumulate in the pores of the oxidized coal samples and, thereby, reduce the number of coal–oxygen contact sites. The addition of 10% malic acid promotes the conversion of functional groups (FG) and free radicals in pre‐oxidized coal, inhibits the catalytic effect of metal ions, generates more active sites, and increases the total heat release during the combustion process. There are strong endothermic points in the malic acid‐treated coal samples, and the free water evaporation blocked by small particles in the holes delays the initial heat release temperature of the coal samples. Pre‐oxidation can promote changes in the valence state of metal ions in coal, increase the adhesion between broken pre‐oxidized coal particles via malic acid chelation, and lose the catalytic effect of metal ions; this inhibits the process of oxidative re‐ignition of coal samples.

Reducing the unwanted deflagration enhancement of C3HF7 on fuel-lean hydrogen-air mixture by diluting CO2: An experimental and numerical research

To prevent the explosion hazards of hydrogen energy, in this work, the deflagration behaviors of H2-air mixtures at equivalence ratios from 0.6 to 1.4 under the effects of C3HF7 and CO2 are experimentally investigated. Deflagration pressure and time indexes at ambient pressure and temperature are obtained. The characteristic parameters of chemical kinetics are analyzed according to a detailed mechanism. The results suggest that C3HF7 has dual effects of pressure enhancement and suppression with the rising volume ratio in fuel-lean H2-air mixtures. It is the F-involved reactions that govern the exothermic process, facilitate the comprehensive conversion of crucial free radicals, and augment the exothermicity of the principal reaction, leading to the elevation in peak pressure. Dilution of CO2 would decrease the heat release rate of the F-involved reactions and reduce the explosion enhancement effect of C3HF7. The results of this work are beneficial to the formulation of mitigation measures for hydrogen explosions.

Deep insight into the effect of bicarbonate on pollutant abatement in the UV/chlorine process

The UV/chlorine process has gained significant attention from researchers and practitioners and is considered as a viable alternative to the UV/H2O2 process. HCO3–, widely spread in natural water, was traditionally perceived to act as a quencher in advanced oxidation processes (AOPs), converting less selective radicals into the more selective CO3·–. Unlike other radical precursors (e.g., persulfate and H2O2), HOCl rapidly reacts with CO3·–, resulting in the formation of ClO·. Consequently, HCO3– introduces complexity to the radical chemistry within the UV/chlorine process. This study comprehensively investigated the role of HCO3– in the UV/chlorine process with regards to pollutant degradation, employing 1,4-dimethoxybenzene (DMOB) as the target contaminant. Adding 2 mM of HCO3− in the UV/chlorine system significantly amplifies the generation of ClO· by ∼ 2 times at pH 7.0, thereby markedly expediting the degradation of DMOB. The reaction rate constant of CO3·− with free chlorine was measured to be 8.82 × 107 M−1 s−1 at pH 7.0, and the rate depends on pH and the species of chlorine. The influence of HCO3− on radical distribution within the UV/chlorine process is also contingent upon other solution conditions, including pH and chlorine doses. Furthermore, this study demonstrates that the HCO3−-mediated radical conversion remains relatively unaffected by background constituents. The experimental data on pollutant degradation via the UV/chlorine process in pure water can be extrapolated to estimate the treatment efficiency in actual water scenarios. These findings enhance our understanding of the intricacies of UV/chlorine chemistry in practical water treatment, thus advancing its potential as an emerging AOP for specialized applications.

Boosted Photocatalytic Degradation of Atrazine Using Oxygen-Modified g-C3N4: Investigation of the Reactive Oxygen Species Interconversion.

Elaborating the specific reactive oxygen species (ROS) involved in the photocatalytic degradation of atrazine (ATZ) is of great significance for elucidating the underlying mechanism. This study provided conclusive evidence that hydroxyl radicals (·OH) were the primary ROS responsible for the efficient photocatalytic degradation of ATZ, thereby questioning the reliability of widely adopted radical quenching techniques in discerning authentic ROS species. As an illustration, oxygen-modified g-C3N4 (OCN) was prepared to counteract the limitations of pristine g-C3N4 (CN). Comparative assessments between CN and OCN revealed a remarkable 10.44-fold improvement in the photocatalytic degradation of ATZ by OCN. This enhancement was ascribed to the increased content of C-O functional groups on the surface of the OCN, which facilitated the conversion of superoxide radicals (·O2-) into hydrogen peroxide (H2O2), subsequently leading to the generation of ·OH. The increased production of ·OH contributed to the efficient dealkylation, dechlorination, and hydroxylation of ATZ. Furthermore, toxicity assessments revealed a significant reduction in ATZ toxicity following its photocatalytic degradation by OCN. This study sheds light on the intricate interconversion of ROS and offers valuable mechanistic insights into the photocatalytic degradation of ATZ.

Differential expression of various isoforms of superoxide dismutase in the cells of the human exocrine pancreas.

Superoxide dismutase (SOD) is an enzyme that plays acrucial role in protecting cells from oxidative damage. Our study aims to address the lack of papers simultaneously analyzing the immunoreactivity of all three distinct isoforms of SOD in human exocrine pancreas cells. Superoxide dismutases (SODs) facilitate the conversion of superoxide radicals into less harmful substances. By neutralizing superoxide radicals, SODs help prevent the formation of highly reactive and destructive species that can adversely affect manifold cellular components. The study analyzed immunoreactivity of SODs in samples of six healthy adult human pancreases, while using the indirect immunohistochemical method under alight microscope. SOD1 was predominantly found in centroacinar cells and epithelial cells of the duct system while SOD2 was mainly detected in the epithelial cells of interlobular ducts. Both enzymes were prominently present in the basal region of acinar cells near the cell nucleus. The expression of SOD3 was observed to be rare. Understanding the intracellular metabolism of SODs in healthy exocrine pancreas cells serves as abasis for determining the precise role of oxidative damage and SOD signaling in the pathogenesis of various pancreatic diseases, including chronic pancreatitis and pancreatic cancer (Fig. 6, Ref. 24). Text in PDF www.elis.sk Keywords: antioxidants, histology, immunohistochemistry, pancreas, superoxide dismutase.