Toxicity Of Degradation Products Research Articles

Evaluation of the Potential of High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry for the Determination of Chemical Warfare Agents and Their Toxic Degradation Products.

The determination of chemical warfare agents (CWAs) and their toxic degradation products (DPs) has become increasingly important for public and military safety in recent years. We focused on assessing the possibility of the HPLC-ICP-MS analytical technique to verify the provisions of the Chemical Weapons Convention. This technique enables the identification and determination of minimal concentrations (ppt range) of elements in various matrices. This fact is important for the determination of CWAs and other highly harmful compounds, even small amounts of which can have serious consequences for living organisms. We have critically analysed the results of scientific research on the identification and quantitative determination of extremely toxic organophosphorus, organosulfur and organoarsenic CWAs, their derivatives and their degradation products using high-performance liquid chromatography (HPLC) coupled with inductively coupled plasma-mass spectrometry (ICP-MS).

Influence of UV-B and culinary treatment on vitamin D2 and agaritine in button mushrooms

This study investigated the effects of different culinary treatments on the levels of vitamin D2 and agaritine in irradiated white button mushrooms. In addition, the intake of this vitamin via mushroom dishes was evaluated. In fresh irradiated white button mushrooms, the vitamin D2 content was 21.5 ± 2.4 µg/100 g fresh weight, 42 % of which was in the cap skin. The highest losses of vitamin D2 (63 %) were found in samples boiled in acidic water. In contrast, the lowest losses were found in samples boiled in non-acidified water. In the baking and frying experiments, vitamin D2 retention depended more on the cooking time than on the temperature. This resulted in high-heat frying being the second-best treatment for retaining vitamin D2 content in the samples. In the case of agaritine, no effect of UV treatment on its content was observed, and cooking treatment reduced its consumption. At the same time, the formation of toxic degradation products was not observed. The Recommended Daily Intake (RDI) of vitamin D can be achieved by consuming about 75–190 g of cooked, irradiated white button mushrooms, which can thus be an important dietary source of this vitamin.

Photocatalytic remediation of fluoranthene contaminated soil by eco-friendly GQDs/TiO2/α-FeOOH composite photocatalyst: Efficiency, influence factors, mechanism, and toxicity analysis

Polycyclic aromatic hydrocarbons (PAHs), as a persistent organic pollutant, have adverse effects on soil environment and human health. In this study, a new type of iron-based material graphene quantum dots (GQDs)/TiO2/α-FeOOH was used to construct a photocatalytic system to achieve effective degradation of fluoranthene in soil. The hydrothermal method and sol–gel method were used to synthesize GQDs/TiO2/α-FeOOH composite photocatalyst, which exhibited enhanced photocatalytic activity by promoting charge transfer, increasing specific surface area, and broadening light absorption range. The degradation ratio of fluoranthene in soil suspension by GQDs/TiO2/α-FeOOH was 67.37 % under the condition of 24 h of simulated sunlight irradiation, water/soil ratio of 10:1, and catalyst dosage of 50 mg/g. •O2– and h+ played the major roles in degradation process, and the catalytic mechanism was proposed. The degradation products and degradation pathway of fluoranthene were analyzed by GC–MS detection and DFT calculation, and the toxicity of degradation products was predicted by simulation calculation. The effect of remedial soil on seed germination was investigated through germination test of tomato seeds, and results showed that the productivity of fluoranthene contaminated soil was recovered in a certain extent.

UV-enhanced Fe2+/PDS system for degradation of acid orange 7: Kinetics, degradation mechanism and toxicity assessment

Based on the deficiency of the Fe2+ catalyzed persulfate (PDS) process, ultraviolet (UV) synergistic Fe2+ activated PDS system was introduced in this study for the degradation of acid orange 7 (AO7) dye. The effects of different initial pH, PDS dosage, Fe2+ dosage, and different UV intensities on the degradation rate of AO7 were investigated, and a kinetic model for the apparent reaction rate was determined. The results showed that the UV/ Fe2+/ PDS system was effective in degrading AO7 in a wide pH range. Under optimal conditions, 96 % removal of AO7 was achieved in 10 min. The effects of different inorganic anions on AO7 were discussed; Cl− had little effect on the degradation effect, and SO42−, NO3− and HCO3− inhibited the degradation of AO7 by the system to varying degrees. The presence of reactive radicals (SO4·− and·OH) in the reaction was determined by quenching experiments and EPR capture and their degradation contribution was further investigated. Nine intermediates of AO7 were detected by LC- MS/ MS, and the degradation pathway of AO7 was inferred by combining with UV– Vis spectra. Finally, the ecotoxicity and tritogenic effects of AO7 intermediates were assessed by Toxtree and T.E.S.T toxicity prediction models, which showed that the final degradation product toxicity was non-mutagenic, non-teratogenic, and devoid of hereditary and non-hereditary carcinogenicity.

Deciphering the degradation of sulfonamides by UV/chlorination in aqueous solution: kinetics, reaction pathways, and toxicological evolution

UV/Cl is a cost-effective process and is often used in municipal water treatment plants as well as in industrial applications. UV/Cl method is found highly effective in degrading contaminants, including pathogens, The conventional methods for water treatment have been proven inefficient for the complete elimination of pollutants and generate harmful by-products in the environment. This study evaluated the efficacy of three different treatment methods, chlorination alone, UV photolysis, and UV/Cl, for the degradation of sulfonamides (SAs) in water. The results highlighted that UV/Cl treatment was an efficient method for enhancing the degradation of sulfisoxazole (SFX), sulfadimethoxine (SAT), and sulfaguanidine (SG), with substrates degrading in 5, 6.5, and 4 min. The study also investigated the reactive species generated in the UV/Cl system and found that ·OH was the species responsible for the elimination of SFX. Additionally, the study explored the intermediate products generated during the degradation of SFX under the UV/Cl system, identifying VI distinct degradation pathways. The presence of ·OH radicals significantly enhanced the degradation of SFX, while some chlorine species also contributed to the degradation. The study predicted the toxicity of degradation products from the UV/Cl system using the ECOSAR (Ecological Structure Activity Relationships) program and found that the final degradation products of SFX were non-toxic, but concerns were raised about acute toxicity.

A review of the physiological effects of microgravity and innovative formulation for space travelers.

During the space travel mission, astronauts' physiological and psychological behavior will alter, and they will start consuming terrestrial drug products. However, factors such as microgravity, radiation exposure, temperature, humidity, strong vibrations, space debris, and other issues encountered, the drug product undergo instability This instability combined with physiological changes will affect the shelf life and diminish the pharmacokinetic and pharmacodynamic profile of the drug product. Consequently, the physicochemical changes will produce a toxic degradation product and a lesser potency dosage form which may result in reduced or no therapeutic action, so the astronaut consumes an additional dose to remain healthy. On long-duration missions like Mars, the drug product cannot be replaced, and the astronaut may relay on the available medications. Sometimes, radiation-induced impurities in the drug product will cause severe problems for the astronaut. So, this review article highlights the current state of various space-related factors affecting the drug product and provides a comprehensive summary of the physiological changes which primarly focus on absorption, distribution, metabolism, and excretion (ADME). Along with that, we insist some of the strategies like novel formulations, space medicine manufacturing from plants, and 3D printed medicine for astronauts in longer-duration missions. Such developments are anticipated to significantly contribute to new developments with applications in both human space exploration and on terrestrial healthcare.

Insight the long-term biodegradable Mg-RE-Sr alloy for orthopaedics implant via friction stir processing

Magnesium alloys, noted for their substantial mechanical strength and exceptional biocompatibility, are increasingly being considered for use in biodegradable implants. However, their rapid degradation and significant hydrogen release have limited their applications in orthopaedics. In this study, a novel Mg-RE-Sr alloy was created by friction stir processing to modify its microstructure and enhance its degradation performance. Through microstructural characterization, the friction stir processing effectively refined the grains, accelerated the re-dissolution of precipitates, and ensured a uniform distribution of these phases. The processed alloy demonstrated improved comprehensive properties, with an in vitro corrosion rate of approximately 0.4 mm/y and increases in ultimate tensile strength and elongation by 37 % and 166 %, respectively. Notably, in vivo experiments involving a rat subcutaneous implantation model revealed a slower degradation rate of 0.09 mm/y and a uniform degradation process, basically achieving the requirements for ideal performance in orthopaedic applications. The superior degradation characteristics were attributed to the synergistic effect of attenuated galvanic corrosion and the formation of a dense Y(OH)3/Y2O3 film induced by an exceptional microstructure with a highly solid-soluted matrix and uniformly refined precipitates. Meanwhile, the alloys exhibited excellent biocompatibility and did not cause undesirable inflammation or produce toxic degradation products. These improvements in biocompatibility and degradation characteristics indicate great promise for the use of this friction stir processed alloy in osteosynthesis systems in the clinical setting.

Solvothermal preparation of CuO/g-C3N4 and photocatalytic degradation of ciprofloxacin

Composite materials CuO/g-C3N4 (CuOCN) were prepared using a solvothermal method to investigate their degradation effect on ciprofloxacin (CIP). The materials were characterized through X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible diffuse reflectance spectrophotometry (DRS), and X-ray photoelectron spectroscopy (XPS). The toxicity of degradation products of CIP was assessed through antibacterial experiments, and the degradation mechanism of CIP was investigated using quenching agent capture and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The results of XRD and FTIR indicate that the CuOCN composite has been successfully synthesized. The photocatalytic experiment shows that adding 15% (w/w) of Cu3(BTC)2(H2O)3 in melamine (CuOCN2) has a relatively good degradation effect on CIP and can be reused multiple times. The TEM results indicate that both CuO and g-C3N4 have a layered structure and are attached together. HRTEM analysis reveals that the two components in CuOCN2 are arranged in a layered structure, with CuO displaying two crystal planes. Energy Dispersive Spectrometer (EDS) analysis reveals that the proportion of CuO in the three composite materials is 7.86% (w/w), 15.93% (w/w), and 84.83% (w/w), respectively. DRS detection reveals that the greater the amount of CuO added, the broader the visible light absorption range of the composite material, and the narrower the bandgap width. The photocurrent and photoresistance indicate that CuOCN2 exhibits a good photoelectric effect. XPS analysis shows that the CuOCN2 composite material possesses both the chemical composition and structure of CuO and g-C3N4. During the catalytic degradation process of CIP, four active substances, h+, e−, ·O2 −, and ·OH, were produced, leading to a reduction in the toxicity of the degradation products. Through HPLC-MS analysis, it was found that CIP undergoes reactions such as defluorination, ring opening of piperazine, and quinolone during degradation, resulting in reduced toxicity. This study provides an experimental basis for the degradation of CIP by CuOCN2.

Efficient removal of moxifloxacin through PMS activation by CuFeS2/MXene.

Due to the frequent detection and potential toxicity of moxifloxacin (MOX), its removal technology had attracted attention in recent years. In this research, CuFeS2/MXene was prepared and used to activate peroxymonosulfate (PMS) to remove MOX. The degradation efficiencies, kinetics, influences, and reaction mechanism of MOX by CuFeS2/MXene/PMS were investigated. The synergistic effect of CuFeS2 and MXene significantly enhanced PMS activation, producing SO4•-, HO•, and 1O2 as the main active species. By adding 0.12g/L CuFeS2/MXene and 0.12mM PMS, MOX removal efficiency reached 99.1% within 40min, with a rate constant of 0.1073min-1. The composite ratios of CuFeS2/MXene impacted PMS activation more significantly than catalyst dosages and PMS concentrations. Acidic conditions were favorable for the degradation of MOX, while HCO3-, HPO42-, Mn2+, and HA had the inhibitory effects. Twelve major products were detected by HPLC-MS, and DFT was used to illustrate possible degradation pathways of MOX, including the removal of nitrogen-containing heterocycle and transformations of quinolone moieties. Toxicity analysis showed that the developmental toxicity, mutagenicity, and acute toxicity of degradation products tended to decrease. CuFeS2/MXene could exhibit excellent reusability, maintaining an average MOX degradation efficiency of 90.8% in the 7-cycle experiments.

Synergistic catalysis by Fe-oxide-biochar modified with WS2/PMS system for the removal of metformin

Metformin (MET) is frequently detected in aquatic environments, with its presence posing potential risks to flora and fauna. To enhance the redox cycling efficiency of Fe2+/Fe3+ in the Fenton reaction, a catalyst WSF@BC was synthesized by innovatively loading WS2 and iron oxides onto reed biochar to construct a novel non-homogeneous Fenton-like system for the degradation of MET in wastewater. This study investigated various parameters such as initial pH, peroxymonosulfate dosage, and catalyst dosage to determine their effects on the degradation efficiency. The results indicated that MET was degraded by 85.1 % within 30 min. The synergistic effect of WS2 and FeOx distinctly improved the removal efficiency of MET in this system, whereby SO4− dominated the rapid degradation of MET, as demonstrated by radical quenching experiments, electron paramagnetic resonance spectrometry (EPR) studies, and X-ray photoelectron spectroscopy (XPS) analysis. Frontier orbital theory calculations and intermediate product analyses revealed that the main reaction sites for MET degradation were CN and CN, resulting in reduced toxicity of degradation products. Three potential degradation pathways of MET via denitrification, amino oxidation, and hydroxylation were proposed by theoretical predictions and LC-MS/MS analysis. Additionally, characterization and recycling outcomes demonstrated excellent stability and reusability of the catalyst. This research highlights the significant application value of novel non-homogeneous catalysts for MET degradation in Fenton-like systems and provides theoretical support for achieving complete mineralization of MET.

Novel MOF-derived Fe/CoNHDC-400@GF cathode with improved in-situ catalytic degradation of chloroquine phosphate during heterogeneous electro-Fenton process

The preparation of stable and high-efficiency heterogeneous electro-Fenton cathodes for the treatment of pollutants is important for environmental remediation. Herein, a novel N-doped MOF-derived Fe/Co bimetallic catalyst was in-situ grown on graphite felt (GF) surface to yield a composite cathode Fe/CoNHDC-400@GF for use in electro-Fenton process. The introduction of cobalt accelerated electron transfer due to existing polyvalent metals. The synergistic effect between Co0, CoⅡ, CoШ, FeⅡ, and FeШ enabled the continuous generation of reactive oxygen species (•OH and •O2−). Under near-neutral conditions (pH=6.5), complete removal of 10 mg L−1 chloroquine phosphate (CQP) was achieved within 60 min. Additionally, efficient removal was also achievable over a wide pH range (pH=3–11). The mechanistic investigations indicated •OH as a major active oxygen species for CQP degradation. A combination of the experimental results with density functional theory calculations (DFT) clarified the degradation pathway and intermediate products of CQP. Moreover, the toxicity of degradation products significantly reduced. Overall, valuable insights on preparing composite cathodes grown in-situ for efficient removal of refractory pollutants from wastewater during the heterogeneous electro-Fenton process were provided, useful for future consideration.

Chronic toxic effects of erythromycin and its photodegradation products on microalgae Chlorella pyrenoidosa

The photodegradation products (PDPs) of antibiotics in the aquatic environment received increasing concern, but their chronic effects on microalgae remain unclear. This study initially focused on examining the acute effects of erythromycin (ERY), then explored the chronic impacts of ERY PDPs on Chlorella pyrenoidosa. ERY of 4.0 − 32 mg/L ERY notably inhibited the cell growth and chlorophyll synthesis. The determined 96 h median effective concentration of ERY to C. pyrenoidosa was 11.78 mg/L. Higher concentrations of ERY induced more serious oxidative damage, antioxidant enzymes alleviated the oxidative stress. 6 PDPs (PDP749, PDP747, PDP719, PDP715, PDP701 and PDP557) were identified in the photodegradation process of ERY. The predicted combined toxicity of PDPs increased in the first 3 h, then decreased. Chronic exposure showed a gradual decreasing inhibition on microalgae growth and chlorophyll content. The acute effect of ERY PDPs manifested as growth stimulation, but the chronic effect manifested as growth inhibition. The malonaldehyde contents decreased with the degradation time of ERY at 7, 14 and 21 d. However, the malonaldehyde contents of ERY PDPs treatments were elevated compared to those in the control group after 21 d. Risk assessment still need to consider the potential toxicity of degradation products under long-term exposure.

Insight on magnetic nitrogen-doped graphene oxide composite electrode constructing heterogeneous Electro-Fenton system for treating organophosphorus pesticide wastewater

The treatment of organic phosphorus pesticide (OPP) wastewater faces challenges such as incomplete degradation and low reaction efficiency. While heterogeneous electro-Fenton (Hetero-EF) has emerged as the preferred technology for addressing these issues due to its high treatment efficiency, further optimization is still necessary. This study used a one-pot hydrothermal method to prepare magnetic nitrogen-doped graphene oxide (Fe3O4@N-GO) composite electrodes to construct a novel Hetero-EF system. Dimethoate (DIM) was chosen as the representative pollutant to investigate the effects of parameters such as current density, pH, electrode spacing, and loading amount on degradation efficiency. The results demonstrated complete degradation of DIM within 40 min. Density functional theory (DFT) calculations and intermediate product analysis revealed that the reactive sites for DIM degradation were the P=S and P=S bonds, involving both hydrolysis and •OH pathways, with a decrease in toxicity of degradation products observed. Compared to graphite electrodes, Fe3O4@N-GO composite electrodes significantly increased H2O2 production, achieving complete DIM degradation even after 5 cycles, with a phosphate conversion rate of 30–40 %. This study highlights the innovative strategy of the Hetero-EF system in its significant application value for OPP treatment.

The CoO-doped carbon nanotubes enhance electronic performance and effectively activate persulfate for the degradation of sulfafurazole

In recent studies, carbon nanotube (CNTs) materials and their composites have demonstrated remarkable catalytic activity in the activation of persulfate (PS), facilitating the efficient degradation of organic pollutants. In this study, a novel Co loaded carbon nanotubes (CoO@CNT) catalyst was prepared to promote PDS activation for the degradation of sulfafurazole (SIZ). Experimental results, the CNT as a carrier effectively reduces the leaching of cobalt ions and improves the electron transport capacity，whereas the introduced Co effectively activates the PDS, promoting the generation of highly reactive radicals to degrade SIZ. Under optimized conditions (a catalyst dose of 0.2 g/L, a PDS dose of 1 g/L and an initial pH = 9.0), the obtained CoO@CNT demonstrated favorable Fenton-like performance, reaching a degradation efficiency of 95.55% within 30 min. Furthermore, density functional theory (DFT) calculations demonstrate that the introduction of cobalt (Co) accelerates electron transfer, promoting the decomposition of PDS while facilitating the Co2+/Co3+ redox cycling. We further employed the environmental chemistry and risk assessment system (ECOSAR) to evaluate the ecological toxicity of intermediate products, revealing a significant reduction in ecological toxicity associated with this degradation process, thereby confirming its environmental harmlessness. Through batch experiments and studies, we gained a comprehensive understanding of the mechanism and influencing factors of CoO@CNT in the role of SIZ degradation, and provided robust support for evaluating the ecological toxicity of degradation products. This study provides a significant strategy for the development of efficient catalysts incorporating Co for the environmentally friendly degradation of organic pollutants.

Identification and Mechanistic Analysis of Toxic Degradation Products in the Advanced Oxidation Pathways of Fluoroquinolone Antibiotics.

The degradation of fluoroquinolones (FQs) via advanced oxidation processes (AOPs) is a promising avenue, yet the complete mineralization of certain FQ molecules remains elusive, raising concerns about the formation of toxic by-products. This study delineates five primary AOP degradation pathways for 16 commercially available FQ molecules, inferred from existing literature. Density functional theory (DFT) was employed to calculate the bond dissociation energies within these pathways to elucidate the correlation between bond strength and molecular architecture. Subsequently, Comparative Molecular Similarity Index Analysis (CoMSIA) models were constructed for various degradation reactions, including piperazine ring cleavage, defluorination, hydroxylation, and piperazine ring hydroxylation. Three-dimensional contour maps generated from these models provide a deeper understanding of the interplay between FQ molecular structure and bond dissociation energy. Furthermore, toxicity predictions for 16 FQ molecules and their advanced oxidation intermediates, conducted using VEGA 1.2.3 software, indicate that degradation products from pathways P2 and P5 pose a heightened health risk relative to their parent compounds. Furthermore, the application of the Multwfn program to compute the Fukui function for FQ molecules discerns the disparity in degradation propensities, highlighting that N atoms with higher f0 values can augment the likelihood of piperazine ring cleavage. HOMO-LUMO distribution diagrams further confirm that methoxy substitution at the 1-position leads to a dilution of HOMOs on the piperazine ring and an increased energy gap for free radical reactions, diminishing the reactivity with hydroxyl radicals. This study elucidates the pivotal role of structural characteristics in FQ antibiotics for their degradation efficiency within AOPs and unveils the underlying mechanisms of bond dissociation energy disparities. The toxicity parameter predictions for FQ molecules and their intermediates offer unique perspectives and theoretical underpinnings for mitigating the use of high-risk FQs and for devising targeted degradation strategies to circumvent the generation of toxic intermediates in AOPs through molecular structure optimization.

The acute toxicity of Novichok's degradation products using quantitative and qualitative toxicology in silico methods.

The emergence of Novichok agents, potent organophosphorus nerve agents, has spurred the demand for advanced analytical methods and toxicity assessments as a result of their involvement in high-profile incidents. This study focuses on the degradation products of Novichok agents, particularly their potential toxic effects on biological systems. Traditional in vivo methods for toxicity evaluation face ethical and practical constraints, prompting a shift toward in silico toxicology research. In this context, we conducted a comprehensive qualitative and quantitative analysis of acute oral toxicity (AOT) for Novichok degradation products, using various in silico methods, including TEST, CATMoS, ProTox-II, ADMETlab, ACD/Labs Percepta, and QSAR Toolbox. Adopting these methodologies aligns with the 3Rs principle, emphasising Replacement, Reduction, and Refinement in the realm of toxicological studies. Qualitative assessments with STopTox and admetSAR revealed toxic profiles for all degradation products, with predicted toxicophores highlighting structural features responsible for toxicity. Quantitative predictions yielded varied estimates of acute oral toxicity, with the most toxic degradation products being EOPAA, MOPGA, MOPAA, MPGA, EOPGA, and MPAA, respectively. Structural modifications common to all examined hydrolytic degradation products involve substituting the fluorine atom with a hydroxyl group, imparting consequential effects on toxicity. The need for sophisticated analytical techniques for identifying and quantifying Novichok degradation products is underscored due to their inherent reactivity. This study represents a crucial step in unravelling the complexities of Novichok toxicity, highlighting the ongoing need for research into its degradation processes to refine analytical methodologies and fortify readiness against potential threats.

Embedded iron and nitrogen co-doped carbon quantum dots within g-C3N4 as an exceptional PMS photocatalytic activator for sulfamethoxazole degradation: The key role of Fe[sbnd]N bridge

The covalent modification of graphite-phase carbon nitride (g-C3N4) by carbon quantum dots (CQDs) is a promising way to improve its photocatalytic performance. Although CQDs can act as charge mediator for electrons storage and transfer, it is crucial to construct efficient interfaces, which serves as active sites for tight connect with g-C3N4 and fast release of electrons. Herein, a novel iron and nitrogen co-doped carbon quantum dots (Fe, N-CQDs) assembled g-C3N4 composite (FNCCN) was constructed via FeN bridge by hydrothermal and thermal polymerization methods. The FNCNN rivaled popular nitrogen-doped carbon quantum dots (N-CQDs) combined with g-C3N4 composites for peroxymonosulfate (PMS) activation and degradation of sulfamethoxazole (SMX). The SMX degradation rate (0.0963 min−1) is 5.38 and 3.15 times higher than that of g-C3N4 and N-CQDs/g-C3N4. The characterization and DFT calculation results suggest that Fe, N-CQDs was successfully incorporated into carbon matrix of g-C3N4 via FeN covalent bond, which joints the two counterparts closely and creates electron transport channels for higher electrons transfer efficiency. The FeN coordinated structure promotes PMS reduction on Fe2+ of FeN sites for HO and SO4- production and expedited photo carries separation through Fe3+/Fe2+ cycling. In addition, the degradation efficiency, ROS identification, EPR test and degradation pathway of SMX was determined, and the intermediate toxicity of degradation products was predicted. This work constructed a tight atomic-level connection between hydrophobic g-C3N4 and hydrophilic CQDs, which improved an effective strategy for accelerating electron transport and efficient photocatalytic activation of PMS.

Photocatalytic degradation of oxytetracycline using ZnO catalyst

AbstractIn the present study, the degradation of oxytetracycline (OTC) under ultraviolet (UV) light in the presence of ZnO catalyst was investigated, and optimum parameters for degradation efficiency were determined. Different pH values, ZnO dosages, reaction times, OTC concentrations, and UV lights were used in this study. The optimum conditions found were as follows: pH 4, ZnO 1 g L−1, reaction time 25 min, and OTC concentration 10 mg L−1. Degradation efficiency was 42.1%, 76%, 70.7%, and 61.7% for ZnO and photocatalytic (for UV‐A, UV‐B, and UV‐C) degradation at optimal conditions, respectively. The resulting products after the photocatalytic oxidation of OTC were determined in the study. To identify the toxicity of degradation products and OTC, the lowest LC 50 (50% lethal concentration) and EC 50 (50% effective concentration) values were found. The resulting ethanamine, 2‐(2,6‐dimethylphenoxy)‐N‐methyl‐ by‐products were observed to be more toxic than OTC. Furthermore, it was seen that isopropoxy carbamic acid, ethyl ester by‐products were formed, whose presence is environmentally risky for aquatic environments due to their low EC50 values.

Flavonoid-Labeled Biopolymer in the Structure of Lipid Membranes to Improve the Applicability of Antioxidant Nanovesicles.

Nanovesicles produced with lipids and polymers are promising devices for drug and bioactive delivery and are of great interest in pharmaceutical applications. These nanovesicles can be engineered for improvement in bioavailability, patient compliance or to provide modified release or enhanced delivery. However, their applicability strongly depends on the safety and low immunogenicity of the components. Despite this, the use of unsaturated lipids in nanovesicles, which degrade following oxidation processes during storage and especially during the proper routes of administration in the human body, may yield toxic degradation products. In this study, we used a biopolymer (chitosan) labeled with flavonoid (catechin) as a component over a lipid bilayer for micro- and nanovesicles and characterized the structure of these vesicles in oxidation media. The purpose of this was to evaluate the in situ effect of the antioxidant in three different vesicular systems of medium, low and high membrane curvature. Liposomes and giant vesicles were produced with the phospholipids DOPC and POPC, and crystalline cubic phase with monoolein/DOPC. Concentrations of chitosan-catechin (CHCa) were included in all the vesicles and they were challenged in oxidant media. The cytotoxicity analysis using the MTT assay (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) revealed that concentrations of CHCa below 6.67 µM are non-toxic to HeLa cells. The size and zeta potential of the liposomes evidenced the degradation of their structures, which was minimized by CHCa. Similarly, the membrane of the giant vesicle, which rapidly deteriorated in oxidative solution, was protected in the presence of CHCa. The production of a lipid/CHCa composite cubic phase revealed a specific cubic topology in small-angle X-ray scattering, which was preserved in strong oxidative media. This study demonstrates the specific physicochemical characteristics introduced in the vesicular systems related to the antioxidant CHCa biopolymer, representing a platform for the improvement of composite nanovesicle applicability.

Anchoring CoTiO3/TiO2 heterostructure on fiber network actuates flow-through Fenton-like oxidation: Electronic modulation and rapid pollutants degradation

Versatile catalytic oxidation filtration system, especially under low operating pressure conditions, is a frontier technology for organic wastewater purification. Herein, CoTiO3/TiO2 heterostructure was anchored on fiber network (CTO/TOF) to actuate flow-through peroxymonosulfate (PMS) based oxidation toward organics removal. The well-developed built-in electric field in CoTiO3/TiO2 heterostructure induced local charge redistribution, and promoted the targeted adsorption and activation of PMS, thereby facilitating the activation process. Meanwhile, the 3D network of CTO/TOF fully exposes active sites, providing an ideal platform for mass transfer and surface reactions. Above 91% for nimesulide degradation was maintained after 24 h of catalytic permeation under high permeate flux (300.7 L/m2·h), corresponding to ultrafast retention time (4.9 s). Practical application experiments demonstrated that CTO/TOF+PMS system had strong anti-interference capability under diverse conditions. Synergy of radical-nonradical mixed pathways for pollutant removal was verified by electron paramagnetic resonance spectra, quenching tests, and electrochemical measurements. The degradation intermediates and possible degradation pathways of nimesulide were also proposed. The toxicity assessments confirmed decreased toxicity of degradation products. This study is dedicated to designing high-performance filters and broadening Fenton-like oxidation in environmental remediation.