Quinolone Ring Research Articles

Pig manure biochar in soil forms catalytic system with endogenous H2O2 to degrade ciprofloxacin in purple soil

Biochar might improve ciprofloxacin (CIP) removal in soil, but little was known about how it goes on in purple soil. Thus, we investigated the variations of CIP in soil amended with pig manure (PM) derived biochar generated at 300℃ and 600℃ (PMC3 and PMC6). Compared with CK, PM, PMC3 and PMC6 decreased residual CIP by 42.3%, 48.8%, and 46.1%, respectively, confirming the enhancement of PM, PMC3 and PMC6 on CIP dissipation and indicating a higher performance of PMC3 and PMC6 in CIP removal than that of PM. Signal of persistent free radicals (PFRs) was observed in PMC3 and PMC6, which was contributed to the formation of O2·- and H2O2. Compared to PM, the secretion of H2O2 by microbe in PMC3 and PMC6 were enhanced by 71.5%-97.5% and 57.4%-79.5%, respectively. Meanwhile, catalase contents in PMC3 and PMC6 were reduced by 18.7%-68.6% and 8.4%-59.7%, respectively. These results suggested that H2O2 accumulated much easily in PMC3 and PMC6 than that in CK, which was benefited to the ·OH formation through the reaction between H2O2 and PFRs. Pearson correlation analysis identified that ·OH was the major contributor for 72.2%-80.2% of CIP removal in soil. In addition, degradation products were identified using UPLC-Q-TOF analysis. The results showed that the quinolone ring and piperazinyl ring were the main CIP degradation products. Under the action of ·OH, the piperazinyl ring in the CIP was completely destroyed. The phytotoxicity analysis was evaluated by bioreporter and Estimation Programs Interface (EPI) Suite. This study implies that biochar is a useful material for controlling CIP contamination through forming catalytic system with endogenous H2O2. These process insights have important implications for the pathway for CIP dissipation by biochar.

Degradation of norfloxacin by the synergistic effect of micro-nano bubbles and sodium hypochlorite: kinetics, influencing factors and pathways.

This study thoroughly investigated the degradation of norfloxacin (NOR) under the influence of micro-nanobubbles (MNBs) and sodium hypochlorite (NaClO), focusing on their synergistic effects. The impact of various environmental factors, including NaClO concentration, pH, inorganic anions, and surfactants, on NOR degradation efficiency within the MNBs/NaClO system was systematically assessed. The basic properties of the MNBs/NaClO system and the degradation kinetics of NOR were explored. The degradation products and pathways of NOR were explored to reveal the degradation mechanism of antibiotics in the MNBs/NaClO system by employing density functional theory (DFT) and high-performance liquid chromatography-mass spectrometry (HPLC-MS). The redox potential of the MNBs/NaClO system exhibited significantly superior properties than the single system, with bubble sizes predominantly in the nanoscale. The degradation kinetics of NOR adhered to a pseudo-first-order reaction model, with optimal degradation occurring at a 0.025% NaClO volume concentration. Acidic conditions promoted the degradation of NOR, and alkaline conditions inhibited the degradation of NOR. Inorganic anions PO43-, HCO3-, and CO32- in the water matrix led to strong inhibition of NOR degradation. Cationic surfactants accelerated the degradation process of NOR, while anionic and nonionic surfactants had a consistent inhibitory effect on the degradation of NOR. Based on the degradation behavior, three potential pathways for NOR degradation were proposed: quinolone group transformation, defluorination reaction, piperazine ring cracking and quinolone ring decomposition. This research contributes a novel technical approach for addressing antibiotic pollution and offers a theoretical framework for understanding the fate of antibiotics in the environment.

Degradation mechanism and ecotoxicity analysis of levofloxacin by palladium-modified nano zero-valent iron doped coconut shell biochar

The palladium-modified nano zero-valent iron (nZVI) doped coconut shell biochar (Pd-nZVI/BC) was successfully obtained through bimetallic modification and liquid-phase reduction. The synthesized Pd-nZVI/BC was further enhanced by the addition of an H2O2 co-catalyst for the removal of antibiotic levofloxacin (LVF). Results demonstrated that removal of LVF by Pd-nZVI/BC accomplished 94.6 % under proper conditions. Adsorption and degradation processes were involved in the LVF removal, and the predominant free radicals were •OH and •O2-. Adsorption relied mainly on electrostatic interactions, π-π interactions, and hydrogen bonding. While demethylation, deamidation, quinolone ring aldolization, depiperazinylation, deacetylation, decarboxylation, dehydroxylation, and oxidative breakage of the piperazine ring occurred during the degradation processes. Based on the degradation pathways, the ecotoxicity of LVF and its degradation intermediates were compared and assessed. Results implied that majority of the antibiotic LVF pollutant was eliminated or mineralized, and the toxicity potential of LVF was reduced in the Pd-nZVI/BC system. Simultaneous biochar utilization and pollutants removal could be achieved.

Sludge carbon promotes barium titanate piezoelectric property to activate persulfate degradation of enrofloxacin

AbstractBACKGROUNDPiezoelectric catalysis using perovskite‐type barium titanate (BaTiO3) has been applied to the decomposition of refractory organic pollutants through piezoelectric catalytic persulfate (PS). Nevertheless, challenges such as a limited specific surface area, poor electrical conductivity and a tendency towards agglomeration in BaTiO3 necessitate the exploration of novel methods to enhance its piezoelectric efficiency.RESULTSSludge carbon (SC) from sewage treatment and BaTiO3 was utilized to develop a novel piezoelectric catalytic material (BaTiO3/SC). The specific surface area of BaTiO3/SC reached 67.92 m2 g−1, which is nine times larger than that of BaTiO3 alone. The inclusion of SC in the composite enhanced the number of active sites and contributed to a higher degree of graphitization, improved electrical conductivity, and provided a more stable structure for BaTiO3/SC. This material was capable of harvesting mechanical vibration energy from ultrasound, thereby generating piezoelectric catalytic properties and activating PS to achieve a 93% decomposition ratio of enrofloxacin (ENR) in water within 80 min. The activation of PS by BaTiO3/SC piezocatalysis led to the production of reactive oxygen species (ROS), such as •OH and SO4−•. These ROS attack the quinolone ring of ENR, which is susceptible to cleavage, resulting in the decomposition of ENR into intermediates of lower toxicity.CONCLUSIONThe incorporation of SC has enhanced the piezoelectric performance of BaTiO3, rendering BaTiO3/SC a novel perovskite‐type piezoelectric catalytic material that improves piezoelectric efficiency. The BaTiO3/SC system, through its piezoelectric catalytic activation of PS, demonstrates potential for decomposition of refractory organic pollutants in water treatment. © 2024 Society of Chemical Industry (SCI).

Endogenous iron-enriched biochar loaded nickel-foam cathode in electro-Fenton for ciprofloxacin degradation: performance, mechanism and DFT calculation

Steel mill wastewater sludge, with abundant endogenous iron resources, could be pyrolyzed into iron-enriched biochar (SBC) in one step and loaded onto nickel foam cathode (Ni-Foam) to construct a heterogeneous electro-Fenton system (SBC@Ni-Foam/EF). The purpose of this study were to optimize SBC@Ni-Foam/EF for efficient ciprofloxacin (CIP) removal, and its degradation mechanism and pathway in the presence of endogenous iron were elucidated by DFT calculation. The results showed that the highest CIP degradation efficiency (95.11 %) was achieved at a SBC pyrolysis temperature of 800 °C, an initial solution pH of 3, a Na2SO4 concentration of 0.05 mol L−1, a current density of 40 mA cm−2, and an aeration rate of 200 mL min−1. The degradation of CIP by SBC@Ni-Foam/EF was dominated by cathodic catalytic oxidation, and ·OH played a major role in the CIP degradation process. Combined with characterization and DFT calculation, the endogenous iron was dispersed in the stable Fe3O4 crystalline phase, which provided surface defects and catalytic sites for the cathode and promoted H2O2 activation to generate ·OH through iron cycling. The possible degradation pathways of CIP were proposed to include the cleavage of piperazine and quinolone rings, hydroxylation, and substitution or detachment of fluorine, etc., and the overall toxicity of the intermediates was alleviated after SBC@Ni-Foam/EF treatment. Therefore, this study was expected to achieve a win–win situation for iron-enriched sludge biomass resource utilization and CIP wastewater treatment.

Efficient co-removal of aqueous Cr(VI) and ciprofloxacin by alkali lignin-derived carbon supported nanoscale zero-valent iron via adsorption and redox synergistic mechanisms

Developing an efficient co-removal strategy is crucial for the treatment of combined contaminants with heavy metals and antibiotics due to their great threat to sustainable advancement and ecological preservation. Herein, the efficient co-removal of aqueous hexavalent chromium (Cr(VI)) and ciprofloxacin (CIP) is achieved via a newly developed composite of nanoscale zero-valent iron particles embedded into alkali lignin-derived carbon (nZVI/ALC) without external assistance (such as light, advanced oxidants). nZVl/ALC demonstrates superior co-removal efficiencies of Cr(VI) (99.9 %) and CIP (89.9 %) with high removal kinetic rate constants of 1.595 and 0.779 min−1, respectively. The underlying mechanisms involving the co-removal of Cr(VI) and CIP verify that Cr(VI) ions are adsorbed onto the skeleton of nZVI/ALC originating from the electrostatic interaction, and CIP molecules adsorbed on nZVl/ALC act as a bridge, complexing with the Cr(VI) ions to promote Cr(VI) removal. Meanwhile, the CIP adsorption by nZVI/ALC involves hydrogen bonding, π-π interaction, and complexation. The coexisting Cr(VI) ions are transformed into Cr(III) components with abundant electron transfer, leading to the generation of more •O2– radicals, thus the self-generating reactive oxygen species (•OH, •O2– and 1O2) in ambient-air condition promote CIP degradation in the binary system. The CIP molecules’ degradation pathways mainly include piperazine ring cracking, piperazine epoxidation, quinolone ring opening and defluorination according to the analysis of HPLC-MS and FuKui function, along with the gradual reduction in toxicity throughout the degradation process of CIP molecules. This study offers a new insight on the co-removal of Cr(VI) and CIP, which would provide promising guidance for the remediation of compound wastewater with heavy metals and antibiotics.

Synthesis and Antimicrobial Activity of Newly Synthesized Nicotinamides.

Antioxidants are promising compounds with antimicrobial activity against drug-resistant pathogens, especially when combined with conventional antimicrobials. Our study aimed to characterize the structure of nicotinamides synthesized from nicotinic acid and thiocarbohydrazones and to evaluate their antibacterial and antifungal activity. Seven nicotinic acid hydrazides (NC 1-7) were synthesized using mono-thiocarbohydrazones with hydroxyl group substituents, along with quinolone, phenolic, and pyridine rings known for their antimicrobial activity. The in vitro antimicrobial activity of NC 1-7, at concentrations ranging from 0.001 to 1 mM, was tested against Staphylococcus aureus (ATCC 6538), Enterococcus faecalis (ATCC 29212), Pseudomonas aeruginosa (ATCC 27853), Klebsiella pneumoniae (NCIMB 9111), and Candida albicans (ATCC 24433) using the broth microdilution method per EUCAST 2024 guidelines. Microorganism survival percentages were calculated based on optical density, and target fishing using the PharmMapper database identified potential molecular targets. The results showed that P. aeruginosa was most susceptible to the compounds, while C. albicans was the least susceptible. NC 3 significantly inhibited P. aeruginosa and K. pneumoniae growth at 0.016 mM, while higher concentrations were required for S. aureus, E. faecalis, and C. albicans. NC 5 was most effective against gram-positive bacteria at 0.03 mM. Only NC 4 completely inhibited C. albicans below 1 mM. NC 3, with the lowest concentration for 50% growth inhibition (0.016-0.064 mM), showed promising antibacterial potential against specific AMR-related proteins (bleomycin resistance protein, HTH-type transcriptional regulator QacR, and streptogramin A acetyltransferase), suggesting that this class of compounds could enhance or restore the activity of established antibiotics.

Insight into the catalytic performances of Fe0@chitosan/cellulose green hybrid structure for enhanced photo-Fenton's oxidation of levofloxacin toxic residuals: Pathway and toxicity

A green hybridized structure of Fe0 painted chitosan/cellulose base (Fe0@CS/CF) has been developed using cellulose extracted from sugarcane bagasse along with reduction agents sourced from Khaya senegalensis leaves. The composite was assessed as an affordable, powerful, and multifunctional catalyst for enhancing the degradation of Levofloxacin (LVX) remnants within water supplies via photo-Fenton's interactions. Using a dosage of 0.5 g/L, the Fe0@CS/CF blend demonstrated noteworthy catalytic qualities, resulting in the complete photo-Fenton's degradation of LVX at a level of 25 mg/L after 40 min. However, the complete diminution of organic carbon (TOC) occurred only after 100 min, suggesting the presence of significant intermediate residues. The identified intermediate chemicals and confirmed hydroxyl radicals as the main oxidizer suggest that the degradation pathway involves carboxylation/decarboxylation, hydroxylation, demethylation, and oxidation of quinolone rings. The toxicity properties of untreated LVX solutions and their subsequent oxidized byproducts were assessed by evaluating their inhibiting impact on Vibrio fischeri over various durations. The samples that experienced partial oxidation at initial testing demonstrated a higher level of toxicity in comparison to the parent LVX. However, the sample that was treated for 100 min demonstrated substantial biological safety and a non-toxic nature. The blend of ingredients has a synergistic impact that enhances the uptake, Fenton's, photocatalytic, and photo-Fenton's characteristics of the hosted Fe0 nanoparticles.

Structural analysis of Kynurenic acid and derivatives by NMR spectroscopy and DFT calculations

The 4-quinolinone derivatives present a keto-enol tautomerism, which can be studied using different analytical techniques, including NMR. In this work, the spectroscopic study in solution of numerous derivatives with different substitution patterns in positions 1–4 of the quinolone rings, and their correlation with simulated spectra by density functional theory-gauge independent atomic orbitals method (DFT-GIAO) approximation is presented. Polyfunctionalized derivatives where the tautomeric equilibrium is blocked by N- or O-substitution allow us to observe the different behavior in chemical shifts by NMR. The study of some derivatives in the solid state by ss-NMR and X-ray Crystallography is also included.

Enhanced degradation of enoxacin using ferrihydrite-catalyzed heterogeneous photo-Fenton process

The ferrihydrite-catalyzed heterogeneous photo-Fenton reaction shows great potential for environmental remediation of fluoroquinolone (FQs) antibiotics. The degradation of enoxacin, a model of FQ antibiotics, was studied by a batch experiment and theoretical calculation. The results revealed that the degradation efficiency of enoxacin reached 89.7% at pH 3. The hydroxyl radical (∙OH) had a significant impact on the degradation process, with a cumulative concentration of 43.9 μmol L−1 at pH 3. Photogenerated holes and electrons participated in the generation of ∙OH. Eleven degradation products of enoxacin were identified, with the main degradation pathways being defluorination, quinolone ring and piperazine ring cleavage and oxidation. These findings indicate that the ferrihydrite-catalyzed photo-Fenton process is a valid way for treating water contaminated with FQ antibiotics.

Photocatalytic degradation of enrofloxacin with CoAl-LDH mediated persulfate system: Efficiency evaluations and reaction pathways

Residual enrofloxacin (ENR) exposed in aqueous environments is challenging to the ecosphere. In this work, a layered double hydroxide CoAl-LDH was used to activate the common oxidizing agent persulfate (PS) for photodegradation of ENR, and the degradation pathways of ENR were scrutinized and elucidated. The results indicated that, under the optimal conditions obtained through orthogonal experiments, even though the degradation rate of ENR was as high as 97.72%, the removal of total organic carbon (TOC) from the system was only about 30%. Eleven probable reaction pathways were categorized, and thirty-one types of intermediates were identified in participating in the complex degradation process. The major products of ENR were P4 (C17H20FN3O3), P22 (C19H22FN3O4), P19 (C17H18FN3O3), which are mainly derived from the cleavage of the piperazine groups and quinolone rings. Density functional theory (DFT) calculations of the Fukui index for ENR revealed that the two N atoms in the piperazine ring were the core reactive sites in triggering the degradation chains, which were sensitive for electrophilic attack by the dominant radicals (•OH and SO4•-) generated from the composite PS-UV-CoAl-LDH system.

How Should We Activate Ferrate(VI)? Fe(IV) and Fe(V) Tell Different Stories about Fluoroquinolone Transformation and Toxicity Changes.

Many studies have investigated activation of ferrate (Fe(VI)) to produce reactive high-valent iron intermediates to enhance the oxidation of micropollutants. However, the differences in the risk of pollutant transformation caused by Fe(IV) and Fe(V) have not been taken seriously. In this study, Fe(VI)-alone, Fe3+/Fe(VI), and NaHCO3/Fe(VI) processes were used to oxidize fluoroquinolone antibiotics to explore the different effects of Fe(IV) and Fe(V) on product accumulation and toxicity changes. The contribution of Fe(IV) to levofloxacin degradation was 99.9% in the Fe3+/Fe(VI) process, and that of Fe(V) was 89.4% in the NaHCO3/Fe(VI) process. The cytotoxicity equivalents of levofloxacin decreased by 1.9 mg phenol/L in the Fe(IV)-dominant process while they significantly (p < 0.05) increased by 4.7 mg phenol/L in the Fe(V)-dominant process. The acute toxicity toward luminescent bacteria and the results for other fluoroquinolone antibiotics also showed that Fe(IV) reduced the toxicity and Fe(V) increased the toxicity. Density functional theory calculations showed that Fe(V) induced quinolone ring opening, which would increase the toxicity. Fe(IV) tended to oxidize the piperazine group, which reduced the toxicity. These results show the different-pollutant transformation caused by Fe(IV) and Fe(V). In future, the different risk outcomes during Fe(VI) activation should be taken seriously.

Green synthesis of Co-Ce ZIF derivatives for enhanced O3/PMS degradation of levofloxacin

Antibiotics that permeate aquatic environments present significant risks to both ecosystems and human health. In this study, we employed the techniques of room temperature aqueous solution precipitation to fabricate ZIF-67 derivatives, and established a Co3O4/CeO2/O3/PMS (Co-Ce/OP) system. Furthermore, a 10 mg/L Levofloxacin (LEF) solution could reach rapid degradation (97.2%) and effective mineralization (40.4%) under specific conditions. Subsequent investigations identified the primary active substances, intermediates, and reaction mechanism in the Co-Ce/OP system. Evidence from Electron Paramagnetic Resonance (EPR) and quenching experiments indicates that SO4·-, OH·, O2·- and 1O2 contribute to the degradation process. Applying High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), we discovered that the principal degradation mechanisms for LEF encompass the cleavage and subsequent loss of the piperazine, quinolone, and morpholine rings, in addition to decarboxylation and defluorination reactions. Besides, we studied the acute toxicity, bioconcentration factor, developmental toxicity, and mutagenicity of LEF and its intermediate products. Our findings reveal a notable reduction in the toxicity of the intermediate products relative to LEF. Later experiment demonstrates that the degradation rate of LEF sustains above 90% after five cycles of reactions, indicative that the catalyst has excellent recyclability and stability. Furthermore, this study employed experiments across four different natural water matrices, demonstrating the system's considerable potential for effective application within authentic aquatic settings.

Degradation of enoxacin with different dissociated species during the transformation of ferrihydrite-antibiotic coprecipitates

Ferrihydrite acts as a natural reservoir for nutrient elements, organic matter, and coexisting pollutants through adsorption and coprecipitation. However, the degradation of emerging fluoroquinolone antibiotics during the transformation of ferrihydrite coprecipitates, especially those with various dissociated species, remains insufficiently explored. In this study, Enoxacin (ENO), employed as a model antibiotic, was introduced to prepare ferrihydrite-ENO coprecipitates. The influence of coprecipitated ENO on the transformation of the ferrihydrite-ENO coprecipitate was investigated across different pH conditions. The results revealed that ferrihydrite-ENO coprecipitates thermodynamically transformed into more stable goethite and/or hematite under all pH conditions. In neutral and alkaline conditions, ENO promoted the transformation of coprecipitates into goethite while hindering hematite formation. Conversely, under acidic conditions, ENO directly obstructed the transformation of coprecipitates into hematite. Different dissociated species of ENO displayed distinct degradation pathways. The cationic form of ENO exhibited a greater tendency for hydroxylation and defluorination, while the zwitterion form leaned toward piperazine ring oxidation, with limited preference for quinolone ring oxidation. The anionic form of ENO exhibited the fastest degradation rate. It is essential to emphasize that the toxicity of the degradation products was intricately connected to the specific reaction sites and the functional groups they acquired post-oxidation. These findings offer fresh insights into the role of antibiotics in coprecipitation, the transformation of ferrihydrite coprecipitates, and the fate of coexisting antibiotics.

Synthesis of novel cyano quinolone derivatives and their antibacterial activities

Seven cyano 4-quinolone derivatives were synthesized 2 (A-G) and the synthesized compound's antibacterial activity was tested. Structural elucidation of the synthesized compounds was carried out by their mass, infrared and N.M.R analysis. Antibacterial activity was evaluated against six bacterial strains e.g. Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Salmonella enterica and Pseudomonas aeruginosa. After the analysis of the antibacterial activity, it was inferred that compounds 2C and 2G were found to be more active against Gram-negative and Gram-positive bacteria and are found to be potential candidates for the antibacterial drug. A different approach of replacing the 6th position fluorine of the quinolone ring with the cyanide group was carried out. Compound 2E was found to be the most active with MIC values of 0.0047, 0.0031, 0.0013, 0.0011, 0.0008, 0.012 respectively. This research leads to the development of cyano4-quinolones.

Synthesis and Catalytic Degradation of PEF, ENR, and CIP by g-C3N4/TCNQ/Eu Composite.

By using melamine as a precursor for the copolymerization process, g-C3N4 and g-C3N4/TCNQ/Eu complexes with various amounts of doping were created. These complexes were then examined using XRD, FT-IR, SEM, TEM, XPS, PL, UV-vis, and I-T. The degradation rates of pefloxacin (PEF), enrofloxacin (ENR), and ciprofloxacin (CIP) were 91.1%, 90.8%, and 93.2% under visible light (λ > 550 nm). The photocatalytic performance of the composite was analyzed, and the best effect was obtained for CIP photocatalysis when Eu doping was 3 mg at 20 °C and pH 7. Kinetic analysis showed that there was a linear relationship between the sample and the photocatalytic time, and the degradation rate was about 5 times that of g-C3N4. The cyclic stability of the g-C3N4/TCNQ/Eu composite sample was found to be good through repeated experiments. UPLC-MS visualizes the degradation process of CIP. The extremely low stability of piperazine ring induced subsequent degradation, followed by the fracture of quinolone ring promoting the complete decomposition of CIP.

Chemical conversion of imine- into quinoline-linked covalent organic frameworks for photocatalytic oxidation

Post-synthetic modification is an important strategy for improving and enhancing the properties and functions of covalent organic frameworks (COFs). Two imine-linked COFs are converted into the quinolone-linked COFs by converting the dynamic imine linkages in the COFs into more robust quinolone ring via aza-Diels-Alder cycloaddition reaction. The prepared quinolone-linked COFs not only maintain good crystallinity and porosity, but also possess expanded conjugate planes, enhanced light absorption and excellent stability. The quinolone-linked COFs present remarkable performance of photocatalytic oxidation reactions, including oxidation of phenylboric acids, coupling of benzylamine, and oxidation of thioethers. This work is helpful for preparing organic porous photocatalytic materials with high performance and long life.

Unique roles of exfoliated bentonite in S-scheme BiOBr/Bi2MoO6 heterojunction for boosted ciprofloxacin degradation

S-scheme heterojunction retained the strong redox potential of catalysts, yet confronting severe photocorrosion and particle agglomeration, resulting in poor stability. Herein, the dual Bi-based S-scheme heterojunction supported by exfoliated bentonite (BiOBr/Bi2MoO6/BTex) was fabricated via a facile microwave hydrothermal strategy. BTex could promote the dispersion of photocatalysts and reinforce heterojunction stability through intensive surface interaction, thus reducing leakage of metal ions. The optimal BiOBr/10% Bi2MoO6/BTex exhibited excellent visible light photocatalytic performance and 94% ciprofloxacin (CIP) could be degraded within 120 min. Furthermore, the high catalytic efficiency could be maintained within the pH range from 5 to 9, and efficient degradation of tetracycline and dyes could also be achieved. Basing the analysis of band structures and determination of active species, enhanced separation and migration efficiency of photogenerated carriers could be ascribed to the synergistic effect of internal electron field (IEF) from heterojunction and surface charge repulsion from BTex. Additionally, the susceptible sites of CIP were obtained by density functional theory calculations, and three possible degradation pathways, including breakage of the quinolone ring, oxidation of the piperazine ring and defluorination were speculated combined with HPLC-MS results. With prolonging photocatalysis time, the diminished toxicity of intermediates was confirmed. This study supplied new insights to improve performance and control morphology of S-scheme heterojunctions by introducing cost-effective nature bentonite.

A biochar-based catalyst prepared by potassium ferrate oxidation coupled high-temperature pyrolysis and its application for the activation of peroxymonosulfate towards the degradation of norfloxacin: Performance and mechanism insight

Developing an efficient catalyst for persulfate activation is critical to the high-efficiency degradation of organic pollutants in an aqueous solution using a persulfate-based advanced oxidation method. A biochar-based catalyst, 800Fe2BC2, was prepared using a novel technology of potassium ferrate oxidation coupled with high-temperature pyrolysis based on the biomass raw material of waste branches pruned from apple trees in an orchard. Batch tests were conducted to degrade norfloxacin using 800Fe2BC2 to activate peroxymonosulfate (PMS). Norfloxacin was almost completely degraded within 10 min. The reactive oxygen species (ROS), for instance, •OH, SO4•−, O2•−and 1O2, were generated in the 800Fe2BC2/PMS system. The iron oxides, defective structures, and CO groups in 800Fe2BC2 served as catalytic sites for generating free radicals. However, the recombination of superoxide radicals, the interaction of CO groups on the catalyst surface with PMS, and the self-decomposition of PMS contributed to generating 1O2. The quenching test showed that the degree of the contribution of •OH, SO4•−, O2•−and 1O2 to NOR degradation was approximately 1O2 > O2•− > SO4•− > •OH, respectively. We proposed three potential NOR degradation pathways: piperazine ring opening (P), quinolone ring oxidation (Q), and benzene ring defluorination (F). Then part of these intermediates was completely mineralized into inorganics like CO2, H2O, NO3− and F−. The acute and chronic toxicity of the degradation products were estimated, and the evolution of toxicity in the present catalytic system could not be ignored and should be overcome by deeper mineralization. The prepared 800Fe2BC2 demonstrated a good application prospect with good stability, recyclability, low metal leaching, and versatility to various refractory pollutants. Therefore, this study offered a new way of producing biochar-based catalysts for activating PMS using biomass wastes.

Proficient protocol for synthesis of Quinoline and Pyrazole derivatives using greener reagent: Glycerol

A forthright, effectual and more viable catalyst-free method has been developed for the synthesis of quinolone and pyrazole ring system in glycerol to achieve yields that were equivalent to or better than, those in conventional media. It is notable that the reaction was exclusively carried out in glycerol–acetic acid system, representing methodology is highly valuable from both environmental and economic points of view