Norfloxacin Research Articles

Phytotoxic effects on chloroplast and UHPLC-HRMS based untargeted metabolomic responses in Allium tuberosum Rottler ex Sprengel (Chinese leek) exposed to antibiotics

Introduction of antibiotics into agricultural fields poses serious health risks to humans. This study investigated the uptake of antibiotics, their effects on metabolic pathways, and chloroplast structure changes of Allium tuberosum exposed to norfloxacin (NFL), oxytetracycline (OTC), and tetracycline (TC). Among all the antibiotic treatments, the highest accumulation of antibiotics in roots (4.15 mg/kg) and leaves (0.29 mg/kg) was TC, while in bulbs it was NFL (5.94 mg/kg). OTC was with the lowest accumulation in roots: 0.19 mg/kg, bulbs: 0.18 mg/kg, and leaves: 0.11 mg/kg. The number of mitochondira and the number of plastoglobulli increased. The chloroplast structure was disturbed under the stress of NFL, OTC, and TC. Disturbance in the chloroplast ultrastructure leads to altered chlorophyll fluorescence variables. Simultaneously, metabolomic profiling of leaves demonstrated that NFL stress regulated more of metabolic pathways than OTC and TC. Differences in metabolic pathways among the antibiotic treatments showed that each antibiotic has different impact even under the same experimental conditions. TC and NFL have more toxic effects than OTC antibiotic. Metabolic variations induced by antibiotics stress highlighted pools of metabolites that affect the metabolic activities, chlorophyll fluorescence, ultrastructural adjustments, and stimulate defensive impact in A. tubersoum. These findings provide an insight of metabolic destabilization as well as metabolic changes in defensive mechanism and stress response of A. tuberosum to different antibiotics.

A biocompatible bismuth based metal-organic framework as efficient light-sensitive drug carrier

The low toxicity and good photo active property endow bismuth based metal–organic frameworks (MOFs) potential candidates for efficient light-sensitive drug carrier. In this work, SU-101, composed of Bi and ellagic acid (EA), is found to display high ciprofloxacin (CIP) loading ratio (85.8%) and controlled CIP release under light illumination (the maximum CIP release ratio is 95.56%). Further investigations suggest that hydrogen bond between the CO group in EA and the –OH group in CIP is responsible for above behavior. Light irradiation decreases the electron density around the CO group in EA, which consequently leads to the broken of the hydrogen bond and therefore the release of CIP. Further investigations suggest that SU-101 is universal for other drugs, such as norfloxacin (NOR), amoxicillin (AMO), tetracycline (TET) and doxorubicinhydrochloride (DOX), since all of them can form hydrogen bond with SU-101. This work suggests that SU-101 holds great potential as efficient light-sensitive drug carrier, and the investigation of other Bi based MOFs as drug carrier is under investigation.

Activation of hydrogen peroxide by graphite supported H2SO4-CeO2 for isoniazid degradation under neutral pH

Abstract Graphite felt (GF) supported cerium oxide (CeO2) composite with sulfation pretreatment (H2SO4-CeO2/GF) was prepared by the impregnation method and employed as the catalyst to activate H2O2 for degradation of isoniazid (INH). The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectrum (XPS). The results showed that H2SO4-CeO2/GF had good properties in activating H2O2 for the degradation of INH. The INH removal was about 89.4% in 120 min under the following conditions: H2O2 2.94 mM, H2SO4-CeO2/GF 2.6 g/L, INH 10 mg/L, initial pH at 6.8 and temperature at 25 °C. The effects of some reaction parameters, including initial H2O2 concentration, initial INH concentration, initial pH value, the catalyst dosage and reaction temperature, on INH degradation were investigated. On the basis of mechanism study and intermediate analysis, the possible degradation pathway of INH was proposed. Besides, effective degradation of methyl orange (MO) and norfloxacin (NOF) also confirmed the high activity of H2SO4-CeO2/GF in activation of H2O2. The H2SO4-CeO2/GF was relatively stable, showing good application prospects.

Bisligand-coordinated cadmium organic frameworks as fluorescent sensors to detect Ions, antibiotics and pesticides in aqueous solutions

Three bisligand-coordinated two-dimensional or one-dimensional cadmium-based luminescent coordinated polymers, namely, [Cd3(BTC)2(DTP)(H2O)6]·(H2O)2.5 (1) (BTC = benzene-1,3,5-tricarboxylic acid and DTP = 3,5-di(1,2,4-triazol-1-yl)pyridine); [Cd2(IPA)2(DTP)(H2O)4]·(H2O)3(DMF)2 (2) (IPA = isophthalic acid and DMF = dimethylformamide); and [Cd4(DFDA)4(DTP)2(H2O)8]·(H2O)17 (3) (DFDA = 2,5-dihydrofuran-2,5-dicarboxylic acid), were constructed by solvothermal synthesis. The obtained MOFs were characterized by employment of single crystal X-ray diffraction, powder XRD analysis, elemental analysis, IR, TGA and luminescence analysis. Fluorescence sensing experiments show that complexes 1–3 are effective and selective in sensing MnO4−, Fe3+ and Cr2O72−. For the analysis of antibiotics and pesticides, complex 1 exhibited the highest quenching rates for norfloxacin (NOR) and nitenpyram (NTP). For complexes 2–3, cefixime (CFX) and metamitron (MMT) caused the most obvious fluorescence quenching of all of the tested antibiotics and pesticides, respectively. During the sensing processes, both the inner filter effect (IFE) and fluorescence resonance energy transfer (FRET) play a key role in fluorescence quenching for all three complexes.

Norfloxacin co-amorphous salt systems: Effects of molecular descriptors on the formation and physical stability of co-amorphous systems

Amorphization technology has been a promising strategy to improve the solubility and dissolution of drugs. This study aims to prepare norfloxacin (NFX) co-amorphous (CA) systems and evaluate the association between molecular descriptors and the formation and physical stability of NFX CAs. The molecular miscibility between NFX and 17 co-former candidates was firstly predicted using Hansen solubility parameters (HSPs) and six NFX CAs were successfully prepared by dry ball mill. Compared with crystalline NFX, four NFX CAs showed enhanced solubility (up to 2.50-fold) and dissolution rates. NFX CAs exhibited excellent physical stability under dry conditions. According to the quantitative calculations of Pearson correlation coefficient and Ridge regression, molecular descriptors have a great effect on NFX CA formation with structural parameters (Weight, VDW_vol, VDW_area, Rings) stronger than miscibility parameter Δ δ¯ and pKa. These molecular descriptors corresponding to π···π interactions, molecular miscibility and ionic interactions are also responsible for physical stability. The results demonstrate that NFX CA can be stably formed if the co-former has more rings, smaller Δ δ¯ (less than or close to 5 MPa0.5) and larger ΔpKa. This study offers a potential strategy to screen and design a CA system using multivariate data analysis based on theoretical considerations of molecular descriptors.

ANTIMICROBIALS IN ANIMAL FAECES (CHICKEN, COW AND SWINE) FROM THE BREEDING FARMS IN THE UPSTREAM OF SAI GON RIVER

The widespread use of antimicrobials in husbandry has increased antimicrobial residues in animal faeces. Therefore, the investigation of antimicrobials in animal faeces is essential because they are the main cause of environmental pollution. This study analyzed and assessed samples of chiken, cow and swine faeces for seven antimicrobials, namely trimethoprim (TRI), ormethoprim (ORM), ofloxacin (OFL), norfloxacin (NOR), tetracycline (TET), chlortetracycline (CTE) and tylosin (TLS). Samples were taken from faeces heaps at breeding farms in the upstream of the Sai Gon river. The samples were analyzed in the laboratory by using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine antimicrobials. TRI, with the highest mean concentration, was found in all fecal samples (10,399 - 47,987 mg/kg) while ORM with the lowest average concentration was only detected in chicken fecal samples (542 mg/kg). CTE, with the second high mean concentration, was also found in all fecal samples (1,085 - 12,385 mg/kg), whereas TET was only detected in chicken fecal samples (9,050 mg/kg). OFL with the third average concentration, was aloso found in all fecal samples (1,516 - 9280 mg/kg), while NOR was detected in cow fecal samples at a low mean concentration (2,479 mg/kg). TLS was only found in chicken and cow fecal samples (798 - 5,802 mg/kg). These numbers show a very large amount of consumption of antimicrobials in livestock production. The results from this study are likely to encourage further monitoring of antimicrobials used in livestock production, and promote discussion of existing policies regarding the inclusion of antimicrobials in animal feed rations and veterinary medicines.

The magnetically recoverable C-ZnFe2O4 as a microwave absorption catalyst for the degradation of norfloxacin by persulfate: Mechanism, degradation pathway, toxicity, and stability

Norfloxacin (NOR), a widely used fluoroquinolone antibiotic, has been a focus of attention in recent years due to its adverse effect on human beings and aquatic ecosystems. Magnetic C-ZnFe2O4 (C-ZFO) composite was fabricated by a one-step hydrothermal method and characterized via SEM, TEM, XRD, XPS, VSM. Under given conditions:[NOR] = 5 mg/L, [persulfate (PS)] = 0.25 mM, [pH]0 = 6.7, [C-ZFO] = 1.5 g/L, MW = 400 W, T = 70 ℃, the degradation of NOR reached 86.2% in 40 min, and the highest TOC removal ratio reached 69.6%. The presence of active species (SO4·−,·O2−, HO·, h+) was monitored in C-ZFO activated persulfate under microwave irradiation system (MW-C-ZFO/PS) through radical scavenger study. Meanwhile, intermediate products of NOR and five possible degradation pathways were identified using HPLC-MS. Moreover, the toxicity of NOR intermediates was analyzed by the Vibrio fischeri to evaluate the health risk of the treated water. Overall, microwave irradiation is an efficient technology for degrading NOR in environmental remediation.

Enhancement of Fenton processes at initial circumneutral pH for the degradation of norfloxacin with Fe@FeS core–shell nanowires

ABSTRACT The disadvantages of narrow working pH range (2.5–4.0), accumulation of iron sludge and incomplete degradation have hindered the practical application of the traditional homogeneous Fenton technique. In this research, Fe@FeS core–shell nanowires were synthesised and the innovative Fe@FeS/Fe2+/H2O2 system was adopted for norfloxacin (NOR) degradation at an initial circumneutral pH. More than 95% NOR has been removed in the Fe@FeS/Fe2+/H2O2 system within 30 min at pH 7. After investigating the concentration change of total iron, Fe2+ and H2O2 during the degradation process, NOR degradation in the Fe@FeS/Fe2+/H2O2 system might be attributed to the combined effect of homogeneous Fenton reaction and heterogeneous Fenton process. Besides that, the added Fe@FeS has accelerated Fe3+/Fe2+ redox cycle with extremely high degree. The generated reactive ●OH has been identified by electron paramagnetic resonance spectrometer results, possible degradation intermediates have also been proposed according to Gas chromatography-mass spectrometry analysis results. Moreover, Fe@FeS core–shell nanowires showed excellent reusability, it is a promising heterogeneous Fenton catalyst that is applicable for practical application.

High-capacity NCNT-encapsulated metal NP catalysts on carbonised loofah with dual-reaction centres over C–M bond bridges for Fenton-like degradation of antibiotics

The intensification of electron transport between the dual-reaction centres in Fenton-like catalyst is demonstrated through the incorporation of carbon-metal (C–M) bond bridges. Herein, nitrogen-doped carbon nanotube-encapsulated Fe3C (Fe3C@NCNT) with dual-reaction centres over short C–Fe bond was constructed through DFT calculation, and accordingly a series of NCNTs-encapsulated Fe/Fe3C, Co, and Mo2C nanoparticles on carbonised loofah were developed by dynamic thermal impregnation and subsequent pyrolysis process. The resultant catalysts displayed satisfactory degradation properties of antibiotics, in which Fe/Fe3C@NCNTs-CL-800 achieved norfloxacin (NOR) removal efficiency of 93.8% in 90 min under neutral pH, and presented excellent cycle stability in NOR removal as well as universality in various antibiotic degradation systems. The remarkable degradation performance of heterogeneous Fenton-like catalysts was attributed to enhancing electron transport to electron-rich M centres over short C–M bond bridges. This study will open a new perspective on the rational design of catalysts for Fenton-like degradation.

Groundwater antibiotics and microplastics in a drinking-water source area, northern China: Occurrence, spatial distribution, risk assessment, and correlation

In recent years, antibiotics and microplastics have both received increasing attention. However, the contamination and correlation between the two pollutants in the groundwater of drinking-water source areas has not yet been considered. In this study, eight antibiotics were detected in 81 groundwater samples from a drinking-water source area. These were trimethoprim (TMP), sulfadimidine (SDD), sulfadiazine (SDZ), sulfamethoxazole (SMX), sulfachloropyridazine (SCP), norfloxacin (NOR), ciprofloxacin (CIP) and enrofloxacin (ENRO). Detection rates ranged from 1.23% to 95.06% and the maximum concentration ranged from 0.44 ng/L to 45.40 ng/L. Antibiotics in the groundwater pose no threat to human health, while only ENRO, CIP, NOR, SMX, and SDZ posed medium to low risks to the aquatic ecosystem. In contrast, the detection rate of microplastics was 100% with abundance values ranging from 4 n/L to 72 n/L, with an average of 29 n/L. Microplastic polymers were identified as polyamide, polyethylene, polypropylene, polyvinyl chloride and polystyrene. These also occurred in surface water but the particle sizes in groundwater were lower than those in the surface water. Through correlation analysis, it was found that NOR, ENRO and total antibiotic concentrations were significantly correlated with microplastic abundances. This study revealed the contamination and potential risks of antibiotics and microplastics in the groundwater of a drinking-water source area and found a correlation between them, indicating that risk management of antibiotics and microplastics in groundwater should be highly concerned.

Effects of long-term exposure of norfloxacin on the HPG and HPT axes in juvenile common carp.

Currently, there is a relatively lack of relevant research on the interference effect of quinolone antibiotics on the endocrine of aquatic animals. In this study, the toxicity of norfloxacin (NOR) on the endocrine system of juvenile common carp (Cyprinus carpio) was evaluated, as well as the hematocyte parameters. Specifically, two important endocrine axes were assessed: the hypothalamus-pituitary-thyroid (HPT) axis and hypothalamus-pituitary-gonadal (HPG) axis. Norfloxacin was used as a representative of quinolone antibiotics. According to the concentration of water pollution areas and considering the bad situation that may be caused by wastewater discharge, a control, 100ng/L NOR, and 1mg/L NOR treatment groups were set up. The juvenile carp, as the test animal, was subjected to an exposure experiment for 42days. Thyroid hormones (T3 and T4) and related genes in HPT axis and sex hormones (11-ketotestosterone [11-KT] and progesterone [PROG]) and related genes in HPG axis and blood count are tested. It was found that the T4 iodine level and conversion process were enhanced after NOR treatment, which in turn led to the increase of T3 content and biological activity in the blood. One hundred nanograms per liter NOR can inhibit the level of sex hormones and inhibit the expression of HPG axis-related genes. In the 1mg/L NOR treatment group, long-term exposure over a certain concentration range may lead to the development of adaptive mechanisms, making the changes in hormones and related genes insignificant. In conclusion, this study provides reference data for the endocrine interference of quinolone antibiotics on aquatic organisms, and has ecological significance for assessing the health of fish populations of quinolone antibiotics. However, the specific sites and mechanisms of action related to the effects of NOR on the endocrine system remain unclear and require further study.

Antifouling and antibacterial zwitterionic hydrogels as soft contact lens against ocular bacterial infections

Antifouling and antibacterial zwitterionic hydrogels were prepared and used as soft contact lens for ocular bacterial infections therapy. The zwitterionic hydrogels are mainly composed of zwitterionic segments and tuned by a small part of other hydrophilic and hydrophobic monomers for optimal properties, which achieve high transmittance of 94% in the range of visible wavelength, high water content, good water retention rate and stable dehydration-rehydration property. Moreover, even after five co-culture cycles with non-specific protein and bacteria, the zwitterionic hydrogels showed much better antifouling properties than the commercial contact lens (CL). Besides, functional monomer acrylic acid was incorporated in the zwitterionic hydrogels to load norfloxacin (NF) and control its release by molecular imprinting technology. Thus, the zwitterionic hydrogels have significant in vitro and in vivo bactericidal function. By constructing a conjunctivitis model of rabbits, we found that delivery of NF by the zwitterionic hydrogels had a better therapeutic outcome than delivery of NF through eye-drops. These results indicate that the zwitterionic hydrogels are competitive candidates for the application of wearing contact lens and ophthalmic drug delivery.

Improved degradation of tetracycline, norfloxacin and methyl orange wastewater treatment with dual catalytic electrode assisted self-sustained Fe2+ electro-Fenton system: Regulatory factors, mechanisms and pathways

The environmental hazards associated with the presence of antibiotics and dyes in water sources require the development of efficient and appropriate wastewater treatment technologies. In the research, a dual catalytic electrode assisted self-sustained Fe2+ electro-Fenton system was constructed to degrade tetracycline, norfloxacin and methyl orange in wastewater efficiently and economically. The novel titanium mesh based PbO2/SnO2 anode electrode was prepared by electrodeposition with the best oxidation performance at the ratio of Sn to Pb 0.5:1, and silver doped Zinc-based organic framework ([email protected]) mixed crystal cathode catalyst was synthesized by precipitation at room temperature. Meanwhile, a sacrificial iron anode was introduced into the system in an acidic solution without a power supply, realizing the endogenous supply of Fe2+. The results indicated that the process was capable of self-supporting H2O2 and Fe2+ under the optimized conditions of pH range of 3.5–4.0, iron area of 10 cm2 and current intensity of 9 mA. The current efficiency was calculated to be as high as 369.5%. The type of conductive substrate supported cathode catalyst is an important factor determining the performance of the novel coupled electric-Fenton system. Electro-Fenton system using [email protected] catalytic electrode loaded with conductive substrates (stainless steel mesh (SS), carbon felt (CF), and activated charcoal granules (ACG)) was constructed to degrade tetracycline (TC), with the degradation efficiencies of 100% (k = 0.03048), 99.7% (k = 0.01831), 99.7% (k = 0.01421). Moreover, the experiment group of [email protected] electrode had achieved good degradation effects for TC, norfloxacin (NOR), methyl orange (MO), and the degradation efficiency was 99.1%, 92.8% and 100%, respectively. The possible degradation pathways of TC, NOR and MO were proposed by analyzing the intermediates. This work demonstrates the scaling-up potential of the system in the treatment of antibiotics and dye wastewater.

Antimicrobial Resistance and Antibiogram of Thermotolerant Campylobacter Recovered from Poultry Meat in Baghdad Markets, Iraq.

Antimicrobial resistance is a critical public health issue that affects people all over the world. Since bacteria have a proclivity for rapidly acquiring and propagating the resistance gene, antimicrobial-resistant Campylobacter has a negative impact on public health. As a result, the creation of new and highly pathogenic clones is facilitated, making antimicrobial treatment more challenging. This study aimed to determine the antimicrobial resistance pattern (ARP) models, multiple drug resistance (MDR) models, and multiple antibiotic resistance (MAR) index of Campylobacter species isolated from poultry meat sold in Baghdad markets, Iraq. By employing the disc diffusion test, 30 Campylobacter strains from chicken meat, including C. jejuni (n=10) and C. coli (n=20), were exposed to tetracycline (TET), erythromycin, Gentamicin, nalidixic acid, ciprofloxacin, and norfloxacin (NOR). The ARP of the Campylobacter isolates revealed up to five antibiotypes for two species, which revealed resistance to one or more antimicrobials, and 67% of them had MDR resistance to two or more experienced antimicrobials. The NOR-TET model is the most common MDR, having a prevalence of 30% among experienced isolates. In addition, the MAR index, equal to and lower than one, was found in 87% of the isolates. Antibiotic resistance in Campylobacter raises the probability of treatment failure in humans and animals, as well as the propagation of antimicrobial resistance genes. As a result, the presence of Campylobacter in meat could pose a risk of human infection and pollution of the environment.

A study on the adsorption behaviors of three hydrophobic quinolones by ordered mesoporous CMK-3

In this work, a series of ordered mesoporous carbon nanomaterials (CMK-3) have been synthesized by a hard-template method at temperatures of 80 °C, 100 °C and 130 °C, which can serve as adsorbents for efficient adsorption of quinolones in aqueous solutions. The physicochemical properties and the morphologies of these CMK-3 have been well characterized, showing mesoporous channels with the specific surface area reaching up to 1290 m2/g. Adsorption studies have been performed on three hydrophobic quinolones: norfloxacin (NOR), ciprofloxacin (CIP) and enrofloxacin (ENR), with the adsorption capacities of 403 mg/g, 479 mg/g and 510 mg/g, respectively, at room temperature. The adsorption kinetics of the three quinolones are in accordance with the pseudo-second kinetic model, and the adsorption isotherm curves conform to Langmuir isotherm model. Significantly, the adsorption thermodynamics confirms that the adsorption processes are spontaneous endothermic. Finally, the adsorption mechanism has been discussed, which can be attributed to the synergistic effect of pore diffusion, hydrophobic bond, and electron donor-acceptor interaction.

Role of Efflux Pump-Mediated Antibiotic Resistance in Quorum Sensing-Regulated Biofilm Formation by Salmonella Typhimurium.

This study was designed to assess the influence of efflux pump activity on the biofilm formation in Salmonella Typhimurium. Salmonella enterica subsp. enterica serovar Typhimurium ATCC 19585 (STWT) and clinically isolated S. Typhimurium CCARM 8009 (STCI) were treated with ceftriaxone (CEF), chloramphenicol (CHL), ciprofloxacin (CIP), erythromycin (ERY), norfloxacin (NOR), and tetracycline (TET) in autoinducer-containing media in the absence and presence of phenylalanine-arginine β-naphthylamide (PAβN) to compare efflux pump activity with biofilm-forming ability. The susceptibilities of STWT and STCI were increased in the presence of PAβN. ERY+PAβN showed the highest decrease in the minimum inhibitory concentration (MIC) of ERY from 256 to 2 μg/mL against STWT and STCI. The antimicrobial activity of NOR against planktonic cells was significantly increased in the presence of PAβN, showing the lowest numbers of STWT (3.2 log CFU/cm2), and the TET+PAβN effectively inhibited the growth of STCI (5.2 log CFU/cm2). The lowest biofilm-forming abilities were observed at NOR+PAβN against STWT (biofilm-forming index, BFI < 0.41) and CEF+PAβN against STCI (BFI = 0.32). The bacteria swimming motility and relative fitness varied depending on the antibiotic and PAβN treatments. The motility diameters of STWT were significantly decreased by NOR+PAβN (6 mm) and TET+PAβN (15 mm), while the lowest motility of STCI was observed at CIP+PAβN (8 mm). The significant decrease in the relative fitness levels of STWT and STCI was observed at CIP+PAβN and NOR+PAβN. The PAβN as an efflux pump inhibitor (EPI) can improve the antimicrobial and anti-biofilm efficacy of antibiotics against S. Typhimurium. This study provides useful information for understanding the role of efflux pump activity in quorum sensing-regulated biofilm formation and also emphasizes the necessity of the discovery of novel EPIs for controlling biofilm formation by antibiotic-resistant pathogens.

Enhanced adsorption of fluoroquinolone antibiotics on Cu-modified porous boron nitride nanofibers in aqueous solution

The microecology and human health threats caused by the abuse of antibiotics are increasingly serious, for which it is urgent to develop highly efficient adsorbents. In the current study, Cu modified porous boron nitride nanofibers (BNNF-Cu) with uniform distributions and stable structures were successfully synthesized. The surface area of BNNF-Cu can reach to 737.194 m2 g−1, which includes porous microstructure and rich surface groups. The removal performance of BNNF-Cu as an adsorbent for ofloxacin (OFL) in aqueous solution was systemically studied. Due to the addition of modifier copper, the adsorption capacities for fluoroquinolones pollutants including OFL, norfloxacin (NOR) and enrofloxacin (ENR) were greatly enhanced. The adsorption kinetic data and equilibrium adsorption isotherms are in line with the pseudo-second-order and the Freundlich models (R2 = 0.999), respectively, indicating that the adsorption of OFL onto BNNF-Cu was mainly multilayer chemisorption. Significantly, the adsorbent exhibits excellent removal percentage for OFL (99.74%) and the maximum adsorption capacity can reach to 305.32 mg g−1 at the pollutant concentration of 100 mg L−1. In addition, the influences of pH, temperatures and salinity on adsorption were also further researched. The outstanding removal efficiency can be maintained after several cycles, which proves excellent reusability. Finally, the BNNF-Cu adsorbent can offer a wide range of possibilities to eliminate antibiotics efficiently in industrial wastewater.

Magnetic Fe2O3/biochar composite prepared in a molten salt medium for antibiotic removal in water

The large-scale use of antibiotics is causing serious water pollution problems, and it is of great significance to develop new technologies to remove antibiotics from water. As an environmentally friendly and economical adsorption material, carbon derived from biomass is a low-cost and feasible material for removing antibiotics in sewage, but the current removal efficiencies are not high enough for large-scale practical application. In this study, poplar wood chips are used as raw material, and a magnetic biochar is prepared by co-pyrolysis of poplar wood chips and FeCl3/CaCl2 mixed molten salt. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2-isothermal adsorption and desorption, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) techniques showed the successful synthesis of Fe2O3/bioC composite. In-situ formed Fe2O3 makes the biochar possess the characteristic of superparamagnetic, which is conducive to the recycling of biochar. Due to the etching effect of the molten salts, rough surface was formed on Fe2O3/bioC, resulting in a maximum norfloxacin (NOR) adsorption ability up to 38.77 mg g−1 at pH 6.0. The NOR adsorption behavior on Fe2O3/bioC followed the pseudo second order kinetic model and the equilibrium data was best fitted the Langmuir model. In addition, the adsorption process of NOR on Fe2O3/bioC was thermodynamically spontaneous. The results show that this low-cost and reusable magnetic biochar has the potential for rapid and efficient removal of antibiotic from aqueous solution.

Synergy between cobalt and nickel on NiCo2O4 nanosheets promotes peroxymonosulfate activation for efficient norfloxacin degradation

Developing an ultraefficient heterogeneous catalyst for peroxymonosulfate (PMS) activation at a wide pH range is a challenge. Herein, ultrathin NiCo2O4 nanosheets (NiCo2O4NS, ~1 nm), with the dominant exposure of (311) facet, was designed for PMS activation. The NiCo2O4NS/PMS system exhibited superior degradation of norfloxacin (NOR) over a wide pH range. The synergistic effects between Ni and Co were the dominant activation mechanism. Compared with Co3O4, NiCo2O4NS adsorb PMS through a unique “bridge” mode, where both Co and adjacent Ni interact with the same O atom in PMS, increasing the number of electron transfer for enhanced breakage of OO bond. NiCo2O4NS with high cycling stability, could reach 100% degradation of other typical pollutants, and showed higher degradation performance in actual wastewater. This work unveils the intrinsic origin of the superior activity of Co-Ni spinel oxides for PMS activation for the first time, and demonstrates its application potential for organic contaminants degradation.

Degradation of norfloxacin by MOF-derived lamellar carbon nanocomposites based on microwave-driven Fenton reaction: Improved Fe(III)/Fe(II) cycle

In this paper, a new type of iron-based magnetic nanoparticle material embedding mesoporous carbon (Fe@C700) was prepared by simple pyrolysis of a MIL-101-Fe precursor and employed in the microwave-catalyzed degradation of norfloxacin (NOR) with the presence of H2O2. Characterization results showed successful anchoring of Fe0 nanoparticles in the carbon matrix. Under optimal treatment conditions (Calcination temperature = 700 °C, H2O2 dosage = 40 mM, MW power = 500 W, NOR dosage = 50 mg L−1 and initial pH = 4), the degradation efficiency of NOR reached 95.22%. The catalyst showed exceptional degradation properties over a relatively wide pH range. The mesoporous carbon in the catalyst promoted electron transfer, enhanced the Fe(III)/Fe(II) cycle, increased contact between Fe0 and Fe2+ with H2O2, and accelerated the production of ·OH. Furthermore, density functional theory (DFT) calculations were used to predict the fragile active sites in NOR and to analyze the degradation pathway of NOR in combination with intermediates. Fe@C700 retained good activity after 5 cycles. Reduced toxicity of intermediates predicted by T.E.S.T. compared to NOR. This study presented a new avenue for the rational design of Fe0-carbon composites as microwave-assisted Fenton-like catalysts for potential applications in wastewater treatment.