Enhancement of ionizing radiation-induced catalytic degradation of antibiotics using Fe/C nanomaterials derived from Fe-based MOFs

Gamma irradiation induced degradation of organic pollutants: Recent advances and future perspective

Different organic compounds in aquatic bodies have been recognized as an emerging issue in Environmental Chemistry. The gamma irradiation technique, as one of the advanced oxidation techniques, has been widely investigated in past decades as a technique for the degradation of organic molecules, such as dyes, pesticides, and pharmaceuticals, which show high persistence to degradation. This review gives an overview of what has been achieved so far using gamma irradiation for different organic compound degradations giving an explanation of the mechanisms of degradations as well as the corresponding limitations and drawbacks, and the answer to why this technique has not yet widely come to life. Also, a new approach, recently presented in the literature, regards coupling gamma irradiation with other techniques and materials, as the latest trend. A critical evaluation of the most recent advances achieved by coupling gamma irradiation with other methods and/or materials, as well as describing the reaction mechanisms of coupling, that is, additional destabilization of molecules achieved by coupling, emphasizing the advantages of the newly proposed approach. Finally, it was concluded what are the perspectives and future directions towards its commercialization since this technique can contribute to waste minimization i.e. not waste transfer to other media. Summarizing and generalization the model of radiolytic degradation with and without coupling with other techniques can further guide designing a new modular, mobile method that will satisfy all the needs for its wide commercial application.

Application and Development Prospect of Nanoscale Iron Based Metal-Organic Frameworks in Biomedicine

Metal-organic frameworks (MOFs) are coordination polymers that comprise metal ions/clusters and organic ligands. MOFs have been extensively employed in different fields (eg, gas adsorption, energy storage, chemical separation, catalysis, and sensing) for their versatility, high porosity, and adjustable geometry. To be specific, Fe2+/Fe3+ exhibits unique redox chemistry, photochemical and electrical properties, as well as catalytic activity. Fe-based MOFs have been widely investigated in numerous biomedical fields over the past few years. In this study, the key index requirements of Fe-MOF materials in the biomedical field are summarized, and a conclusion is drawn in terms of the latest application progress, development prospects, and future challenges of Fe-based MOFs as drug delivery systems, antibacterial therapeutics, biocatalysts, imaging agents, and biosensors in the biomedical field.

Detection and removal technologies for ammonium and antibiotics in agricultural wastewater: Recent advances and prospective

With the extensive development of industrial livestock and poultry production, a considerable part of agricultural wastewater containing tremendous ammonium and antibiotics have been indiscriminately released into the aquatic systems, causing serious harms to ecosystem and human health. In this review, ammonium detection technologies, including spectroscopy and fluorescence methods, and sensors were systematically summarized. Antibiotics analysis methodologies were critically reviewed, including chromatographic methods coupled with mass spectrometry, electrochemical sensors, fluorescence sensors, and biosensors. Current progress in remediation methods for ammonium removal were discussed and analyzed, including chemical precipitation, breakpoint chlorination, air stripping, reverse osmosis, adsorption, advanced oxidation processes (AOPs), and biological methods. Antibiotics removal approaches were comprehensively reviewed, including physical, AOPs, and biological processes. Furthermore, the simultaneous removal strategies for ammonium and antibiotics were reviewed and discussed, including physical adsorption processes, AOPs, biological processes. Finally, research gaps and the future perspectives were discussed. Through conducting comprehensive review, future research priorities include: (1) to improve the stabilities and adaptabilities of detection and analysis techniques for ammonium and antibiotics, (2) to develop innovative, efficient, and low cost approaches for simultaneous removal of ammonium and antibiotics, and (3) to explore the underlying mechanisms that governs the simultaneous removal of ammonium and antibiotics. This review could facilitate the evolution of innovative and efficient technologies for ammonium and antibiotics treatment in agricultural wastewater.

Heterogeneous irradiation system: enhanced degradation of methylene blue by electron beam irradiation combined with graphite carbon nitride/carbon nanodots

In the present work, the degradation of methylene blue (MB) was investigated by electron beam irradiation combined with graphite carbon nitride/carbon nanodots (EBI&g-C₃N₄/CDs). In comparison with EBI alone, the EBI&g-C₃N₄/CDs method showed a higher removal efficiency of high concentrations of MB (500 mg L^-1) from aqueous solution. Investigation on the effect of the synthesized g-C₃N₄/CDs revealed that CDs and g-C₃N₄ were both contributing factors, while the latter could enhance the degradation of MB through surface reactions that occurred after adsorption. Experiments on the existence of hydrogen peroxide revealed the synergistic effect between g-C₃N₄/CDs and hydrogen peroxide. An excellent degradation effect was obtained at natural pH, and the total organic carbon was significantly reduced. Regeneration experiments revealed that the g-C₃N₄/CDs material has good stability and reusability. The studies in the presence of assorted radical scavengers suggested that ·OH played a vital role in the degradation process and a total of 17 intermediates were detected using liquid chromatograph-mass spectrometer (LC-MS) analysis. The possible degradation mechanisms of MB were proposed.

Degradation of Organic Dyes Using the Ionizing Irradiation Process in the Presence of the CN/CD3/Fe6 Composite: Mechanistic Studies

Organic dyes are ubiquitous pollutants in various aquatic environments as they are produced in abundance and used widely. In the present work, the degradation and mineralization of various organic dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB), following the electron beam irradiation method in the presence of a graphitic carbon nitride/carbon nanodots/Fe(II) (CN/CD3/Fe6) composite, were studied. The removal efficiency of MB reached 81.7% under conditions of electron beam irradiation (EBI) when the total irradiation dose was 5 kGy. This increased to 91.2% in the presence of the CN/CD3/Fe6 composite. The mineralization efficiency increased from 30.1 to 47.3% when the composite was added, and the total irradiation dose was 20 kGy. The removal efficiency of organic dyes was not significantly affected in the pH range of 3-11. Results from cyclic experiments conducted using MB degradation indicated that the CN/CD3/Fe6 composite exhibited good stability and reusability even after five irradiation cycles. Results from scavenging experiments revealed that •OH was the predominant reactive species during the MB degradation process. Intermediates produced in the synergistic system (EBI&CN/CD3/Fe6 system) consisting of the CN/CD3/Fe6 composite and EBI were detected using the liquid chromatography-mass spectrometry (LC-MS) technique. Based on the results, the possible degradation mechanism and pathways for MB were proposed.

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.

Biochar-Supported TiO2-Based Nanocomposites for the Photocatalytic Degradation of Sulfamethoxazole in Water-A Review

Sulfamethoxazole (SMX) is a frequently used antibiotic for the treatment of urinary tract, respiratory, and intestinal infections and as a supplement in livestock or fishery farming to boost production. The release of SMX into the environment can lead to the development of antibiotic resistance among the microbial community, which can lead to frequent clinical infections. SMX removal from water is usually done through advanced treatment processes, such as adsorption, photocatalytic oxidation, and biodegradation. Among them, the advanced oxidation process using TiO2 and its composites is being widely used. TiO2 is a widely used photocatalyst; however, it has certain limitations, such as low visible light response and quick recombination of e-/h+ pairs. Integrating the biochar with TiO2 nanoparticles can overcome such limitations. The biochar-supported TiO2 composites showed a significant increase in the photocatalytic activities in the UV-visible range, which resulted in a substantial increase in the degradation of SMX in water. The present review has critically reviewed the methods of biochar TiO2 composite synthesis, the effect of biochar integration with the TiO2 on its physicochemical properties, and the chemical pathways through which the biochar/TiO2 composite degrades the SMX in water or aqueous solution. The degradation of SMX using photocatalysis can be considered a useful model, and the research studies presented in this review will allow extending this area of research on other types of similar pharmaceuticals or pollutants in general in the future.

Degradation of antibiotic Cephalosporin C in different water matrices by ionizing radiation: Degradation kinetics, pathways, and toxicity

Cephalosporin antibiotics are ubiquitous emerging pollutants in various aquatic environments due to their extensive production and application. Herein, the radiolytic degradation of antibiotic Cephalosporin C (CEP-C) in different water matrices was comprehensively investigated using gamma radiation at various experimental conditions. The results revealed that CEP-C oxidation obeyed pseudo first-order kinetics, and 100%, 94.9%, 67.0%, 44.6% and 34.5% removal of CEP-C with 10-200 mg/L was achieved at 0.4 kGy, respectively. The degradation was faster at higher absorbed dose and acidic conditions (pH = 3.5). The inorganic anions, including SO₄^2-, NO₃^-, and HCO₃^-, had negative influence on the degradation of CEP-C, the corresponding rate constant decreased from 4.603 to 3.667, 1.677 and 2.509 kGy^-1 respectively in the presence of SO₄^2-, NO₃^-, and HCO₃^-. The analysis of intermediate products indicated that CEP-C was oxidized to generate about 10 intermediate products. Besides, it was inferred that the thioether sulfur oxidation, β-lactam ring opening, acetyl dissociation from dihydrothiazine ring and D-α-aminohexylamide group abscission were the major reaction mechanisms of CEP-C degradation by gamma radiation. Importantly, the antibacterial activity of CEP-C could be completely vanished by gamma radiation alone, while more toxic intermediate products might be formed. Addition of hydrogen peroxide and peroxymonosulfate could significantly improve the CEP-C degradation, and reduce the toxicity of intermediates of CEP-C degradation. Similar degradation behavior was observed in the groundwater and wastewater, implying that ionizing radiation can be used for degradation of Cephalosporin in water and wastewater.

Assessment of degradation characteristic and mineralization efficiency of norfloxacin by ionizing radiation combined with Fenton-like oxidation

In this study, the degradation of norfloxacin was investigated by ionizing radiation combined with Fenton-like oxidation in order to enhance the degradation and mineralization of norfloxacin. The result showed that the removal efficiency of norfloxacin was 100%, 81.8%, 64.5%, 51.9%, and 45.6% at 0.4 kGy radiation when its concentration was 5, 10, 20, 30, and 40 mg/L. Norfloxacin could be completely degraded over pH range of 3.06-10.96 at 2 kGy radiation. The presence of inorganic anions had obvious influence on the degradation of norfloxacin, which decreased from 89.4% to 59.0%, 76.9%, 86.9%, 88.7% and 83.9% in the presence of 10 mmol/L CO₃^2-, HCO₃^-, NO₃^-, SO₄^2-, Cl^-, HPO₄^2-. The removal efficiency of norfloxacin decreased from 100% to 11.8%, 27.6% and 89.3% in the presence of peptone, glucose, and humic acid. The addition of Fenton-like catalysts, such as magnetite and goethite, could improve the mineralization ratio of norfloxacin because they could decompose hydrogen peroxide generated during the radiation process, to form hydroxyl radicals, leading to the enhancement of removal efficiency of norfloxacin. Finally, the intermediate products of norfloxacin degradation were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF), and the degradation pathway was proposed.

An asymmetric supercapacitor with an interpenetrating crystalline Fe-MOF as the positive electrode and its congenetic derivative as the negative electrode

Interpenetrating crystalline Fe-based materials of FeSC and congenetic derivative FeSC# have been assembled into an asymmetric supercapacitor, which can offer an excellent supercapacitor performance.

Catalytic hydrolysis of β-lactam antibiotics via MOF-derived MgO nanoparticles embedded on nanocast silica

The antibiotics abuse and the proliferation of antibiotic-resistant bacteria in the environment have a severe impact on both human health and ecosystem. In this study, a silica-nanocasting method was applied in Mg-MOF-74 template to generate a series of MgO/SiO₂ catalysts for the hydrolysis of β-lactam antibiotics. The Mg-based subunits in MOF-74 were converted to highly dispersed MgO nanoparticles with controllable particle size. MgO/SiO₂-80 with the smallest MgO particle size exhibits the best catalytic performance in the hydrolysis of four β-lactam antibiotics. The kinetics study reveals the higher degradation rate and lower activation energy of MgO/SiO₂-80 than other benchmark solid base catalysts. The proposed mechanism suggests that small MgO particle size provides more accessible oxygen anions with high proton affinity for the cleavage of the β-lactam ring, so that all hydrolytic products lose antimicrobial activity. The MgO/SiO₂-80 serves as the potential high-performance solid base catalyst for the real-world antibiotic wastewater treatment.

Glucose oxidase@Cu-hemin metal-organic framework for colorimetric analysis of glucose

The work presents a novel glucose oxidase@Cu-hemin metal-organic frameworks (GOD@ Cu-hemin MOFs) with a ball-flower structure as bienzymatic catalysts for detection of glucose. The GOD@Cu-hemin MOFs exhibits great stability as compared with free horseradish peroxidase and GOD toward harsh conditions because the ball-flower-like shell of Cu-hemin MOF effectively protects from GOD. Thus, the GOD@Cu-Hemin MOFs can be used in external harsh conditions such as high temperature and acid/base. The GOD@Cu-hemin MOFs is capable of sensitive and selective detection of glucose via peroxidase-like of Cu-hemin MOFs and GOD by using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. Under the existence of glucose, O₂ is reduced into H₂O₂ via GOD@Cu-hemin MOFs. The produced H₂O₂ as well as Cu-hemin MOFs oxidize TMB into blue oxTMB which shows UV-Vis absorbance at 652. The absorption intensity of oxTMB linearly increases with the increasing concentration of glucose from 0.01 to 1.0 mM with detection limit of 2.8 μM. An integrated agarose hydrogel film (Aga/GOD@Cu-hemin MOF/TMB) sensor is rationally designed for colorimetric detection of glucose. The sensor displays a response range of 30 μM-0.8 mM with a detection limit of 0.01 mM. The result indicates that the Cu-hemin MOFs are an ideal carrier for the encapsulation of enzymes.

Critical Perspective on Advanced Treatment Processes for Water and Wastewater: AOPs, ARPs, and AORPs

Emerging contaminants’ presence in water, wastewater, and aquatic environments has been widely reported. Their environmental and health-related effects, and the increasing tendency towards wastewater reuse require technology that could remove to a greater degree, or even mineralize, all these contaminants. Currently, the most commonly used process technologies for their removal are advanced oxidation processes (AOPs); however, recent advances have highlighted other advanced treatment processes (ATPs) as possible alternatives, such as advanced reduction processes (ARPs) and advanced oxidation-reduction processes (AORPs). Although they are not yet widely diffused, they may remove contaminants that are not readily treatable by AOPs, or offer better performance than the former. This paper presents an overview of some of the most common or promising ATPs for the removal of contaminants from water and wastewater, and their application, with discussion of their limitations and merits. Issues about technologies’ costs and future perspectives in the water sector are discussed.