Advancements in electrochemical technologies for the removal of fluoroquinolone antibiotics in wastewater: A review

Solvent-free synthesis of defective Zr-based metal-organic framework from waste plastic bottles for highly efficient lomefloxacin removal

Large amount of polyethylene terephthalate (PET) plastics waster and emerging contaminants in water, including fluoroquinolone antibiotics, pose challenges to human survival. In this work, a green synthesis scheme is proposed in which the defective UiO-66 (d-UiO-66) is fabricated via a solvent-free routine by using PET plastics waster as raw materials for lomefloxacin (LOM) removal. In comparison with defect-free UiO-66, the created defect imparts d-UiO-66 with higher porosity and abundant defective Zr sites, which are beneficial to boost LOM adsorption. As expected, d-UiO-66 exhibited excellent LOM adsorption performances, showcasing a saturation adsorption capacity of 588 mg g-1 and a kinetic rate constant of 0.204 g mg-1 h-1, which are 3.5 and 2.0 times higher than those of the pristine UiO-66, respectively. Remarkably, the LOM saturation adsorption capacity of d-UiO-66 surpasses that of all reported adsorbents. Mechanism study reveals that this outstanding adsorption performance of d-UiO-66 is mainly ascribed to the abundant defective sites, high porosity, together with the strong hydrogen bonding interaction and π-π stacking interaction between d-UiO-66 and LOM. Therefore, the d-UiO-66 obtained by the solvent-free method can not only effectively upcycle PET plastic waster, but also efficiently remove LOM, demonstrating a potential routine to simultaneous address the solid PET waster and wastewater.

In silico degradation of fluoroquinolones by a microalgae-based constructed wetland system

Fluoroquinolone antibiotics (FQs) have been used worldwide due to their extended antimicrobial spectrum. However, the overuse of FQs leads to frequent detection in the environment and cannot be efficiently removed. Microalgae-based constructed wetland systems have been proven to be a relatively proper method to treat FQs, mainly by microalgae, plants, microorganisms, and sediments. To improve the removal efficiency of microalgae-constructed wetland, a systematic molecular design, screening, functional, and risk evaluation method was developed using three-dimensional quantitative structure-activity relationship models, molecular dynamics simulation, molecular docking, and TOPKAT approaches. Five designed ciprofloxacin alternatives with improved bactericidal effects and lower human health risks were found to be more easily degraded by microalgae (16.11-167.88 %), plants (6.72-58.86 %), microorganisms (9.10-15.02 %), and sediments (435.83 %-1763.51 %) compared with ciprofloxacin. According to the mechanism analysis, the removal effect of the FQs can be affected via changes in the number, bond energy, and molecular descriptors of favorable and unfavorable amino acids. To the best of our knowledge, this is the first comprehensive study of improving the microalgae, plants, microorganisms, and sediment removal efficiency of FQs in constructed wetlands, which provides theoretical support for the treatment of FQ pollution.

Molybdenum disulphide nanoparticles accelerate the transformation of levofloxacin in planting soil upon exposure

The use of nanocatalytic particles for the removal of refractory organics from wastewater is a rapidly growing area of environmental purification. However, little has been done to investigate the effects of nanoparticles on soil-plant systems with antibiotic contamination. This work assessed the effect of molybdenum disulfide (MoS2) on the soil-Phragmites communis system containing levofloxacin (LVX). The results showed that the addition of MoS2 had restoration potential for stressed plant. The MoS2 with catalytic activity promoted the transformation of LVX in rhizosphere soils. The transformation pathways of LVX in the different exposure groups were proposed. The continuous output of radicals in the high MoS2 dosage group facilitated the transformation of LVX to small molecule compounds, which were eventually mineralized. Moreover, the electron-density-difference analysis revealed the easier flow of electrons from the MoS2 surface towards the LVX molecules. This finding provides theoretical support for the application of nanocatalytic particles in ecological environments.

Sustainable photoelectrocatalytic oxidation of antibiotics using Ag-CoFe2O4@TiO2 heteronanostructures for eco-friendly wastewater remediation

Developing high-performance and durable catalysts presents a significant challenge for oxidizing toxic inorganic and pharmaceutical compounds in wastewater. Recently, there has been a surge in the development of new heterogeneous catalysts for degrading pharmaceutical compounds, driven by advancements in electrocatalysts and photoelectrocatalysts. In this study, a plasmonic Ag nanoparticles decorated CoFe2O4@TiO2 heteronanostructures have been successfully designed to fabricate a high-performing photoelectrode for the oxidation of pharmaceutical compounds. The developed Ag-CoFe2O4@TiO2 possessed a higher electrochemical stability and effectively harvested the UV to visible and NIR radiation in sunlight which generates the enormous photochemical reactive species that involved in the oxidation of ibuprofen in wastewater. Under direct sunlight irradiation, Ag-CoFe2O4@TiO2 achieved complete oxidation of ibuprofen in wastewater at 0.8 V vs RHE. This indicates that metallic Ag nanoparticles are involved in the charge separation and transport of charge carriers from the photoactive sites of CoFe2O4@TiO2, promoting the generation of abundant hydroxy, oxy, and superoxide radicals that actively break the bonds of ibuprofen. Additionally, oxidation agents such as urea and H2O2 were utilized to enhance the formation of superoxide ions and hydroxyl radicals, which rapidly participate in the oxidation of ibuprofen. Significantly, testing for recyclability confirmed the stability of the Ag-CoFe2O4@TiO2 photoanode, ensuring its suitability for prolonged use in photoelectrochemical advanced oxidation processes. Integrating Ag-CoFe2O4@TiO2 photoanodes into water purification systems could enhance economic feasibility, reduce energy consumption, and improve efficiency.

From wastewater to clean water: Recent advances on the removal of metronidazole, ciprofloxacin, and sulfamethoxazole antibiotics from water through adsorption and advanced oxidation processes (AOPs)

Antibiotics released into water sources pose significant risks to both human health and the environment. This comprehensive review meticulously examines the ecotoxicological impacts of three prevalent antibiotics-ciprofloxacin, metronidazole, and sulfamethoxazole-on the ecosystems. Within this framework, our primary focus revolves around the key remediation technologies: adsorption and advanced oxidation processes (AOPs). In this context, an array of adsorbents is explored, spanning diverse classes such as biomass-derived biosorbents, graphene-based adsorbents, MXene-based adsorbents, silica gels, carbon nanotubes, carbon-based adsorbents, metal-organic frameworks (MOFs), carbon nanofibers, biochar, metal oxides, and nanocomposites. On the flip side, the review meticulously examines the main AOPs widely employed in water treatment. This includes a thorough analysis of ozonation (O3), the photo-Fenton process, UV/hydrogen peroxide (UV/H2O2), TiO2 photocatalysis, ozone/UV (O3/UV), radiation-induced AOPs, and sonolysis. Furthermore, the review provides in-depth insights into equilibrium isotherm and kinetic models as well as prospects and challenges inherent in these cutting-edge processes. By doing so, this review aims to empower readers with a profound understanding, enabling them to determine research gaps and pioneer innovative treatment methodologies for water contaminated with antibiotics.

Bimetallic iron-copper nanozyme for determination and degradation of norfloxacin in foods

Iron-copper nanozymes (Fe-Cu NZs) with good peroxidase activity were prepared through hydrothermal method by using copper nitrate as copper source, iron acetate as iron source and 2, 5-dihydroxyterephthalic acid as organic ligand. Upon oxidation of the colourless TMB to light blue products by Fe-Cu NZs, the addition of Norfloxacin (NOR) resulted in a colour change to dark blue. The absorbance of the system correlated linearly with NOR concentration in the range of 3.3 μM to 66 μM, and the detection limit (LOD) was 0.386 μM. A rapid colourimetric assay for the determination of NOR in food matrices was developed, with a detection time of only one minute. Additionally, the assay facilitated the simultaneous catalytic degradation of NOR via Fe-Cu NZs. The primary degradation mechanism of NOR was identified as the transformation of the quinolone ring and the cleavage of the C9 = C10 double bond, which was substantiated by high-performance liquid chromatography (HPLC).

Fluoroquinolone antibiotics in the aquatic environment: environmental distribution, the research status and eco-toxicity

The increasing presence of fluoroquinolone (FQ) antibiotics in aquatic environments is a growing concern due to their widespread use, negatively impacting aquatic organisms. This paper provides an overview of the environmental distribution, sources, fate, and both single and mixed toxicity of FQ antibiotics in aquatic environments. It also examines the accumulation of FQ antibiotics in aquatic organisms and their transfer into the human body through the food chain. The study identifies critical factors such as metabolism characteristics, physiochemical characteristics, light, temperature, dissolved oxygen, and environmental compatibility that influence the presence of FQ antibiotics in aquatic environments. Mixed pollutants of FQ antibiotics pose significant risks to the ecological environment. Additionally, the paper critically discusses advanced treatment technologies designed to remove FQ antibiotics from wastewater, focusing on advanced oxidation processes (AOPs) and electrochemical advanced oxidation processes (EAOPs). The discussion also includes the benefits and limitations of these technologies in degrading FQ antibiotics in wastewater treatment plants. The paper concludes by proposing new approaches for regulating and controlling FQ antibiotics to aid in the development of ecological protection measures.

Ciprofloxacin Removal via Acid-Modified Red Mud: Optimizing the Process, Analyzing the Adsorption Features, and Exploring the Underlying Mechanism

In this study, RM (red mud) was acidified with sulfuric acid, and the acidified ARM (acidified red mud) was utilized as an innovative adsorption material for treating antibiotic-containing wastewater. The adsorption conditions, kinetics, isotherms, thermodynamics, and mechanism of ARM for CIP (ciprofloxacin) were investigated. The characterization of the ARM involved techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), and NH3-TPD analysis. Adsorption studies employed a response surface methodology (RSM) for the experimental design. The results showed that ARM can absorb CIP effectively. The RSM optimal experiment indicated that the most significant model terms influencing adsorption capacity were solution pH, CIP initial concentration, and ARM dosage, under which the predicted maximum adsorption capacity achieved 7.30 mg/g. The adsorption kinetics adhered to a pseudo-second-order model, while equilibrium data fitted the Langmuir-Freundlich isotherm, yielding maximum capacity values of 7.35 mg/g. The adsorption process occurred spontaneously and absorbed heat, evidenced by ΔGθ values between -83.05 and -91.50 kJ/mol, ΔSθ at 281.6 J/mol/K, and ΔHθ at 0.86 kJ/mol. Analysis using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) indicated a complex reaction between the Al-O in the ARM and the ester group -COO in CIP. The C=O bond in CIP was likely to undergo a slight electrostatic interaction or be bound to the internal spherical surface of the ARM. The findings indicate that ARM is a promising and efficient adsorbent for CIP removal from wastewater.

A novel enrofloxacin-degrading fungus, Humicola sp. KC0924g, isolated from the rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L

A novel enrofloxacin-degrading fungus was isolated from a rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L.. The isolate, designated KC0924g, was identified as a member of the genus Humicola based on morphological characteristics and tandem conserved sequence analysis. The optimal temperature and pH for enrofloxacin degradation by strain KC0924g were 28 °C and 9.0, respectively. Under such condition, 98.2% of enrofloxacin with an initial concentration of 1 mg L-1 was degraded after 72 h of incubation, with nine possible degradation products identified. Four different metabolic pathways were proposed, which were initiated by cleavage of the piperazine moiety, hydroxylation of the aromatic ring, oxidative decarboxylation, or defluorination. In addition to enrofloxacin, strain KC0924g also degraded other fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, and ofloxacin), malachite green (an illegal additive in aquaculture), and leucomalachite green. Pretreatment of cells of strain KC0924g with Cu2+ accelerated ENR degradation. Furthermore, it was speculated that a flavin-dependent monooxygenase was involved in ENR degradation, based on the increased transcriptional levels of these two genes after Cu2+ induction. This work enriches strain resources for enrofloxacin remediation and, more importantly, would facilitate studies on the molecular mechanism of ENR degradation with degradation-related transcriptome available.

Source apportionment and predictable driving factors contribute to antibiotics profiles in Changshou Lake of the Three Gorges Reservoir area, China

Lakes, crucial antibiotic reservoirs, lack thorough exploration of quantitative relationships between antibiotics and influencing factors. Here, we conducted a comprehensive year-long investigation in Changshou Lake within the Three Gorges Reservoir area, China. The concentrations of 21 antibiotics spanned 35.6-200 ng/L, 50.3-348 ng/L and 0.57-57.9 ng/g in surface water, overlying water and sediment, respectively. Compared with abundant water period, surface water and overlying water displayed significantly high antibiotic concentrations in flat and low water periods, while sediment remained unchanged. Moreover, tetracyclines, fluoroquinolones and erythromycin posed notable risks to algae. Six primary sources were identified using positive matrix factorization model, with aquaculture contributing 21.2%, 22.7% and 25.4% in surface water, overlying water and sediment, respectively. The crucial predictors were screened through machine learning, redundancy analysis and Mantel test. Our findings emphasized the pivotal roles of water quality parameters, including water temperature (WT), pH, dissolved oxygen, electrical conductivity, inorganic anions (NO3⁻, Cl⁻ and F⁻) and metal cations (Ca, Mg, Fe, K and Cr), with WT influencing greatest. Total nitrogen (TN), cation exchange capacity, K, Al and Cd significantly impacted sediment antibiotics, with TN having the most pronounced effect. This study can promise valuable insights for environmental planning and policies addressing antibiotic pollution.

Photoelectrochemical advanced oxidation processes for simultaneous removal of antibiotics and heavy metal ions in wastewater using 2D-on-2D WS2@CoFe2O4 heteronanostructures

The presence of antibiotics in water poses significant threats to both human health and the environment. Addressing this issue requires the effective treatment of medical wastewater. Photoelectrochemical advanced oxidation processes (PEAOPs) are emerging as promising solutions for wastewater treatment. This process utilizes photocatalysts to convert charge carriers into reactive species such as hydroxyl radicals and superoxide ions, which are essential for degrading pollutants in wastewater. However, limitations in charge carrier separation and transport have hindered the efficiency of photoelectrochemical advanced oxidation processes. To overcome these limitations, we designed WS2@CoFe2O4 heterojunctions, optimizing their energy levels to enhance charge transport and separation. This improvement significantly increased the oxidation of antibiotics such as amoxicillin and azithromycin. Multiple reactions occurred at the WS2@CoFe2O4 heterojunctions during photoelectrochemical advanced oxidation processes, leading to the impressive degradation of up to 99% of antibiotics under visible light irradiation at 0.8 V. Urea and H2O2 acted as oxidation agents within photoelectrochemical advanced oxidation processes, amplifying the generation of hydroxyl radicals and superoxide ions, further enhancing antibiotic oxidation. Moreover, the WS2@CoFe2O4 photoanode efficiently oxidized toxic antibiotics while converting As(III) into the less harmful As(V). Crucially, recyclability tests confirmed the robustness of the WS2@CoFe2O4 photoanode, ensuring its suitability for prolonged use in photoelectrochemical advanced oxidation processes. Integrating WS2@CoFe2O4 photoanodes into water purification systems can enhance efficiency, reduce energy consumption, and improve economic viability. This technology's scalability and its ability to protect ecosystems while conserving water resources make it a promising solution for addressing the critical issue of antibiotic pollution in water environments.