Removal of antibiotic tetracycline by metal-organic framework MIL-101(Cr) loaded nano zero-valent iron

Synergistic approach for synthesis of functionalized biochar for efficient adsorption of Lopinavir from polluted water

The COVID-19 pandemic has led to a significant increase in antibiotic consumption, along with a 70% rise in antiviral drug concentrations in aquatic ecosystems. For the effective adsorption of antibiotics, biochar was modified by incorporating layered double hydroxide (LDH) through hydrothermal method. The results showed that LDH provides additional hydroxyl groups, positive surface charges and ion exchange. Whereas biochar component provides a larger specific surface area (467.8 m2/g). Batch adsorption experiments of biochar @ layered double hydroxide (BC@LDH) showed enhanced adsorption performance (832.9 mg/g), compared to pristine LDH (420.3 mg/g) and unmodified biochar (548.5 mg/g). Adsorption data were best interpreted (R2 = 0.99) by pseudo second order, Freundlich, and Temkin isotherm models. Adsorption was a synergism of LDH and biochar physiochemical properties, whereas pore-filling was the primary mechanism. The recyclability of BC@LDH confirmed its good structural stability. This study introduces a sustainable and efficient method for synthesizing a versatile adsorbent with superior antibiotic removal.

Impact of Polythiophene ((C4H4S)n; n = 3, 5, 7, 9) Units on the Adsorption, Reactivity, and Photodegradation Mechanism of Tetracycline by Ti-Doped Graphene/Boron Nitride (Ti@GP_BN) Nanocomposite Materials: Insights from Computational Study

This study addresses the formidable persistence of tetracycline (TC) in the environment and its adverse impact on soil, water, and microbial ecosystems. To combat this issue, an innovative approach by varying polythiophene ((C4H4S)n; n = 3, 5, 7, 9) units and the subsequent interaction with Ti-doped graphene/boron nitride (Ti@GP_BN) nanocomposites was applied as catalysts for investigating the molecular structure, adsorption, excitation analysis, and photodegradation mechanism of tetracycline within the framework of density functional theory (DFT) at the B3LYP-gd3bj/def2svp method. This study reveals a compelling correlation between the adsorption potential of the nanocomposites and their corresponding excitation behaviors, particularly notable in the fifth and seventh units of the polythiophene configuration. These units exhibit distinct excitation patterns, characterized by energy levels of 1.3406 and 924.81 nm wavelengths for the fifth unit and 1.3391 and 925.88 nm wavelengths for the seventh unit. Through exploring deeper, the examination of the exciton binding energy emerges as a pivotal factor, bolstering the outcomes derived from both UV-vis transition analysis and adsorption exploration. Notably, the calculated exciton binding energies of 0.120 and 0.103 eV for polythiophene units containing 5 and 7 segments, respectively, provide compelling confirmation of our findings. This convergence of data reinforces the integrity of our earlier analyses, enhancing our understanding of the intricate electronic and energetic interplay within these intricate systems. This study sheds light on the promising potential of the polythiophene/Ti-doped graphene/boron nitride nanocomposite as an efficient candidate for TC photodegradation, contributing to the advancement of sustainable environmental remediation strategies. This study was conducted theoretically; hence, experimental studies are needed to authenticate the use of the studied nanocomposites for degrading TC.

Construction of urchin-like core-shell Fe/Fe2O3@UiO-66 hybrid for effective tetracycline reduction and photocatalytic oxidation

Although Fe/Fe2O3 has potential application compared with nanoscale zero-valent iron (nZVI), its smooth structure largely limits the catalytic performance. To address this challenge, we innovatively constructed highly efficient composite Fe/Fe2O3@UiO-66 via employing an urchin-like core-shell structure of Fe/Fe2O3 onto UiO-66 through a facile ion exchange precipitation method without inert gas protection. The characterization results show the urchin-like core-shell configuration can extend the life span of Fe0 and produce more active sites. Besides, the absorption spectrum is broadened by Fe2O3 which has narrow band gap and the high-efficiency separation of photogenerated electron-hole pairs is obtained with the load of Fe/Fe2O3. Moreover, Two-parameter pseudo-first-order decay model fits well with the reduction and adsorption of composites in the dark reaction, and a plausible pathway for tetracycline (TC) degradation is also proposed. The findings of this research provide a promising method for promoting the catalytic properties of MOF-based materials and Fe/Fe2O3.

Natural phenol-inspired porous polymers for efficient removal of tetracycline: Experimental and engineering analysis

Efficient and feasible removal of trace antibiotics from wastewater is extremely important due to its environmental persistence, bioaccumulation, and toxicity, but still remains a huge challenge. Herein, three natural phenol-inspired porous organic polymers were fabricated from natural phenolic-derived monomers (p-hydroxy benzaldehyde, 2,4-dihydroxy benzaldehyde and 2,4,6-trihydroxy benzaldehyde) and melamine via polycondensation reaction. Characterization highlighted that the increasing contents of hydroxyl groups in monomers induced an increase of the polymer total porosity and promoted the formation of a highly microporous structure. With mesopore-dominated pore (average pore diameter 9.6 nm) and large pore volume (1.78 cm³/g), p-hydroxy benzaldehyde-based porous polymer (1-HBPP) exhibited ultra-high maximum adsorption capacity (q_max) of 697.6 mg/g for tetracycline (TC) antibiotic. Meanwhile, the porous networks and plentiful active sites of 1-HBPP enabled fast adsorption kinetics (within 10 min) for TC removal, which could be well described by the pseudo-second-order model. Dynamic adsorption studies showed that 1-HBPP could be used in fixed-bed adsorption column (FBAC) with high removal efficiency (breakthrough volume per unit mass, 13.2 L/g) and dynamic adsorption capacity (201.6 mg/g), which were much higher than other reported adsorbents. The breakthrough curves both well matched with Thomas and Yoon-Nelson models in FBAC treatment. Moreover, removal mechanism analysis affirmed that pore-filling, hydrogen bonding, electrostatic interactions and π-π stacking interactions were main driving forces for TC adsorption. The prepared natural phenol-inspired porous adsorbents show great potential in antibiotics removal from wastewater, and this strategy would promote the sustainable and high-value utilization of natural phenolic compounds.

Tetracycline capture from aqueous solutions by nanocomposite of MWCNTs reinforced with glutaraldehyde cross-linked poly (vinyl alcohol)/chitosan

The presence of pharmaceuticals as the emerging contaminates needs novel approaches and new materials to be remediated. This study aimed to develop and apply MWCNTs reinforced with glutaraldehyde cross-linked poly (vinyl alcohol)/chitosan nanocomposite (MWCNTs/CS-PVA/GA NC) for removal of tetracycline (TC) as a model of antibiotics from aqueous solutions. The successful synthesis of NC was supported by techniques of SEM, XRD, TGA, FTIR, and EDX. The prepared NC was then utilized for TC adsorption under the main effective parameters of TC concentration (25-125 mg/L), sonication time (0-8 min), NC dose (1-130 mg), and tempearure (5-45 °C). The process behavior was comparably explored with different methods of central composite design (CCD), artificial neural networks (ANN), and general regression neural network (GRNN). The results showed that under the optimum settings presented by desirability function (DA), in which the respective values for the factors were 125 mg/L, 6.8 min, 130 mg, and 45 °C, the efficiency and adsorption capacity of NC is supposed to be 99.07% and ∼525 mg/g, respectively. From the models studied, although all were able to express the process with satisfactory accuracy, ANN provided the best accuracy and reliability owning to the highest R² (0.999) and lowest RMSE, ADD, MAE. The kinetics, isotherms, and thermodynamic studies showed that the process is fast (over 4.5 min), chemisorption, heterogeneous with multilayer nature, spontaneous, feasible, and endothermic. In addition, the as prepared NC could be recycled for five times without significant fail in its performance. All in all, the developed MWCNTs/CS-PVA/GA NC can be considered as a promising candidate in dealing with aqueous solutions' pollution with antibiotic.

Advances in Metal-Organic Frameworks MIL-101(Cr)

MIL-101(Cr) is one of the most well-studied chromium-based metal-organic frameworks, which consists of metal chromium ion and terephthalic acid ligand. It has an ultra-high specific surface area, large pore size, good thermal/chemical/water stability, and contains unsaturated Lewis acid sites in its structure. Due to the physicochemical properties and structural characteristics, MIL-101(Cr) has a wide range of applications in aqueous phase adsorption, gas storage and separation, and catalysis. In this review, the latest synthesis of MIL-101(Cr) and its research progress in adsorption and catalysis are reviewed.

Adsorption removal and photocatalytic degradation of azithromycin from aqueous solution using PAC/Fe/Ag/Zn nanocomposite

The improper use of antibiotics and their discharge into the environment can have serious and hazardous consequences. The purpose of this research is to synthesize an activated carbon impregnated magnetite composite (PAC/Fe), prepare PAC/Fe/Ag/Zn nanocomposites, and innovate by simultaneously synthesizing two metals, zinc and silver, on magnetically activated carbon and check its ability to remove azithromycin antibiotic (AZT) from an aqueous solution via UV system. PAC/Fe/Ag/Zn nanocomposites were characterized by various techniques including XRD, FESEM, and EDX. A series of batch experiments were carried out under various experimental conditions such as pH of the solution (3-11), contact time (0-120 min), initial concentration of AZT (10-40 ppm), amount of PAC/Fe/Ag/Zn nano-absorbent (0.01-0.04 g/l), and recoverability and reuse. Some common isotherm models were used for the study of AZT adsorption removal and finding the best model. Also, kinetic studies of AZT removal were performed by fitting the experimental data on first-order and second-order models. In this system, under optimal conditions of pH = 9, 120 min with 0.04 g/l of PAC/Fe/Ag/Zn, 99.5% of 10 ppm AZT were degraded under UV-C irradiation. Furthermore, the obtained results of isotherm and kinetic studies revealed that Langmuir (R² = 0.9336) isotherm model, and the pseudo-first-order kinetic model (R² = 0.9826) had the highest correlation with the experimental data of AZT antibiotic adsorption. Finally, the reusability experiments showed that PAC/Fe/Ag/Zn nanocomposites have a high ability of antibiotic adsorption and high stability after four cycles of application (99.5 to 40%).

Synthesis of magnetic nanocomposite Fe3O4@ZIF-8@ZIF-67 and removal of tetracycline in water

We prepared a double-layer magnetic nanocomposite Fe₃O₄@ZIF-8@ZIF-67 by layer-by-layer self-assembly. Fe₃O₄@ZIF-8@ZIF-67 was used to remove tetracycline from an aqueous solution via a combination of adsorption and Fenton-like oxidation. Depending on the outstanding porous structure of the Fe₃O₄@ZIF-8@ZIF-67, a high adsorption capacity for tetracycline was 356.25 mg g^-1, with > 95.47% removal efficiency within 100 min based on Fenton-like oxidation. To better understand the mechanisms involved in integrated adsorption and Fenton-like oxidation, various advanced characterization techniques were used to monitor the changes in morphology and composition of Fe₃O₄@ZIF-8@ZIF-67 before and after removal of tetracycline. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) all supported adsorption and Fenton oxidation of tetracycline. This study extends the application of Fe₃O₄@ZIF-8@ZIF-67 for environmental remediation.

An efficient and low-cost magnetic heterogenous Fenton-like catalyst for degrading antibiotics in wastewater: Mechanism, pathway and stability

Metal-doped MgFe₂O₄ spinel ferrite synthesized from saprolite laterite nickel ore was verified as an efficient heterogeneous Fenton-like catalyst for degrading antibiotics including tetracycline (TC) and metronidazole (MNZ) in a "catalyst/oxalic acid (H₂C₂O₄)/visible light (vis)" system. The degradation efficiencies reached over 95% and total organic carbon (TOC) removal efficiencies were nearly 50% of the two antibiotics within 210 min, under the optimal conditions, especially 90% catalytic activity of the fresh catalyst was maintained after five cycles, suggesting the ferrite possessed excellent degrading performance, cycling stability and applicability. Moreover, the degradation mechanism and pathway of TC were elucidated in detail. Results revealed that the [≡Fe(C₂O₄)₃]^3- complex ions formed by octahedral Fe³⁺ in spinel ferrite with oxalate ions on the surface of MgFe₂O₄, played the key role in production of ·OH radicals which decomposed antibiotic TC into small molecules even mineralized in three pathways. Cost-effective preparation, high catalytic performance and long cycle life may accelerate the practical application of the heterogeneous Fenton-like catalyst.

Removal of organic pollutants from aqueous solution using metal organic frameworks (MOFs)-based adsorbents: A review

The development of metal organic frameworks (MOFs) has recently drawn a lot of scientific interest in water treatment due to the unique properties such as tunable porosities, large pore volumes, hierarchical structures, excellent adsorption and regeneration performances. MOFs represent an eco-friendly alternative to conventional adsorbents especially for the adsorptive removal of noxious organic pollutants from aqueous solution. Advanced MOFs' performances are justified by the introduction of functional groups, magnetic moieties, and specific foreign materials onto MOFs. This however leads to increase in the manufacturing costs of MOFs and consequently possess a huge challenge in large-scale applications. This review hence critically discusses the recent progresses in the development of MOFs-based adsorbents for the removal of selected organic pollutants (e.g., dyes, antibiotics and pesticides) from aqueous solution. Furthermore, major interaction mechanisms between MOFs and organic pollutants in response to numerous experimental conditions, such as pH, temperature, coexisting ions are put forward. Finally, some recommendations in support for designing MOFs with improved adsorption performances are also highlighted.

Preparation of Sepiolite Nanofibers Supported Zero Valent Iron Composite Material for Catalytic Removal of Tetracycline in Aqueous Solution

The heavy use of antibiotics in medicine, stock farming and agriculture production has led to their gradual accumulation in environmental media, which poses a serious threat to ecological environment and human safety. As an efficient and promising catalyst for the degradation of antibiotics, nanoscale zero valent iron (nZVI) has attracted increasing attention in recent years. In this study, sepiolite nanofiber supported zero valent iron (nZVI/SEP) composite was prepared via a facile and environmentally friendly method. The nZVI particles (with size of 20–60 nm) were dispersed evenly on the surface of sepiolite nanofibers, and the catalytic performance for the removal of tetracycline hydrochloride (TC-HCl) in aqueous system was investigated. The effect of nZVI loading amount, catalyst dosage, H₂O₂ concentration and pH on the removal efficiency of TC-HCl were studied. It was revealed that the sepiolite supporter effectively inhibited the agglomeration of nZVI particles and increased the contact area between contaminant and the active sites, resulting in the higher catalytic performance than pure nZVI material. The TC-HCl removal efficiency of nZVI/SEP composite was up to 92.67% when TC-HCl concentration of 20 mg/L, catalyst dosage of 1.0 g/L, H₂O₂ concentration of 1.0 mM, pH value of 7. Therefore, the nZVI/SEP composites possess high catalytic activity for TC-HCl removal and have great application prospects in antibiotic wastewater treatment.

Application of Magnetic Composites in Removal of Tetracycline through Adsorption and Advanced Oxidation Processes (AOPs): A Review

Water pollution induced by the tetracycline (TC) has caused global increasing attention owing to its extensive use, environmental persistence, and potential harm for human health. Adsorption and advanced oxidation processes (AOPs) have been promising techniques for TC removal due to ideal effectiveness and efficiency. Magnetic composites (MCs) which exploit the combined advantages of nano scale, alternative sources, easy preparation, and separation from wastewater are widely used for catalysis and adsorption. Herein, we intensively reviewed the available literature in order to provide comprehensive insight into the applications and mechanisms of MCs for removal of TC by adsorption and AOPs. The synthesis methods of MCs, the TC adsorption, and removal mechanisms are fully discussed. MCs serve as efficient adsorbents and photocatalysts with superior performance of photocatalytic performance in TC degradation. In addition, the TC can be effectively decomposed by the Fenton-based and SO4•− mediated oxidation under catalysis of the reported MCs with excellent catalytic performance. Based on the existing literature, we further discuss the challenge and future perspectives in MCs-based adsorption and AOPs in removing TC.

A review of metal organic framework (MOFs)-based materials for antibiotics removal via adsorption and photocatalysis

Antibiotic abuse has led to serious water pollution and severe harm to human health; therefore, there is an urgent need for antibiotic removal from water sources. Adsorption and photodegradation are two ideal water treatment methods because they are cheap, simple to operate, and reusable. Metal organic frameworks (MOFs) are excellent adsorbents and photocatalysts because of their high porosity, adaptability, and good crystal form. The aim of this study is to suggest ways to overcome the limitations of adsorption and photocatalysis treatment methods by reviewing previous applications of MOFs to antibiotic adsorption and photocatalysis. The different factors influencing these processes are also discussed, as well as the various adsorption and photocatalysis mechanisms. This study provides a valuable resource for researchers intending to use MOFs to remove antibiotics from water bodies.

Green synthesis of hydrophilic activated carbon supported sulfide nZVI for enhanced Pb(II) scavenging from water: Characterization, kinetics, isotherms and mechanisms

For green synthesis of nZVI with low aggregation and high antioxidation, green tea extracts were explored as reductant during the synthesis with modification by hydrophilic porous activated carbon (HPAC) and sulfidation technology. Characterization results identified the effective preparation of porous activated carbon (PAC) with microporous and mesoporous characteristics, and the successful loading of S-nZVI nanoparticles on S-nZVI@HPAC. Moreover, HPAC was identified to have a higher degree of hydrophilicity surface compared to PAC, while the S-nZVI with an atomic ratio of S/Fe (0.16) further improved the hydrophilic performance of S-nZVI@HPAC. Batch adsorption revealed that the S-nZVI@HPAC possessed a pH-dependent adsorption performance with a fast kinetic equilibrium within 120 min and an outstanding Pb(II) binding of 295.30 mg/g at pH = 5.0 and 50 °C. Thermodynamic results exhibited positive ΔH° and ΔS°, clearly indicative of the endothermic property of Pb(II) uptake onto S-nZVI@HPAC with an increase in randomness, while the negative ΔG° uncovered a favorable and spontaneous process. Furthermore, the S-nZVI@HPAC was believed to enhance the Pb(II) uptake via the synergistic effects of electrostatic attraction, chemical precipitation, complexation and reduction. The results of this work highlighted the hydrophilic porous activated carbon supported sulfide nZVI for efficient remediation of Pb(II) contaminated water.

Microwave-assisted synthesis of β-cyclodextrin functionalized celluloses for enhanced removal of Pb(II) from water: Adsorptive performance and mechanism exploration

Herein, β-cyclodextrin (β-CD) was efficiently grafted onto rice husk-based celluloses using different cross-linking agents of epichlorohydrin (EPI) and glutaraldehyde (GA). By feat of microwave irradiation, the functionalization procedure was completed in 17 min, and the synthesized RHEPIMWβ-CD and RHGAMWβ-CD exhibited fast adsorption equilibrium for Pb(II) within 20 min, excellent monolayer adsorption capacities of 216.06 and 279.08 mg g^-1 across an extensive pH scope of 3.0-6.0, unaffected affinity to Pb(II) during the existence of co-existing ions, superior reusability with over 81% and 87% of Pb(II) uptake sustained for four adsorption-desorption cycles. Thermodynamic parameters implied that the uptake process of Pb(II) occurred spontaneously (-ΔG⁰) with an endothermic characteristic (+ΔH⁰). Furthermore, electrostatic attraction and complexation were demonstrated to enhance the Pb(II) uptake onto the RHEPIMWβ-CD and RHGAMWβ-CD. In fix-bed columns, these two adsorbents also efficiently eliminated Pb(II) under various flow rates with experimental breakthrough curves well simulated by Thomas and Yoon-Nelson models. Significantly, the RHEPIMWβ-CD and RHGAMWβ-CD could effectively purify acid battery effluent containing Pb(II) for meeting regulatory requirement. Overall, the fast fabrication, excellent adsorption and recycling performance facilitate the development of tailored adsorbents for Pb(II) elimination in wastewater.

Constructing Mesoporous Adsorption Channels and MOF-Polymer Interfaces in Electrospun Composite Fibers for Effective Removal of Emerging Organic Contaminants

Recently, metal-organic framework (MOF)-based electrospun fibers have attracted considerable attention as adsorbents for organic contaminant removal from water. To prepare these fibers, two common strategies including blending electrospinning and surface coating are employed. However, fibers obtained from the two strategies still have some disadvantages, such as adsorption site blockage and unstable loading. Here, we constructed interconnected mesopores in the electrospun zeolitic imidazolate framework-8 (ZIF-8)/polyacrylonitrile (PAN) fibers with the assistance of poly(vinylpyrrolidone) to expose more adsorption sites of ZIF-8 and make ZIF-8 more stable. Moreover, the mesopores could also enhance the diffusion of contaminant molecules and create MOF-polymer interfaces in the fiber, which improve the adsorption rate and adsorption capacity, respectively. The obtained fibers were used to adsorb antibiotic tetracycline from water. Benefiting from the mesoporous adsorption channels and the MOF-polymer interface, porous ZIF-8/PAN fibers showed faster adsorption kinetics than ZIF-8/PAN blending fibers and larger adsorption capacity than ZIF-8-coated PAN fibers and ZIF-8/PAN blending fibers. The maximum adsorption capacity of porous ZIF-8/PAN fibers was 885.24 mg/g, which is close to that of pure ZIF-8. After 10 adsorption-desorption cycles, the removal efficiency was still above 97%. In addition, porous ZIF-8/PAN fibers could act as the membrane adsorbents to dynamically separate tetracycline with a treated capacity of 9.93 × 10³ bed volumes. These results demonstrate that our prepared porous ZIF-8/PAN fibers have great potential in antibiotic drug removal.