The application of MOFs-based materials for antibacterials adsorption

Rational Design of Core-Shell MoS2@ZIF-67 Nanocomposites for Enhanced Photocatalytic Degradation of Tetracycline

Zeolitic imidazolate frameworks (ZIFs) and their composites are attractive materials for photocatalytic applications due to their distinct characteristics. Core-shell ZIFs have lately emerged as a particularly appealing type of metal-organic frameworks, with improved light-absorption and charge-separation capabilities. In this study, hybrid nanocomposite materials comprising a zeolitic imidazolate framework-67 and molybdenum disulfide (MoS2) were fabricated with a core-shell structure. The prepared core-shell MoS2@ZIF-67 nanocomposites were studied using XRD, FTIR, XPS, and HR-TEM techniques. The crystalline nature and the presence of characteristic functional groups of the composites were analyzed using XRD and FTIR, respectively. The photocatalytic degradation of antibiotic tetracycline (TC) was measured using visible light irradiation. Compared to pristine MoS2 (12%) and ZIF-67 (34%), the most active MoS2@ZIF-67 nanocomposite (72%) exhibited a greater tetracycline degradation efficacy.

Exploring the state-of-the-art in metal-organic frameworks for antibiotic adsorption: a review of performance, mechanisms, and regeneration

The application of metal-organic frameworks (MOFs) towards the adsorption of antibiotics is a new and emerging area of study. The rise in use or misuse of antibiotic products has exacerbated their ongoing presence and persistence in the natural environment. Even at low concentrations, antibiotic residues exert pressure on bacterial populations, eventually leading to the emergence of resistant bacteria. Metal-organic frameworks, known for their high porosity, vast specific surface area, and ease of modification, have emerged to be a promising and sustainable antibiotic adsorbent. In an effort to advance the development of this adsorbent, this study provides a state-of-the-art review of recent research published from 2020 to the present, specifically examining the use of MOFs for removing antibiotics from aqueous solutions. Multiple MOF adsorbents were analyzed, with approximately 59% demonstrating significant adsorption capacity within the pH range of 6.0-8.0. In 75% of the instances, the adsorption system reached equilibrium in under 2 hr. Adsorption capacities compared well to other published works in the literature and exceeded conventional adsorbents in many instances. Notable cases of MOF performance were MIL-53(Al) adsorption of amoxicillin (AMX) and SA-g-P3AP@MOF(Fe)/Ag adsorption of neomycin where adsorption capacities of 758.5 and 625.0 mg/g were attained, respectively. The reusability of MOFs was extensively reported at the laboratory batch scale. Analysis of the reported studies revealed the most effective eluents were acetone, ethanol, and methanol, with mostly 3-5 cycles attainable without appreciable loss in efficiency. The recent literature confirmed that MOFs are highly efficient in the adsorption of antibiotics; however, there are some areas that warrant further development. It is intended that this work will bring recent trends to the forefront, identify knowledge gaps, and help guide future research proposals.

Inhibitory effect of organometallic framework composite nanomaterial ZIF8@ZIF67 on different pathogenic microorganisms of silkworms

The domestic silkworm (Bombyx mori) is of considerable economic importance, but is highly susceptible to various pathogens, which leads to substantial losses in sericulture. Nanomaterials, particularly metal-organic frameworks (MOFs), have shown promise in antibacterial applications due to their broad-spectrum activity and low toxicity. This study presented the synthesis, characterization, and antibacterial evaluation of MOF-based nanomaterials, specifically ZIF8, ZIF67, and their composite ZIF8@ZIF67, for their potential as antibacterial agents against silkworm pathogens. Our findings revealed that the composite material ZIF8@ZIF67 demonstrates better antibacterial efficacy against Bacillus cereus and Serratia marcescens in vitro than pristine ZIF8 and ZIF67, with minimal inhibitory concentrations of 2.5 μg/mL and 3.0 μg/mL, respectively. Furthermore, cytotoxicity assays indicate that neither ZIF8 at 100 μg/mL nor ZIF67 and ZIF8@ZIF67 at 200 μg/mL adversely affected the viability of BmN cells. At the same time, under these concentrations, the proliferation of Nosema bombycis at both 48 h and 72 h post-infection was significantly inhibited. Moreover, supplementation of 300 μg/g ZIF8@ZIF67 to silkworm larvae significantly enhanced their survival rates upon infection with the bacteria above without adversely affecting silkworm growth or cocoon weight. The underlying mechanisms of action may include disruption of bacterial cell membranes, induction of oxidative stress via generation of reactive oxygen species (ROS), and initiation of apoptosis. The biocompatibility and non-toxicity of ZIF8@ZIF67 and its antibacterial efficacy suggest its potential as a safe and effective agent for silkworm disease control. Conclusively, our research offers important insights for advancing MOFs-based nanomaterials for potential antibacterial treatment in silkworms or other insects.

Design and preparation of non-porous amorphous PEI-based polymers and their adsorption properties for anionic dyes

In this study, we report the design and synthesis of a series of non-porous amorphous polyethyleneimine-based adsorbents, specifically PEI-PD, PEI-TC, and PEI-CC, for selective adsorption of anionic dyes from aqueous solutions. Utilizing pyromellitic dianhydride (PD), terephthaloyl chloride (TC), and cyanuric chloride (CC) as cross-linking agents, we produced adsorbents with distinct morphological and adsorption characteristics. Scanning electron microscopy (SEM) revealed that PEI-PD and PEI-TC exhibit rough, folded surfaces, with total pore volumes of 0.0001 cm³ /g, 0.0002 cm³ /g, respectively, whereas PEI-CC displays particulate features with total pore volumes of 0.0040 cm³ /g, confirming non-porous nature. XRD and SAED analyses confirmed the amorphous state. Zeta potential increased for the PEI based adsorbents, correlating with enhanced electrostatic adsorption. IGMH analysis revealed non-covalent interactions, including hydrogen bonding, also contribute to adsorption. Further adsorption studies indicated pseudo-second-order and Langmuir model fits, suggesting chemisorption and monolayer adsorption. The adsorption performance was evaluated using various dyes, demonstrating that cross linker structure significantly influences adsorption efficiency. PEI-TC demonstrates the highest adsorption capacity for Congo red, reaching 3089.49 mg/g, due to its para-substituted linkage enhancing molecular flexibility, while the adsorption capacity of PEI-CC was 793.85 mg/g, as the meta-substituted CC linkage causes the molecular chains stack closely together and reduces the available free space, leading to a decreased specific surface area. Under simulated real conditions, the removal rate remained above 90 %. This study offers insights into the critical role of building blocks in the development of efficient adsorbents, highlighting the importance of polymer structure on adsorption performance.

Recent Progress in Antibacterial Surfaces for Implant Catheters

Catheter-related infections (CRIs) caused by hospital-acquired microbial infections lead to the failure of treatment and the increase of mortality and morbidity. Surface modifications of the implant catheters have been demonstrated to be effective approaches to improve and largely reduce the bacterial colonization and related complications. In this work, we focus on the last 5-year progress in the surface modifications of biomedical catheters to prevent CRIs. Their antibacterial strategies used for surface modifications are further divided into 5 classifications through the antimicrobial mechanisms, including active surfaces, passive surfaces, active and passive combination surfaces, stimulus-type response surfaces, and other types. Each feature and the latest advances in these abovementioned antibacterial surfaces of implant catheters are highlighted. Finally, these confronting challenges and future prospects are discussed for the antibacterial modifications of implant catheters.

Simultaneous detection and removal of tetracycline antibiotics in water using silver-based metal-organic frameworks

Tetracyclines (TCs), a class of broad-spectrum antibiotics, are major contaminants in water, have adverse effects on the ecosystem, and are toxic non-target organisms. A straightforward and efficient strategy for both the detection and removal of TCs from water remains highly desirable but is challenging to develop. In this study, a dual-functional platform for detecting and removing TCs was developed using highly stable silver-based metal-organic frameworks (Ag-MOFs). This platform enabled the specific detection of TCs over a broad concentration range (from 1 × 10⁻10 to 1 × 10⁻3 mol/L), with a low detection limit of 8.4 nM. By leveraging its high surface area, the Ag-MOFs exhibited exceptional adsorption capacities, reaching 276 mg/g for chlortetracycline. To elucidate the potential response mechanism and electronic transfer pathway, density functional theory calculations and charge density difference analyses were performed. This Ag-MOFs-based platform achieved both rapid detection and efficient removal of TCs from the environment. The design principles proposed herein are expected to inspire the development of novel platforms for the simultaneous sensing and removal of specific pollutants.

Hourglass-shaped europium cluster-based secondary building unit in metal-organic framework for photocatalytic wastewater purification and sterilization via enhanced reactive oxygen species production

A large number of diseases caused by water pollution have become a global public health issue, and the development and construction of innovative and efficient photocatalytic systems for water remediation is vital to improve water quality and prevent bacteria-induced diseases. Herein, a europium-based metal-organic framework (Eu-MOF) was self-assembled with complex hourglass-shaped Eu9 clusters as secondary building units (SBUs), achieving excellent photoinduced reactive oxygen species (ROS) generation ability. Moreover, Eu-MOF can quickly and efficiently degrade organic dyes and kill a variety of bacteria under low-power light irradiation conditions. Time-dependent scanning electron microscopy (SEM) and infrared absorption spectroscopy (IR) were used for the first time to track the formation process of complex clusters into cluster-based MOFs, and the gradual transformation of amorphous intermediates into crystalline Eu-MOF was clearly tracked. Electrochemical impedance spectroscopy (EIS) results showed that Eu-MOF has a smaller semicircle than the organic ligands, demonstrating its excellent charge separation ability. The excellent ROS generation capacity of Eu-MOF was jointly demonstrated by electron paramagnetic resonance (EPR) spectroscopy and the results obtained using the 2',7'-dichlorodihydrofluorescein (DCFH) indicator. More importantly, using low-power (60 mW/cm2) Xe lamp irradiation, Eu-MOF can almost completely degrade 10 mg/L aqueous solutions of rhodamine B (RhB), methylene blue (MB), and crystal violet (CV) within 30, 90, and 120 min, respectively. In addition, the excellent light-induced ROS production ability of Eu-MOF contributes to its significant cell killing and antibacterial effects. Under light irradiation conditions, Eu-MOF can effectively kill Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with average inhibition zone sizes of 2.54 ± 0.17 and 2.56 ± 0.08 cm, respectively. This work opens up new horizons for the build of efficient photocatalytic systems based on lanthanide porous materials and promotes the progress of lanthanide MOFs (Ln-MOFs) crystal engineering.

Polyvinyl alcohol/sodium alginate-based conductive hydrogels with in situ formed bimetallic zeolitic imidazolate frameworks towards soft electronics

Bimetallic zeolitic imidazolate frameworks (BZIFs) have received enormous attention due to their unique physi-chemical properties, but are rarely reported for electrically conductive hydrogel (ECH) applications arising from low intrinsic conductivity and poor dispersion. Herein, we propose an innovative strategy to prepare highly conductive and mechanically robust ECHs by in situ growing Ni/Co-BZIFs within the polyvinyl alcohol/sodium alginate dual network (PZPS). 2-methylimidazole (MeIM) ligands copolymerize with pyrrole monomers, enhancing the electrical conductivity; meanwhile, MeIM ligands act as anchor points for in-situ formation of BZIFs, effectively avoiding phase-to-phase interfacial resistance and ensuring a uniform distribution in the hydrogel network. Due to the synergism of Ni/Co-BZIFs, the PZPS hydrogel exhibits a high areal capacitance of 630.3 mF·cm-2 at a current density of 0.5 mA·cm-2, promising for flexible energy storage devices. In addition, PZPS shows excellent mechanical strength and toughness (with an ultimate tensile strength of 405.0 kPa and a toughness of 784.2 kJ·m-3 at an elongation at break of 474.0 %), a high gauge factor of up to 4.18 over an extremely wide stress range of 0-42 kPa when used as flexible wearable strain/pressure sensors. This study provides new insights to incorporating highly conductive and uniformly dispersed ZIFs into hydrogels for flexible wearable electronics.

Adsorption behavior of ZIF-67 to bisphenol compounds affects combined toxicity on Photobacterium phosphoreum

ZIF-67, as a typical MOF material, is considered a new type of high-potential adsorbent due to its ample surface area and tunable surface chemistry, which has the potential to interact with other contaminants in unforeseen ways, resulting in combined toxicity. To further elucidate this possibility, we chose typical bisphenol compound (BP) which is widely used in commercial manufacturing, to explore the combined toxicity with MOF. MOF showed a high adsorption capacity for BPAF (> 80 %) and the weakest adsorption capacity for BPA (< 10 %), and DFT confirmed the different interaction strengths of MOF for BPs. The difference in adsorption capacity for BPs resulted in different amounts of free BPs, contributing to combined toxicity. Based on flow cytometry and TEM, the results showed that membrane damage was reduced and the ability of ZIF-67 to enter the cell was decreased in the low-concentration ZIF-67 mixing group, and the ability of ZIF-67 to enter the cell was increased in the high-concentration ZIF-67 mixing group, and the membranes were severely damaged. RT-PCR and biochemical indicators measurements helped to explain the underlying toxicity mechanism. This study is of practical significance for the development of environmental guidelines for mixed contaminant effects and accurate risk assessments.

Synthesis and characterization of magnetic aluminum metal-organic frameworks encapsulated with chitosan and carboxymethyl cellulose for effective elimination of atrazine from aqueous solutions: Adsorption evaluation, DFT calculations and Box-Behnken design optimization

The discharge of herbicides is a primary contributor to water contamination, presenting significant environmental and public health hazards. Encapsulating herbicides in a chemical compound called MAl-MOF/CS-CMC hydrogel bead (MACC) made from magnetic aluminum metal-organic frameworks (MAl-MOF) and crosslinked with chitosan (CS) and carboxymethyl cellulose (CMC) shows promise for potential use. The research successfully developed and examined MACC microspheres, utilizing various analytical techniques including PXRD, FESEM, TEM, FT-IR, and XPS. The efficiency of MACC in eliminating atrazine (ATZ) from wastewater was also simulated. Additionally, density functional theory (DFT) was employed to assess the electrical characteristics, reactivity, and arrangement of ATZ at a structural level. The results of the DFT analysis demonstrate a significant relationship between the locations of nucleophilic and electrophilic attacks and the molecular orbitals of the HOMO and LUMO. Using MACC as an adsorbent provides considerable advantages due to its expansive surface area of 860.92 m2/g and a pore size of 1.48 nm, meeting the mesoporous classification criteria outlined by IUPAC standards. In addition, it possesses a pore volume of 1.22 cm3/g. Nevertheless, following the adsorption procedure, the pore volume reduced to 0.78 cm3/g, and the surface area decreased to 650.42 m2/g. Several factors contributing to the capacity to attract and retain substances were analyzed. These factors encompass temperature, duration of contact, quantity of the attracting substance, initial atrazine (ATZ) concentration, and solution pH. The primary method of adsorption that was determined is chemisorption, as evidenced by the calculated adsorption energy of 29.3 kJ per mole. The thermodynamic analysis indicates that the adsorption of ATZ by the micropores of MACC occurs spontaneously and is characterized as endothermic, as evidenced by the positive ΔHo value and negative ΔGo value. It has been proposed that a range of adsorption mechanisms, including chemisorption, π-π interactions, pore filling, hydrogen bonding, and electrostatic interactions, may be responsible for removing the herbicide from the MACC material.

Co/Cd-MOF-Derived Porous Carbon Materials for Moxifloxacin Adsorption from Aqueous Solutions

In this study, Co/Cd-MOFs were synthesized via a solvothermal method. The resulting material was subjected to calcination at 900 °C for 2 h and characterized using FT-IR, XRD, and SEM techniques to assess its efficacy in moxifloxacin removal. The experimental findings revealed that the maximum adsorption capacity of Co/Cd-MOFs for moxifloxacin was observed at 350.4 mg/g within a 5 h timeframe. Furthermore, the analysis based on the pseudo-second-order kinetic model demonstrated that the adsorption process adhered to this specific model. Additionally, the adsorption isotherm analysis indicated that Freundlich multilayer adsorption provided the best description of the interaction between moxifloxacin and the Co/Cd-MOF material. These experimental and theoretical results collectively suggest that employing Co/Cd-MOFs as adsorbents holds promise for wastewater treatment applications.

Metal-organic frame material encapsulated Rhodamine 6G: A highly sensitive fluorescence sensing platform for the detection of picric acid contaminants in water

As a water pollutant with excellent solubility, 2,4,6-trinitrophenol (also known as picric acid, PA) poses a potential threat to the natural environment and human health, so it is crucial important to detect PA in water. In this study, a novel composite material (MIL-53(Al)@R6G) was successfully synthesized by encapsulating Rhodamine 6G into a metal-organic frame material, which was used for fluorescence detection of picric acid (PA) in water. The composite exhibits bright yellow fluorescence emission with a fluorescence quantum yield of 58.23 %. In the process of PA detection, the composite has excellent selectivity and anti-interference performance, and PA can significantly quench the fluorescence intensity of MIL-53(Al)@R6G. MIL-53(Al)@R6G has the advantages of fast detection time (20 s), wide linear range (1-100 µM) and low detection limit (4.8 nM). In addition, MIL-53(Al)@R6G has demonstrated its potential for the detection of PA in environmental water samples with satisfactory results.

Chitosan-based GOx@Co-MOF composite hydrogel: A promising strategy for enhanced antibacterial and wound healing effects

A novel composite hydrogel was synthesized via Schiff base reaction between chitosan and di-functional poly(ethylene glycol) (DF-PEG), incorporating glucose oxidase (GOx) and cobalt metal-organic frameworks (Co-MOF). The resulting CS/PEG/GOx@Co-MOF composite hydrogel was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and energy-dispersive X-ray spectroscopy (EDS). The results confirmed successful integration and uniform distribution of Co-MOF within the hydrogel matrix. Functionally, the hydrogel exploits the catalytic decomposition of glucose by GOx to generate gluconic acid and hydrogen peroxide (H2O2), while Co-MOF gradually releases metal ions and protects GOx. This synergy enhanced the antibacterial activity of the composite hydrogel against both Gram-positive (S. aureus) and Gram-negative bacteria (E. coli), outperforming conventional chitosan-based hydrogels. The potential of the composite hydrogel in treating wound infections was evaluated through antibacterial and wound healing experiments. Overall, CS/PEG/GOx@Co-MOF hydrogel holds great promise for the treatment of wound infections, paving the way for further research and potential clinical applications.

Development of packaging films based on UiO-66 MOF loaded melatonin with antioxidation functions for spinach preservation

Spinach tends to deteriorate after harvest due to physiological metabolic activities. As a natural, pollution-free, and environmentally friendly preservative, melatonin (MT) can effectively maintain the quality of fruits and vegetables after harvest and delay senescence. To enhance the preservation effect of MT, this study developed antioxidant films using MT-loaded UiO-66 metal-organic framework (MOF) nanoparticles. This approach effectively extends the shelf life of spinach while preserving its quality. The underlying mechanism involves leveraging the microporous structure and stability of UiO-66 MOF. Experimental results obtained from the packaging films demonstrated significant improvements in both mechanical strength and antioxidant properties when UiO-66 was loaded with MT at a concentration of 0.20 mg/mL and combined with sodium alginate. Freshness preservation experiments also indicated the effective preservation effect of these films on spinach. In conclusion, the results of this study suggest that MT-loaded UiO-66 MOF is a promising active packaging material for spinach preservation.

Nanocomposites against Pseudomonas aeruginosa biofilms: Recent advances, challenges, and future prospects

Pseudomonas aeruginosa is an opportunistic bacterial pathogen that causes life-threatening and persistent infections in immunocompromised patients. It is the culprit behind a variety of hospital-acquired infections owing to its multiple tolerance mechanisms against antibiotics and disinfectants. Biofilms are sessile microbial aggregates that are formed as a result of the cooperation and competition between microbial cells encased in a self-produced matrix comprised of extracellular polymeric constituents that trigger surface adhesion and microbial aggregation. Bacteria in biofilms exhibit unique features that are quite different from planktonic bacteria, such as high resistance to antibacterial agents and host immunity. Biofilms of P. aeruginosa are difficult to eradicate due to intrinsic, acquired, and adaptive resistance mechanisms. Consequently, innovative approaches to combat biofilms are the focus of the current research. Nanocomposites, composed of two or more different types of nanoparticles, have diverse therapeutic applications owing to their unique physicochemical properties. They are emerging multifunctional nanoformulations that combine the desired features of the different elements to obtain the highest functionality. This review assesses the recent advances of nanocomposites, including metal-, metal oxide-, polymer-, carbon-, hydrogel/cryogel-, and metal organic framework-based nanocomposites for the eradication of P. aeruginosa biofilms. The characteristics and virulence mechanisms of P. aeruginosa biofilms, as well as their devastating impact and economic burden are discussed. Future research addressing the potential use of nanocomposites as innovative anti-biofilm agents is emphasized. Utilization of nanocomposites safely and effectively should be further strengthened to confirm the safety aspects of their application.

Metal-Organic Framework-Enabled Sustainable Agrotechnologies: An Overview of Fundamentals and Agricultural Applications

With aggravated abiotic and biotic stresses from increasing climate change, metal-organic frameworks (MOFs) have emerged as versatile toolboxes for developing environmentally friendly agrotechnologies aligned with agricultural practices and safety. Herein, we have explored MOF-based agrotechnologies, focusing on their intrinsic properties, such as structural and catalytic characteristics. Briefly, MOFs possess a sponge-like porous structure that can be easily stimulated by the external environment, facilitating the controlled release of agrochemicals, thus enabling precise delivery of agrochemicals. Additionally, MOFs offer the ability to remove or degrade certain pollutants by capturing them within their pores, facilitating the development of MOF-based remediation technologies for agricultural environments. Furthermore, the metal-organic hybrid nature of MOFs grants them abundant catalytic activities, encompassing photocatalysis, enzyme-mimicking catalysis, and electrocatalysis, allowing for the integration of MOFs into degradation and sensing agrotechnologies. Finally, the future challenges that MOFs face in agrotechnologies were proposed to promote the development of sustainable agriculture practices.

A review on carbon-based biowaste and organic polymer materials for sustainable treatment of sulfonamides from pharmaceutical wastewater

Frequent detection of sulfonamides (SAs) pharmaceuticals in wastewater has necessitated the discovery of suitable technology for their sustainable remediation. Adsorption has been widely investigated due to its effectiveness, simplicity, and availability of various adsorbent materials from natural and artificial sources. This review highlighted the potentials of carbon-based adsorbents derived from agricultural wastes such as lignocellulose, biochar, activated carbon, carbon nanotubes graphene materials as well as organic polymers such as chitosan, molecularly imprinted polymers, metal, and covalent frameworks for SAs removal from wastewater. The promising features of these materials including higher porosity, rich carbon-content, robustness, good stability as well as ease of modification have been emphasized. Thus, the materials have demonstrated excellent performance towards the SAs removal, attributed to their porous nature that provided sufficient active sites for the adsorption of SAs molecules. The modification of physico-chemical features of the materials have been discussed as efficient means for enhancing their adsorption and reusable performance. The article also proposed various interactive mechanisms for the SAs adsorption. Lastly, the prospects and challenges have been highlighted to expand the knowledge gap on the application of the materials for the sustainable removal of the SAs.

Photocatalytic Degradation of Tetracycline Hydrochloride Based on the Structure-Property Exploration of BiOCl

The correlation between structure and properties in the photodegradation reaction of bismuth oxychloride (BiOCl) was explored in this work. Three BiOCl samples with different sizes, morphological structures, and defects were prepared through a hydrothermal method with experimental manipulation. Their structural properties were comprehensively characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron spin resonance, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy, and photoluminescence. Taking the photodegradation of tetracycline hydrochloride (TC-HCl) as the probe reaction, we found that high activity could be achieved by decreasing their crystal size and thickness, introducing proper defects in the structure, and assembling the nanosheets to get microball structure. Combined with radical-scavenge experiments and electron spin resonance (ESR) spin-trap spectra, we conclude that ̇O2- was the dominant reactive oxygen species for the degradation reaction. The degradation detailed pathway of TC-HCl was further analyzed using liquid chromatography-mass spectrometry. This work explores the structure-property correlation of BiOCl and provides strategies for the rational design of active photocatalysts for water remediation.

Highly efficient removal of tetracyclines from water by a superelastic MOF-based aerogel: Mechanism quantitative analysis and dynamic adsorption

Metal-organic frameworks (MOFs) were promising adsorbents for removing antibiotics, but the inherent poor recyclability of MOF powders limits further application. Moreover, the dominant adsorption mechanisms and their quantitative assessment are less studied. Here, ultrahigh adsorption capacities of 821.51 and 931.87 mg g-1 for tetracycline (TC) and oxytetracycline (OTC), respectively, were realised by a novel adsorbents (biochar loaded with MIL-88B(Fe), denoted as BC@MIL-88B(Fe)), which were further immobilised in a 3D porous gelatin (GA) substrate. The obtained BCM/GA200 showed superior adsorption performance under wide pH ranges and under the interference of humic acid. Moreover, it can survive >8 cycles and even maintain high adsorption efficiency in different actual water samples. Notably, BCM/GA200 can selectively remove tetracyclines in a multivariate system containing other kinds of antibiotics and from a dynamic adsorption system. Most importantly, the results of X-ray photoelectron spectroscopy, 2D Fourier transform infrared correlation spectroscopy (2D-FTIR-COS) and density functional theory techniques revealed that (1) for TC adsorption, at pH < 4.0, the contribution of complexation was 25 %-45 %, whereas pore filling and hydrogen bonding accounted for 39 %-72 % of the total uptake. At 4.0 < pH < 10.0, the contribution of complexation increased to 60 %-82 %, whereas electrostatic attraction and π-π interaction were 4 %-13 % and 2 %-10 %, respectively. (2) For OTC adsorption, complexation was dominant at 3.0 < pH < 10.0, accounting for 55 %-86 % of the total uptake, and electrostatic attraction and π-π interactions caused 3 %-10 % and 3 %-15 %, respectively. (3) At pH > 10.0, pore filling dominated TC and OTC adsorption. Finally, the reaction sequences of the main adsorption mechanisms were also probed by 2D-FTIR-COS. This work solves the poor recyclability of MOF powders and provides a mechanistic insight into antibiotic removal by MOFs.

Nanoarchitectonics Design Strategy of Metal-Organic Framework and Bio-Metal-Organic Framework Composites for Advanced Wastewater Treatment through Adsorption

Freshwater depletion is an alarm for finding an eco-friendly solution to treat wastewater for drinking and domestic applications. Though several methods like chlorination, filtration, and coagulation-sedimentation are conventionally employed for water treatment, these methods need to be improved as they are not environmentally friendly, rely on chemicals, and are ineffective for all kinds of pollutants. These problems can be addressed by employing an alternative solution that is effective for efficient water treatment and favors commercial aspects. Metal organic frameworks (MOFs), an emerging porous material, possess high stability, pore size tunability, greater surface area, and active sites. These MOFs can be tailored; thus, they can be customized according to the target pollutant. Hence, MOFs can be employed as adsorbents that effectively target different pollutants. Bio-MOFs are a kind of MOFs that are incorporated with biomolecules, which also possess properties of MOFs and are used as a nontoxic adsorbent. In this review, we elaborate on the interaction between MOFs and target pollutants, the role of linkers in the adsorption of contaminants, tailoring strategy that can be employed on MOFs and Bio-MOFs to target specific pollutants, and we also highlight the effect of environmental matrices on adsorption of pollutants by MOFs.

Precursor-oriented design of nano-alumina for efficient removal of antibiotics

Rapid and efficient removal of environmental antibiotics is vital to curb bacterial resistance. Through rational precursors-oriented design, we attain the best Al2O3 absorbent by 500 °C calcination of ammonium aluminium carbonate hydroxide (AACH) precursor from NH4HCO3 route (AACH-NH4HCO3-500) for fast and efficient removal of tetracycline (TC) and other antibiotics from environmental waters including high-salinity wastewater. AACH-NH4HCO3-500 (0.25 g·L-1) can remove (69.92 ± 1.78)% of aqueous TC (0.025 g·L-1) within 5 min and (97.62 ± 2.75)% within 2 h, and the adsorption capacity is 444.4 mg·g-1, which is the highest qmax of TC for the 2 h-adsorptions among numerous adsorbents. AACH-NH4HCO3-500 has fine tolerance to the coexisting substances, and can be easily regenerated and reused, and has no harm even discarded. The relations among the synthetic methods, the structural features, and the adsorption functions of Al2O3 are disclosed through a systematic comparison of the commercial Al2O3 and different Al2O3 nanomaterials attained from three precursors produced by five different routes. The reasons behind the exceptional adsorption performance are discussed throughout. Our findings would facilitate the development of excellent adsorbents for removal of other pollutants.

Efficient removal of veterinary drugs from aqueous solutions using magnetically separable carbonaceous materials derived from cobalt and iron metal-organic frameworks

Rapid synthesis of carbon-based magnetic materials derived from cobalt and iron metal-organic frameworks (MOFs), ZIF-67, and MIL-100(Fe), by microwave-assisted method, followed by carbonization under a N₂ atmosphere is described in this study. The carbon-derived MOFs (CDMs) were evaluated for the removal of the emerging pollutants sulfadiazine (SDZ) and flumequine (FLU) used as veterinary drugs. The study aimed to link the adsorption behavior with their surface properties and elemental composition. C-ZIF-67 and C-MIL-100(Fe) showed hierarchical porous structures with specific surface areas of 295.6 and 163.4 m² g^-1, respectively. The Raman spectra of the CDMs show the characteristic D and G bands associated with defect-rich carbon and sp² graphitic carbon, respectively. The CDMs exhibit cobalt species (Co₃O₄, CoO, and Co) in C-ZIF-67 and iron species (Fe₂O₃, Fe₃O₄, and Fe) in C-MIL-100 (Fe) which are related to the magnetic behavior of CDMs. C-ZIF-67 and C-MIL-100 (Fe) had saturation magnetization values of 22.9 and 53.7 emu g^-1, respectively, allowing easy solid-liquid separation using a magnet. SDZ and FLU removal rates on CDMs follow pseudo-second-order kinetics, and adsorption isotherms fit the Langmuir model based on regression coefficient values. Adsorption thermodynamics calculations showed that the adsorption of SDZ and FLU by CDMs was a thermodynamically favorable process. Therefore, these properties of C-ZIF-67 and C-MIL-100 (Fe) and their regeneration ability facilitate their use as adsorbents for emerging pollutants.

Post-synthesis introduction of dual functional groups in metal-organic framework for enhanced adsorption of moxifloxacin antibiotic

Highly effective removal of antibiotics from aqueous solution is of importance while still faces challenge. Herein, we report a novel metal-organic framework (MOF) adsorbent, MOF-808-SIPA (SIPA, 5-sulfoisophthalic acid), constructed via post-synthesis exchange strategy. On the basis, dual active groups including sulfonic acid and carboxyl groups are successfully introduced. The novel MOF-808-SIPA exhibits a high adsorption capacity of 287.1 mg g^-1 for moxifloxacin hydrochloride (MOX·HCl), superior to that (174.6 mg g^-1) of the pristine MOF-808-AA (AA, acetic acid). Besides, MOF-808-SIPA shows rapid adsorption equilibrium of ∼ 30 min, strong anti-interference ability from pH and inorganic ions, and feasible regeneration. The superiority renders MOF-808-SIPA a potential adsorbent for MOX removal. Density function theory (DFT) calculation and experiment confirm that H-bond interaction contributes largely to the excellent adsorption in MOF-808-SIPA. Our work provides a guideline for designing high-efficiency MOF-based adsorbent.

Thiol-decorated defective metal-organic framework for effective removal of mercury(II) ion

Removal of mercury (Hg) ion from water is important while still faces challenges in capacity and adsorption speed. Herein, using thiol-containing mercaptoacetic acid (MA) as the template, we constructed a novel metal-organic framework (MOF) adsorbent, Zr-MSA-MA (MSA, mercaptosuccinic acid). Unlike other monodentate acids such as acetic acid and formic acid, MA benefits to maintain high-content binding sites, in the meantime of defect formation. On the basis, Zr-MSA-MA exhibits a high adsorption capacity of 714.8 mg g^-1 for Hg²⁺ and fast adsorption kinetics, superior to other MOF-based adsorbents. Co-existing metal ions and pH have only slight interference for the adsorption behavior. Besides, the adsorption is proved to an endothermic reaction and the adsorbent can be regenerated based on a simple elution. Further analysis indicates the strong chemical bonding of Hg²⁺ and -SH is the main adsorption mechanism. Thus, our work demonstrates the Zr-MSA-MA can serve as a potential adsorbent for Hg²⁺, and provides a novel strategy to construct defective adsorbent via using active group-containing template.

Photocatalytic assessed adsorptive removal of tinidazole from aqueous environment using reduced magnetic graphene oxide-bismuth oxychloride and its silver composite

Antibiotics (tinidazole (TNZ)) in wastewater, exhibit adverse effects on humans and ecosystem. The current study was aimed to synthesize photocatalysts mrGO/BiOCl and mrGO/BiOCl/Ag. mrGO was coupled with BiOCl by hydrothermal method and Ag was deposited over it. The synthesized mrGO/BiOCl and mrGO/BiOCl/Ag were confirmed by Pzc analysis (5.5 and 4.4 for mrGO/BiOCl and mrGO/BiOCl/Ag, respectively), surface area analysis (380 m2 g-1, 227.7 m2 g-1, 220 m2 g-1 for mrGO, mrGO/BiOCl and mrGO/BiOCl/Ag respectively), elemental analysis (Ag, O, Bi, Fe), surface morphology (rough ball like sphere of mrGO/BiOCl and cubic Ag nanoparticles in mrGO/BiOCl/Ag), functional groups and band gap (Eg) determination. The Eg was determined using Kubelka-Munk equation as 3.5 and 2.8 eV for mrGO/BiOCl and mrGO/BiOCl/Ag respectively. During the adsorption study, the best experimental conditions for various operating parameters such as pH (2), contact time (5 min for mrGO/BiOCl and 10 min for mrGO/BiOCl/Ag under UV irradiation), TNZ concentration (18 μgL-1) and catalyst dosage (0.001 g) were achieved. Kinetic study revealed that both composites followed pseudo second order kinetics (R2 = 0.9979 and 0.9986, respectively). Data of rGO/BiOCl was fitted to Freundlich adsorption model (R2 = 0.9687) and rGO/BiOCl/Ag fitted to Langmuir adsorption model (R2 = 0.9994). Moreover, thermodynamic parameters confirmed that a photodegradation phenomenon was spontaneous and exothermic. The results confirmed that rGO/BiOCl and rGO/BiOCl/Ag are appropriate composites for TNZ removal from the aqueous environment with removal efficiency of 97 and 24%, respectively.

ZIF-8 metal organic framework materials as a superb platform for the removal and photocatalytic degradation of organic pollutants: a review

Metal organic frameworks (MOFs) are attracting significant attention for applications including adsorption, chemical sensing, gas separation, photocatalysis, electrocatalysis and catalysis. In particular, zeolitic imidazolate framework 8 (ZIF-8), which is composed of zinc ions and imidazolate ligands, have been applied in different areas of catalysis due to its outstanding structural and textural properties. It possesses a highly porous structure and chemical and thermal stability under varying reaction conditions. When used alone in the reaction medium, the ZIF-8 particles tend to agglomerate, which inhibits their removal efficiency and selectivity. This results in their mediocre reusability and separation from aqueous conditions. Thus, to overcome these drawbacks, several well-designed ZIF-8 structures have emerged by forming composites and heterostructures and doping. This review focuses on the recent advances on the use of ZIF-8 structures (doping, composites, heterostructures, etc.) in the removal and photodegradation of persistent organic pollutants. We focus on the adsorption and photocatalysis of three main organic pollutants (methylene blue, rhodamine B, and malachite green). Finally, the key challenges, prospects and future directions are outlined to give insights into game-changing breakthroughs in this area.

A novel approach based on the ultrasonic-assisted microwave method for the efficient synthesis of Sc-MOF@SiO2 core/shell nanostructures for H2S gas adsorption: A controllable systematic study for a green future

In this work, for the first time, novel Sc-MOF@SiO₂ core/shell nanostructures have been synthesized under the optimal conditions of ultrasonic-assisted microwave routes. The final products showed small particle size distributions with homogeneous morphology (SEM results), high thermal stability (TG curve), high surface area (BET adsorption/desorption techniques), and significant porosity (BJH method). The final nanostructures of Sc-MOF@SiO₂ core/shell with such distinct properties were used as a new compound for H₂S adsorption. It was used with the systematic investigation based on a 2^K−1 factorial design, which showed high-performance adsorption of about 5 mmol/g for these novel adsorbents; the optimal experimental conditions included pressure, 1.5 bar; contact time, 20 min; and temperature, 20°C. This study and its results promise a green future for the potential control of gas pollutants.

Universitetet i Oslo-67 (UiO-67)/graphite oxide composites with high capacities of toluene: Synthesis strategy and adsorption mechanism insight

In this paper, a simple solvothermal synthesis method was proposed for the preparation of metal organic framework/graphene oxide hybrid nanocomposite (UiO-67/GO). A series of UiO-67/GO composites were prepared by varying the addition forms and amounts of GO, and the optimal synthesis conditions were screened. The composites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission Electron Microscope (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopic (XPS), water contact angles (CA) and thermogravimetric analysis (TGA). The adsorption capacity and the adsorption process of toluene were investigated by dynamic adsorption and adsorption kinetics, respectively. The results indicated that 67/GO-0.5% reached the maximum adsorption capacity (876 mg g^-1), which far exceeded the other adsorbents. Kinetic model and the Weber-Morris model correlated satisfactorily to the experimental data. The improved adsorption performance was attributed to GO, which enhanced π-π interaction, promoted defect generation and provided more adsorption sites. Finally, the excellent regeneration performance of the adsorbent was verified by temperature programmed desorption (TPD) and cyclic adsorption-desorption experiments. Moreover, the adsorption mechanism was further revealed. Combined with the related adsorption experiments and the density functional theory (DFT) analysis, the efficient removal of toluene by UiO-67/GO was attributed to the cooperation of defects, π-π interaction and hydrogen bonding.

An Efficient Ultrasound-Assisted Synthesis of Cu/Zn Hybrid MOF Nanostructures With High Microbial Strain Performance

Metal organic frameworks (MOFs) are a promising choice for antibacterial and antifungal activity due to their composition, unique architecture, and larger surface area. Herein, the ultrasonic method was used to synthesize the Cu/Zn-MOF material as an effective hybrid nanostructure with ideal properties. SEM images were used to investigate the product's morphology and particle size distribution. The XRD pattern revealed that the Cu/Zn hybrid MOF nanostructures had a smaller crystalline size distribution than pure Cu and Zn-MOF samples. Furthermore, the BET technique determined that the hybrid MOF nanostructures had a high specific surface area. TG analysis revealed that the hybrid MOF structures were more thermally stable than pure samples. The final product, with remarkable properties, was used as a new option in the field of antibacterial studies. Antibacterial activity was assessed using MIC and MBC against Gram negative and Gram positive strains, as well as antifungal activity using MIC and MFC. The antimicrobial properties of the synthesized Cu/Zn hybrid MOF nanostructures revealed that they were more effective than commercial drugs in some cases. This study's protocol could be a new strategy for introducing new hybrid nanostructures with specific applications.

Effective extraction of fluoroquinolones from water using facile modified plant fibers

In this study, ecofriendly and economic carboxy-terminated plant fibers (PFs) were used as adsorbents for the effective in-syringe solid phase extraction (IS-SPE) of fluoroquinolone (FQ) residues from water. Based on the thermal esterification and etherification reaction of cellulose hydroxy with citric acid (CA) and sodium chloroacetate in aqueous solutions, carboxy groups grafted onto cotton, cattail, and corncob fibers were fabricated. Compared with carboxy-terminated corncob and cotton, CA-modified cattail with more carboxy groups showed excellent adsorption capacity for FQs. The modified cattail fibers were reproducible and reusable with relative standard deviations of 3.2%–4.2% within 10 cycles of adsorption-desorption. A good extraction efficiency of 71.3%–80.9% was achieved after optimizing the extraction condition. Based on carboxylated cattail, IS-SPE coupled with ultra-performance liquid chromatography with a photodiode array detector was conducted to analyze FQs in environmental water samples. High sensitivity with limit of detections of 0.08–0.25 μg/L and good accuracy with recoveries of 83.8%–111.7% were obtained. Overall, the simple and environment-friendly modified waste PFs have potential applications in the effective extraction and detection of FQs in natural waters.

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Plant fibers were functionalized by green methods.

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The bio-adsorbents were applied for the extraction of fluoroquinolones.

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The higher carboxy content in fibers improved extraction performance.

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Carboxylated cattail was efficient in the adsorption of fluoroquinolones in environmental waters.

Construction of Au and C60 quantum dots modified materials of Institute Lavoisier-125(Ti) architectures for antibiotic degradation: Performance, toxicity assessment, and mechanistic insight

High-performance and stabilized photocatalytic degradation of antibiotic contaminants still remains a challenge in environmental photocatalysis and has been studied worldwide. In this work, hybrid Au and C60 quantum dots decorated Materials of Institute Lavoisier-125(Ti) (MIL-125(Ti)) composites were successfully fabricated for visible-light photocatalytic tetracycline degradation with pristine MIL-125(Ti) as a comparison. The experimental results revealed that the introduction of C60 quantum dots and Au nanoparticles resulted in highly enhanced visible-light harvesting and charge separation for efficient tetracycline degradation. The optimal Au/C60-MIL-125(Ti)-1.0% sample exhibited the highest visible-light photocatalytic performance, and the corresponding rate constant was approximately 9.19 times of MIL-125(Ti), indicating the significant roles of Au and C60 quantum dots in boosting visible-light absorption and charge separation. Furthermore, the radical species, possible degradation pathways and toxicity assessment, and photocatalytic mechanism were also investigated. Current work indicates a synergistic strategy for enhancing visible-light harvesting and charge separation to fabricate high-performance composite photocatalysts.

Recent Advances in Nanozymes for Bacteria-Infected Wound Therapy

Bacterial-infected wounds are a serious threat to public health. Bacterial invasion can easily delay the wound healing process and even cause more serious damage. Therefore, effective new methods or drugs are needed to treat wounds. Nanozyme is an artificial enzyme that mimics the activity of a natural enzyme, and a substitute for natural enzymes by mimicking the coordination environment of the catalytic site. Due to the numerous excellent properties of nanozymes, the generation of drug-resistant bacteria can be avoided while treating bacterial infection wounds by catalyzing the sterilization mechanism of generating reactive oxygen species (ROS). Notably, there are still some defects in the nanozyme antibacterial agents, and the design direction is to realize the multifunctionalization and intelligence of a single system. In this review, we first discuss the pathophysiology of bacteria infected wound healing, the formation of bacterial infection wounds, and the strategies for treating bacterially infected wounds. In addition, the antibacterial advantages and mechanism of nanozymes for bacteria-infected wounds are also described. Importantly, a series of nanomaterials based on nanozyme synthesis for the treatment of infected wounds are emphasized. Finally, the challenges and prospects of nanozymes for treating bacterial infection wounds are proposed for future research in this field.

A Novel Copper Metal-Organic Framework Catalyst for the Highly Efficient Conversion of CO2 with Propargylic Amines

The rapid increase in atmospheric carbon dioxide has resulted in the greenhouse effect. Hence, carbon dioxide capture and further fixation into valuable chemical products are particularly important for reducing atmospheric...

The Effectiveness of MOFs for the Removal of Pharmaceuticals from Aquatic Environments: A Review Focused on Antibiotics Removal

There is an increasing level of various pollutants and their persistence in aquatic environments. The improper use of antibiotics and their inefficient metabolism in organisms result in their release into aquatic environments. Antibiotic abuse has led to hazardous effects on human health. Thereby, efficient removal of pharmaceuticals, particularly antibiotics, from wastewater and contaminated water bodies is greatly interested in international research communities. Metal-organic framework (MOF) materials, as a hybrid group of material containing metallic center and organic linkers, offer a porous structure that is highly efficient for removing different pollutants from contaminated water and wastewater streams. This article aims to review the recent advancement in using MOF-based adsorbents and catalysts for the removal of pharmaceuticals, especially antibiotics, from polluted water. Applying MOFs-based structures for removing antibiotics using photocatalytic removal and adsorptive removal techniques will be discussed and evaluated in this review paper. Various MOF-based materials such as functionalized MOFs, MOF-based composites, magnetic MOF-based composites, MOFs templated-metal oxide catalysts for removing pharmaceuticals, personal care products, and antibiotics from contaminated aqueous media are discussed. Furthermore, effective operational parameters on the adsorption, adsorption mechanisms, adsorption isotherms, and thermodynamic parameters are explained and discussed. Finally, in the concluding remarks, the challenges and future outlooks of using MOFs-based adsorbents and catalysts for removing antibiotics are summarized.