Preparation of NH2-MIL-101(Fe) Metal Organic Framework and Its Performance in Adsorbing and Removing Tetracycline.

Tetracycline's accumulation in the environment poses threats to human health and the ecological balance, necessitating efficient and rapid removal methods. Novel porous metal-organic framework (MOF) materials have garnered significant attention in academia due to their distinctive characteristics. This paper focuses on studying the adsorption and removal performance of amino-modified MIL-101(Fe) materials towards tetracycline, along with their adsorption mechanisms. The main research objectives and conclusions are as follows: (1) NH2-MIL-101(Fe) MOF materials were successfully synthesized via the solvothermal method, confirmed through various characterization techniques including XRD, FT-IR, SEM, EDS, XPS, BET, and TGA. (2) NH2-MIL-101(Fe) exhibited a 40% enhancement in tetracycline adsorption performance compared to MIL-101(Fe), primarily through chemical adsorption following pseudo-second-order kinetics. The adsorption process conformed well to Freundlich isotherm models, indicating multilayer and heterogeneous adsorption characteristics. Thermodynamic analysis revealed the adsorption process as a spontaneous endothermic reaction. (3) An increased adsorbent dosage and temperature correspondingly improved NH2-MIL-101(Fe)'s adsorption efficiency, with optimal performance observed under neutral pH conditions. These findings provide new strategies for the effective removal of tetracycline from the environment, thus holding significant implications for environmental protection.

Degradation of Orange G Using PMS Triggered by NH2-MIL-101(Fe): An Amino-Functionalized Metal-Organic Framework.

As an azo dye, OG has toxic and harmful effects on ecosystems. Therefore, there is an urgent need to develop a green, environmentally friendly, and efficient catalyst to activate peroxymonosulfate (PMS) for the degradation of OG. In this study, the catalysts MIL-101(Fe) and NH2-MIL-101(Fe) were prepared using a solvothermal method to carry out degradation experiments. They were characterized by means of XRD, SEM, XPS, and FT-IR, and the results showed that the catalysts were successfully prepared. Then, a catalyst/PMS system was constructed, and the effects of different reaction systems, initial pH, temperature, catalyst dosing, PMS concentration, and the anion effect on the degradation of OG were investigated. Under specific conditions (100 mL OG solution with a concentration of 50 mg/L, pH = 7.3, temperature = 25 °C, 1 mL PMS solution with a concentration of 100 mmol/L, and a catalyst dosage of 0.02 g), the degradation of OG with MIL-101(Fe) was only 36.6% within 60 min; as a comparison, NH2-MIL-101(Fe) could reach up to 97.9%, with a reaction constant k value of 0.07245 min-1. The NH2-MIL-101 (Fe)/PMS reaction system was able to achieve efficient degradation of OG at different pH values (pH = 3~9). The degradation mechanism was analyzed using free-radical quenching tests. The free-radical quenching tests showed that SO4•-, •OH, and 1O2 were the main active species during the degradation of OG.

Efficient and Sustainable in†situ Photo-Fenton Reaction to Remove Phenolic Pollutants by NH2 -MIL-101(Fe)/Ti3 C2 Tx Schottky-Heterojunctions.

Metal-organic frameworks (MOFs) with abundant active sites, a class of materials composed of metal nodes and organic ligands, is widely used for photocatalytic degradation of pollutants. However, the rapid recombination of photoinduced carriers of MOFs limits its photocatalytic degradation performance. Herein, Ti3 C2 Tx nanosheets-based NH2 -MIL-101(Fe) hybrids with Schottky-heterojunctions were fabricated by in situ hydrothermal assembly for improved photocatalytic activity. The photodegradation efficiencies of the NH2 -MIL-101(Fe)/Ti3 C2 Tx (N-M/T) hybrids for phenol and chlorophenol were 96.36 % and 99.83 % within 60 minutes, respectively. The N-M/T Schottky-heterojunction duly transferred electrons to the Ti3 C2 Tx nanosheets surface via built-in electric fields, effectively suppressing the recombination of photogenerated carriers, thereby improving the photocatalytic performance of NH2 -MIL-101(Fe). Moreover, the Fe-mixed-valence in the N-M/T led to improvement in the efficiency of the in situ generated photo-Fenton reactions, further enhancing the photocatalytic activity with more generated reactive oxygen species (ROS). The study proposes a highly effective removal of phenolic pollutants in wastewater.

Tris(bipyridine)ruthenium(II)-functionalized metal-organic frameworks for the ratiometric fluorescence determination of aluminum ions.

A novel ratiometric fluorescence probe was designed for the determination of Al3+ by self-assembling of NH2-MIL-101(Fe) and [Ru(bpy)3]2+. Under the excitation wavelength of 360 nm, the NH2-MIL-101(Fe)@[Ru(bpy)3]2+ presented a dual-emitting luminescent property at 440 and 605 nm, respectively. In the presence of Al3+, the blue fluorescence of NH2-MIL-101(Fe)@[Ru(bpy)3]2+ at 440 nm was enhanced remarkably, while the red emission at 605 nm was almost not influenced. Therefore, taking the fluorescence at 440 nm as the report signal and 605 nm as the reference signal, quantitative determination was achieved for Al3+ concentration in the ranges 0.2-25 µM and 25-250 µM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 73 nM and 244 nM, respectively. The sensing mechanisms were studied by theoretical calculation and optical spectra. The analysis of real food samples confirmed the suitability of the proposed method. More importantly, portable fluorescent test papers were successfully manufactured to provide a strategy for visual, rapid, and on-site detection of Al3+.

Magnetic amino-functionalized metal-organic frameworks as a novel solid support in ionic liquids-based effervescent tablets for efficient extraction of polycyclic aromatic hydrocarbons in milks.

Herein, a kind of novel multi-layer core-shell nanocomposites (NSPN) was prepared by employing SiO2 and polyvinylpyrrolidone (PVP) polymers as modifiers and amino-functionalized metal-organic frameworks (NH2-MIL101(Fe)) as coating. It was referred to as the NSPN and ILs-based effervescence-assisted dispersive solid-phase microextraction, hereafter abbreviated as NIE-DSM. In terms of extraction efficiency, SiO2 and PVP as modifiers and NH2-MIL(Fe) as coating onto the surface of NiFe2O4 cores played a synergistically enhancing effect on adsorption/extraction. Effervescent tablets were prepared by integrating the NSPN magnetic nanoparticles as adsorbents with imidazolium-based ionic liquids (ILs) as extractants as well as acidic and alkaline sources. Under vigorous dispersion of CO2 bubbles, the NIE-DSM method realized the goal of rapidly diffusing and separating the adsorbent/extractant (~3 min) without needing conventional vortexing or centrifugation step. Consequently, the NIE-DSM approach combined dispersion and adsorption/extractant in a synchronous way. Under optimized conditions, the NIE-DSM/HPLC-FLD method gave low limits of detection (0.008-0.034 µg kg-1) and satisfactory extraction recoveries (74.1-101.6%) for five polycyclic aromatic hydrocarbons (PAHs; fluorene, anthracene, pyrene, chrysene and benzo(a)pyrene) in milk samples. The intra-day and inter-day precision, expressed as relative standard deviations, was < 5.9% and 6.5%, respectively, demonstrating a high precision. Owing to no requirement for electrical power, this method shows great potential for outdoor monitoring of trace-level PAHs in food matrices.

Effective removal of acetamiprid and eosin Y by adsorption on pristine and modified MIL-101(Fe).

In this work, the efficacy of two metal-organic frameworks (MIL-101(Fe) and NH2-MIL-101(Fe)) in eliminating acetamiprid (ATP) insecticide and eosin Y (EY) dye from aqueous solution is tested. An analysis was conducted on the developed nanocomposite's optical, morphological, and structural characteristics. The adsorption isotherm, kinetics, thermodynamics, reusability, and mechanisms for ATP and EY dye removal were assessed. NH2-MIL-101(Fe) adsorbed 76% and 90% of ATP pesticide and EY dye, respectively after 10 to 15 min in optimum conditions. For both adsorbents, with regard to explaining the isotherm data, the Langmuir model offered the most accurate description. Moreover, the adsorption of ATP and EY dye is described by the pseudo-second-order kinetic model. The maximum adsorption capacities of ATP and EY dye on MIL-101(Fe) were 57.6 and 48.9 mg/g compared to 70.5 and 97.8 mg/g using NH2-MIL-101(Fe). The greatest amount of ATP and EY dye clearance was obtained at a neutral medium for both adsorbents. The results of this investigation demonstrate the effectiveness of MIL-101(Fe) and NH2-MIL-101(Fe) as effective substances in the adsorption process for removing pesticides and dyes from aqueous solution.

Efficient photocatalytic reduction of nitrate byproducts during anammox process by novel extracellular polymeric substances-embedded NH2-MIL-101(Fe) photocatalysts.

Anaerobic ammonium oxidation (anammox) is an efficient nitrogen removal process; however, nitrate byproducts hampered its development. In this study, extracellular polymeric substances (EPS) were embedded into NH2-MIL-101(Fe), creating NH2-MIL-101(Fe)@EPS to reduce nitrate. Results revealed that chemical nitrate reduction efficiency of NH2-MIL-101(Fe)@EPS surpassed that of NH2-MIL-101(Fe) by 17.3 %. After adding 0.5 g/L NH2-MIL-101(Fe)@EPS within the anammox process, nitrate removal efficiency reached63.9 %, consequently elevating the total nitrogen removal efficiency to 92.4 %. 16S rRNA sequencing results elucidated the predominant role of Candidatus Brocadia within NH2-MIL-101(Fe)@EPS-anammox system. Concurrently, sufficient photogenerated electrons were transferred to microorganisms, promoting the growth of Desnitratisoma and OLB17. Additionally, photogenerated electrons activated flavin and Complex III, thereby up-regulating crucial genes involved in intra/extracellular electron transfer. Subsequently, denitrification and dissimilatory nitrate reduction to ammonium were activated to reduce nitrate. In summary, this study achieved a notable rate of photocatalytic nitrate reduction within anammox process through the NH2-MIL-101(Fe)@EPS photocatalysts.

Developing a magnetic SERS nanosensor utilizing aminated Fe-Based MOF for ultrasensitive trace detection of organophosphorus pesticides in apple juice.

The unreasonable use of organophosphorus pesticides leads to excessive pesticide residues in food, seriously threatening public health, and the potential of surface-enhanced Raman spectroscopy (SERS) technology, incorporating a metal-organic framework, is substantial for the rapid detection of trace pesticide residues. Here, a novel Fe3O4@NH2-MIL-101(Fe)@Ag (FNMA) SERS nanosensor was developed. Results indicated that the FNMA had a high enhancement factor of 1.53 × 108, a low limit of detection (LOD) of 4.55 × 10-12 M, and a relative standard deviation of 7.73 % for 4-nitrothiophenol, demonstrating its good SERS sensitivity and uniformity, and also possessed good storage stability for one month. In quantifying fenthion and methyl parathion in standard solutions and apple juice in the range of 0.05/0.02-20 mg/L, it showed LODs of 3.02 × 10-3 mg/L and 1.43 × 10-3 mg/L, and 0.0407 and 0.0075 mg/L, respectively, demonstrating potentials in ultrasensitive trace detection of pesticides in food.

A Novel Method for Monitoring N-Nitrosamines Impurities Using NH2-MIL-101(Fe) Mediated Dispersive Micro-Solid Phase Extraction Coupled with LC-MS/MS in Biopharmaceuticals.

A highly efficient and convenient method for the simultaneous determination of 12 N-nitrosamines (NAs) has been developed using an amine-functionalized metal-organic framework (NH2-MIL-101(Fe)) as sorbent for dispersive micro-solid phase extraction (D-µSPE) coupled with LC-MS/MS in biopharmaceuticals. The experimental variables involved in the extraction process (i.e., amount of the sorbent, extraction time, desorption time, ionic strength, desorption solvent and volume) were optimized to achieve the best extraction efficiency of the target analytes. Under the optimum conditions, the method was successfully validated, showing good linearity in the range of 0.5-3.0 µg/L with determination coefficients (R2) higher than 0.990, repeatability (RSD ≤ 10.0%, spiked level at 2.0 µg/L) and precision (RSD ≤ 8.2%). The limit of detection (LOD) and limit of quantitation (LOQ) were in the range of 0.005-0.025 µg/L and 0.010-0.250 µg/L, respectively. Satisfactory recoveries ranging from 82.4 to 116.8% were obtained by spiking standards at three different concentrations (0.5 µg/L, 2.0 µg/L and 3.0 µg/L). Other validation parameters, including specificity, stability, and robustness, met the validation criteria. More importantly, the plausible adsorption mechanism on NH2-MIL-101(Fe) was proposed by Fourier-transform infrared (FTIR) spectra technique. Finally, this method was successfully applied to detect trace nitrosamines in biopharmaceuticals.

An S-scheme NH2-MIL-101(Fe)@MCN/Bi2O3 heterojunction photocatalyst for the degradation of tetracycline and production of H2O2.

Effective and durable photocatalysts are essential for the decomposition of persistent contaminants and the generation of hydrogen peroxide. In this study, we successfully constructed an S-type heterojunction by in situ growing Bi2O3 nanocrystals and NH2-MIL-101(Fe) onto surface-modified g-C3N4. The process of charge transfer in the S-type heterojunction was confirmed using ISI-XPS, DFT calculations, capture experiments, and EPR signals. The combined influence of the heterojunction and MOF demonstrated remarkable photocatalytic performance in the breakdown of tetracycline (TC) and the generation of hydrogen peroxide (H2O2). In the enhanced setup (10%-NH2-MIL-101(Fe)@MCN/Bi2O3), full degradation of TC was accomplished within 50 min under visible light exposure. Additionally, a notable H2O2 yield of 655.63 µmol/g was attained, all achieved without the necessity of sacrificial agents or supplementary oxygen. Based on the outcomes of the dual functionality, the exceptional performance of the ternary composite material can be ascribed to the collaborative influence of the heterojunction and MOF. This collaborative effect expands the light absorption range in the visible region, suppresses the recombination of electron-hole pairs, and enhances the photocatalytic redox ability. The system demonstrates significant potential in the efficient in situ production of H2O2 and removal of recalcitrant organic pollutants in pure water.

Porous NH2-MIL-101(Fe) metal organic framework for effective photocatalytic degradation of azo dye in wastewater treatment.

The porous iron-based metal organic frameworks (NH2-MIL-101(Fe)), which consists of 2-amino benzene dicarboxylic acid (H2BDC-NH2) and ferrous ions were synthesized through one-step hydrothermal method. The surface area and pore volume of as-synthesized NH2-MIL-101(Fe) were 66.48 m2/g and 0.09 cm3/g, respectively. The excellent photocatalytic performance endows NH2-MIL-101(Fe) to generate hydroxyl radical (•OH), which then acting as efficiently active sites for azo dye degradation in wastewater. Meanwhile, the outstanding stability ability of NH2-MIL-101(Fe) indicates the potential candidate for wastewater treatment.

High-Efficiency Photodynamic Antibacterial Activity of NH2-MIL-101(Fe)@MoS2/ZnO Ternary Composites.

Bacterial infections are a serious threat to human health, and the development of effective antibacterial agents represents a critical solution. In this study, NH2-MIL-101(Fe)@MoS2/ZnO ternary nanocomposites are successfully prepared by a facile wet-chemistry procedure, where MoS2 nanosheets are grown onto the MIL-101 scaffold forming a flower-like morphology with ZnO nanoparticles deposited onto the surface. The ternary composites exhibit a remarkable sterilization performance under visible light irradiation toward both Gram-negative and Gram-positive bacteria, eliminating 98.6% of Escherichia coli and 90% of Staphylococcus aureus after exposure to visible light for 30 min, a performance markedly better than that with NH2-MIL-101(Fe)@MoS2 binary composites and even more so than MoS2 nanosheets alone. This is ascribed to the unique electronic band structure of the composites, where the separation of the photogenerated carriers is likely facilitated by the S-scheme mechanism in the NH2-MIL-101(Fe)@MoS2 binary composites and further enhanced by the formation of a p-n heterojunction between MoS2 and ZnO in the ternary composites. This interfacial charge transfer boosts the effective production of superoxide radicals by the reduction of oxygen, and the disproportionation reaction with water leads to the formation of hydroxy radicals, as attested in spectroscopic and microscopic measurements. Results from this study highlight the significance of structural engineering of nanocomposites in the manipulation of the electronic band structure and hence the photodynamic activity.

Selective reduction of nitrate into N2 by novel Z-scheme NH2-MIL-101(Fe)/BiVO4 heterojunction with enhanced photocatalytic activity.

Nitrate and its metabolites as common pollutants in water had attracted widespread attentions. Converting nitrate to nontoxic and harmless nitrogen via photocatalysis was a promising approach. In this study, a novel Z-scheme NH2-MIL-101(Fe)/BiVO4 heterojunction was successfully prepared. As-prepared Z-scheme heterojunction along with built-in electric field facilitated the charge separation and enhanced the photocatalytic activity in nitrate reduction. The results showed that 0.10-MBiVO photocatalyst exhibited the highest nitrate removal rate of 94.8% (initial concentration 100 mgN/L) and final selectivity to N2 of 93.4% in 50 min under ultraviolet irradiation. Moreover, formic acid was proved as better hole scavenger compared with methanol and oxalic acid. And the concentration of formic acid had significant influence on the process of nitrate photocatalytic reduction. 0.10-MBiVO photocatalyst exhibited excellent reusability in the recycling tests, indicating its great potential in practical application of nitrate photocatalytic removal. The mechanism of the enhancement as well as reaction pathways for nitrate photocatalytic reduction on NH2-MIL-101(Fe)/BiVO4 were comprehensively explored and described at the end.

A Robust PVDF-Assisted Composite Membrane for Tetracycline Degradation in Emulsion and Oil-Water Separation.

Tetracycline (TC) contamination in water has progressively exacerbated the environmental crisis. It is urgent to develop a feasible method to solve this pollution in water. However, polluted water often contains oil. This paper reported a glass fiber (FG)-assisted polyvinylidene fluoride (PVDF) hybrid membrane with dual functions: high TC degradation efficiency in emulsion and oil-water separation. It can meet the catalytic degradation of tetracycline in complex water. This membrane was decorated by coating the glass fiber with PVDF solution containing hydrophilic graphene oxide hybridized NH2-MIL-101(Fe) particles. Moreover, due to its strong mechanical strength enhanced by the glass fiber, it can be reused as TC degradation catalysts for dozens of times without cracking. Thanks to the hydrophobicity of PVDF and the surface pore size of MOFs, the prepared membrane showed a good oil-water separation performance. Besides, the hydrophilic graphene oxide (GO) and NH2-MIL-101(Fe) improved the membrane's anti-fouling performance, allowing it to be reused as the separation membrane. Therefore, the outstanding stability and recoverability of the membrane make it as a fantastic candidate material for large-scale removal of TC as well as oil-water separation application.

Novel impedimetric sensing strategy for detecting ochratoxin A based on NH2-MIL-101(Fe) metal-organic framework doped with cobalt phthalocyanine nanoparticles.

Iron-based metal-organic framework, NH2-MIL-101(Fe), was doped with different dosages of cobalt phthalocyanine nanoparticles (CoPc) to synthesize a series of NH2-MIL-101(Fe)@CoPc nanocomposites. The NH2-MIL-101(Fe)@CoPc nanocomposites were then employed to construct novel impedimetric aptasensors for the detection of ochratoxin A (OTA). Combining the intrinsic advantages of NH2-MIL-101(Fe) (highly porous structure and excellently electrochemical activity) and CoPc (good physiochemical stability and strong bioaffinity), the NH2-MIL-101(Fe)@CoPc nanocomposites show promising properties, which are beneficial for immobilizing OTA-targeted aptamer strands. Amongst, the developed impedimetric aptasensor based on NH2-MIL-101(Fe)@CoPc6:1, prepared using the mass ratio of NH2-MIL-101(Fe):CoPc of 6:1, exhibits the best amplified electrochemical signal and highest sensitivity for detecting OTA. The detection limitation is 0.063 fg·mL-1 within the OTA concentration of 0.0001-100 pg·mL-1, accompanying with high selectivity, good reproducibility and stability, acceptable regenerability, and wide applicability in diverse real samples. Consequently, the proposed sensing strategy can be applied for detecting OTA to cope with food safety.

The obvious advantage of amino-functionalized metal-organic frameworks: As a persulfate activator for bisphenol F degradation.

In this study, two iron-based metal-organic framework compounds (MOFs), were used and compared as catalysts for persulfate (PS) activation to degrade bisphenol F (BPF). The outstanding advantage of using amino-functionalized MOFs in the catalytic system was verified under different reaction conditions, and the mechanism was explored. The results indicated that NH2-MIL-101(Fe)/PS system not only had a wide pH application range, but also possessed an excellent catalytic performance towards interference from the coexisting anions and humic acid. Density functional theory (DFT) calculations showed that, compared with MIL-101(Fe), the -NH2 modification could significantly improve the electronic conductivity of NH2-MIL-101(Fe) by enhancing its Fermi level (-4.28 eV) and binding energy to PS (-1.19 eV). The free radical quenching experiments were combined with electron paramagnetic resonance (EPR) confirmed that free radicals (SO4-, OH, O2-) worked together with the non-radical (1O2) reaction to remove 91% BPF within 40 min in the NH2-MIL-101(Fe)/PS system. The two proposed BPF degradation pathway were related to hydroxylation, oxidation and ring cracking. The toxicity of the BPF degradation intermediates as well as its final products were also evaluated.