Preparation of BiVO4 /MIL-125(Ti) composite with enhanced visible-light photocatalytic activity for dye degradation

Solar-driven seawater desalination via plasmonic hybrid MOF/polymer and its antibacterial activity

In recent years, solar seawater desalination has been considered to be a promising and cost-effective technique to produce clean sources for water treatment and water deficiency. In addition, this technique shows high photothermal conversion efficiency by solar collectors to transfer solar energy into heat and the transformation of molecules in the capillaries of solar evaporators. In this study, we report the preparation of graphene-supported MIL-125 with polyurethane foam (MGPU) for solar steam generation. We modified MGPU by using the plasmonic nanoparticles of Ag and a polymer of polyaniline to increase the evaporation rate. Polyurethane foam can float on the surface of water and self-pump water by its hydrophilic porous structure, superior thermal insulation capabilities, and easy fabrication. MIL-125 has a high salt rejection and higher water permeability. It can reduce the affinity between water molecules and the pore surface of membrane, making it simple for water molecules to move through the pores. GO is a great alternative for steam generation applications since it exhibits broad-band light. The strong solar absorption, photothermal conversion efficiency, and photoreaction efficiency are enhanced by the use of silver nanoparticles in the photoreaction. The salt resistance capability is enhanced in saline water in the presence of polyaniline in a composite. Under one solar irradiation, the Ag/PANI/GO@MIL-125 (Ag-PMG) nanocomposite demonstrates an average 1.26 kg m² h^-1 rate of evaporation and an efficiency as high as 90%. The composite exhibits remarkable stability and durability after more than 10 cycles of use without a noticeable decrease in activity. In addition, the composite exhibits excellent organic dye removal from contaminated water and generates pure condensed freshwater. The antibacterial photoactivity of the photocatalysts was examined against B. subtilis and E. coli. The results demonstrate that Ag-PMG shows higher antibacterial activity than MIL-125 and PMG. It was shown that the presence of rGO, PANI, and Ag in the sample enhances the antimicrobial activity.

Adsorption of nitrophenol onto a novel Fe3O4-κ-carrageenan/MIL-125(Ti) composite: process optimization, isotherms, kinetics, and mechanism

Water pollution is a dreadful affair that has incessantly aggravated, exposing our planet to danger. In particular, the persistent nitro aromatic compound like nitrophenols causes anxiety to the researchers due to their hazardous impacts, excessive usage, and removal difficulty. For this purpose, a novel multi-featured composite was constructed based on κ-Carrageenan (κ-Carr), MOF (MIL-125(Ti)), and magnetic Fe3O4 for efficient adsorptive removal of o-nitrophenol (o-NP). Interestingly, BET measurements revealed the high surface area of Fe3O4-κ-Carr/MIL-125(Ti) of about 163.27 m2/g, while VSM showed its excellent magnetic property (20.34 emu/g). The comparison study pointed out the synergistic effect between Fe3O4, κ-Carr, and MIL-125(Ti), forming a composite with an excellent adsorption performance toward o-NP. The adsorption data obeyed pseudo-second-order kinetic model, and Freundlich isotherm model was better fitted than Langmuir and Temkin. Furthermore, Langmuir verified the supreme adsorption capacity of o-NP onto Fe3O4-κ-Carr/MIL-125(Ti) since the computed qmax reached 320.26 mg/g at pH 6 and 25 °C. Furthermore, the XPS results postulated that the adsorption mechanism pf o-NP proceeded via H-bonding, π-π interaction, and electron donor-acceptor interactions. Interestingly, Fe3O4-κ-Carr/MIL-125(Ti) composite retained good adsorption characteristics after reusing for five cycles, suggesting its viable applicability as an efficient, renewable, and easy-separable adsorbent for removing nitro aromatic pollutants.

Isolation of Cytochrome C for Proteomics with Lindqvist-type Polyiodate Modified Metal Organic Framework

Separation and purification of Cytochrome C (Cyt-C) is important for proteomic. High efficient and selective pretreatment method for Cyt-C in real samples are always needed. Herein, polyniobate (K₇H[Nb₆O₁₉]·13H₂O, Nb₆O₁₉) is modified on a metal-organic framework MIL-125(Ti) through intermolecular hydrogen bonds and an aqueous-stable composite Nb₆O₁₉/MIL-125(Ti) is successfully prepared to pretreat complex protein sample. Protein adsorption studies have shown that Nb₆O₁₉/MIL-125(Ti) can promote the selective adsorption of Cyt-C due to the synergistic effect of electrostatic and hydrogen-bond interactions. At pH=10.0 (Britton-Robinson buffer), the adsorption efficiency of 300 μL 100 μg·mL^-1 Cyt-C onto 1.0 mg Nb₆O₁₉/MIL-125(Ti) can reach 99.5%. The adsorption behavior of Cyt-C fits well with the Langmuir adsorption model, corresponding to a maximum theoretical adsorption capacity of 168.35 mg·g^-1. Using 3 mol·L^-1 NaCl as the eluent, a high elution efficiency of 92.19% is obtained. In addition, the results of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis confirm that Nb₆O₁₉/MIL-125(Ti) efficiently adsorbed Cyt-C from scrofa heart extraction. LC-MS/MS spectrometry results show that the purification of Cyt-C reduces the abundance from the 12th to the 154th place after Nb₆O₁₉/MIL-125(Ti) treatment. Moreover, low abundant proteins, e.g., Superoxide dismutase 1, IF rod domain-containing protein and Ubiquitin-60S ribosomal protein L40 were considerably enriched. These outcomes confirm the practicability of Nb₆O₁₉/MIL-125 (Ti) as a Cyt-C extractant has potential application value in scrofa heart proteomics.

Titanium-based metal-organic framework MIL-125(Ti) for the highly selective isolation and purification of immunoglobulin G from human serum

Titanium-based metal-organic framework MIL-125(Ti) was synthesized by the hydrothermal method of terephthalic acid and tetra butyl titanate in N-N dimethylformamide and methanol. MIL-125(Ti) was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, nitrogen adsorption-desorption, energy-dispersive X-ray spectroscopy, zeta potential, scanning electron microscope and transmission electron microscopy. The results showed MIL-125(Ti) could be used as a potential adsorbent for protein separation and purification due to the high specific surface area, high stability and strong hydrophobicity. As a result, MIL-125(Ti) had adsorption selectivity for immunoglobulin G, which was due to hydrogen bond between MIL-125(Ti) and protein. At pH 8.0, the maximum adsorption efficiency of 0.25 mg MIL-125(Ti) for 300 μL 100 μg mL^-1 immunoglobulin G was 98.3%, and its maximum adsorption capacity was 232.56 mg g^-1 . The elution efficiency of immunoglobulin G was 92.4% by 0.1% SDS. SDS-PAGE result demonstrated the successful isolation of highly purified immunoglobulin G from the human serum. Therefore, a new method of separation and purification of immunoglobulin G in human serum using titanium-based metal-organic framework MIL-125(Ti) as a solid-phase adsorbent was established, which broadened the application scope of metal-organic frameworks. This article is protected by copyright. All rights reserved.

Highly efficient and selective photocatalytic CO2 reduction of MIL-125(Ti) based on LiFePO4 and CuO QDs surface-interface regulation

In this study, the CuO quantum dots was encapsulated MIL-125 (Ti) MOF by a simple oxidation method, and then further formed LiFePO4/CuO@MIL-125(Ti) with LiFePO4 loading. Due to the protection of...

Fabrication of easy separable and reusable MIL-125(Ti)/MIL-53(Fe) binary MOF/CNT/Alginate composite microbeads for tetracycline removal from water bodies

In this investigation, we aimed to fabricate easy separable composite microbeads for efficient adsorption of tetracycline (TC) drug. MIL-125(Ti)/MIL-53(Fe) binary metal organic framework (MOF) was synthetized and incorporated with carbon nanotube (CNT) into alginate (Alg) microbeads to form MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads. Various tools including FTIR, XRD, SEM, BET, Zeta potential and XPS were applied to characterize the composite microbeads. It was found that the specific surface area of MIL-125(Ti)/MIL-53(Fe)/CNT@Alg microbeads was 273.77 m2/g. The results revealed that the adsorption of TC augmented with rising CNT proportion up to 15 wt% in the microbeads matrix. In addition, the adsorption process followed the pseudo-second-order and well-fitted to Freundlich and Langmuir models with a maximum adsorption capacity of 294.12 mg/g at 25 ◦C and pH 6. Furthermore, thermodynamic study clarified that the TC adsorption process was endothermic, random and spontaneous. Besides, reusability test signified that MIL-125(Ti)/MIL-53(Fe)/CNT@Alg composite microbeads retained superb adsorption properties for six consecutive cycles, emphasizing its potentiality for removing of pharmaceutical residues.

Photocatalytic Degradation of Diazinon with a 2D/3D Nanocomposite of Black Phosphorus/Metal Organic Framework

Metal–organic frameworks (MOFs) are promising materials for the removal and photodegradation of pesticides in water. Characteristics such as large surface area, crystalline structure and catalytic properties give MOFs an advantage over other traditional adsorbents. The application of MOFs in environmental remediation is hindered by their ability to only absorb in the UV region. Therefore, combining them with an excellent charge carrier 2D material such as black phosphorus (BP) provides an attractive composite for visible-light-driven degradation of pesticides. In the study, a nanocomposite of black phosphorus and MIL-125(Ti), defined as BpMIL, was prepared using a two-stage hydrothermal and sonication route. The as-prepared composite was characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) spectroscopy. These techniques revealed that the circular and sheet-like morphology of the nanocomposites had minimum charge recombination, allowing them to be effective photocatalysts. Furthermore, the photocatalysts exhibited extended productive utilization of the solar spectrum with inhibited recombination rate and could be applied in visible-light-driven water treatment. The photodegradation of diazinon in water was studied using a series of BpMIL (4%, 6% and 12% by mass) nanocomposites as a photocatalyst. The optimal composite was determined to be 4%BpMIL. The degradation parameters were optimized and these included photocatalyst dosage, initial diazinon concentration and pH of the solution. The optimal conditions for the removal and degradation of diazinon were: neutral pH, [diazinon] = 20 mg/L, photocatalyst dosage = 0.5 g/L, achieving 96% removal of the pesticide after 30 min with 4%BpMIL, while MIL-125(Ti) showed 40% removal. The improved photodegradation efficiency of the 4%BpMIL composite was attributed to Ti3+-Ti4+ intervalence electron transfer and the synergistic effect between MIL-125(Ti) and BP. The photodegradation followed pseudo-first-order kinetics with a rate constant of 1.6 × 10−2 min−1.

Construction of Core-Shell MOFs@COF Hybrids as a Platform for the Removal of UO22+ and Eu3+ Ions from Solution

The binary nanocomposites of metal/covalent-organic frameworks (NH₂-MIL-125(Ti)@TpPa-1) were constructed by solvothermal method, which was developed as a multifunctional platform with adsorption and photocatalysis for radionuclides removal. The batch experiments and physicochemical property (FT-IR, XRD, SEM, TEM, XPS, etc.) corroborated: (i) core-shell NH₂-MIL-125(Ti)@TpPa-1 had a more stable, multilayer pore structure and abundant active functional groups; (ii) NH₂-MIL-125(Ti)@TpPa-1 had fast a removal rate, as well as a high adsorption capacity of 536.73 mg (UO₂²⁺)/g and 593.97 mg (Eu³⁺)/g; (iii) the pseudo-second-order and Langmuir model provided a more reasonable description, indicating the immobilization process was endothermic, spontaneous chemisorption; (iv) the adsorption mechanism was chelation and electrostatic attraction, ascribed to the nitrogen/oxygen-containing functional groups. These results illustrated that NH₂-MIL-125(Ti)@TpPa-1 was a prospective adsorbent for the remediation polluted by radionuclides. In addition, the research provided the theoretical basis for further investigation on the UO₂²⁺(VI) photoreduction.

Metal oxide integrated metal organic frameworks (MO@MOF): rational design, fabrication strategy, characterization and emerging photocatalytic applications

This review focuses on the possible synthesis route, characterization techniques, and mechanistic pathways involved in the photocatalytic applications of MO@MOFs.

Functionalized metal-organic frameworks for photocatalytic degradation of organic pollutants in environment

Currently, many kinds of organic pollutants in air and water have a negative impact on humans and the environment. Notably, as a type of new functional materials, metal-organic frameworks (MOFs) with well-ordered porous structures and numerous active sites have been proven to be ideal photocatalysts for the degradation of organic pollutants. In the past few years, many encouraging achievements have been made in the research field of MOFs for photocatalysis. And a large number of functionalized MOFs have been constructed to improve photocatalytic activity. In this review, recent progress in the photocatalytic degradation of organic pollutants in both air and water using functionalized MOFs are summarized in detail. The focus is on photocatalytic mechanisms and some strategies employed to achieve higher degradation efficiency. Furthermore, the challenges and outlooks in this promising filed are also discussed. We hope this review would be useful for designing more functionalized MOFs with greater photocatalytic performance for the degradation of organic pollutants in the environment.

A Highly Efficient Composite Catalyst Constructed From NH2-MIL-125(Ti) and Reduced Graphene Oxide for CO2 Photoreduction

Substantial consumption of fossil fuels causes an increase in CO2 emissions and intensifies global pollution problems, such as the greenhouse effect. Recently, a new type of ultra-low-density porous material, metal-organic frameworks (MOFs), has been developed for the photocatalytic conversion of CO2. Herein, a composite photocatalytic catalyst based on NH2-MIL-125(Ti) and reduced graphene oxide (rGO@NH2-MIL-125) was fabricated through a facile "one-pot" process. The acquired materials were characterized to obtain their structures, morphologies, and optical information. The experimental results showed that methyl formate (MF) was the predominant reaction product, and rGO@NH2-MIL-125 exhibited the highest yield of 1,116 μmol·g-1·h-1, more than twice that of pure MIL-125. The high photoactivity of rGO@NH2-MIL-125 can be ascribed to the effective spatial separation and transfer of photoinduced carriers, largely due to the synergistic effect of amino functionality and rGO incorporation. rGO@NH2-MIL-125 also displayed acceptable repeatability in cyclic runs for CO2 reduction.

Flower-like BiOBr/UiO-66-NH2 nanosphere with improved photocatalytic property for norfloxacin removal

Metal-organic frameworks (MOFs) have attracted widespread concerns in the photocatalysis research. However, MOFs-based photocatalyts for antibiotics treatment are still very limited. There are also few reports on selecting MOFs as supports to regulate the morphology of Bismuthoxyhalides. In this study, BiOBr/UiO-66-NH₂ composites with three-dimensional structure of flower-like nanosphere were fabricated via a facile synthetic route. Various characterizations, such as XRD, SEM and XPS, proved the successful synthesis of composite and revealed that BiOBr nanoplates grow on the surfaces of the UiO-66-NH₂ with an intimate interaction. A typical fluoroquinolones antibiotics, norfloxacin (NOR) was selected to estimate the photocatalytic efficiency of the BiOBr/UiO-66-NH₂ complex. A series of the composites all exhibited higher NOR removal performance than the pure components and mechanically mixed sample under simulated sunlight. Among them, the composite with UiO-66-NH₂ content of 20 w% (BUN-20), had good structural stability and the best performance on the removal of NOR. The removal efficiency of NOR (10 mg/L) over BUN-20 (0.3 g/L) was 93.60% within 180 min irradiation. Three factors during the fabricating process, such as increased surface active sites, improved photoadsorption capacity and lower recombination probability of electron-hole pair might be accountable for the meliorative photocatalytic performance. Ultimately, a plausible photocatalytic mechanism was also proposed.

Visible-light-driven CQDs@MIL-125(Ti) nanocomposite photocatalyst with enhanced photocatalytic activity for the degradation of tetracycline

In the present study, a novel photocatalyst, CQDs@MIL-125(Ti) (CQDs = carbon quantum dots), was prepared via a solvothermal procedure. The photocatalytic properties were tested by the degradation of tetracycline (TC) with a 250 W Xe lamp (λ > 420 nm). Compared with pure MIL-125(Ti), the 10 wt% CQDs@MIL-125(Ti) photocatalyst can significantly improve the degradation process of TC, and the degradation efficiency can reach 90% within 4 h. The enhancement in the photocatalytic performance is due to the CQDs, which can promote the absorption of visible light and also efficiently accelerate the separation of photogenerated electron–hole pairs. We have also demonstrated that superoxide radicals (·O₂⁻) and holes (h⁺) play crucial roles in the photocatalytic degradation of TC through capture experiments. The current work provides a new idea for constructing high-efficiency photocatalysts based on MIL-125(Ti).

A novel CQDs@MIL-125(Ti) photocatalyst had been synthesized by a facile solvothermal process for the degradation of TC. The possible degradation mechanism was proposed based on the active species trapping experiments.

Polyethylene glycol-doped BiZn2VO6 as a high-efficiency solar-light-activated photocatalyst with substantial durability toward photodegradation of organic contaminations

In this study, we focus on a simple, low-priced, and mild condition hydrothermal route to construct BiZn₂VO₆ nanocompounds (NCs) as a novel photocatalyst with strong solar light absorption ability for environmental purification using solar energy. NCs were further doped with polyethylene glycol (PEG) to improve their photocatalytic efficiency for photodegradation processes through inhibition of fast charge carrier recombination rates and higher charge separation efficiency. Surface morphology, phase structure, optical characteristics, and band structure of the as-prepared samples were analyzed using XRD, EDX, XPS, SEM, UV-vis spectroscopy, CL, and BET techniques. PEG-doped BiZn₂VO₆ NCs were applied as effective materials to degrade various kinds of organic pollutants including cationic and anionic types, and these NCs exhibited excellent photocatalytic efficiency as compared to traditional photocatalysts. In particular, the PEG-doped BiZn₂VO₆ (0.10% w/v) photocatalyst exhibited highly enhanced photocatalytic performance with improvements of about 46.4, 28.3, and 7.23 folds compared with PEG-doped ZnO nanorods (NRs), pristine BiVO₄, and BiZn₂VO₆ samples, respectively, for the decomposition of congo red (CR) dye. After 40 minutes of sunlight irradiation, 97.4% of CR was decomposed. In this study, scavenging experiments indicated that both hydroxyl radicals and holes play dominant roles in CR photodegradation under simulated solar light irradiation. Meanwhile, the optimal photocatalyst demonstrated good reproducibility and stability for successive cycles of photocatalysis.