Addition Of Metal-organic Frameworks Research Articles

Constructing carbon-based materials loaded with MOFs to realize efficient anaerobic digestion of rural organic waste

The application of anaerobic digestion (AD) technology could convert rural organic waste (ROW) into renewable energy such as methane, which can help to mitigate the scarcity of fossil fuels and positively impact the global environment. However, the inhibition of ammonia nitrogen remains a significant obstacle to the methane production process with high concentrations of AD. Hence, in this study, three adsorption materials for ammonia nitrogen, namely FeMn-MOF, FeMn/MOF-CFs, and FeMn/MOF-CFC, were synthesized through distinct protocols. Their ability to mitigate the effect of ammonia nitrogen inhibition was investigated in a Continuous Stirred-Tank Reactor (CSTR) with total solid (TS) concentration of 10% under a semi-continuous operation of ROW digestion system. The results show that the addition of Metal-Organic Frameworks (MOFs) material substantially mitigated the inhibition of ammonia nitrogen and enhanced methane production. Compared with the control group, FeMn/MOF-CFC exhibited the best performance, with a 40.21% decrease in ammonia nitrogen concentration and 66.96 L/L-reactor cumulative methane production. Furthermore, the potential mechanisms underlying microbial community characteristics were explored, indicating that the addition of FeMn/MOF-CFC to AD provides the optimal enhancement of methane production. The addition of FeMn/MOF-CFC can enrich Methanosarcina, enhance the acetoclastic pathway for methane production, and increase the relative activity of coenzyme F420, achieving a 193.68% increase.

MOFs Containing Solid-State Electrolytes for Batteries.

The use of metal-organic frameworks (MOFs) in solid-state electrolytes (SSEs) has been a very attractive research area that has received widespread attention in the modern world. SSEs can be divided into different types, some of which can be combined with MOFs to improve the electrochemical performance of the batteries by taking advantage of the high surface area and high porosity of MOFs. However, it also faces many serious problems and challenges. In this review, different types of SSEs are classified and the changes in these electrolytes after the addition of MOFs are described. Afterward, these SSEs with MOFs attached are introduced for different types of battery applications and the effects of these SSEs combined with MOFs on the electrochemical performance of the cells are described. Finally, some challenges faced by MOFs materials in batteries applications are presented, then some solutions to the problems and development expectations of MOFs are given.

Enhanced carbon dioxide biomethanation with hydrogen using anaerobic granular sludge and metal–organic frameworks: Microbial community response and energy metabolism analysis

In this work, metal–organic frameworks (MOFs) were prepared to evaluate its impact on carbon dioxide (CO2) biomethanization during anaerobic degradation (AD). The results showed that MOFs significantly improved the CO2 biomethanation efficiency, especially in the AD reactors using a concentration of 1.0 g/L MOFs. Furthermore, MOFs promoted direct interspecific electron transfer and alleviated the hydrogen competition of bacteria. Meanwhile, hydrogenotrophic methanogens were enriched in the AD reactors with MOFs. After the addition of MOFs, there was 3.28 times and 3.41 times increase in the abundance of metabolic functions related to methanogenesis by CO2 reduction with hydrogen and dark hydrogen oxidation, respectively. There was an increased abundance of all genes that encode the key enzymes used in methane metabolism. However, functional genes involved in nitrate reduction had their expressions inhibited. The work may offer a contribution to helping the industry achieve the carbon capture and utilization policy.

Optimized safranin adsorption onto poly(vinylidene fluoride)-based nanofiber via response surface methodology

This study is a comparative work on the surface interactions and adsorptive properties of poly(vinylidene fluoride) nano-fibers (PVDF NFs) and UiO-66/PVDF NFs prepared by using the electro-spinning method. X-ray diffraction (XRD), fourier transform infrared (FT-IR), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and energy-dispersive X-ray (EDX) have been applied to confirm and determine physicochemical changes during preparing and to modify PVDF NFs. The results of XRD, FT-IR, SEM, TGA, and EDX show significant changes in porosity that happened on the surface of adsorbents. The PVDF NFs and UiO-66/PVDF NFs have been applied to remove safranin O (SO) dye in aqueous solution as a cationic azo dye. Three essential factors of the initial concentration of SO, contact time, and pH were optimized by using the Box-Behnken response surface methodology (BBRSM). By using PVDF NFs, the maximum equilibrium adsorption capacity of 28.201 mg g−1 is obtained at optimal adsorption parameters of a contact time of 117.972 min, initial concentration of dye 34.896 mg L−1and pH of 9.975. And also by applying UiO-66/PVDF NFs, the maximum equilibrium adsorption capacity of 25.896 mg g−1 is achieved at optimal parameters of a contact time of 58.47 min, initial concentration of 34.83 mg L−1 and pH of 7.2, which clearly shows that the addition of metal-organic frameworks (MOFs) to the PVDF NFs is reduced the contacted time by half. The adsorptive experimental data were correlated by the famous isotherm and kinetic models. The extrapolated data showed that the SO dye adsorption on the PVDF NFs and UiO-66/PVDF NFs follow better the Langmuir isotherm and the pseudo-second-order kinetic model. Moreover, the thermodynamics result of the nano-fibers shows that, the adsorption process is exothermic and spontaneous. The high efficiency and adequate adsorption ability in the SO removal suggest that the UiO-66/PVDF NFs could be effectively applied as a good applicant in the water filtration of azo dyes.

Metal Organic Framework - Based Mixed Matrix Membranes for Carbon Dioxide Separation: Recent Advances and Future Directions.

Gas separation and purification using polymeric membranes is a promising technology that constitutes an energy-efficient and eco-friendly process for large scale integration. However, pristine polymeric membranes typically suffer from the trade-off between permeability and selectivity represented by the Robeson's upper bound. Mixed matrix membranes (MMMs) synthesized by the addition of porous nano-fillers into polymer matrices, can enable a simultaneous increase in selectivity and permeability. Among the various porous fillers, metal-organic frameworks (MOFs) are recognized in recent days as a promising filler material for the fabrication of MMMs. In this article, we review representative examples of MMMs prepared by dispersion of MOFs into polymer matrices or by deposition on the surface of polymeric membranes. Addition of MOFs into other continuous phases, such as ionic liquids, are also included. CO2 separation from hydrocarbons, H2, N2, and the like is emphasized. Hybrid fillers based on composites of MOFs with other nanomaterials, e.g., of MOF/GO, MOF/CNTs, and functionalized MOFs, are also presented and discussed. Synergetic effects and the result of interactions between filler/matrix and filler/filler are reviewed, and the impact of filler and matrix types and compositions, filler loading, surface area, porosity, pore sizes, and surface functionalities on tuning permeability are discoursed. Finally, selectivity, thermal, chemical, and mechanical stability of the resulting MMMs are analyzed. The review concludes with a perspective of up-scaling of such systems for CO2 separation, including an overview of the most promising MMM systems.

Investigation of cross-linked and additive containing polymer materials for membranes with improved performance in pervaporation and gas separation.

Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems. Covalent interlacing with 3-hydroxypropyldimethylmaleimide as photocrosslinker can be investigated in situ in solution as well as in films, using transient UV/Vis and FTIR spectroscopy. The photocrosslinking yield can be determined from the FTIR-spectra. It is restricted by the stiffness of the copolyimide backbone, which inhibits the photoreaction due to spatial separation of the crosslinker side chains. Mixed-matrix membranes (MMMs) with MOFs as additives (fillers) have increased permeabilities and often also selectivities compared to the pure polymer. Incorporation of MOFs into polysulfone and Matrimid® polymers for MMMs gives defect-free membranes with performances similar to the best polymer membranes for gas mixtures, such as O2/N2 H2/CH4, CO2/CH4, H2/CO2, CH4/N2 and CO2/N2 (preferentially permeating gas is named first). The MOF porosity, its particle size and content in the MMM are factors to influence the permeability and the separation performance of the membranes.