UiO-66 metal-organic frameworks for water treatment

Metal-organic frameworks (MOFs), specifically Zr-based UiO-66, have gained attention for removing toxic pollutants due to their unique attributes. These include a large surface area, high porosity, active adsorption sites, tunable chemistry, pore control, and robust host-guest interactions. However, the practical use of pure MOF powders in water treatment faces limitations such as insolubility, processability, brittleness, safety concerns, and separation challenges. One of the significant concerns when using MOFs for water treatment is how well they maintain stability when exposed to aqueous environments. Therefore, this thesis demonstrates the stability of UiO-66 MOF over one year in water and chloroform, with minor changes observed in structure when exposed to dimethylformamide (DMF). The results from the stability studies contribute to a better understanding of UiO-66's stability in aqueous media. UiO-66 exhibits effective removal of organic pollutants, including methyl red (MR), methyl orange (MO), malachite green (MG), and methylene blue (MB), which possess different charges. The stable UiO-66 polycrystalline MOFs still grapple with the challenge of effective separation from the treated water. This thesis pursued a magnetic approach for the magnetization of UiO-66, coupled with subsequent post-modification. This strategy aimed to facilitate the efficient separation of UiO-66 from treated water using an external magnet. A two-step post-modification procedure, utilizing 2,4,6-trichloro-1,3,5-triazine (TCT) and 5-phenyl-1H-tetrazole (PTZ) agents, was introduced to enhance the adsorption performance of the magnetic nanocomposite. Despite a reduction in porosity and specific surface area compared to the pristine UiO-66-NH2, the resulting magnetic post-modified UiO-66 exhibited significantly improved adsorption capacity. Notably, magnetic UiO-66-TCT demonstrated a high adsorption capacity of approximately 298 mg/g for methyl orange (MO), offering facile MOF separation via an external magnet. The research further underscores the significance of post-modifying UiO-66 with novel functional groups to create effective adsorbents for the removal of organic contaminants. Combining MOFs with electrospun nanofibers offers efficient water treatment, addressing challenges linked to polycrystalline MOFs and their separation from treated water. This thesis employed a hybrid approach by integrating UiO-66 with thermally oxidized nanodiamond (TOND) to enhance its affinity for removing targeted organic contaminants. These hybrid UiO-66 particles were then incorporated into chitosan/ polyvinyl alcohol (PVA) nanofibers. The resulting nanofiber composite, containing 1.5 wt% hybrid UiO-66, exhibited a twofold increase in the maximum adsorption capacity for anionic Congo red dye (1429 mg/g) compared to the unfilled nanofiber (769 mg/g). Further advancements in UiO-66 nanofiber composite development were achieved by functionalizing UiO-66-NH2 with TCT and PTZ, followed by their incorporation into chitosan/PVA nanofibers. The optimal composite, consisting of 7 wt% functionalized MOF, exhibited a remarkable maximum adsorption capacity for MO (619 mg/g), surpassing most previously reported adsorbents such as activated carbon.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat

Electrospun nanofibers of chitosan/polyvinyl alcohol/UiO-66/nanodiamond: Versatile adsorbents for wastewater remediation and organic dye removal

| openaire: EC/H2020/788489/EU//BioELCell Funding Information: Dr. Arjmand would like to thank the Canada Research Chairs program for the financial support. The authors would like to acknowledge Syilx Okanagan First Nation for allowing us to conduct research in their unceded ancestorial traditional territory. Mr. Ahmadijokani, Dr. Kamkar, and Dr. Rojas are grateful for funding support from the Canada Excellence Research Chair Program (CERC-2018-00006) and the Canada Foundation for Innovation (Project number 38623). Dr. Rojas also acknowledges the European Research Council under the European Union's Horizon 2020 research and innovation program (ERC Advanced grant No. 788489, “BioElCell”). The authors also would like to thank Mr. Aydin Badrian (aydinbadrian.com) for his efforts on the graphical parts of this study.The appeal of metal–organic frameworks (MOFs) in wastewater treatment is tempered by their polycrystalline, powdery state, and challenges associated with their deployment. In the case of UiO-66, one of the most stable and widely-used MOFs, a low tendency for removing some organic contaminants has been observed on top of the mentioned issues. To address these challenges, herein, we take two complementary steps, i.e., hybridization of UiO-66 with organic nanodiamond (ND) followed by the integration of the hybrid nanoparticles in electrospun polymeric nanofibers based on chitosan/polyvinyl alcohol (PVA). We present the electrospinning of polymer/MOFs as a promising technique to fabricate highly efficient adsorbents for water remediation. We use the electrospun chitosan/PVA nanofibers (ECPN) as a versatile host for MOF nanoparticles that remove cationic methylene blue and anionic Congo red dyes. Four nanofiber composites containing thermally oxidized nanodiamond (TOND), ND, UiO-66, and TOND@UiO-66 are utilized tounravel the effect of nanoparticles type and loading on dye adsorption capacity. It is shown that incorporation of a small loading of nanoparticles in ECPN significantly enhaces the maximum dye adsorption capacity. More importantly, the rationally engineered hybrid TOND@UiO-66 nanoparticles exhibit the best performance in dye adsorption; for instance, an 80 % increase in maximum dye adsorption capacity, from 769 to 1429 mg/g, is recorded for ECPN loaded with TOND@UiO-66 compared to the unfilled ECPN. On top of that, the designed adsorbent showed appreciable regeneration ability after 6 adsorption–desorption cycles. All in all, this study offers a new generation of engineered advanced materials to remove emerging contaminants from water streams.Peer reviewe

Waste organic dye removal using MOF-based electrospun nanofibers of high amine density

Funding Information: Dr. Arjmand would like to thank the Canada Research Chairs program for its financial support. The authors would like to acknowledge Syilx Okanagan First Nation for allowing to conduct research in their unceded ancestorial traditional territory. Mr. Ahmadijokani, Dr. Kamkar, and Dr. Rojas are grateful for funding support from the Canada Excellence Research Chair Program ( CERC-2018-00006 ) and the Canada Foundation for Innovation (Project number 38623). The authors also would like to thank Mr. Aydin Badrian (aydinbadrian.com) for his efforts on the graphical parts of this study. Publisher Copyright: © 2023 The AuthorsThe exceptional structural stability of UiO-66 metal–organic framework (MOF) and ligands' functional groups render UiO-66 as a versatile candidate for multiple applications, including wastewater treatment. The possibility of a broad spectrum of post-synthetic modification of UiO-66 further expands its prospective uses. However, commercial applications of UiO-66 have been hindered by the polycrystalline nature of the powder. In this research, modification to obtain UiO-66-NH2 and post-processing with nanofibers comprising chitosan and polyvinyl alcohol (PVA) were applied to faciliate deployment as a suitable option for water decontamination. MOF nanoparticles were post-synthetically modified with 2,4,6-trichloro-1,3,5-triazine (TCT) and 5-phenyl-tetrazole (PT) to produce high-amine containing UiO-66, thus introducing active nitrogen-containing functional groups that enhanced the removal efficiency of targeted molecules from aqueous media. A systematic study was undertaken to optimize the supporting nanofibers and to demonstrate that even a low MOF functionalization, of up to 7- wt%, offered a maximum methyl orange adsorption capacity of 619 mg/g, superior to most adsorbents reported so far. Furthermore, selectivity, regeneration ability, and the effect of ambient conditions were demonstrated.Peer reviewe

Functional Janus structured liquids and aerogels.

Janus structures have unique properties due to their distinct functionalities on opposing faces, but have yet to be realized with flowing liquids. We demonstrate such Janus liquids with a customizable distribution of nanoparticles (NPs) throughout their structures by joining two aqueous streams of NP dispersions in an apolar liquid. Using this anisotropic integration platform, different magnetic, conductive, or non-responsive NPs can be spatially confined to opposite sides of the original interface using magnetic graphene oxide (mGO)/GO, Ti3C2Tx/GO, or GO suspensions. The resultant Janus liquids can be used as templates for versatile, responsive, and mechanically robust aerogels suitable for piezoresistive sensing, human motion monitoring, and electromagnetic interference (EMI) shielding with a tuned absorption mechanism. The EMI shields outperform their current counterparts in terms of wave absorption, i.e., SET ≈ 51 dB, SER ≈ 0.4 dB, and A = 0.91, due to their high porosity ranging from micro- to macro-scales along with non-interfering magnetic and conductive networks imparted by the Janus architecture