Performance of MIL-101(Cr) and MIL-101(Cr)-Pore Expanded as Drug Carriers for Ibuprofen and 5-Fluorouracil Delivery.

Metal-organic frameworks (MOFs) have been extensively investigated as nanocarriers for drug delivery applications owing to their remarkable surface area and porosity, which allow for impregnation of large quantities of drugs with fast pharmacokinetics. In this work, we developed a pore-expanded version of MIL-101(Cr), MIL-101(Cr)-P, and assessed its potential as a carrier for ibuprofen and 5-fluorouracil drugs along with its regular MIL-101(Cr) analogue. The pore expansion strategy gave rise to a higher surface area and mesopore volume for MIL-101(Cr)-P relative to regular MIL-101(Cr). The characterization results revealed successful incorporation of 30, 50, and 80 wt % of both drugs within the MOF structure. Upon incorporation of species, the surface area and porosity of the two MOF carriers decreased drastically; however, the drug-loaded MOFs still retained some degree of porosity, even at high drug loadings. For both drugs, the delivery experiments conducted in phosphate-buffered saline (PBS) showed that MIL-101(Cr)-P possessed better pharmacokinetic behavior than MIL-101(Cr) by delivering higher amounts of drug at all three loadings and exhibiting much faster release rates. Such behavior was originated from large mesopores that were created during pore expansion, providing diffusional pathways for efficient delivery of the drugs. The highest rate constant obtained by fitting the release kinetics to the Higuchi model was found to be 0.44 h-1/2 for the release of 30 wt % 5-fluorouracil from MIL-101(Cr)-P. The findings of this study highlight the role of tuning physiochemical properties of MOFs in improving their pharmacokinetic behavior as drug carriers.

Cooperative and Bifunctional Adsorbent-Catalyst Materials for In-situ VOCs Capture-Conversion.

Volatile organic compounds (VOCs) are gases that are emitted into the air from products or processes and are major components of air pollution that significantly deteriorate air quality and seriously affect human health. Different types of metals, metal oxides, mixed-metal oxides, polymers, activated carbons, zeolites, metal-organic frameworks (MOFs) and mixed-matrixed materials have been developed and used as adsorbent or catalyst for diversified VOCs detection, removal, and destruction. In this comprehensive review, we first discuss the general classification of VOCs removal materials and processes and outline the historical development of bifunctional and cooperative adsorbent-catalyst materials for the removal of VOCs from air. Subsequently, particular attention is devoted to design of strategies for cooperative adsorbent-catalyst materials, along with detailed discussions on the latest advances on these bifunctional materials, reaction mechanisms, long-term stability, and regeneration for VOCs removal processes. Finally, challenges and future opportunities for the environmental implementation of these bifunctional materials are identified and outlined with the intent of providing insightful guidance on the design and fabrication of more efficient materials and systems for VOCs removal in the future.

Influence of Interfering Ions and Adsorption Temperature on Radioactive Iodine Removal Efficiency and Stability of Ni-MOF-74 and Zr-UiO-66.

Metal-organic frameworks (MOFs) often exhibit an exceptional adsorption-based separation performance for a variety of gases, ions, and liquids. While most radioactive iodine removal studies focus on the capture of radioactive iodine from off-gas streams, few studies have systematically investigated the effect of structure-property relationships of MOFs on iodine removal performance in the presence of interfering ions in liquid solutions. Herein, we investigated the iodide ion (I-) adsorption performance of two model MOFs (e.g., Ni-MOF-74 and Zr-UiO-66) in liquid phase as a function of iodine concentration (e.g., 0.125 to 0.25 and 0.50 mmol/L) and adsorption temperature (e.g., 25 to 40 and 60 °C), and in the presence of interfering ions such as Cl- and CO32- through batch-mode experiments. Under identical experimental conditions, Ni-MOF-74 outperformed Zr-UiO-66 in immobilizing iodine from the solution by achieving a maximum iodine removal efficiency of 97% at 60 °C. The results showed that the presence of other interfering ions marginally affects the iodine removal efficiency (e.g., capacity and rate of iodine capture) over both MOF adsorbents. The adsorption kinetics was found to be controlled by multiple transport processes encompassing external surface adsorption, intraparticle diffusion, and final equilibrium. Moreover, the leach test results revealed 8 and 12% iodine release from Ni-MOF-74 and Zr-UiO-66, respectively, at 25 °C after 48 h aging. This study establishes guiding principles for sustainable removal of iodine in the presence of Cl- and CO32- species in cyclohexane.