Development of metal organic framework filled PDMS/PI composite membranes for biobutanol recovery

PEBA/PDMS Composite Multilayer Hollow Fiber Membranes for the Selective Separation of Butanol by Pervaporation

The growing interest in the production of biofuels has motivated numerous studies on separation techniques that allow the separation/concentration of organics produced by fermentation, improving productivity and performance. In this work, the preparation and characterization of new butanol-selective membranes was reported. The prepared membranes had a hollow fiber configuration and consisted of two dense selective layers: a first layer of PEBA and a second (outer) layer of PDMS. The membranes were tested to evaluate their separation performance in the selective removal of organics from a synthetic ABE solution. Membranes with various thicknesses were prepared in order to evaluate the effect of the PDMS protective layer on permeant fluxes and membrane selectivity. The mass transport phenomena in the pervaporation process were characterized using a resistances-in-series model. The experimental results showed that PEBA as the material of the dense separating layer is the most favorable in terms of selectivity towards butanol with respect to the other components of the feed stream. The addition of a protective layer of PDMS allows the sealing of possible pinholes; however, its thickness should be kept as small as possible since permeation fluxes decrease with increasing thickness of PDMS and this material also has greater selectivity towards acetone compared to other feed components.

Polymer Matrix Incorporated with ZIF-8 for Application in Nonlinear Optics

Polymers with embedded metal–organic frameworks (MOFs) have been of interest in research for advanced applications in gas separation, catalysis and sensing due to their high porosity and chemical selectivity. In this study, we utilize specific MOFs with high thermal stability and non-centrosymmetric crystal structures (zeolitic imidazolate framework, ZIF-8) in order to give an example of MOF–polymer composite applications in nonlinear optics. The synthesized MOF-based polymethyl methacrylate (PMMA) composite (ZIF-8–PMMA) demonstrates the possibility of the visualization of near-infrared laser beams in the research lab. The resulting ZIF-8–PMMA composite is exposed to a laser under extreme conditions and exhibits enhanced operating limits, much higher than that of the widely used inorganic materials in optics. Overall, our findings support the utilization of MOFs for synthesis of functional composites for optical application.

Effect of Ionic Radius in Metal Nitrate on Pore Generation of Cellulose Acetate in Polymer Nanocomposite

To prepare a porous cellulose acetate (CA) for application as a battery separator, Cd(NO₃)₂·4H₂O was utilized with water-pressure as an external physical force. When the CA was complexed with Cd(NO₃)₂·4H₂O and exposed to external water-pressure, the water-flux through the CA was observed, indicating the generation of pores in the polymer. Furthermore, as the hydraulic pressure increased, the water-flux increased proportionally, indicating the possibility of control for the porosity and pore size. Surprisingly, the value above 250 LMH (L/m²h) observed at the ratio of 1:0.35 (mole ratio of CA: Cd(NO₃)₂·4H₂O) was of higher flux than those of CA/other metal nitrate salts (Ni(NO₃)₂ and Mg(NO₃)₂) complexes. The higher value indicated that the larger and abundant pores were generated in the cellulose acetate at the same water-pressure. Thus, it could be thought that the Cd(NO₃)₂·4H₂O salt played a role as a stronger plasticizer than the other metal nitrate salts such as Ni(NO₃)₂ and Mg(NO₃)₂. These results were attributable to the fact that the atomic radius and ionic radius of the Cd were largest among the three elements, resulting in the relatively larger Cd of the Cd(NO₃)₂ that could easily be dissociated into cations and NO₃^- ions. As a result, the free NO₃^- ions could be readily hydrated with water molecules, causing the plasticization effect on the chains of cellulose acetate. The coordinative interactions between the CA and Cd(NO₃)₂·4H₂O were investigated by IR spectroscopy. The change of ionic species in Cd(NO₃)₂·4H₂O was analyzed by Raman spectroscopy.