Development of silicone-coated hydrophobic deep eutectic solvent-based membranes for pervaporation of biobutanol

Drug Delivery Applications of Hydrophobic Deep Eutectic Solvent-in-Water Nanoemulsions: A Comparative Analysis of Ultrasound Emulsification and Membrane-Assisted Nanoemulsification

The emergence of green chemistry and engineering principles to enforce sustainability aspects has ensured the prevalence of green solvents and green processes. Our study addresses this quest by exploring drug delivery applications of hydrophobic deep eutectic solvents (DESs) which are alternative green solvents. Initially, this work showcases the hydrophobic drug solubilization capabilities of a natural hydrophobic DES, menthol, and decanoic acid. To consider biomedical applications wherein polar media are encountered, this work further demonstrates the potential drug delivery application of these systems by encapsulating the anti-inflammatory local anesthetic lidocaine in hydrophobic DES-in-water nanoemulsions. NMR studies confirm the high solubility of the hydrophobic drug in hydrophobic DES comprising menthol and decanoic acid (1:2 molar ratio). Ultrasound emulsification and energy-efficient membrane emulsification techniques were employed to disperse 4% (v/v) DES into a 2% (w/w) Tween 20 surfactant aqueous solution. An isoporous microengineered membrane (nominal pore size ∼ 9 μm) was used to produce lidocaine-loaded DES-based nanoemulsions. Such membrane-assisted nanoemulsification was possible because the hydrophobic DES exhibits relatively low interfacial tension with the continuous phase and acts as a cosurfactant. Moreover, increased concentrations of lidocaine within the DES resulted in a further decrease in the interfacial tension and a lower melting point. Among the kinetic models analyzed to evaluate the release of lidocaine encapsulated in hydrophobic DES-in-water nanoemulsions, the Korsmeyer-Peppas kinetic model provided the best fit. The release constant "n" of <0.5 indicates that the drug release mechanism is predominantly governed by diffusion. Additionally, cytotoxicity against various human cell lines demonstrated the nanoemulsion's potential for anti-inflammatory drug delivery applications. Consequently, the nanoemulsion of DES presents a promising solution for the effective loading and delivery of poorly soluble drugs. This innovative approach enhances drug solubility and bioavailability, providing a versatile platform for controlled drug release. By leveraging the advantages of nanoemulsion technology, our study underscores the potential of DES-based formulations to promote drug delivery systems across a variety of therapeutic applications.

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.

Exploring the potential of highly selective deep eutectic solvents (DES) based membranes for dehydration of butanol via pervaporation

N-butanol has unique physicochemical and combustion properties, similar to gasoline, which makes it an environmentally friendly alternative to conventional fuels. To improve the efficiency, the dehydration of butanol is necessary. This paper aims to investigate the performance of Deep Eutectic Solvents (DESs) based membranes for the dehydration of n-butanol by the pervaporation process. Three DES with different combinations of hydrogen bond donors and acceptors, i.e., DL-menthol: Lauric acid (DES), DL-menthol-Palmitic acid (DES), and [TETA] Cl: Thymol (DES), were used. We hypothesized that (i) incorporation of hydrophobic DES would increase the hydrophobicity of the membranes; (ii) specific functional groups (phenolic group, amine group) in DESs would enhance the butanol-philic character of membranes, and (iii) hydrophobic DESs would increase the butanol separation efficiency and permeability of membranes. FTIR analysis and physicochemical parameters of the resultant liquid mixture validated the DESs' production. The DESs were then filled into the permeable support, resulting in supported liquid membranes (SLMs). An additional layer of polydimethylsiloxane (PDMS) was coated directly on the DES-PSf layer to prevent leaching out of DES. A feed containing a 6 wt % aqueous solution of butanol under varying temperatures was studied. The results showed that among all membranes, [TETA] Cl: Thymol DES-based membrane showed the highest sorption of 36% at room temperature. The introduction of DES in membranes resulted in a remarkable increase in the separation factor while sustaining a reasonable flux. Among all the membranes, the DL-menthol: Lauric acid (DES) based membrane exhibited the highest separation factor of 57 with a total flux of 0.11 kg/m². h. Significantly high butanol-water separation was attributed to the low viscosity and high butanol solubility of the chosen DES, which makes it a suitable substitute to conventional ILs.