Phase Inversion Casting Research Articles

Effect of Different Parameters on Lithium Ion Transfer through PVDF-UIO-66 Cation Selective Hybrid Membrane via Electrodialysis Technique

This study aims to increase the efficiency of Li ion recovery via electrodialysis technique by manipulating several parameters. The membrane used for this study consists of a polymer matrix that acts as a backbone, and a metal organic framework (MOF) that acts as the cation selective agent. Polyvinylidene fluoride (PVDF) was chosen for this study due to its mechanical properties and chemical stability. UIO-66 was chosen as the cation selective MOF and prepared via hydrothermal method and characterized using XRD. The membrane matrix was synthesized using phase inversion casting technique. After casting, the membrane was characterized using XRD and FTIR to ensure that the MOF was successfully embedded. The investigated operation parameters are voltage applied, initial Li ion concentration, and time of operation. The tests were conducted at a selected value of each other controlled variable while manipulating only one variable at a time. The studied concentrations were 100, 200, 300, and 400 ppm, while the applied voltage varied from to 10 to 40 V with a 10 V step. The time parameter studeid was 1, 2, 3, and 4 hrs. This study aims to show the parameters’ effects on the recovery of the lithium ion. The highest recovery was recorded for each parameter.

Exploration of shockwaves on polymeric membranephysical properties and performance

The Commercial polymeric membranes like Polysulfone (PSF), Polyvinylidene difluoride (PVDF) and Polyacrylonitrile (PAN) which are an integral part of water purification investigation were chosen for the shockwave (SW) exposure experiment. These membranes were prepared by blending polymer (wt. %) / DMF (solvent) followed by phaseinversion casting technique. Shockwaves are generated by using Reddy Tube lab module (Table-top Shocktube) with range of pressure (1.5, 2.5 and 5 bar). Understanding the changes in membrane before and after shock wave treatment by parameters, i.e., pure water flux (PWF), rejection (%), porosity, surface roughness (AFM), morphology (SEM) and contact angle which can significantly affect the membrane's performance. Flux values PSf membranes shows increase, 465 (pristine) to 524 (1.5wt%) LMH at 50 Psi pressure and similar enhancement was observed at 100Psi (625 to 696 LMH). Porosity also shows improvement from 73.6% to 76.84% for 15wt% PSf membranes. It was observed that membranes made of polymers such as PAN and PSF (of high w/w %) exhibits some resistance against shockwaves impact and are stable compared to other membranes. Shockwave pressure of up to 1.5 bar was sufficient enough to change properties which are crucial for performance. Membranes exposed to a maximum pressure of 5 bar completely scratched the surface and with minimum pressure of 1.5bar is optimum enough to improve the water flux and other parameters. Initial results proved that SW may be suitable alternative route to minimize/control membrane fouling and improve efficiency.

Facile Fabrication of Porous and Hydrophilic Polystyrene Membranes Using Recycled Waste

Micro-porous hydrophilic membranes were successfully fabricated using polystyrene waste by phase inversion casting. Four concentrations (20, 25, 30, and 35 wt%) of recycled high-impact polystyrene (HIPS-R) in N, N-dimethyl formamide (DMF) solution were employed to prepare the membranes. The effect of polystyrene concentration on the characteristics of the different membranes was thoroughly studied. Based on the Fourier transform infrared spectroscopy (FTIR) results, the chemical composition of HIPS-R was analogous to that of pure high-impact polystyrene HIPS raw material of the previous studies. Also, field-emission scanning electron microscopy (FESEM) was employed to study the morphology and porosity of the prepared membranes. The membranes cross-section showed a sponge structure with longitudinal macro voids. The solid walls around these voids have a sponge-like structure, especially for high concentration polystyrene membranes. Furthermore, the number of pores into the membrane surface decreased with the increase of polystyrene concentration. The membranes surface pores size was ranged from 150 nm to 550 nm with the different used concentrations. Water contact angle (CA) of the prepared membrane's surface were measured. All the measured CA of the prepared membranes, except the 35 wt% showed CA of 91o, showed a hydrophilic behavior. Thus, the results suggest effective membranes could be obtained using recycled polystyrene. And then, solve the polymer waste accumulation problem in parallel with help in drinking water crisis solution.

Homogeneous and biphasic cellulose acetate/room temperature ionic liquid membranes for gas separations: Solvent and phase-inversion casting vs. supported ionic liquid membranes

Standard casting methods, using polymer/RTIL solutions, can produce membranes with improved stability. We evaluated the performance of RTIL-membranes cast using either solvent casting (homogeneous polymer/RTIL film) or phase-inversion (biphasic polymer/RTIL films). The study used a model casting polymer, cellulose acetate (CA), and the RTIL 1-ethyl-3-methylimidazolium thiocyanate, ([emim][SCN]). The gas separation performances of the resulting homogeneous and biphasic CA/[emim][SCN] membranes were compared with a conventional supported ionic liquid membrane (SILM) of [emim][SCN]. The evaluations of CO2 removal from CH4 supported our hypotheses that the biphasic phase-inversion cast membranes have higher selectivities and membrane stability compared to the homogeneous film membranes. While the homogeneous membranes had the highest gas permeances, the biphasic membranes had three-fold higher selectivities. The highest CO2/CH4 mixed-gas selectivity reported was 89 ± 12 for the biphasic membrane. It appears that selectivity in cast membranes is a function of free RTIL content. The order of membrane stability vs. cross-membrane pressure was biphasic ≈ SILM > homogeneous, with the biphasic breakthrough pressure being two-fold higher than the homogeneous membrane's. Therefore, the phase-inversion casting method (biphasic membranes) is a viable alternative to SILM membranes for fabricating RTIL-membranes. Infrared spectra and atomic force micrographs characterized the homogeneous and biphasic membrane morphologies.

Preparation and performance of p(OPal-MMA)/PVDF blend polymer membrane via phase-inversion process for lithium-ion batteries

Poly (methyl methacrylate) (PMMA) based gel electrolyte has excellent chemical stability and low interfacial resistance but its mechanical strength is poor. In this study, organic palygorskite modified PMMA (p(OPal-MMA)/poly(vinylidene fluoride)) (PVDF) blend based electrolyte membrane was prepared via phase inversion casting technique. The physical and electrochemical properties of the blend membrane were investigated by XRD, SEM, tensile test and electrochemistry workstation. The results showed that PVDF can significantly improve the mechanical strength. The crystal phase of PVDF disappeared after blending. The porosity and ionic conductivity of the p(OPal-MMA)/PVDF membrane was 57.73% and 4.93×10−3S/cm respectively. The electrochemical stability window of Li/gel B-PVDF electrolyte/SS cell was stable up to 4.7V (vs. Li+/Li), and the cell of Li/gel B-PVDF 43% electrolyte/LiFePO4 exhibited good cycling performance and the Coulombic efficiency was maintained above 98.5% during all the cycling process.

Ultrafast Nanofiltration through Large-Area Single-Layered Graphene Membranes.

Perforated single-layered graphene has demonstrated selectivity and flux that is orders of magnitude greater than state-of-the-art polymer membranes. However, only individual graphene sheets with sizes up to tens of micrometers have been successfully fabricated for pressurized permeation studies. Scaling-up and reinforcement of these atomic membranes with minimum cracks and pinholes remains a major hurdle for practical applications. We develop a large-area in situ, phase-inversion casting technique to create 63 cm2 high-quality single-layered perforated graphene membranes for ultrafast nanofiltration that can operate at pressures up to 50 bar. This result demonstrates the feasibility of our technique for creating robust large-area, high quality, single-layered graphene and its potential use as a pressurized nanofiltration membrane.

Effect of degradation of poly(epsilon-caprolactone) films on functional properties for tissue engineering bioreactors

Event Abstract Back to Event Effect of degradation of poly(epsilon-caprolactone) films on functional properties for tissue engineering bioreactors Nazely Diban1, Sandra Sanchez-González1, Inmaculada Ortiz1 and Ana M. Urtiaga1 1 University of Cantabria, Department of Chemical and Biomolecular Engineering, Spain The regeneration of the central nervous system (CNS) is one of the major challenges that regenerative medicine faces nowadays. In order to promote in vitro neural cell regeneration, the use of artificial substrates may provide support for the neural cell growth and axon regeneration [1]. The scaffolds used in the tissue engineering bioreactors must provide sufficient mechanical stability and high transport of nutrients towards the cells and good removal of the metabolites during the whole lifetime of the in vitro cultures. The scaffold porous structure and hydrophilic character are important properties determining the mechanical and mass transport performance and the functionality of the scaffolds for this application. Scaffolds of biodegradable and biocompatible polymers have been proven as promising substrates to promote cell adhesion and proliferation [2]. The scaffolds must provide an adequate functionality in the bioreactor during suficient time so the regeneration of the tissue occurs simultaneously with the lost of functional properties of the scaffold due to degradation. In our previous work [2], flat Poly(ε-caprolactone) (PCL) films with adequate morphology to allow neuronal tissue growth were fabricated using a phase inversion casting technique and isopropanol (IPA) as coagulant (Figure 1). PCL is a polyester that degrades through a characteristic hydrolitical mechanism. In this work, we explore the effect of degradation on the structural (aspect, porosity, morphology), mechanical and transport properties (water and model ovine serum albumim solution transport) of the PCL films under the typical bioreactor conditions (37 ºC in a Phosphate Buffer Solution (PBS) at pH 7.4). The adequacy of the change of the functional properties to match the neural celular proliferation rate will be studied. Figure 1. SEM images of the cross section and surface of the PCL films and confocal images of U87 human glioblastoma static cell culture after 48 hours on the PCL films. All cell nuclei are shown in blue, and the actin cytoskeletal architecture is show in green. Financial support of the Cantabria Explora call through project JP03.640.69 is gratefully acknowledged

A phase-inversion casting process for preparation of tubular porous alumina ceramic membranes

In this study, a phase-inversion casting method with the self-designed forming mold and preparation route was proposed for preparation of tubular ceramic membranes. Thermal and sintering behaviors of as-prepared green tubular membranes were investigated. The results show that the significant weight loss occurs between 400 and 600°C and three shrinkage stages appear in sintering process. Pore size distribution, image analysis, porosity, mechanical strength and gas flux were also studied to characterize the fabricated ceramic membranes. SEM images illustrate that the tubular membrane has a nearly homogeneous microstructure with good pore interconnect and uniform pore dispersion. With increasing of sintering temperature from 1500 to 1600°C, the porosity decreases from 51.2 to 45.1% and the average pore size from 0.79 to 0.71μm, while the flexural strength increases from 22.2 to 41.5MPa. All these properties clearly suggest the practicability of the phase-inversion casting process to prepare tubular ceramic membranes.

Poly(ε-caprolactone) films with favourable properties for neural cell growth.

The regeneration of brain tissue is one of the major challenges in regenerative medicine due to the lack of viable grafts to support the re-growth of functional tissue after a traumatic injury. The development of biocompatible and biodegradable structures with appropriate morphology for the interaction with neural tissue is required. The objective pursued in this work is to develop a biodegradable 2D scaffold structure for neural tissue engineering. Poly(ε-caprolactone) (PCL) was the selected material due to its biocompatibility and biodegradability in the long term. PCL (15%w/w) was dissolved in N-methylpyrrolidone and the film was fabricated by phase inversion casting technique employing ethanol and isopropanol as coagulation baths. The physical structure, morphology and topography of the flat scaffolds were characterized using different techniques. The two different scaffolds presented homogeneous structure with high porosity (higher than 85%), contact angles higher than 90(o), high roughness (Ra> 0.6 μm) and superficial pore sizes of 0.7 and 1.7 μm, respectively. Permeance tests showed high water permeabilities (~350-590 mL m(-1) bar(-1) h(-1)) indicative of promising nutrients supply to the cells. Finally, in vitro human glioblastoma cells cultures after 48 hours showed good cell attachment, proliferation and penetration in the scaffolds. Detailed evaluation of the interaction between the surface morphology and the properties of the scaffolds with the cell response has been done. Thus, the PCL films herein fabricated show promising results as scaffolds for neural tissue regeneration.

The role of layered silicate loadings and their dispersion states on the gas separation performance of mixed matrix membrane

Mixed matrix membranes (MMMs) embodying different types of organoclays, namely Cloisite® 5, Cloisite® 15A and Cloisite® 30B as the disperse phase for gas separation membranes, were prepared. Polysulfone (PSF) has been used as host matrix to prepare asymmetric membranes attained by the dry–wet phase inversion casting process. FESEM analysis has revealed that defect-free asymmetric MMM morphology with no issues pertaining to non-ideal organic–inorganic interphase was fabricated. The effects of organoclay types and loadings on gas permeation properties were characterized by constant pressure and the variable volume method. From the gas permeation experiment, all nanocomposites exhibited significant reduction in the gas permeation rate even with the addition of very low clay loadings (less than 1wt%). The results suggested that the clay particle loading dictated the extent at which the organoclays were dispersed in the polymer matrix as well as their gas discrimination ability. The information on the degree of clay dispersion, aspect ratio, and the number of clay stacks per tactoid unit was gleaned by making use of the famous phenomenological models derived by Nielsen and Cussler׳s group. PSF–C15A membranes with the loading of 0.05wt% were found to be comprised of exfoliated clay nanoplatelet (confirmed by XRD and TEM analysis) with calculated aspect ratio of more than 500 giving rise to striking selectivity (CO2/CH4 ideal selectivity=52.67 for PSF–C15A0.05) well above the recognized intrinsic selectivity for PSF membrane.

An in-situ integrated system of carbon nanotubes nanocomposite membrane for oil sands process-affected water treatment

This study evaluates membrane systems for the removal of the extractable organic fraction (EOF) from oil sands process-affected water (OSPW). Experiments were performed using in-situ integrated membrane units that consisted of low pressure-driven membrane (LPM) and high pressure-driven membrane (HPM) modules. LPM was prepared with a polysulfone (PSU) phase inversion casting process and HPM was fabricated by polyamide (PA) thin-film composite (TFC) interfacial polymerization. To change membrane physicochemical properties, each membrane was developed with and without multiwalled carbon nanotubes (MWNTs). The MWNTs were modified with strong acid to enhance dispersion in an organic solvent. Dispersion of the MWNTs and physicochemical properties of the membranes were characterized by microscopic and spectroscopic methods. The results showed that acid-modified MWNTs developed surface functional groups that increased their hydrophilicity, increasing the rejection of hydrophobic pollutants, increasing OSPW permeate flux, and significantly reducing membrane fouling. The LPM and HPM combinations with MWNTs were tested for the optimal organic pollutants removal from OSPW.

A program for calculating the observables for single-particle-inclusive production reactions

In this study, a phase-inversion casting method with the self-designed forming mold and preparation route was proposed for preparation of tubular ceramic membranes. Thermal and sintering behaviors of as-prepared green tubular membranes were investigated. The results show that the significant weight loss occurs between 400 and 600 °C and three shrinkage stages appear in sintering process. Pore size distribution, image analysis, porosity, mechanical strength and gas flux were also studied to characterize the fabricated ceramic membranes. SEM images illustrate that the tubular membrane has a nearly homogeneous microstructure with good pore interconnect and uniform pore dispersion. With increasing of sintering temperature from 1500 to 1600 °C, the porosity decreases from 51.2 to 45.1% and the average pore size from 0.79 to 0.71 μm, while the flexural strength increases from 22.2 to 41.5 MPa. All these properties clearly suggest the practicability of the phase-inversion casting process to prepare tubular ceramic membranes.