Porous Polysulfone Hollow Fiber Research Articles

Development of novel composite polydecylmethylsiloxane hollow fiber membranes on highly permeable polysulfone support for С<sub>2+</sub>/С<sub>1</sub> separation

A novel composite hollow fiber membrane has been developed for the separation of C2+ hydrocarbons from their mixture with methane. A high-performance porous polysulfone hollow fiber support was fabricated. Polydecylmethylsiloxane (PDecMS) and polydimethylsiloxane (PDMS) were used as a thin selective layer. Comparison of the results of separation of binary mixture of CH4 and C4H10 using PDecMS/PSF and PDMS/PSF membranes showed that for the PDecMS/PSF module the specific retentate flux and n-butane concentration in the permeate are 1.7 times higher and energy consumption is 9 times lower.

Enhancing Water Treatment Performance of Porous Polysulfone Hollow Fiber Membranes through Atomic Layer Deposition.

Polysulfone (PSF) is one of the most used polymers for water treatment membranes, but its intrinsic hydrophobicity can be detrimental to the membranes' performances. By modifying a membrane's surface, it is possible to adapt its physicochemical properties and thus tune the membrane's hydrophilicity or porosity, which can achieve improved permeability and antifouling efficiency. Atomic layer deposition (ALD) stands as a distinctive technology offering exceedingly even and uniform layers of coatings, like oxides that cover the surfaces of objects with three-dimensional (3D) shapes, porous structures, and particles. In the context of this study, the focus was on titanium dioxide (TiO2), zinc oxide (ZnO), and alumina (Al2O3), which were deposited on polysulfone hollow fiber (HF) membranes via ALD using TiCl4, diethyl zinc (DEZ), and trimethylamine (TMA), respectively, and H2O as precursors. The morphology and mechanical properties of membranes were changed without damaging their performances. The deposition was confirmed mainly by energy-dispersive X-ray spectroscopy (EDX). All depositions offered great performances with a maintained permeability and BSA retention and a 20 to 40° lower water contact angle (WCA) than the raw PSF HF membrane. The deposition of TiO2 offered the best results, showing an enhancement of 50% for the water permeability and 20% for the fouling resistance of the PSF HF membranes.

Enhanced water permeability of hollow fiber composite reverse osmosis membrane using porous α-cellulose/polysulfone hollow fiber membrane as the substrate

The hollow fiber composite (HFC) reverse osmosis (RO) membrane with a special self-supporting structure has attracted a great deal of attention in the fields of separation and purification. However, low permeability is an urgent problem restricting its wide application. A porous polysulfone (PSF) hollow fiber support membrane was fabricated through the dry–wet spinning technique and hydrophilic α-cellulose © powder was incorporated in the PSF membrane matrix to improve the membrane’s water permeability. The HFC RO membrane was prepared via the interfacial polymerization process on the inner surface of the C/PSF support membrane. The membrane morphology and surface hydrophilicity were evaluated through scanning electron microscopy observation and dynamic water contact angle (WCA) measurement. The effects of α-cellulose incorporation on the separation performance of PSF hollow fiber membranes and HFC RO membranes were investigated. The results showed that the surface hydrophilicity and water permeability of the PSF membrane were significantly improved after the introduction of α-cellulose. The WCA of the modified PSF support membrane decreased from 84.6° for the neat PSF membrane to 70.25°, and the pure water flux can reach a maximum value of 102.1 L/(m2 · h) (0.1 Mpa), which was 1.3 times that of the pristine membrane. The HFC RO membrane using the hydrophilic modified PSF membrane as the substrate exhibited an enhanced water flux of 15.6 L/(m2 · h) and, meanwhile, the membrane salt rejection remained above 97.6% (1.0 wt% NaCl aqueous solution, 0.7 Mpa). The HFC RO membrane showed extremely high rejection rates (99%) for different dyes (congo red and methylene blue). No obvious performance deterioration was observed for the HFC RO membrane during continuous vacuum membrane distillation (VMD) experiments for 60 h.

Effects of Dry-Jet Wet Spinning Parameters on Properties of Polysulfone Hollow Fiber Membranes

The influence of parameters of the dry-jet wet spinning process was studied on properties of porous polysulfone hollow fiber membranes. The air gap distance, the dope extrusion pressure, bore fluid pressure and temperature were chosen as the studied parameters. Their effect on the geometric and morphological properties of membranes was investigated. The optimal parameters were revealed for the formation of polysulfone hollow fiber membranes, promising for use as porous supports of composite membranes. High gas permeability were achieved with pore sizes providing the Knudsen flow regime: carbon dioxide permeability P/l(CO2) = 48.3 m3 m–2 h–1 atm–1, and values of ideal selectivity α = 2.63 and 0.87 for He/CO2 and CO2/N2 gas pairs, respectively.

Modeling of Ethylene Absorption from an Ethylene–Ethane Mixture by Silver Nitrate Aqueous Solution in a Hollow-Fiber Membrane Contactor

Convection–diffusion mass transfer in a gas–liquid membrane contactor based on porous polysulfone hollow fiber membranes with a mesoporous (dpore ~ 2 nm) structure of the separation layer has been studied. The characteristics of the membrane contactor have been investigated in the recovery of ethylene from its mixture with ethane using an aqueous silver nitrate solution as the absorption liquid. A procedure based on the method of lines is proposed for calculating a mass transfer in hollow fiber contactor with a longitudinal laminar flow in an array of parallel fibers. An ethylene flux, depending on the process conditions, has been found by solving numerically a set of convection–diffusion equations with allowance for both the chemical reaction in the liquid stream and transmembrane transport.

Fabrication of efficient pervaporation desalination membrane by reinforcement of poly(vinyl alcohol)–silica film on porous polysulfone hollow fiber

ABSTRACTPervaporation membrane technology is commercially successful in the dehydration of organic solvents, and the technology has potential for seawater desalination with high recovery because of its capability to treat highly saline water. But to make the technology advantageous over the other available membrane desalination technologies in terms of productivity flux without additional energy cost, the selective barrier layer is required to be extremely thin, defect‐free, hydrophilic, and selective to water. In this work, we prepared an efficient membrane by reinforcing a highly water‐permeable but continuous barrier layer of poly(vinyl alcohol)–silica (PVA‐SiO2) hybrid material on porous polysulfone hollow fibers. The PVA‐SiO2 in acidified and hydrated ethanol was aged at room temperature for a period to allow solvent evaporation to obtain the solution concentration desired for the reinforcement. The reinforced hollow fiber membrane with optimal PVA‐SiO2 barrier layer thickness exhibited a performance with a flux of 20.6 L m−2 h−1 and 99.9% salt rejection from a saline feed of 2000 ppm NaCl at 333 K. The effects of PVA‐SiO2, temperature, and feed salinity on the pervaporation performance of the membrane were also studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45718.

Carbon dioxide stripping from water through porous polysulfone hollow fiber membrane contactor

Carbon dioxide (CO2) stripping from water was conducted through the porous asymmetric polysulfone (PSf) hollow fiber membrane contactor. The effect of the liquid and gas flow rates on the stripping performance, the liquid phase CO2 concentration and the CO2 stripping efficiency of the membrane module and the effect of liquid phase temperature on CO2 stripping flux were studied. The experimental results showed that the stripping gas velocity had a minor effect on the CO2 desorption flux while the increase in the liquid velocity could enhance CO2 desorption flux in the gas stripping membrane contactor. By increasing liquid flow rate to 200ml/min, the maximum CO2 stripping efficiency of almost 66% was achieved. Enhancement of liquid flow rate from 50 to 200ml/min increased the CO2 flux around 482%. It was found that the CO2 stripping flux was significantly affected by the liquid phase temperature. By increasing liquid temperature from 80 to 90°C, the CO2 stripping flux increased from 1.3×10−4 to 4.9×10−4 molm−2s−1 at liquid velocity of 200mlmin−1. Hence, the higher stripping efficiency can be achieved by applying the higher liquid flow rate in the membrane contactor module. As well, the liquid phase temperature is a key parameter that needs to be controlled.

Effect of additives on the structure and performance of polysulfone hollow fiber membranes for CO 2 absorption

Porous polysulfone (PSf) hollow fiber membranes were fabricated via a phase-inversion method by using low molecular weight additives in the spinning dopes. Polyethylene glycol (PEG200), ethanol, glycerol and acetic acid were used as the additives. An aqueous 95 wt.% 1-methyl-2-pyrrolidone (NMP) solution was used as neutral bore fluid to fabricate inner skinless hollow fibers membranes. The precipitation rate of the polymer dopes with the different additives was studied using cloud point measurement. Effect of the additives on the resulting membrane structure, surface porosity, pore size, critical water entry pressure (CEP w) and CO 2 absorption performance were investigated. Cloud point diagrams indicated that the precipitation rate of the polymer dopes increased following the trend of glycerol > acetic acid > PEG200 > ethanol. Results of gas permeation tests showed that glycerol and PEG200 as additives provided the membranes with the largest and smallest pore size, respectively. Moreover, all the additives resulted in an increase in the surface porosity. The cross-section and inner surface of the membranes were examined via a field emission scanning electronic microscopy (FESEM). Glycerol in the spinning dope provided the membrane structure with a thin finger-like and a thick sponge-like layer, which resulted in a higher CEP w and CO 2 absorption rate than the other PSf hollow fiber membranes.

Determination of alkylphenols and bisphenol-A: A comparative investigation of functional polymer-coated membrane microextraction and solid-phase microextraction techniques

A functional polymer (hydroxylated polymethacrylate) coated on porous polysulfone hollow fiber membrane (PS-HFM) was used as an adsorbent for the extraction of alkylphenols and bisphenol-A from seawater samples. Analyses of the extracts were performed using gas chromatography–mass spectrometry (GC–MS) after injection-port derivatization using bis(trimethylsilyl)trifluoroacetamide (BSTFA). We term the procedure as polymer-coated hollow fiber microextraction (PC-HFME). Owing to high porosity PS-HFM coated with hydroxylated polymer showed high extraction efficiency. Compared with solid-phase microextraction (SPME), PC-HFME showed good selectivity and sensitivity. Detection limits of alkylphenols and bisphenol-A ranged between 0.07 and 2.34 ng l −1. The linearity range was from 0.01 to 15 μg l −1 and the correlation coefficient ( r) up to 0.997. The sensitivity and selectivity of the coated HFM could be potentially tuned by changing the characteristics of the coated hydroxylated polymer. The PC-HFME procedure was applied to the detection of alkylphenols and bisphenol-A in the coastal waters of Singapore.

Preparation of hollow fiber poly(ether block amide)/polysulfone composite membranes for separation of carbon dioxide from nitrogen

The separation of carbon dioxide from nitrogen is relevant to flue gas treatment for greenhouse gas emission control. This study deals with the preparation of hollow fiber poly(ether block amide) (PEBA)/polysulfone (PSf) composite membranes for CO 2/N 2 separation. PEBA 2533 copolymer was shown to be a good permselective membrane material for CO 2/N 2 separation. At 25 °C and 100 psig, a CO 2 permeability of about 260 Barrer and a CO 2/N 2 selectivity of 32 were obtained. The thin-film hollow fiber PEBA/PSf composite membrane comprising of a thin PEBA skin layer (<5 μm) and a porous polysulfone hollow fiber substrate was prepared by the dip-coating technique. The polysulfone hollow fiber substrate was formed by the solution extrusion/phase inversion process. The effects of parameters involved in the procedure of polysulfone hollow fiber spinning and PEBA layer deposition on the permselectivity of the resulting composite membranes were investigated. Defect-free PEBA/PSf composite membranes with an inside and an outside diameters of 350 and 600 μm, respectively, have been obtained which showed a CO 2 permeance of 61 GPU and a CO 2/N 2 selectivity close to the intrinsic selectivity of the PEBA dense membrane. It was shown that the N 2 permeability is essentially independent of the pressure, whereas CO 2 permeability tends to increase with an increase in gas pressure, presumably due to plasticization of the membrane caused by the relatively high solubility of CO 2 in the membrane.