Hydrophobicity properties of graphite and reduced graphene oxide of the polysulfone (PSf) mixed matrix membrane

Hydrophobicity properties of graphite and reduced graphene oxide (rGO) (from exfoliated graphite/rGO) towards PSf polymer membrane characteristic and properties at different additives weight concentrations (1, 2, 3, 4 and 5 wt. %) were investigated. Both PSF/graphite and PSf/rGO membranes were characterized in term of hydrophobicity, surface bonding, surface roughness and porosity. FTIR peaks revealed that membrane with graphite and reduced graphene oxide nearly diminished their O-H bonding which was opposite to the graphene oxide peak that shows a strong O-H bonding as increased exfoliated times. These results were in line with the contact angle results that showed strong hydrophobicity of graphite and reduced graphene oxide membranes as increased these additives concentration. The effect of strong hydrophobicity in these membranes also has resulted in smoother surface roughness compared to pristine PSf membrane. Further investigation of the performance of water flux also proved that both above membranes have strong hydrophobic effect, with the lowest pure water flux rate (L/m2h) was given by PSf/rGO 3% membrane at 19.2437 L/m2h

Permeation, antifouling and desalination performance of TiO2 nanotube incorporated PSf/CS blend membranes

Polysulfone (PSf) and chitosan (CS) blend membranes were prepared by incorporating titanium dioxide nanotubes (TiO2NT) in different compositions. The proper blending of PSf and CS in the PSf/CS/TiO2 membranes was confirmed by ATR-IR spectroscopy. The influence of nanotubes on morphology of membranes was investigated by Field Emission Scanning Electron Microscopy (FESEM). The effect of nanotubes on hydrophilicity of the membranes was studied by water swelling and contact angle measurements. The distribution of TiO2NT on the membrane surface was determined by Transmission Electron Microscope (TEM) analysis. The permeation property of PSf/CS/TiO2NT membranes was carried out by measuring the time dependent pure water flux (PWF). Bovine serum albumin (BSA) protein rejection studies were performed to know the antifouling properties. The rheological percolation threshold of PSf/CS/TiO2NT solutions was measured by viscosity studies. The nanotubes incorporated PSf/CS membranes showed enhanced permeation and antifouling properties compared to PSf/CS and nascent PSf ultrafiltration membranes. Membranes prepared well above rheological percolation threshold showed drastic reduction in pore size and acted as nanofiltration (NF) membranes

A new method to determine the skin thickness of asymmetric UF-membranes using colloidal gold particles

In this paper a new method is presented for the determination of the skin thickness of asymmetric ultrafiltration membranes. The method is based on the use of well-defined, uniformly sized colloidal gold particles, permeated from the sublayer side of the membrane, combined with electron microscopic analysis of the membrane afterward. Using this method poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and polysulfone (PSf) membranes were investigated. PPO membranes appeared to have a well-defined skin layer with a thickness of about 0.2 μm and a pore size distinctly different from that in the macroporous layer underneath. In the case of PSf such a distinct skin layer cannot be defined. The size of the pores in these membranes gradually increases from skin to sublayer

Phase separation phenomena in solutions of polysulfone in mixtures of a solvent and a nonsolvent: relationship with membrane formation

The phase separation phenomena in ternary solutions of polysulfone (PSf) in mixtures of a solvent and a nonsolvent (N,N-dimethylacetamide (DMAc) and water, in most cases) are investigated. The liquid-liquid demixing gap is determined and it is shown that its location in the ternary phase diagram is mainly determined by the PSf-nonsolvent interaction parameter. The critical point in the PSf/DMAc/water system lies at a high polymer concentration of about 8% by weight. Calorimetric measurements with very concentrated PSf/DMAc/water solutions (prepared through liquid-liquid demixing, polymer concentration of the polymer-rich phase up to 60%) showed no heat effects in the temperature range of −20°C to 50°C. It is suggested that gelation in PSf systems is completely amorphous. The results are incorporated into a discussion of the formation of polysulfone membranes

Polysulfone mixed matrix membranes with biosynthesis nanoparticles: enhancement of interface compatibility and antibacterial membrane seperation process

This study investigates the effect of biosynthesis silver nanoparticles (bio-AgNPs) structure towards PSf membranes performance. The addition of bio-AgNPs in the membrane formulation was aimed to improve antibacterial properties and interface compatibility of the polymer mixed matric membrane. In this work, facile green synthesis method of silver nanoparticles was prepared using Parkia speciosa (Petai) leaves extract silver nitrate aqueous solution. The bio-AgNPs/PSf membranes was fabricated using phase-inversion process. Characterization of the synthesized bio�AgNPs and mixed matrix membranes via UV-Vis spectroscopy (UV-Vis), Field emission scanning electron microscope (FESEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Surface plasmon resonance for bio-AgNPs was assigned at 465 nm with brown colour. FTIR spectroscopy identified the biomolecules capped on the surface of nanoparticles are phenol, flavonoid and terpenoid compounds. The microstructure and structural analyses had shown that AgNPs possessed good characteristics with spherical shapes, small average size of particles (59.96 nm), and small crystallite size. The bio-AgNPs also showed significant potential antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The addition of bio-AgNPs was able to enhance the hydrophilicity of composite PSf membranes which proved by decreasing the value of contact angle. Meanwhile, structure on bottom layer shown a porous bulk with finger-like structure and macroviod structure which is responsible for mechanical support. Finger-like structure on top layer became smaller with increment of bio-AgNPs because of its hydrophilicity properties. Hence, the pure water flux also will increase because the hydrophilicity properties was an essential factor for water permeability. The molecular interaction between molecules was investigated using Dynamic mechanical analysis (DMA) and silver leaching analysis by Inductive coupled plasma mass spectrometer (ICP-MS). vi As revealed, the strength of molecular interaction between AgNPs and PSf molecules was improved with addition of bio-AgNPs. Hence, overall the results showed that the incorporation of bio-AgNPs able to improve antibacterial properties and interface compatibility of the polymer mixed matric membran

Selectivity as a function of membrane thickness: gas separation and pervaporation

In this article, the pervaporation selectivity as a function of the membrane thickness is studied for the dehydration of acetic acid. From this study, it appeared that the selectivity of polysulfone (PSF), poly(vinyl chloride) (PVC), and polyacrylonitrile (PAN) decreases with decreasing membrane thickness, below a limiting value of about 15 m. However, in the case of gas separation, the selectivity of PSF membranes is independent of the membrane thickness. This phenomenon could not be explained by a difference in membrane morphology, sorption resistance, thermodynamic interaction, or coupling. It is believed that the decrease in selectivity for thin membranes has to be attributed to defects induced during pervaporation. These defects, crazes (and cracks), result from a reduced value of the critical strain, due to sorption of acetic acid/water and stresses between the polymer chains, due to a concentration gradient across the membrane

Fabrication of thin film composite poly(amide)-carbon-nanotube supported membranes for enhanced performance in osmotically driven desalination systems

The search for lower energy consumption desalination systems has been driving research in the past decade towards the investigation of osmotically driven membrane processes, such as forward osmosis (FO) or osmotic distillation (OD). Despite similarities with reverse osmosis (RO) membranes, thin film composite (TFC) for FO membranes require careful design to reduce salt concentration polarization formation within the large pores composing the supporting layer. An investigation of a novel, highly stable, robust support made solely of carbon nanotubes (CNTs), which could find applications in both RO and FO was undertaken. TFC membranes were fabricated by interfacially polymerizing for the first time a dense poly(amide) (PA) layer on self-supporting bucky-papers (BPs) made of hydroxyl-functionalized entangled CNTs. These hydrophilic supports exhibited low contact angle with water (90%), making it a promising material when compared with poly(sulfone) (PSf), the traditional polymer used to fabricate TFC membrane supports in RO. In addition, the impact of the support hydrophilicity on the stability of the interfacially polymerized film and on water adsorption was investigated by oxygen-plasma treating various potential support materials, exhibiting similar geometrical properties. The morphology and salt diffusion of both CNT BP and PSf supports were investigated, and the novel BP–PA composite membranes were found to be superior to commercially available TFC membranes

Surface characterization data for tethered polyacrylic acid layers synthesized on polysulfone surfaces.

The data presented are supplementary to an article [Kim et al., 2019] on synthesis and surface characterization of tethered polyacrylic acid (PAA) layers on polysulfone (PSf) film/membrane surfaces via atmospheric pressure plasma-induced graft polymerization (APPIGP). Data on surface characterization of the synthesized tethered PAA layers includes: AFM topographic surface images and height distributions of surface features, dry layer thickness, chain rupture length distributions determined via AFM based force spectroscopy (AFM-FS), in addition to measurements of water contact angles. Fouling propensity data for ultrafiltration of alginic acid as a model foulant are also provided for native and PAA grafted PSf ultrafiltration (UF) membranes

Phosphate removal from water by polysulfone ultrafiltration membrane using PVP as a hydrophilic modifier

The phosphate removal from aqueous solution was studied with a dead-end filtration process using ultrafiltration membranes. Polysulfone (PSf) ultrafiltration membranes were prepared by blending PSf with polyvinylpyrrolidone (PVP). The prepared membranes were characterized by water content, contact angle, SEM, EDX, AFM, and FTIR. The hydrophilicity and porosity of membrane improved considerably and water contact angle declined with the incorporation of PVP. While pure PSf membrane did not have any flux, PSf/PVP 3 wt.% (UF2) shows 9.6 L/m2 h permeate flux. The impact of diverse operating parameters, such as PVP concentration, pressure, and pH of the feed solution on the removal of phosphate was examined. A high phosphate removal (93.6%) from aqueous solution was observed for UF2 membrane and 87.2% for UF3 membrane at feed solution pH 2. It was found that the phosphate rejection dropped as the pressure and PVP concentration increased. A reduction in pH of the feed solution gave a higher phosphorus rejection

The effect of flower-like tatania towards characteristics and performance of polysulfone mixed matrix membrane

For ages, the polymeric membrane such as PSf is widely used in liquid separation for various application as the polymer itself offer versatile and attractive properties. However, due to strong hydrophobic nature of PSf property that create serious fouling problem to most of the separation process, thus modification of membrane by integrating strong hydrophilic particles is always practically used among industries and researchers. In this research, the effect of FLT as an additive in the PSf membrane was investigated. With consideration of the FLT that offer larger specific surface area as compared to ST that able to generate better performances and properties of polymer MMM. In this work, the polymer MMM of PSf/FLT and PSf/ST membranes were prepared via phase inversion method at five different concentrations of additive. Membrane characterization involved several observations such as cross-section area, particle distribution, surface roughness, hydrophilicity property, mean pore size, mechanical strength and porosity. Meanwhile, membrane performances were evaluated in terms of HA rejection, PWF, antifouling, antibacterial activity and photocatalytic properties based on self-cleaning antifouling efficiency. From the result, the addition of FLT was strongly influenced overall structure and characteristics of the membrane compared to ST. With a larger surface area of FLT and homogenous distribution inside membrane structure have resulted in better hydrophilicity effect thus improved the membrane performances. The PWF result was increased from 61.33 L/m2h to 137.81 L/m2h for PSf/ST and 155.46 L/m2h for PSf/FLT as increased additive to 3 wt%. Same results were obtained by rejection analysis where the PSf/FLT membrane able to reject more than 96% of HA and improved antifouling and self-cleaning efficiency. It is clearly shown that the present of higher specific surface area of FLT has improved overall characteristics and performances of the membrane compared to ST especially at 3 wt% of concentration