Nonwoven Support Research Articles

Thermally Stabilised Poly(vinyl alcohol) Nanofibrous Materials Produced by Scalable Electrospinning: Applications in Tissue Engineering.

Electrospinning is a widely employed manufacturing platform for tissue engineering applications because it produces structures that closely mimic the extracellular matrix. Herein, we demonstrate the potential of poly(vinyl alcohol) (PVA) electrospun nanofibers as scaffolds for tissue engineering. Nanofibers were created by needleless direct current electrospinning from PVA with two different degrees of hydrolysis (DH), namely 98% and 99% and subsequently heat treated at 180 °C for up to 16 h to render them insoluble in aqueous environments without the use of toxic cross-linking agents. Despite the small differences in the PVA chemical structure, the changes in the material properties were substantial. The higher degree of hydrolysis resulted in non-woven supports with thinner fibres (285 ± 81 nm c.f. 399 ± 153 nm) that were mechanically stronger by 62% (±11%) and almost twice as more crystalline than those from 98% hydrolysed PVA. Although prolonged heat treatment (16 h) did not influence fibre morphology, it reduced the crystallinity and tensile strength for both sets of materials. All samples demonstrated a lack or very low degree of haemolysis (<5%), and there were no notable changes in their anticoagulant activity (≤3%). Thrombus formation, on the other hand, increased by 82% (±18%) for the 98% hydrolysed samples and by 71% (±10%) for the 99% hydrolysed samples, with heat treatment up to 16 h, as a direct consequence of the preservation of the fibrous morphology. 3T3 mouse fibroblasts showed the best proliferation on scaffolds that were thermally stabilised for 4 and 8 h. Overall these scaffolds show potential as 'greener' alternatives to other electrospun tissue engineering materials, especially in cases where they may be used as delivery vectors for heat tolerant additives.

Adsorption of steroid hormone micropollutant by polyethersulfone ultrafiltration membranes with varying morphology

The effective removal of micropollutants necessitates the use of dense membranes, such as thin-film composite (TFC) reverse osmosis (RO) and nanofiltration (NF) membranes. TFCs have a polyamide active layer interfacially polymerized on a support layer that is typically made of polysulfone (PSu) or polyethersulfone (PES). Retention by NF and RO is often incomplete because micropollutants are adsorbed to the polymer material and subsequently permeate via a combination of convection and diffusion, which evidences a breakthrough curve. When describing breakthrough phenomena, the role of the support membrane is commonly neglected, even though the adsorption in this layer can be significant. This work investigated the adsorption of steroid hormone micropollutants (17β-estradiol, E2) by fabricated and commercial PES ultrafiltration membranes with varying morphology.By increasing the coagulation bath temperature between 10 and 70 °C, the pure water permeability increased from 13 to 3800 L/m2·h−1·bar−1, and consequently, the average pore size rose from 12 to 191 nm. The fabricated membranes with smaller pore sizes showed higher E2 removal via adsorption which can be attributed to the higher internal surface area. The adsorbed mass of fabricated PES membranes (using dimethylformamide (coded as PDG) and N-methyl-2-pyrrolidone (coded as PNG) and PES (Istanbul Technical University (ITU), with non-woven supports) varies from 0.30 to 0.60, 0.27–0.60 and 1–1.2 ng·cm−2, respectively. These values are lower than the adsorbed masses with commercial Biomax (Millipore Inc.) membranes (0.5–2.0 ng·cm−2). Ultrafiltration membranes used as support for composite membranes, nanofiltration or as filters in sample preparation benefit from lower micropollutant adsorption.

Permeate gap thermo-osmotic system for simultaneous freshwater production, energy storage, and power generation

The emerging thermo-osmotic system enables harvesting low-grade thermal energy below 100 °C for the simultaneous production of fresh water and electricity. Considering the fluctuation of low-grade heat sources, a novel permeate gap thermo-osmotic system without pump pressurization was proposed in this study, which also allows for energy storage. A lab-scale setup with a 32 cm2 membrane area was built, by which a 2 W light bulb was successfully illuminated through the thermal energy-potential energy-electricity conversion process. In the pressurization process of the permeate side, the hydrophobic membranes with non-woven support exhibit higher pressure resistance, capable of withstanding pressures exceeding 200 kPa. Through experimental and theoretical analyses, the influences of different operation conditions and membrane properties on system performance were studied. Furthermore, utilizing solar energy as the heat source, a case study was conducted based on real meteorological data from a typical coastal city over a consecutive 72-hour period. In the solar-driven PGTO system with a power capacity of approximately 150 kW, the exergy efficiency can achieve 1.04 %, with a power density surpassing 0.1 W m−2, and an average daily freshwater production of over 70000 t. The energy storage function enables stable power generation within the 72 h, and it can sustain steady operation for nearly 7 h thereafter in the absence of sunlight. This study demonstrated the potential of the proposed PGTO system to efficiently utilize fluctuating low-grade thermal energy.

Highly effective ultrafiltration membranes based on plastic waste for dye removal from water.

Applicable and low-cost ultrafiltration membranes based on waste polystyrene (WPS) blend and poly vinylidene fluoride (PVDF) were effectively cast on nonwoven support using phase inversion method. Analysis was done into how the WPS ratio affected the morphology and antifouling performance of the fabricated membranes. Cross flow filtration of pure water and various types of polluted aqueous solutions as the feed was used to assess the performance of the membranes. The morphology analysis shows that the WPS/PVDF membrane layer has completely changed from a spongy structure to a finger-like structure. In addition, the modified membrane with 50% WPS demonstrated that the trade-off between selectivity and permeability is met by a significant improvement in the rejection of the membrane with a reduction in permeate flux due to the addition of PVDF. With a water permeability of 50 LMH and 44 LMH, respectively, the optimized WPS-PVDF membrane with 50% WPS could reject 81% and 74% of Congo red dye (CR) and methylene blue dye (MB), respectively. The flux recovery ratio (FRR) reached to 88.2% by increasing PVDF concentration with 50% wt. Also, this membrane has the lowest irreversible fouling (Rir) value of 11.7% and lowest reversible fouling (Rr) value of 27.9%. The percent of cleaning efficiency reach to 71%, 90%, and 85% after eight cycles of humic acid (HA), CR, and MB filtration, respectively, for the modified PS-PVDF (50%-50%). However, higher PVDF values cause the membrane's pores to become clogged, increase the irreversible fouling, and decrease the cleaning efficiency. In addition to providing promising filtration results, the modified membrane is inexpensive because it was made from waste polystyrene, and as a result, it could be scaled up to treat colored wastewater produced by textile industries. PRACTITIONER POINTS: Recycling of plastic waste as an UF membrane for water/wastewater treatment was successfully prepared and investigated. Mechanical properties showed reasonable response with adding PVDF. The modified membrane with 50% PS demonstrated that the trade-off between selectivity and permeability is met by a significant improvement in the rejection.

Green-Solvent-Processable Composite Micro/Nanofiber Membrane with Gradient Asymmetric Structure for Efficient Microfiltration.

Electrospinning technology has attracted extensive attention in recent decades and is widely used to prepare nanofiber membranes from hundreds of polymers. Polyvinyl formal acetal (PVFA), as a polymer with excellent properties such as high strength and heat resistance, is not reported on the electrospun water treatment membrane. In this paper, the preparation process of electrospun PVFA nanofiber membrane is optimized, and the effect of sodium chloride (NaCl) addition on the physical and mechanical properties and microfiltration performance of nanofiber membrane is also explored. And the hydrophobic PVFA nanofiber filter layer is then combined with a hydrophilic nonwoven support layer to construct a composite micro/nanofiber membrane with a pore-size gradient structure and a hydrophilic/hydrophobic asymmetric structure. Finally, unidirectional water transport and water treatment performance are further investigated. The results show that the tensile breaking strength of the composite membrane can reach up to 37.8 MPa, the retention rate for particles with the size of 0.1-0.3 µm is 99.7%, and the water flux is 513.4 L m-2 h-1 under the hydrostatic pressure. Moreover, it still has a retention of more than 98% after three repeated uses. Therefore, the electrospun PVFA composite membrane has a great potential in microfiltration.

Statistical analyses of pore radii on the performance of PET-nanocomposite membranes in the removal of iron and anions from Ibeshe River

The industrialization in Lagos State has impacted the Ibeshe watershed, as a result, lower water quality is being experienced. Hence, a novel way on the potential use of waste to treat Ibeshe watershed by synthesizing of graphene oxide and incorporating it into PET bottle waste membranes was studied. Polyethylene terephthalate (PET) membranes embedded with 1wt%, 2wt%, and 3wt% graphene oxide (GO) (M1, M2, and M3), were prepared via non-solvent-induced phase separation on polyester nonwoven support with the use of polyethylene glycol (PEG) as an additive. The surface morphologies of the three membranes appeared to be considerably different. The pore volume steadily reduces with an upsurge in the quantity of GO embedded in the membranes. A statistical assessment employing a uniform distribution curve was done using Python and the outcomes depict that the distribution of the radius data was firmly gathered around the mean. From the adsorption study, Fe2+ does not have the power to attract HCO3− in the transitory state at the surface of the membrane; hence HCO3− could not reach equilibrium at 80 min. The membranes’ performance was studied via flux and the rejection of iron and anions. The rejection rate calculated for the three anions and iron was observed to be high in the M3 membrane. The M3 membrane% rejection of the anions and iron is 96%, 85%%, 72%, and 60% for NO3−, Cl−, HCO3− and Fe, respectively. An upsurge in the amount of GO improved the water flux; hence, 3wt% GO gave the maximum water flux.

Separation Mechanisms and Anti-Fouling Properties of a Microporous Polyvinylidene Fluoride-Polyacrylic Acid-Graphene Oxide (PVDF-PAA-GO) Composite Membrane with Salt and Protein Solutions.

This research demonstrates the preparation of composite membranes containing graphene oxide (GO) and investigates the separation mechanisms of various salts and bovine serum albumin (BSA) solutions. A microporous polyvinylidene fluoride-polyacrylic acid-GO (PVDF-PAA-GO) separation layer was fabricated on non-woven support. The GO-incorporating composite resulted in enlarged pore size (0.16 μm) compared with the control membrane (0.12 μm). The zeta potential of the GO composite was reduced to -31 from -19 mV. The resulting membranes with and without GO were examined for water permeability and rejection efficiency with single salt and BSA solutions. Using the non-woven/PVDF-PAA composite, the permeance values were 88-190 kg/m2hMPa, and the salt rejection coefficients were 9-28% for Na2SO4, MgCl2, MgSO4, and NaCl solutions. These salt removals were based on the Donnan exclusion mechanism considering the ion radii and membrane pore size. Incorporating GO into the separation layer exhibited limited impacts on the filtration of salt solutions, but significantly reduced BSA membrane adhesion and increased permeance. The negatively charged protein reached almost complete removal (98.4%) from the highly negatively charged GO-containing membrane. The GO additive improved the anti-fouling property of the composite membrane and enhanced BSA separation from the salt solution.

Development and Industrial-Scale Fabrication of Next-Generation Low-Energy Membranes for Desalination

Spiral-wound modules have been the most common configuration of packing flat-sheet membranes since the early development of polyamide (PA) membranes for water treatment applications. Conventional spiral-wound modules (SWMs) for desalination applications typically consist of several leaf sets, with each leaf set comprising feed spacers, membranes, and a permeate carrier (PC) wrapped around a permeate-collecting tube. The membrane area that can be packed into a given module diameter is limited by the overall leaf set thickness, restricting module productivity for a given membrane permeability. We describe here a novel industrial-scale method for successfully coating the polysulfone (PSf) ultrafiltration (UF) support layer directly onto a permeate carrier, instead of conventional non-woven fabric, as a precursor to the polyamide TFC coating, resulting in twofold benefits: (a) drastically simplifying the membrane fabrication process by eliminating the use of non-woven fabric and (b) increasing the throughput of each membrane module by facilitating the packing of a larger membrane area in a standard module housing. By combining the permeate carrier and membrane into a single sheet, the need for the non-woven support layer was eliminated, leading to a significantly reduced leaf set thickness, enabling a much larger membrane area to be packed in a given volume, leading to lower energy consumption per cubic meter of produced water. Molecular-weight cutoff (MWCO) values in the range of 36–96 kDa were found to be dependent on PC thickness and material. Nevertheless, the reinforced membranes were successfully fabricated with a ~9% reduction in membrane leaf thickness compared to a conventional membrane. Preliminary trials of coating a thin-film composite PA layer resulted in defect-free reverse osmosis (RO) membranes with a salt rejection of 94% and a flux of 40 L m−2 h−1 when tested against a 2000 mg/L NaCl feed solution at an operating pressure of 15 bar. Results from the testing of the 1812 and 2514 elements validated the novel concept and paved the way for further improvements towards full-scale RO membranes with the potential to be the next low-energy workhorse of the water industry.

Effect of Nonwoven Support During Fabrication of Flat Sheet Membranes via Phase Inversion Method

Effect of Nonwoven Support During Fabrication of Flat Sheet Membranes via Phase Inversion Method

Fabrication of mixed nanoceramic waste with polymeric matrix membranes for water desalting

Abstract Mixed matrix membranes were prepared by blending technique between nanoceramic powder and polyethersulfone. Nanoceramic powder (NC) as a fine powder was produced from ceramic industries. The effect of NC as an additive on the membrane matrix was studied. Increasing in NC% on polymeric blend enhances the membrane mechanical properties, where the tensile strength was 13.92 MPa with elongation of 23.67 mm for prepared blend membrane with NC 1 wt%. The highest salt rejection was about 89.3% with permeate flux of 34.6 L/m2 h for R1 membrane using NS of percentage 4 wt% and nonwoven polyester support. The increase in NS% to 6 wt % leads to an increase in the salt rejection to 94.2% after 1 h operating time. The coating was achieved using the layer by layer technique which was carried out on the membrane surface to improve the salt rejection percentage. The salt rejection was found to reach about 99.8% after such coating process; but for permeate flux, it shows a certain decrease. The flux of membrane before the coating was 23.4 L/m2 h for R2 membrane (1 wt% NC &amp; 6 wt% NS), while after coating the flux was reduced to reach 21.6 L/m2 h.

Low-Voltage Bacterial and Viral Killing Using Laser-Induced Graphene-Coated Non-woven Air Filters.

Laser-induced graphene (LIG) is uniquely positioned to advance applications in which electrically conductive carbon coatings are required. Recently, the antifouling, antiviral, and antibacterial properties of LIG have been proven in both air and water filtration applications. For example, an unsupported LIG based filter (pore size: ∼0.3 μm) demonstrated exceptional air filtration properties, while its joule heating effects successfully sterilized and removed unwanted biological components in air despite persisting challenges such as pressure drop, energy consumption, and lack of mechanical robustness. Here, we developed a polyimide (PI) non-woven supported LIG air filter with negligible pressure drop changes compared to the non-woven support material and showed that low electrical current density inactivates aerosolized bacteria. A current density of 4.5 mA/cm2 did not cause significant joule heating, and 97.2% bacterial removal was obtained. The low-voltage antibacterial mechanism was elucidated using bacterial inhibition experiments on a titanium surface and on an LIG surface fabricated on dense PI films. Complete sterilization was obtained using current densities of ∼8 mA/cm2 applied for 2 min or ∼ 6 mA/cm2 for 10 min upon the dense PI-LIG surface. Lastly, >98% bacterial removal was observed using a low-resistance LIG-coated non-woven polyimide air filter at 5 V. However, only very low voltages (∼0.3 V) were needed to remove ∼99% Pseudomonas aeruginosa bacteria and 100% of T4 virus when the LIG-coated filters were hybridized with a stainless steel mesh. Our results show that low current density levels at very low voltages are sufficient for substantial bacterial and viral inactivation, and that these principles might be effectively used in a wide number of air filtration applications such as air conditioners or other ventilation systems, which might limit the spread of infectious particles in hospitals, homes, workplaces, and the transportation industry.

Production of a microfiltration membrane from acrylic fiber (AF) and low-density polyethylene (LDPE) shrink film wastes

The main purpose of this study is the production of a nanofiber membrane from industrial wastes by using the electrospinning technique and determination of its filtration performance. Industrial wastes such as low-density polyethylene shrink film packaging (LDPEWs) and acrylic fiber (AFWs) were used as raw materials to reduce the cost of membrane production as an alternative to expensive commercial membranes. Experiments were carried out to find suitable solvents in order to solve the LDPEWs and AFWs before the electrospinning process, and optimum mixing ratios were determined. After determining the optimum solvent mixture of LDPEWs-AFWs and their proportions, nanofibers were produced by electrospinning process on the surface polypropylene (PP) nonwoven support layer, and their structures were examined. Under optimum conditions, a hydrophilic electrospun membrane with 0.478 µm pore size (MF-microfiltration), 230 nm nanofiber diameter and 20° liquid-membrane contact angle were obtained under optimum conditions, and a membrane module was created to use in wastewater filtration experiments. In order to determine filtration performance of the produced membrane, permeability and wastewater filtration tests were carried out by using real wastewater, and high pollutant removal rates (> 95%) were obtained in our experiments.

Homogeneous Composite Nonwoven Support for High Temperature‐Resistant Separation Membranes

AbstractHigh temperature‐resistant separation membranes are widely considered in various fields. However, incompetent support layer limits the performance of high temperature‐resistant membranes severely. In this work, a homogeneous composite nonwoven support (HCNS) is developed by wet‐laid and hot‐pressing technology using undrawn polyethylene terephthalate fibers as bonding fibers. The significance of hot‐pressing parameters on the performances of the HCNS is investigated, and quadratic regression models are established. The HCNS exhibits a smooth surface (roughness of 118 nm) and a porous structure (porosity of 21.06% and pore size of 6.548 µm) with a mechanical property (tensile index of 45.80 N m g−1). The ultrafiltration membranes supported by the HCNS are prepared from poly(phthalazine ether sulfone ketone), which demonstrates high permeance, high rejection rate, and long‐term stability at raised operation temperature, thereby suggesting the potential application of HCNS in high‐temperature filtration.

Development of Abrasives from Non-woven Based on Used Textiles

ABSTRACT In this paper, the development of a new composite as an abrasive material was reported. The composite was constituted of iron shavings as grains, a prepared non-woven from cellulosic fibers waste as support and a polyurethane resin as matrix. The studied composite was investigated using FT-IR spectroscopy and SEM analyses. FT-IR data confirmed that the non-woven composite was composed of cellulosic fibers and iron. SEM photos indicated that the resin was distributed on the surface of the composite and the iron grains were strongly fixed. The properties of the prepared composites were evaluated and compared with some commercial abrasives. The effect of some chemical modifications on the non-woven characteristics and on the lifetime of the prepared abrasives was studied. The concentration of the resin on the lifetime of abrasives was also discussed. The results showed that the composites made with polyurethane resin had longer life compared to some commercial abrasives. Chemically modified non-woven supports exhibited better results compared to untreated non-woven supports.

Fabrication and Characterization of PVDF/UiO-66(Zr) Mixed Matrix Membrane on Non-Woven PET Support

Polyvinylidene fluoride (PVDF) membranes, enhanced with metal-organic framework (MOF), were fabricated on a non-woven polyethylene terephthalate (PET) support using the non-solvent induced phase inversion (NIPS) method to produce mixed matrix membrane (MMM). Polymer concentration of 10%, 15%, and 20% were used in the study whereas UiO-66(Zr) was used as a MOF filler. The resulting membranes were characterized in terms of their morphology, porosity, wettability, mechanical strength, pure water flux, and gas permeability. Results show that the presence of UiO-66(Zr) filler improved membrane morphology, mechanical strength, and hydrophobicity of MMM as compared to pristine PVDF.

Grafting Thin Layered Graphene Oxide onto the Surface of Nonwoven/PVDF-PAA Composite Membrane for Efficient Dye and Macromolecule Separations.

This study investigates the permeance and rejection efficiencies of different dyes (Rhodamine B and methyl orange), folic acid and a protein (bovine serum albumin) using graphene oxide composite membrane. The ultrathin separation layer of graphene oxide (thickness of 380 nm) was successfully deposited onto porous polyvinylidene fluoride-polyacrylic acid intermediate layer on nonwoven support layer using vacuum filtration. The graphene oxide addition in the composite membrane caused an increased hydrophilicity and negative surface charge than those of the membrane without graphene oxide. In the filtration process using a graphene oxide composite membrane, the permeance values of pure water, dyes, folic acid and bovine serum albumin molecules were more severely decreased (by two orders of magnitude) than those of the nonwoven/polyvinylidene fluoride-polyacrylic acid composite membrane. However, the rejection efficiency of the graphene oxide composite was significantly improved in cationic Rhodamine B (from 9% to 80.3%) and anionic methyl orange (from 28.3% to 86.6%) feed solutions. The folic acid and bovine serum albumin were nearly completely rejected from solutions using either nonwoven/polyvinylidene fluoride-polyacrylic acid or nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane, but the latter possessed anti-fouling property against the protein molecules. The separation mechanism in nonwoven/polyvinylidene fluoride-polyacrylic acid membrane includes the Donnan exclusion effect (for smaller-than-pore-size solutes) and sieving mechanism (for larger solutes). The sieving mechanism governs the filtration behavior in the nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane.

High permeation and antifouling polysulfone ultrafiltration membranes with in situ synthesized silica nanoparticles

Highly hydrophilic and fouling-resistant polysulfone (PSF)-silica based nanocomposite ultrafiltration membranes were prepared using a one-pot method by combining phase inversion and nanoparticle formation in one step. The membrane forming solution prepared by mixing different amounts of tetraethyl orthosilicate (TEOS) with PSF solution in N-methyl-2-pyrrolidone (NMP) was cast on non-woven support and immersed into an aqueous acidic bath for phase inversion and silica nanoparticle formation. The membrane morphologies, nanoparticles distribution, hydrophilicity, and charge nature were investigated using scanning electron microscopy, atomic force microscopy, transmission electron microscopy, and contact angle as well as zeta potential measurements. The water flux, protein adsorption, and rejection were assessed, showing its applicability in filtration and separation technologies. The silica nanoparticle-containing membranes exhibited superior water permeation, rejection, and antifouling performance as compared to the neat PSF membrane. An almost 5-fold decrease in protein adsorption and a 3-fold increase in pure water flux were recorded for the nanocomposite membrane prepared with 20 wt.% TEOS. The results reveal that the membrane properties depend on the concentration of silica nanoparticles, making it possible to achieve a good trade-off between permeation and rejection.

Preparation of solvent resistant supports through formation of a semi-interpenetrating polysulfone/polyacrylate network using UV cross-linking - Part 2: Optimization of synthesis parameters for UV-LED curing

Concerns of energy shortage and pollution, have rapidly increased the demand for efficient separation processes. In this respect, solvent resistant nanofiltration has become an emerging technology with great potential as an energy-efficient and waste-free separation method. Unfortunately, the lack of sufficient stability (especially chemical stability of the support) still restricts the utilization of this separation technique to the more mild industries, leaving several unexploited. As already detailed in part I of this research, one promising approach to increase the chemical stability of supports, used afterwards as starting point for the synthesis of thin film composite nanofiltration membranes, is cross-linking polymeric UF membranes by UV-irradiation. Whereas in the previous part, the 365 nm UV-LED light was selected as the best setup to achieve a high cross-linking efficiency at high throughputs, in this second part the impact of (non-)compositional parameters on the cross-linking efficiency was investigated. The most important parameters with the largest impact on the degree of conversion (DC) were shown to be the cross-linker content, the membrane thickness and the incorporation of a non-woven support. Finally and more importantly, after curing the membranes did not only show enhanced solvent stabilities (viz. part I), they also exhibited greater physical strength while at the same time maintaining the retention at a similar level as the non-cured membrane clearly indicating their industrial importance.

Hot-Pressed Wet-Laid Polyethylene Terephthalate Nonwoven as Support for Separation Membranes.

In this work, a polyethylene terephthalate (PET) nonwoven support was prepared by wet-laid and hot-press technology and used as support for separation membranes. The properties of the PET nonwoven support were studied to determine the effect of hot-pressing parameters and PET fiber ratio, and were optimized by response surface methodology. Result showed that the PET nonwoven support with 62% low melting point PET (LPET-180) fibers obtained satisfactory properties and structure after hot pressing at 220 °C under the pressure of 9 MPa for 20 s. The response surface analysis indicated that the temperature and time of hot pressing and the fiber ratio were the most important factors affecting the strength and air permeability of the PET nonwoven support. After hot pressing, the PET nonwoven support exhibited interconnected structure, small pore size, low porosity, and high strength. Then phase inversion technique was applied to prepare a polysulfone (PSF) layer on the PET nonwoven support and an ultra-thin polyamide (PA) active layer was prepared by interfacial polymerization on the PSF layer. The practicality of PET nonwoven support was verified by testing the pure water flux and retention of the PA composite membrane and the structural change of the PA composite membrane before and after use. The results proved the feasibility and remarkable application prospects of hot-pressed wet-laid PET nonwoven support as support for separation membranes.

Removal of nuclides and boric acid from simulated radioactive wastewater by forward osmosis

In this paper, the removal of nuclides and boric acid from the simulated borate-containing radioactive wastewater was studied using forward osmosis (FO) process. The effect of membrane materials and their orientation, as well as borate concentration on the flux and retentions of nuclides and boric acid was determined. The results indicated that cellulose triacetate with embedded polyester screen support (CTA-ES) membrane had highest Co2+ retention (99.62–99.69%) and Sr2+ retention (96.90–97.85%) when boric acid concentration increased from 0 to 2400 mg L−1 and the active layer facing feed solution (AL-FS) mode was used. Cellulose triacetate with a cast nonwoven support (CTA-NW) and CTA-ES membranes had equivalently high Cs+ retention (∼95%). Thin-film composite with embedded polyester screen support (TFC-ES) membrane had lowest Cs+ retention (below 40%). For both CTA membranes at AL-FS mode, the nuclide retentions did not change obviously with borate concentration. However, the nuclide retention for TFC-ES membrane was affected by borate concentration. Borate retention was lower than 37% for three membranes. For both CTA membranes, borate concentration had no obvious influence on the trans-membrane osmotic pressure, water flux and reverse NaCl flux. CTA-ES membrane has potential for the treatment of borate-containing radioactive wastewater due to its highest nuclide retention, boric acid flux and water flux.