Cellulose Hollow Fiber Research Articles

Performance features of virus removal filters with novel regenerated cellulose hollow fiber membranes

Performance features of virus removal filters with novel regenerated cellulose hollow fiber membranes

Time-dependent mechanical behavior analysis using Weibull models of cellulose hollow fiber membranes produced by green solvent

The mechanical behavior of sustainable (“green”), bio-based cellulose hollow fiber membranes (hereafter, hollow fiber) produced using green solvent, which is potential for desalination and solvent-resistant nanofiltration, can be evaluated either in dry or water-conditioned (wet) states. However, the effect of conditioning time on the mechanical behavior of hollow fibers has not been conclusive. In this work, an extensive evaluation involving an experimental campaign and rigorous application of statistical models for cellulose hollow fibers produced using green solvent (1-ethyl-3-methylimidazolium diethyl phosphate or [EMIM][DEP]) via a dry-jet spinning technique is reported. First, we evaluated the microstructures and separation performance (water permeation, solute rejection) of hollow fibers made of different cellulose concentrations (10–15 wt%) in both pristine and conditioned states. Then, the strength, stiffness, and ductility of hollow fiber samples of different gauge lengths (25 and 50 mm) were measured by a standard tensile test device. Here, the effect of conditioning time on mechanical properties was evaluated after the hollow fiber samples were water-immersed at different times (from 30 s to 2 months). The strength distribution of conditioned hollow fibers was modeled and analyzed using two-parameter and three-parameter Weibull models. Our results showed that the cellulose content of 15 wt% in the hollow fibers produced a denser microstructure, providing the lowest molecular weight cut-off (MWCO). The cellulose content and gauge length slightly modified the mechanical properties of hollow fibers when they were evaluated in pristine, dry conditions. The mechanical properties of hollow fibers were drastically reduced after 10 min of water immersion, beyond which their properties were stabilized. Weibull modeling of mechanical reliability showed that two- or three-parameter Weibull could estimate the failure probability of hollow fibers quite well. Nonetheless, the three-parameter Weibull is better than the two-parameter one in terms of accuracy in determining the threshold strength located at the “lower-end tail.” Our analysis provides a rigorous demonstration of Weibull modeling in evaluating the time-dependent mechanical behavior of ductile, cellulose-based hollow fiber membranes, which is essential to support the design and development of future hollow fiber membranes in desalination industries.

Neuroprotective activity of a virus-safe nanofiltered human platelet lysate depleted of extracellular vesicles in Parkinson's disease and traumatic brain injury models.

Brain administration of human platelet lysates (HPL) is a potential emerging biotherapy of neurodegenerative and traumatic diseases of the central nervous system. HPLs being prepared from pooled platelet concentrates, thereby increasing viral risks, manufacturing processes should incorporate robust virus-reduction treatments. We evaluated a 19 ± 2-nm virus removal nanofiltration process using hydrophilic regenerated cellulose hollow fibers on the properties of a neuroprotective heat-treated HPL (HPPL). Spiking experiments demonstrated >5.30 log removal of 20-22-nm non-enveloped minute virus of mice-mock particles using an immuno-quantitative polymerase chain reaction assay. The nanofiltered HPPL (NHPPL) contained a range of neurotrophic factors like HPPL. There was >2 log removal of extracellular vesicles (EVs), associated with decreased expression of pro-thrombogenic phosphatidylserine and procoagulant activity. LC-MS/MS proteomics showed that ca. 80% of HPPL proteins, including neurotrophins, cytokines, and antioxidants, were still found in NHPPL, whereas proteins associated with some infections and cancer-associated pathways, pro-coagulation and EVs, were removed. NHPPL maintained intact neuroprotective activity in Lund human mesencephalic dopaminergic neuron model of Parkinson's disease (PD), stimulated the differentiation of SH-SY5Y neuronal cells and showed preserved anti-inflammatory function upon intranasal administration in a mouse model of traumatic brain injury (TBI). Therefore, nanofiltration of HPL is feasible, lowers the viral, prothrombotic and procoagulant risks, and preserves the neuroprotective and anti-inflammatory properties in neuronal pre-clinical models of PD and TBI.

Carbon molecular sieve membranes for hydrogen purification from a steam methane reforming process

Asymmetric carbon molecular sieve (CMS) membranes prepared from cellulose hollow fiber precursors were investigated for H2/CO2 separation in this work. The prepared carbon membrane shows excellent separation performance with H2 permeance of 111 GPU and an H2/CO2 selectivity of 36.9 at 10 bar and 110 °C dry mixed gas. This membrane demonstrates high stability under a humidified gas condition at 90 °C and the pressure of up to 14 bar. A two-stage carbon membrane system was evaluated to be techno-economically feasible to produce high-purity H2 (>99.5 vol%) by HYSYS simulation, and the minimum specific H2 purification cost of 0.012 $/Nm3 H2 produced was achieved under the optimal operating condition. Sensitivity analysis on the H2 loss and H2 purity indicates that such membrane is still less cost-effective to achieve ultrapure hydrogen (e.g., >99.8 vol%) unless the higher operating temperatures for carbon membrane systems are applied.

Optimization of triacetate cellulose hollow fiber vitrification (HFV) method for cryopreservation of in vitro matured bovine oocytes

The aim of the current work was to evaluate applicability of triacetate cellulose hollow fiber vitrification (HFV) method for cryopreservation of groups of in vitro matured bovine oocytes (12–17 oocytes per device). We also attempted to optimize HFV protocol by altering concentration of non-permeating cryoprotectant (sucrose) in vitrification solution and concentration of extracellular Ca2+ by using a calcium-free base medium for preparation of vitrification/rewarming solutions with ethylene glycol (EG) as a single permeating cryoprotectant. Neither of modifications of HFV protocol significantly affected survival or fertilization rates of the vitrified bovine oocytes. Embryo development rates in the vitrification groups were lower than those in the control (31.2% of blastocysts at Day 8 post IVF). Use of vitrification/rewarming solutions with lower Ca2+ concentration and EG did not significantly improve embryo development rates. An increase of sucrose concentration in vitrification solution from 0.5 to 1.0 M significantly improved blastocyst yield on Day 8 post IVF (21.1–23.4% vs 3.1–3.5%; p < 0.05). Obtained results indicated that sufficient dehydration of the oocytes and/or the solution surrounding them in hollow fiber before immersion into liquid nitrogen is an important factor for successful vitrification. Use of HFV method allowed simplification and standardization of vitrification/rewarming procedures. Triacetate cellulose hollow fibers can be used successfully for cryopeservation of groups of in vitro matured bovine oocytes.

Preparation of carbon molecular sieve membranes with remarkable CO2/CH4 selectivity for high-pressure natural gas sweetening

Carbon hollow fiber membranes (CHFMs) were fabricated based on cellulose hollow fiber precursors spun from a cellulose/ionic liquid system. By a thermal treatment on the precursors using a preheating process before carbonization, the micropores of the prepared CHFMs were tightened and thus resulting in highly selective carbon molecular sieve (CMS) membranes. By increasing the drying temperature from RT to 140 °C, the cellulose hollow fiber precursors show a substantial shrinkage, which results in a reduction of average pore size of the derived CHFMs from 6 to 4.9 Å. Although the narrowed micropore size causes the decrease of gas diffusion coefficient, stronger resistance to the larger gas molecules, such as CH4, eventually results in an ultra-high CO2/CH4 ideal selectivity of 917 tested at 2 bar for CHFM-140C due to the simultaneously enhanced diffusion and sorption selectivity. The CHFM-140C was further tested with a 10 mol%CO2/90 mol%CH4 mixed gas at 60 °C and feed pressure ranging from 10 to 50 bar. The obtained remarkable CO2/CH4 separation factor of 131 at 50 bar and good stability make these carbon membranes great potential candidates for CO2 removal from high-pressure natural gas.

Optimization of triacetate cellulose hollow fiber vitrification protocol for cryopreservation of bovine oocytes

Optimization of triacetate cellulose hollow fiber vitrification protocol for cryopreservation of bovine oocytes

Asahi Kasei Medical builds new spinning plant for Planova filters

Asahi Kasei Medical has completed a new plant in Nobeoka, Miyazaki, Japan for the spinning of cellulose hollow-fiber membranes for Planova™ virus removal filters.

Cellulose hollow fibers for organic resistant nanofiltration

Cellulose is the most abundant biopolymer, but it is difficult to process due to its low solubility in most of the solvents. In this work, we demonstrate the preparation, of self-standing and defect-free cellulose hollow fiber membranes made by a sustainable process for filtration in organic solvent medium. The hollow fibers were made by the simple spinning technique using ionic liquids as a solvent. The spun solutions were prepared with three different ionic liquids, having imidazolium-based cations and acetate or phosphates as anions. We used X-ray diffraction to evaluate the influence of the different ionic liquids on the crystallinity of the cellulose and the membrane solvent stability. We used cryo-scanning electron microscopy to investigate the porous structure of the hydrated membranes, distinguishing it from that of the dry membranes. The hollow fiber membrane performance was studied using dyes in water and ethanol solutions. The rejection of Congo Red (696 g mol−1) was higher than 90% in ethanol and even closer to 100% in water. The best results were obtained by using 1-ethyl-3-methyimidazolium diethyl phosphate and 1,3-dimethylimidazolium dimethyl phosphate. Our results indicate that by using greener process is possible to obtain solvent resistant cellulose hollow fibers.

Pilot⁻Scale Production of Carbon Hollow Fiber Membranes from Regenerated Cellulose Precursor-Part I: Optimal Conditions for Precursor Preparation.

Industrial scale production of carbon membrane is very challenging due to expensive precursor materials and a multi-step process with several variables to deal with. The optimization of these variables is essential to gain a competent carbon membrane (CM) with high performance and good mechanical properties. In this paper, a pilot scale system is reported that was developed to produce CM from regenerated cellulose precursor with the annual production capacity 700 m2 of CM. The process was optimized to achieve maximum yield (>95%) of high quality precursor fibers and carbonized fibers. A dope solution of cellulose acetate (CA)/Polyvinylpyrrolidone (PVP)/N-methyl-2-pyrrolidone (NMP) and bore fluid of NMP/H2O were used in 460 spinning-sessions of the fibers using a well-known dry/wet spinning process. Optimized deacetylation of spun-CA hollow fibers (CAHF) was achieved by using 90 vol% 0.075 M NaOH aqueous solution diluted with 10 vol% isopropanol for 2.5 h at ambient temperature. Cellulose hollow fibers (CHF) dried at room temperature and under RH (80% → ambient) overnight gave maximum yield for both dried CHF, as well as carbon fibers. The gas permeation properties of carbon fibers were also high (CO2 permeability: 50–450 Barrer (1 Barrer = 2.736 × 10−9 m3 (STP) m/m2 bar h), and CO2/CH4 selectivity acceptable (50–500).

Spinning Cellulose Hollow Fibers Using 1-Ethyl-3-methylimidazolium Acetate⁻Dimethylsulfoxide Co-Solvent.

The mixture of the ionic liquid 1-ethyl-3-methylimidazolium acetate (EmimAc) and dimethylsulfoxide (DMSO) was employed to dissolve microcrystalline cellulose (MCC). A 10 wt % cellulose dope solution was prepared for spinning cellulose hollow fibers (CHFs) under a mild temperature of 50 °C by a dry–wet spinning method. The defect-free CHFs were obtained with an average diameter and thickness of 270 and 38 µm, respectively. Both the XRD and FTIR characterization confirmed that a crystalline structure transition from cellulose I (MCC) to cellulose II (regenerated CHFs) occurred during the cellulose dissolution in ionic liquids and spinning processes. The thermogravimetric analysis (TGA) indicated that regenerated CHFs presented a similar pyrolysis behavior with deacetylated cellulose acetate during pyrolysis process. This study provided a suitable way to directly fabricate hollow fiber carbon membranes using cellulose hollow fiber precursors spun from cellulose/(EmimAc + DMSO)/H2O ternary system.

Cellulose-based virus-retentive filters: a review.

Viral filtration is a critical step in the purification of biologics and in the monitoring of microbiological water quality. Viral filters are also essential protection elements against airborne viral particles. The present review first focuses on cellulose-based filter media currently used for size-exclusion and/or adsorptive filtration of viruses from biopharmaceutical and environmental water samples. Data from spiking studies quantifying the viral filtration performance of cellulosic filters are detailed, i.e., first, the virus reduction capacity of regenerated cellulose hollow fiber filters in the manufacturing process of blood products and, second, the efficiency of virus recovery/concentration from water samples by the viradel (virus adsorption–elution) method using charge modified, electropositive cellulosic filters or conventional electronegative cellulose ester microfilters. Viral analysis of field water samples by the viradel technique is also surveyed. This review then describes cellulose-based filter media used in individual protection equipment against airborne viral pathogens, presenting innovative filtration media with virucidal properties. Some pros and cons of cellulosic viral filters and perspectives for cellulose-based materials in viral filtration are underlined in the review.

Optimization of Deacetylation Process for Regenerated Cellulose Hollow Fiber Membranes

Cellulose acetate (CA) hollow fibers were spun from a CA+ Polyvinylpyrrolidone (PVP)/N-methyl-2-pyrrolidone (NMP)/H2O dope solution and regenerated by deacetylation. The complete deacetylation time of 0.5 h was found at a high concentration (0.2 M) NaOH ethanol (96%) solution. The reaction rate of deacetylation with 0.5 M NaOH was faster in a 50% ethanol compared to a 96 vol.% ethanol. The hydrogen bond between CA and tertiary amide group of PVP was confirmed. The deacetylation parameters of NaOH concentration, reaction time, swelling time, and solution were investigated by orthogonal experimental design (OED) method. The degree of cross-linking, the residual acetyl content, and the PVP content in the deacetylated membranes were determined by FTIR analysis. The conjoint analysis in the Statistical Product and Service Solutions (SPSS) software was used to analyze the OED results, and the importance of the deacetylation parameters was sorted as Solution &gt; Swelling time &gt; Reaction time &gt; Concentration. The optimal deacetylation condition of 96 vol.% ethanol solution, swelling time 24 h, the concentration of NaOH (0.075 M), and the reaction time (2 h) were identified. The regenerated cellulose hollow fibers under the optimal deacetylation condition can be further used as precursors for preparation of hollow fiber carbon membranes.

Preparation of dual‐layer acetylated methyl cellulose hollow fiber membranes via co‐extrusion using thermally induced phase separation and non‐solvent induced phase separation methods

ABSTRACTDual‐layer acetylated methyl cellulose (AMC) hollow fiber membranes were prepared by coupling the thermally induced phase separation (TIPS) and non‐solvent induced phase separation (NIPS) methods through a co‐extrusion process. The TIPS layer was optimized by investigating the effects of coagulant composition on morphology and tensile strength. The solvent in the aqueous coagulation bath caused both delayed liquid–liquid demixing and decreased polymer concentration at the membrane surface, leading to porous structure. The addition of an additive (triethylene glycol, (TEG)) to the NIPS solution resolved the adhesion instability problem of the TIPS and NIPS layers, which occurred due to the different phase separation rates. The dual‐layer AMC membrane showed good mechanical strength and performance. Comparison of the fouling resistance of the AMC membranes with dual‐layer polyvinylidene fluoride (PVDF) hollow fiber membranes fabricated with the same method revealed less fouling of the AMC than the PVDF hollow fiber membrane. This study demonstrated that a dual‐layer AMC membrane with good mechanical strength, performance, and fouling resistance can be successfully fabricated by a one‐step process of TIPS and NIPS. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42715.

Preparation of Cellulose Hollow Fiber Membrane from Bamboo Pulp/1-Butyl-3-Methylimidazolium Chloride/Dimethylsulfoxide System

In this paper, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was synthesized and used as solvent to dissolve bamboo pulp. Dimethylsulfoxide (DMSO) was selected as cosolvent to adjust the solution viscosity. As compared with the bamboo pulp/[Bmim]Cl system, the addition of DMSO decreases the solution viscosity dramatically. Afterward, cellulose hollow fiber membranes were prepared by dry-wet spinning process using 75 wt % [Bmim]Cl + 25 wt % DMSO as solvent. Scanning electron microscope (SEM), mechanical testing, pure water permeability, and retention rate were used to characterize its properties, respectively. The SEM result shows that the prepared cellulose hollow fiber membrane presents dense surface structure, which leads to a relative high tensile strength and retention rate to bovine serum albumin, i.e. 28 MPa and 98%, respectively, but a relative low pure water permeability, i.e. 83 L/m2·h. In the end, the [Bmim]Cl is recovered by azeotropy, and the recycling yield reaches 99 wt %.

Determination of Alachlor and Its Metabolite 2,6-Diethylaniline in Microbial Culture Medium Using Online Microdialysis Enriched-Sampling Coupled to High-Performance Liquid Chromatography

In this study, a simple and novel microdialysis sampling technique incorporating hollow fiber liquid phase microextraction (HF-LPME) coupled online to high-performance liquid chromatography (HPLC) for the one-step sample pretreatment and direct determination of alachlor (2-chloro-2',6'-diethyl-N -(methoxymethyl)acetanilide) and its metabolite 2,6-diethylaniline (2,6-DEA) in microbial culture medium has been developed. A reversed-phase C-18 column was utilized to separate alachlor and 2,6-DEA from other species using an acetonitrile/water mixture (1:1) containing 0.1 M phosphate buffer solution at pH 7.0 as the mobile phase. Detection was carried out with a UV detector operated at 210 nm. Parameters that influenced the enrichment efficiency of online HF-LPME sampling, including the length of the hollow fiber, the perfusion solvent and its flow rate, the pH, and the salt added in sample solution, as well as chromatographic conditions were thoroughly optimized. Under optimal conditions, excellent enrichment efficiency was achieved by the microdialysis of a sample solution (pH 7.0) using hexane as perfusate at the flow rate of 4 μL/min. Detection limits were 72 and 14 ng/mL for alachlor and 2,6-DEA, respectively. The enrichment factors were 403 and 386 (RSD < 5%) for alachlor and 2,6-DEA, respectively, when extraction was performed by using a 40 cm regenerated cellulose hollow fiber and hexane as perfusion solvent at the flow rate of 0.1 μL/min. The proposed method provides a sensitive, flexible, fast, and eco-friendly procedure to enrich and determine alachlor and its metabolite (2,6-DEA) in microbial culture medium.

EFFECT OF COAGULATION BATH TEMPERATURE ON STRUCTURE AND GAS SEPARATION PROPERTIES OF CELLULOSE HOLLOW FIBER MEMBRANES

Cellulose hollow fiber membranes (CHFMs) were prepared by a new dissolving method. The influence of coagulation bath temperature on the morphology and properties such as crystallinity degree, mechanical strength and gas permeation performance of CHFM was systematically investigated. The results showed that with the increase of coagulation bath temperature, the morphology of asymmetric cellulose hollow fiber membranes would become much looser, and more large finger-like pores could be found across the section. At the same time, crystallinity degree almost showed no change and mechanical strength became worse obviously. As a result gas permeation performance of dry CHFMs would increase dramatically with the coagulation bath temperature and show obvious "Knudson-diffusion selective" mechanism. While for wet CHFMs, permeation rates for all gases would decrease sharply and interestingly for CHFMs from coagulation bath temperature of 0 degrees C and 20 degrees C carbon dioxide became the fastest gas because of the permeation mechanism had changed to "solution selective" in wet CHFMs. While for CHFMs from coagulation bath temperature of 40 degrees C and 60 degrees C, this "solution selective" effect cannot be found because of their much looser structure.

Influence of Dope Concentration on Morphology And Properties of Cellulose Hollow Fiber Membranes Prepared from Cellulose/[Amim]Cl Dope Solution

Basing on a L-S phase inversion method, cellulose hollow fiber membranes were spinned using room temperature ionic liquid 1-allyl-3-methylimidazolium chloride ([Amim]Cl) as solvent. The concentration of cellulose/[Amim]Cl solutions (dope) was varied from 6 to 9wt% by an increment of 1wt%. Effects of the dope concentration on the hollow fiber membranes structure and properties were investigated. Inner- and outer- surfaces morphology of the prepared membranes were observed using field emission scanning electron microscope (FESEM). Besides, various properties of the membranes, including apparent viscosity, pure water flux (PWF), retention rate (Rt), equilibrium water content (EWC), ultimate tensile strength (UTS) and elongation at break (Eb) were also tested. The results induced that, with the increase of dope concentration, the both surfaces showed more regular. Pure water flux and equilibrium water content of the membranes decreased with a increasing dope concentration, properties of retention rate, ultimate tensile strength and elongation at break showed a increased tendency oppositely.

Preparation of dual-layer cellulose/polysulfone hollow fiber membrane and its performance for isopropanol dehydration and CO 2 separation

Dual-layer cellulose/polysulfone (PSf) hollow fiber membrane used for isopropanol (IPA) dehydration and CO 2 separation was prepared by using co-extrusion technique with a triple-orifice spinneret. N-methylmorpholine-N-oxide monohydrate (NMMO·H 2O) was selected as the cellulose solvent since it can dissolve cellulose through a purely physical process. Scanning electron microscopy (SEM) images show that there is no obvious delamination between the inner and outer layer and no obvious defect can be seen in the outer skin of the fiber. In order to find out the advantage of novel prepared dual-layer membrane over homogeneous cellulose membrane, tests including isopropanol dehydration by pervaporation and CO 2 separation were carried out. For pervaporation experiments, the effects of operation conditions including feed concentration and operation temperature on pervaporation (PV) performance were investigated systemically. The results showed that similar with the flat cellulose membrane, the permeation flux increased obviously with the increase of both water concentration in feed and operation temperature. Under all tested conditions, water contents in permeate maintained higher than 99.90 wt.%, and it reached a maximum value of 99.98 wt.% with a water content of 5 wt.% in feed at 25 °C. Moreover, the water-swollen dual-layer cellulose/PSf hollow fiber membrane showed much higher gas permeation rate and comparable selectivities of CO 2/H 2, CO 2/N 2 and CO 2/CH 4. The CO 2 permeance of dual layer cellulose/PSf hollow fiber membrane was ∼3 GPU, which was five times higher than that of single-layer cellulose hollow fiber membrane. In a word, the performance, especially the permeation rate of new developed dual layer cellulose/PSf hollow fiber membrane was greatly improved by its reduced separation layer, and this could definitely increase its potential for later practical application.

On‐line microdialysis coupled solid‐phase extraction to decrease matrix interference in the HPLC analysis of urinary ketamine and its metabolites

A microdialysis sampling (MDS) on-line SPE (MDS/SPE) has been applied to redeem the detection after dilution to decrease matrix interference in the analysis of ketamine (K) and its two main metabolites, norketamine (NK) and dehydronorketamine (DHNK) in urine by HPLC. After being filtrated, diluted and adjusting the pH, K and its metabolites in the diluted sample solution were collected through MDS and then trapped on an on-line SPE for HPLC analysis. The optimal conditions for MDS/SPE were investigated and then applied to real sample analysis. Experimental results indicated that the MDS/SPE by using regenerated cellulose hollow fiber (8-cm length) and 1 mM sulfuric acid as the perfusate at 20 microL/min flow-rate to collect analytes from 100-fold diluted urine sample (20 mL at pH 6.0), and then having been trapped in octadecyl-modified silica phase SPE for 30 min, offered the optimum efficiency. The concentration levels of 41, 42 and 28% (m/m) for K, NK and DHNK, respectively, in urine were redeemed for determination. The detection limits were 0.38, 0.33 and 0.34 ng/mL (in 100-fold diluted sample) for K, NK and DHNK, respectively. The method provides a very simple, inexpensive and eco-friendly procedure to determine K, NK and DHNK in urine.