Polyurethane Sponge Research Articles

Enhanced nitrate, fluoride, and phenol removal using polyurethane sponges loaded with rice husk biochar in immobilized bioreactor

Polyurethane sponges loaded with rice husk biochar were prepared to immobilize Aquabacterium sp. CZ3 for intensified removal of nitrate, fluoride (F−), and phenol, with the maximum efficiency of 100 %, 91 %, and 99 %, respectively. The biochar load and increased carbon-to-nitrogen (C:N) ratio (below 3.0) stimulated the secretion of soluble microbial product, improved the electron transport system activity, and promoted denitrification, phenol co-metabolism, and F− and calcium crystallization. The characterization results suggested that F− was removed as fluoride-containing calcium precipitates. According to the microbial community analyses, Aquabacterium was the dominant bacterium. PICRUSt analyses showed that biochar and adequate carbon sources (C:N ratio 3.0) significantly increased the functional abundances of amino acid metabolism, carbohydrate metabolism, energy metabolism, and cell motility. The introduction of biochar reduces the demand for C:N ratio in the system, and expands the application potential of biomineralization technique in the remediation of multiple pollutants contaminated water.

A New Insight into the Role of Silicate-Type Binders on the Crushing Strength of Alumina Foams

Semi-closed cell macroporous alumina foams with relative densities ranging from 0.26 to 0.35 have been produced by the well-established replication method based on the coating of a polyurethane (PU) template foam by a ceramic slurry, followed by burnout of the PU template, and sintering of the ceramic skeleton. Collapse of the three-dimensional structure upon the volatilisation of the PU sponge can only be prevented using appropriate binders. Scarce data are available on the slurry formulations of commercial alumina foams. The aim of this study was to investigate the influence of silicate-type binders, namely kaolin and bentonite additives, on the crushing strength of alumina foams. The highest crushing strength of around 10 MPa was observed at a porosity of 66 ± 2%. The open-cell model is inadequate to fit the crushing strength data of such semi-closed cell type structures. Both microscopic and macroscopic flaws resulting from the foam processing method contribute to the wide scatter of the strength, thereby explaining the Weibull modulus ranging from 4 to 7. Both flaw populations require further improvement to maximise the crushing strength of these foams with high potential for the design of structured catalyst carriers and molten aluminium filters.

Influence of negative pressure on changes in blood supply in donor zones of perforant flaps formation

Our study is based on the establishment of normative indicators of the effect of negative pressure on the skin of the thigh. To do this, a group of healthy volunteers was examined – 35 people: 17 women and 18 men aged 19 to 58. The study was conducted on the clinical basis of the burn centre in 2020-2021. The local vacuum was created using a negative pressure device “AGAT-Dnepr” by applying a silver-containing polyurethane sponge directly on the front surface of the thigh. The pressure (P) – 110-160 mmHg has been applied for 30 minutes. Tissue perfusion was monitored by laser Doppler flowmetry and thermal imaging research. Measurements were performed before vacuum, immediately after the end of the application of negative pressure, for three days at the same time at a constant temperature. According to the results of the cluster analysis, based on the effect of negative pressure on the thigh skin, patients with three types of reactions were identified – low, medium and high perfusion changes. The perfusion level of tissue volume per unit time increased the most rapidly: in the group of high perfusion by 45.56 (95% CI 42.09-51.96) PU; in the group of average perfusion – by 22.49 (95% CI 19.93-28.99) PU; in the low perfusion group – by 22.43 (95% CI 15.90-25.13) PU. The number of erythrocytes per unit tissue changed at a medium rate: in the high perfusion group by 57.77 (95% CI 53.05-62.48) AU; in the group of average perfusion – by 55.86 (95% CI 49.62-65.06) PU; in the low perfusion group – by 34.85 (95% CI 13.19-53.55) PU. Among those surveyed, 12 people were included in the low perfusion group (34.29%), 16 people in the medium perfusion group (45.71%) and 7 people in the high perfusion group (20.0%). Before VAC-action the ascending level of thigh skin temperature T1 ranged from 28.60 to 32.90°C and averaged 31.46 (95% CI 30.97-31.95)°C. Immediately, after the offset of the negative pressure the area of the fields of local skin temperature rise increased, the average temperature level ranged from 30.60 to 35.0°C and the average T2 was 33.59 (95% CI 33.16-34.01)°C. The temperature rise occurred on average by 2.13 (95% 1.72-2.54)°C, which corresponded to an increase of 6.77% with significant (p<0.001) statistical differences. Only 1 examined had a slight decrease in the tem­perature of the thigh skin from 31.9 to 31.6°C, in the rest of the examined the rise was by 6.4°С maximally, from 28.6 to 35.0°С, there was a temperature rise by 2°С or more degrees among 9 people (25.71%). After 24 hours there was a rise in local body temperature among all examined (100%), after 48 hours – among 25 (71.43%), and after 72 hours – among 21 examined (60.0%). When choosing a donor site of the perforant flaps, we recommend relying on areas which will belong to the group of indicators with high perfusion. According to the analysis, the group of high perfusion will include patients with an initial average level of perfusion in the donor areas per unit time of 15.84 (14.47-17.21) PU, the number of erythrocytes per unit tissue – 58.73 (53.44-64.02) AU and skin temperature – 29.23 (28.65-29.80)°С; to the average according to F rates – 14.36 (13.0-15.73) PU, C rates – 45.37 (39.74-51.0) AU, T rates – 28.17 (27.74-28.60)°С; to the group of low perfusion, respectively, according to F rates – 12.38 (10.74-14.0) PU, C rates – 43.89 (40.18-47.61) AU, T rates – 29.79 (29.17-30.40)°С. In general, the effect of negative pressure contributes to increased perfusion and local microcirculation in tissues, as evidenced by dynamic infrared thermography: increased “hot” skin fields, increased temperature with a temperature gra­dient ∆T2.1=2.13 (95% 1.72-2.54)°C and for indicators of laser Doppler flowmetry – increase in perfusion by 2.42 times (p<0.001).

A stacked triboelectric nanogenerator coupled with elastomer and non-elastomer for mechanical energy harvesting and hand motion recognition

It is common to improve the adaptability and contact effect by using elastomer materials to fabricate triboelectric nanogenerator (TENG). However, compared with the traditional TENG made of non-elastomer, the existing design still has the disadvantages of low output and cumbersome preparation. This study proposes a TENG based on stacking teflon (PTFE), fluoro rubber (FKM), and polyurethane sponge (PU), the TENG not only combines the advantages of an elastomer and non-elastomer but also integrates the triboelectric characteristics of three materials to achieve higher performance. The stacked PTFE/FKM/PU TENG in single-electrode mode achieves a maximum instantaneous open-circuit voltage of 1250 V and short-circuit current of 108.9 μA, driving more than 1000 LEDs. It can also effectively recognize motion of flapping, wiping, squeezing, scratching, clicking, or poking by specific output feedback. Therefore, the stacked PTFE/FKM/PU TENG is expected to contribute to collection of discrete energy and development of human sensing technology.

Arabic-dome-inspired hierarchical design for stable and high-efficiency solar-driven seawater desalination

Interfacial solar steam generation (ISSG) has shown extraordinary promise in achieving high-efficiency seawater desalination. However, a high evaporation rate cannot be maintained because of the seemingly unavoidable heat losses caused by the excessive water in solar absorber. Herein, inspired by the Arabic dome-architectural style, we report an integrated solar evaporator developed through foaming straw-based photothermal polyurethane sponge (SPPU) in the cavity of natural corn straw (NCS). This hierarchical design traps water at the interface between SPPU and NCS during ISSG, which balances water supply and evaporation and prevents harvested solar energy from heating superfluous unevaporated water. Moreover, SSPU with Arabic-dome-style structure ensures excellent photothermal conversion at different light incident angles. The so-fabricated evaporator displays an outstanding evaporation rate (2.18 kg/m2/h) under 1 sun illumination and the small-scale prototype produces a positive freshwater yield (3.58 kg/m2/day) under natural sunlight. This work provides an ingenious route to construct 3D solar evaporator with good water regulation for seawater purification.

Photothermal activation of peroxydisulfate using iron nanoparticles/MXene@polyurethane sponge module for treatment of landfill leachate: From lab to pilot scale

Treatment of landfill leachate and recovery of recycled water in photothermal activation of peroxydisulfate (PDS) process using iron nanoparticles/MXene-coated polyurethane sponge module (Fe NPs/MXene@PU) were investigated from lab to pilot scale for the first time. In the module preparation process, nanoscale zero-valent iron (NZVI) and iron oxides were in situ generated on Ti3C2 MXene surface. Fe NPs/MXene@PU module reached the 147.7 °C interfacial temperature due to the synergistic effect of MXene and in-situ generated Fe NPs. Sulfate radical (SO4•-) and hydroxyl radical (HO•) were generated in photothermal activation of PDS process. Under optimized reaction conditions, almost complete removal of chemical oxygen demand (COD), nitrate nitrogen (NO3–), ammonia nitrogen (NH3-N) and total phosphorus (TP) of landfill leachate was achieved after about 40 d pilot-scale experiment in the open air. The recycled water collected by natural condensation was also purified, which contained ultralow concentrations of COD, NH3-N, NO3–, TP and heavy metals and met the discharge limits of various countries. This study provides an eco-friendly and energy-efficient technology for treatment of landfill leachate and recovery of recycled water.

Magneto-Tactile Sensor Based on a Commercial Polyurethane Sponge.

In this paper, we present the procedure for fabricating a new magneto-tactile sensor (MTS) based on a low-cost commercial polyurethane sponge, including the experimental test configuration, the experimental process, and a description of the mechanisms that lead to obtaining the MTS and its characteristics. It is shown that by using a polyurethane sponge, microparticles of carbonyl iron, ethanol, and copper foil with electroconductive adhesive, we can obtain a high-performance and low-cost MTS. With the experimental assembly described in this paper, the variation in time of the electrical capacity of the MTS was measured in the presence of a deforming force field, a magnetic field, and a magnetic field superimposed over a deformation field. It is shown that, by using an external magnetic field, the sensitivity of the MTS can be increased. Using the magnetic dipole model and linear elasticity approximation, the qualitative mechanisms leading to the reported results are described in detail.

Cultivation of previously uncultured microorganisms with a continuous-flow down-flow hanging sponge (DHS) bioreactor, using a syntrophic archaeon culture obtained from deep marine sediment as a case study.

In microbiology, cultivation is a central approach for uncovering novel physiology, ecology, and evolution of microorganisms, but conventional methods have left many microorganisms found in nature uncultured. To overcome the limitations of traditional methods and culture indigenous microorganisms, we applied a two-stage approach: enrichment/activation of indigenous organisms by using a continuous-flow down-flow hanging sponge bioreactor and subsequent selective batch cultivation. Here, we provide a protocol for this bioreactor-mediated technique using activation of deep marine sediment microorganisms and downstream isolation of a syntrophic co-culture containing an archaeon closely related to the eukaryote ancestor (Candidatus Promethearchaeum syntrophicum strain MK-D1) as an example. Both stages can easily be tailored to target other environments and organisms by modifying the inoculum, feed solution/gases, attachment material and/or cultivation media. We anaerobically incubate polyurethane sponges inoculated with deep-sea methane seep sediment in a reactor at 10 °C and feed anaerobic artificial seawater medium and methane. Once phylogenetically diverse and metabolically active microorganisms are adapted to synthetic conditions in the reactor, we transition to growing community samples in glass tubes with the above medium, simple substrates and selective compounds (e.g., antibiotics). To accommodate for the slow growth anticipated for target organisms, primary cultures can be incubated for ≥6-12 months and analyzed for community composition even when no cell turbidity is observed. One casamino acid- and antibiotic-amended culture prepared in this way led to the enrichment of uncultured archaea. Through successive transfer in vitro combined with molecular growth monitoring, we successfully obtained the target archaeon with its partner methanogen as a pure syntrophic co-culture.

Aggregation-induced demulsification technology for the separation of highly emulsified oily wastewater produced in the petrochemical industry

To improve the resource utilization of oily wastewater emulsion produced in the petrochemical industry, an aggregation-induced demulsification (AID) technology, consisting of multi-stage packed beds filled with polyurethane sponge in a gradient configuration mode, was developed in this study. Based on the verification on the technical principle of AID, an industrial-scale setup was performed, targeting on removing highly emulsified oil in wastewater. The results showed that when the inlet pressure was 0.2–0.4 MPa and average temperature of raw water was 35 °C, the chemical oxygen demand (COD) in the emulsion was reduced from 3000-12450 mg/L to below 500 mg/L with simultaneous recovery of emulsified oil. When the flow was 600–1300 L/h, the average COD of the final effluent was 329 mg/L with an oil removal efficiency of 93.52%. In addition, the AID technology achieved the environmental protection goal with advantages of zero chemical consumption and simplified treatment process, thus providing a cleaner alternative for oily wastewater treatment.

A Sponge-Type oil skimmer for highly efficient removal of floating Oils: Superabsorbent and oleophilic sponge with Nano-Scale interface roughness

In an industrial environment, the contamination by oil has caused manufacturing processes and environmental problems. In this study, the modified polyurethane (PU@PDA) sponge with superabsorbent properties was produced by adjusting the nano-roughness on the surface of the polyurethane (PU) sponge by a simple polydopamine (PDA) self-polymerization method. Nano scale interface roughness which affected the wettability of the sponge was induced through a facile synthesis reaction in alkaline conditions. SEM images and AFM results were used to confirm whether the PDA was uniformly formed on the PU surface and roughness evaluation, and the oil absorption time of PU@PDA sponge was less than 1 s through the contact angle evaluation method of the oil droplet. An oil skimmer device was manufactured on its own to evaluate the floating oil removal rate and durability of sponges in practically applicable industrial environments, and in terms of efficiency, it was confirmed that the oil removal efficiency was 100 times higher than the rubber-type oil skimmer. In the repeated cycle oil removal efficiency experiment, the oil removal efficiency of 5760 (4 days, 1 rpm) and 11,502 (8 days, 1 rpm) times were maintained at 98 % and 82 %, respectively.

Fluorinated graphene nanosheet supported halloysite nanoarchitectonics: Super-wetting coatings for efficient and recyclable oil sorption

Designing selective oil sorption and recovery systems to tackle oil/organics spills in water bodies by using special-wetting property are gaining huge attention. In the present work, we develop a coating material based on functionalized halloysite nanotubes (HNT) supported over fluorinated graphene (FG) nanosheets displaying super-wetting functions. The HNTC-FG hybrids were methodically analysed by various spectroscopic, microscopic and solvent wetting studies. The water contact angle (145 ± 2°) for HNTC-FG hybrids with a surface free energy of 18.1 mJ/m2 significantly affects the solvent wettability. To carry out oil–water separation, the HNTC-FG dispersion was imbibed on polyurethane (PU) sponge via dip-coating method. The HNTC-FG-PU sponges were probed towards the remediation of oil/organics spill under static, turbulent and continuous modes. The sorption capacity of HNTC-FG-PU sponges for various oils and organics falls in the range of 38–62 g/g with excellent recyclability under static and turbulent conditions besides remarkable corrosive, thermal and mechanical stabilities. Furthermore, the HNTC-FG-PU sponges were effectively used in the selective continuous separation of organic solvents by vacuum pump-assisted process over 10 cycles with flux ranging from 1593 and 4690 L.m−2.h−1 for kerosene and mesitylene respectively. The stable hydrophobicity, chemical stability and remarkable recyclability of these HNTC-FG-PU sponges drive the oil/organics recovery prototypes.

Hydrophobic microporous extraction on polyurethane sponges for convenient and sensitive analysis of organic molecules in water.

Various solvent supports have been developed to overcome solvent instability during liquid-phase microextraction. The hydrophobic polyurethane sponge (PS) possesses numerous cross-linked internal microchannels and terminal micropores that can facilitate steady solvent storage capacity, high extraction efficiency, extractant loading, and recycling convenience. In this study, an easy, convenient, and efficient PS-supported liquid-phase microextraction (PS-LPME) coupled with gas chromatography-mass spectrometry (GC-MS) method was developed for the trace analysis of different organic compounds in aqueous solutions. Different extraction solvents, PS dosages, stirring speeds, and extraction times were first investigated by extracting eight polycyclic aromatic hydrocarbons (PAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene), and then applied for the analysis of triazines, amides, chloroacetamides, and organophosphorus compounds. High enrichment factors (approximately 208-439) were observed for the monitored PAHs. Good linearities, with determination coefficients (r2 ) greater than 0.9992, were achieved in the concentration range of 0.01-50 μg L-1 . Low limits of detection and quantification were found in the ranges of 0.3-3ng L-1 and 1-10ng L-1 , respectively. At three spiked concentrations (0.1, 1, and 10μg L-1 ), good recoveries were obtained in the range of 91.6-118.5% with intra- and inter-day relative standard deviations of less than 6.4% and 11.7%, respectively. The developed PS-LPME method coupled with GC-MS was successfully applied in the analysis of different organic compounds in aqueous solutions and has shown great convenience and satisfactory enrichment performance in microextraction analysis.

Fabrication of g-C3N4@Bi2MoO6@AgI floating sponge for photocatalytic inactivation of Microcystis aeruginosa under visible light

In this work, a floating photocatalyst was constructed by loading g-C3N4@Bi2MoO6@AgI (GBA) nanocomposite on a modified polyurethane sponge via a simple dip-coating method and applied for the inactivation of Microcystis aeruginosa under visible light. GBA ternary photocatalyst was fabricated successfully and the morphology, structure, chemical state, and optical properties were characterized systematically. The floating catalyst achieved near 100% removal efficiency of algae cells under 6 h visible light irradiation and also could be retrieved and used at least three times repeatedly. The influences of various conditions on photocatalytic performance such as loading content of nanoparticles, algae density, and concentration of natural organic matters were also studied, which revealed that the GBA floating catalyst exhibited excellent photocatalytic performance of algae removal under different conditions. Furthermore, the physiological characteristics of algae cells during the photocatalytic process, including cell morphology, membrane permeability, Zeta potential, photosynthetic system, antioxidant system, and the metabolic activity were investigated. Results confirmed that the algae cells were severely damaged during the photocatalytic inactivation and the normal physiological functions were significantly affected, which resulted in the death of algae cells at last. Finally, a possible photocatalytic inactivation mechanism of algae cells was proposed. In summary, GBA floating catalyst can effectively inactivate Microcystis aeruginosa under visible light, which confirmed the high efficiency of the novel photocatalytic algae removal technology. Meanwhile, the recyclable floating material also makes the practical application in eutrophic waters of the algae removal technology possible.

Rational design and preparation of superhydrophobic photo-cured hybrid epoxy coating modified by fluorocarbon substituted silsesquioxane-based nanoparticles

Functional superhydrophobic coating has caused intense concern due to its potential applications. A facile and mild dip-coating method is proposed for fabricating superhydrophobic coatings in this work. The epoxy resin (EP) modified by fluorocarbon substituted silsesquioxanes (SQ-F) could be coated on filter paper (FP) and polyurethane sponge (PU), respectively. SQ-F nanoparticles can self-assemble to form multiscale nano-/microstructures during photopolymerization, which improve the hydrophobicity of epoxy. The successful incorporation of SQ-F/EP on filter paper and polyurethane sponge is demonstrated by FT-IR, X-ray photoelectron spectroscopy and energy dispersive spectrometer. SQ-F/EP@FP could separate a series of oil–water mixtures and emulsion effectively with high separation efficiencies over 99.99 %. Furthermore, both liquid pollutant and solid stains are removed by the surface's self-cleaning ability. In comparation with SQ-F/EP@FP, SQ-F/EP@PU with lipophilic and hydrophobic characteristics, possesses oil adsorption capacity about 102 times of its original weight. Moreover, SQ-F/EP@PU could absorb the crude oil within a few minutes and the adsorption capacity reaches as high as 92 times of its original weight.

Immobilization of hydrolytic/fermentative bacteria to achieve ultra-low fouling in anaerobic membrane bioreactor

Membrane fouling remains the key challenge that limits the application of anaerobic membrane bioreactors (AnMBRs). Free-living bacteria, particularly hydrolytic/fermentative bacteria (HFB) in sludge supernatant, have recently been identified as the predominant foulants in AnMBRs. Here, a pretreatment tank filled with porous polyurethane sponges as carriers for biomass attachment and/or entrapment was developed for influent organic hydrolysis/fermentation, named HFB-immobilization tank. Then, two parallel AnMBRs (i.e., with and without an HFB-immobilization tank) treating synthetic domestic wastewater were operated to determine the roles of HFB capture in fouling mitigation as well as reactor performance. Higher methane yields were observed in the experimental than in the control AnMBR. Interestingly, the HFB-immobilization helped to achieve a non-fouling state of the experimental AnMBR for more than 100 days, while the average fouling cycle of the control AnMBR was 20 days. Dead-end filtration tests corroborated better filterability of sludge supernatant in the experimental than the control AnMBR. The 16S rRNA gene sequencing revealed substantially lower abundances of HFB (e.g., Aminicenantales, SJA-15) but higher abundances of methanogens (e.g., Methanosaeta, Methanolinea, Methanospirillum) in the mixed liquor of the experimental than the control AnMBR, indicating efficient niche separation by the HFB immobilization. Particularly, the sequencing data, together with fluorescent staining, showed that the amounts and abundances of HFB in sludge supernatant were largely lower in the experimental than the control AnMBR. This study provides a promising alternative for fouling control in AnMBRs.

729 Endoluminal Vacuum Therapy in the Management of Boerhaave Syndrome: A Case Series

Abstract Background Boerhaave syndrome is a rare condition associated with poor prognosis: high morbidity and mortality. Prompt intervention greatly improves outcomes, with surgery being the mainstay of management. Recent advances in therapeutic endoscopy have led to increasing interest in endoluminal vacuum therapy (EVT). EVT is a minimally invasive technique, allowing wound debridement and drainage, and granulation tissue formation. EVT has been associated with excellent clinical outcomes, including lower mortality rates when compared to surgery and stenting. EVT has been adopted into practice across Europe, however, only two cases have been reported in the UK. We report three cases of Boerhaave syndrome, successfully managed with EVT, using the EsoSPONGE ® (B.Braun, Medical Ltd, Sheffield, UK). Method EVT involves the placement of a polyurethane sponge into the wound cavity. The cavity is initially assessed endoscopically before an overtube is introduced. The sponge is pushed into the cavity through the overtube, and the overtube is removed. Sponge position is confirmed and adjusted if necessary. The sponge is connected via a trans-nasal drain to continuous negative pressure suction and is changed every 3–5 days. Results Having been deemed surgically unfit, all three patients were referred for EVT, using the EsoSPONGE. All patients made excellent recovery and were discharged home. Conclusions EVT is an effective management strategy for surgically unfit Boerhaave syndrome patients. EsoSPONGE use aided drainage of the septic focus and closure of the defect, leading to complete recovery. Our findings support the existing evidence that EVT is a promising solution for Boerhaave syndrome.

Polyimide-based superhydrophilic porous membrane with enhanced thermal insulation for efficient interfacial solar evaporation

Interfacial solar evaporation (ISE) is a sustainable and efficient strategy to address the freshwater shortage. Herein, we report the fabrication of a novel polyimide-based porous membrane (PI-CB-MHGM) by using synthesized polyamide acid, modified hollow glass microspheres (MHGM), conductive carbon black (CB) and pore-forming agent NaCl particles through spin coating method, followed by hydrophilic modification, and then a bilayer solar evaporator was constructed by using PI-CB-MHGM photothermal membrane as the upper layer and polyurethane (PU) sponge as the bottom layer for ISE. Based on the PI-CB-MHGM photothermal membrane with broadband high light absorption, low thermal conductivity, superhydrophilicity wettability and porous structure, along with the assistance of a porous PU sponge, the as-prepared bilayer solar evaporator exhibits a high evaporation rate of 1.4904 kg m−2 h−1 under 1 sun (1 kW m−2) solar irradiation, as well as excellent evaporation stability and salt resistance. More interestingly, the PI-CB-MHGM membrane possesses self-floating ability, electrical conductivity, superior flexibility, and strong mechanical properties. Furthermore, considering the low cost and simple preparation method, the PI-CB-MHGM based evaporator may hold great potential for a variety of applications, such as, desalination, electricity generation, and wastewater treatment, etc.

Production of the Polysaccharide Pullulan by Aureobasidium pullulans Cell Immobilization

This review examines the immobilization of A. pullulans cells for production of the fungal polysaccharide pullulan. Pullulan is a water-soluble gum that exists structurally as a glucan consisting primarily of maltotriose units, which has a variety of food, non-food and biomedical applications. Cells can be immobilized by carrier-binding or entrapment techniques. The number of studies utilizing carrier-binding as a method to immobilize A. pullulans cells appears to outnumber the investigations using cell entrapment. A variety of solid supports, including polyurethane foam, sponge, diatomaceous earth, ion-exchanger, zeolite and plastic composite, have been employed to immobilize pullulan-producing A. pullulans cells. The most effective solid support that was used to adsorb the fungal cells was polyurethane foam which produced polysaccharide after 18 cycles of use. To entrap pullulan-producing fungal cells, agents such as polyurethane foam, polyvinyl alcohol, calcium alginate, agar, agarose, carrageenan and chitosan were investigated. Polysaccharide production by cells entrapped in polyurethane foam, polyvinyl alcohol or calcium alginate was highest and the immobilized cells could be reutilized for several cycles. It was shown that the pullulan content of the polysaccharide synthesized by cells entrapped in calcium alginate beads was low, which limits the method’s usefulness for pullulan production. Further, many of the entrapped fungal cells synthesized polysaccharide with a low pullulan content. It was concluded that carrier-binding techniques may be more effective than entrapment techniques for A. pullulans cell immobilization, since carrier-binding is less likely to affect the pullulan content of the polysaccharide being synthesized.

A new technique for separating platelet-rich plasma by a copolymer device － without a centrifugation process

BackgroundPlatelet-rich plasma (PRP) is beneficial for clinical applications in various medical fields. Although commercial PRP preparation kits are already available in the market, most of these kits employ centrifugation. MethodsWe used a new cationic copolymer coating on a polyurethane (PU) sponge to promote platelet separation from the blood. This copolymer showed no cytotoxicity against cell viability or hemolysis. We further evaluated the efficiency of the new PRP preparation device by comparing it with that of a commercially available kit (RegenKit-THT). ResultsWe demonstrated that PRP obtained using copolymer device contains high concentrations of platelets and angiogenic growth factors (epidermal growth factor, vascular endothelial growth factor-A, growth differentiation factor 2, and interleukin-8). The separated PRP also displayed beneficial effects on cell migration, angiogenesis, and matrix metalloproteinase gene expression. ConclusionBased on these results, we developed a cationic copolymer-coated PU sponge as a PRP preparation device without the need for any centrifugation.

Fast and efficient removal of dyes and Cr(VI) ion from wastewater using halloysite nanotubes-covalently coated polyurethane sponges

Inspired by the mussel adhesion protein, dopamine was used to prepare polydopamine (PDA)-coated polyurethane sponge (PDA-PUS) via self-polymerization reaction. Halloysite nanotubes (HNTs) were grafted with γ-aminopropyltriethoxysilane (APTES). The new organic-inorganic hybrid adsorption material (HNTs@PUS) was fabricated by covalent link of APTES-grafted HNTs and PDA-PUS through Schiff base reaction/Michael addition. The as-prepared HNTs@PUS showed much higher mechanical stability and compressive property than polyurethane sponge (PUS). HNTs@PUS had 7.7, 7.1, 1.7 and 8.5 times adsorption capacity of PUS for Congo red (CR), Methyl orange (MO), Rhodamine 6 G (R6G) and heavy metal ion Cr(VI), respectively. HNTs@PUS had a fast adsorption rate and most of CR, MO, R6G and Cr(VI) were adsorbed by HNTs@PUS within 20 min. In addition, HNTs@PUS maintained 70.3%, 66.5%, 67.3% and 77.4% of its adsorption capacity for CR, MO, R6G and Cr(VI), respectively, after 5 cycles of regeneration. HNTs@PUS could be easily recovered to avoid secondary contamination. Besides, using HNTs@PUS as adsorbents, a continuous flow adsorption device was developed, through which anionic and cationic dyes and heavy metal ion could be continuously and effectively removed from the flowing solution. These results demonstrated that HNTs@PUS had potentially ideal attributes for use as adsorbents in the ultrafast, high efficiency and large-scale removal of anionic and cationic dyes and heavy metal ions from wastewaters. The fabrication strategy not only solved the problem of the poor recyclability and low permeability of HNTs, but also greatly improved the adsorption capacity of PUS, which might accelerate the application of natural “green” HNTs in wastewater treatment.