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Youlo Hsieh - One of the best experts on this subject based on the ideXlab platform.
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dual wet and dry resilient cellulose ii fibrous Aerogel for hydrocarbon water separation and energy storage applications
ACS omega, 2018Co-Authors: Feng Jiang, Youlo HsiehAbstract:Cellulose fibrous Aerogels have been fabricated by a facile and aqueous process that disintegrated electrospun cellulose fibers (ECFs) and reassembled via freezing/freeze-drying with significantly improved dry resiliency and spontaneous 89% shape recovery from ca. 70% compressive strain. Owing to the resilient and 200-300 nm wide ECFs, the cellulose fibrous Aerogels exhibited excellent dual dry and wet resiliency as well as improved pore accessibility. The fibrous cellular walls interconnect the Aerogel pore structure to allow extraordinary liquid absorption capacity up to 373 g/g, accounting for 95% of the theoretical absorption capacity. Both highly dry resilient and absorbent properties of the ECF Aerogel are highly advantageous for hydrocarbon/oil contamination removal and for hydrocarbon/water separation applications. In addition, the ECF Aerogel could be carbonized into carbon Aerogel in supercapacitors for energy storage.
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adsorption and desorption of cationic malachite green dye on cellulose nanofibril Aerogels
Carbohydrate Polymers, 2017Co-Authors: Feng Jiang, Darren M Dinh, Youlo HsiehAbstract:Ultra-light Aerogels have been assembled from cellulose nanofibrils into hierarchically macroporous (several hundred μm) honeycomb cellular structure surrounded with mesoporous (8-60nm) thin walls. The high specific surface (193m2/g) and surface carboxyl content (1.29mmol/g) of these Aerogels were demonstrated to be highly capable of removing cationic malachite green (MG) dye from aqueous media. The rapid MG adsorption was driven by electrostatic interactions and followed a pseudo-second-order adsorption kinetic and monolayer Langmuir adsorption isotherm. At a low 1:5mg/mL Aerogel/MG ratio, both initial MG adsorption rate (2.3-59.8mgg-1min-1) and equilibrium adsorption capacity (53.0-203.7mgg-1) increased with increasing initial MG concentrations from 10 to 200mg/L, reaching a maximum adsorption of 212.7mgg-1. The excellent dye removal efficiency was demonstrated by complete MG removal through four repetitive adsorptions at a low 1:5mg/mL Aerogel/MG ratio and 10mg/L dye concentration as well as 92% MG adsorption in a single batch at one order of magnitude higher10:5mg/mL Aerogel/MG ratio and 100mg/L dye concentration. The adsorbed MG in Aerogels could be desorbed in aqueous media by increasing ionic strength, demonstrating facile recovery of both dye and Aerogel as well as the robust capability of this Aerogel for repetitive applications.
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cellulose nanofibril Aerogels synergistic improvement of hydrophobicity strength and thermal stability via cross linking with diisocyanate
ACS Applied Materials & Interfaces, 2017Co-Authors: Feng Jiang, Youlo HsiehAbstract:A facile gelation cross-linking approach was devised to fabricate meso- and macroporous cellulose nanofibril (CNF) Aerogels with multiple improved properties. CNF hydrogels made using a freezing–thawing method with a 94 kPa modulus were solvent exchanged with acetone and then cross-linked with methylene diphenyl diisocyanate (MDI) to produce Aerogels with significantly improved compressive properties that follow a power law increment against Aerogel density with impressive 1.69, 2.49, and 1.43 scaling factors for Young’s modulus, yield stress, and ultimate stress, respectively. The optimally cross-linked Aerogels had nearly tripled specific surface area (228 m2/g) and doubled pore volume (1 m3/g) from numerous new 9–12 nm wide mesopores as well as significantly improved thermal stability (43% char residue at 500 C vs 9.1% for un-cross-linked Aerogel). Cross-linking also made the amphiphilic CNF Aerogel highly hydrophobic and capable of completely separating chloroform from water via simple filtration. The...
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amphiphilic superabsorbent cellulose nanofibril Aerogels
Journal of Materials Chemistry, 2014Co-Authors: Feng Jiang, Youlo HsiehAbstract:Ultra-light (1.7 to 8.1 mg cm−3) and ultra-porous (99.5 to 99.9%) Aerogels have been assembled from cellulose nanofibrils (CNFs) that were defibrillated from rice straw cellulose at 96.8% yield. The as-prepared Aerogels, amphiphilic super-absorbents, absorbing 210 and 375 times water and chloroform, respectively, are far superior to any previously reported cellulose Aerogel. Vapor deposition with triethoxyl(octyl) silane turned the amphiphilic Aerogel more hydrophobic and oleophilic, capable of absorbing 139–356 times non-polar hydrocarbons, polar aprotic solvents and oils, surpassing all previously reported polymeric, cellulosic and carbonaceous Aerogels by 2 to nearly 20 times. These Aerogels are excellent amphiphilic super-absorbents for selective oil removal and recovery.
Irina Smirnova - One of the best experts on this subject based on the ideXlab platform.
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tailor made protein based Aerogel particles from egg white protein whey protein isolate and sodium caseinate influence of the preceding hydrogel characteristics
Food Hydrocolloids, 2018Co-Authors: Christian Kleemann, Irina Smirnova, Ilka Selmer, Ulrich KulozikAbstract:Abstract Protein based Aerogel particles derived from heat set whey and egg white protein hydrogels were prepared. The influence of the hydrogel preparation on Aerogel properties was studied. Variations in pH, ionic strength and protein type and concentration were assessed as a means to vary hydrogel and corresponding Aerogel structures in a targeted manner. An adjustment of pH of the precursor protein solution led to fragile hydrogels with obvious syneresis in the pH region around the isoelectric point. Corresponding Aerogels were brittle and lacked the typically large specific inner surface area of Aerogels. In an acidic environment, hydrogels were firm but also fragile. Aerogels were brittle but had a large specific inner BET-surface area. In an alkaline environment, the hydrogels were soft and elastic. Thus, resulting Aerogels were mechanically stable and possessed a large BET-surface area. The addition of sodium chloride or calcium chloride to the protein solution had the same effect as lowering the pH towards the isoelectric point. The process of supercritical drying was also applied to enzymatically cross-linked sodium caseinate hydrogels with varying protein concentration. Corresponding Aerogels had a smaller BET-surface area compared to heat set gels. The protein concentration did not affect the BET-surface area of the Aerogel. Finally, an emulsion method was used to produce protein Aerogel particles, suitable for microencapsulation purposes. All three types of protein formed single spherical Aerogel particles with comparable Aerogel properties to the related Aerogel monolith. The properties of the protein Aerogel particles may be tailored towards special needs for microencapsulation purposes in food, cosmetic or pharmaceutical applications.
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Aerogel production current status research directions and future opportunities
Journal of Supercritical Fluids, 2017Co-Authors: Irina Smirnova, Pavel GurikovAbstract:Abstract Being the lightest solid materials known, and given the great variety of possible chemistries capable of yielding wet-gels, Aerogels and composite Aerogel materials have a tremendous potential in a wide range of applications, where high pore volume and high surface area play major roles. Today, the main commercialized application of Aerogels is thermal insulation, although Aerogels can be used for a huge variety of applications such as electrochemistry (super capacitors), carrier of catalysts and other active agents, filling materials, materials for tissue engineering etc. However, industrial production of Aerogels is so far mostly limited to silica-based systems, limiting the possibility to prove the potential application by prototyping. In this paper first the state of the art of the Aerogel manufacturing and applications are briefly discussed. Based on the current status, main knowledge gaps and challenges are identified and the future research directions from the point of view of the authors are derived. In the next future, we expect significant further development in the area of the organic and hybrid Aerogel Aerogels, optimization of their manufacturing processes and their transfer to the market.
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Polysaccharide-based Aerogel microspheres for oral drug delivery
Carbohydrate Polymers, 2015Co-Authors: Carlos A. García-gonzález, John Gerth, M. Jin, Carmen Alvarez-lorenzo, Irina SmirnovaAbstract:Polysaccharide-based Aerogels in the form of microspheres were investigated as carriers of poorly water soluble drugs for oral administration. These bio-based carriers may combine the biocompatibility of polysaccharides and the enhanced drug loading capacity of dry Aerogels. Aerogel microspheres from starch, pectin and alginate were loaded with ketoprofen (anti-inflammatory drug) and benzoic acid (used in the management of urea cycle disorders) via supercritical CO2-assisted adsorption. Amount of drug loaded depended on the Aerogel matrix structure and composition and reached values up to 1.0 × 10-3and 1.7 × 10-3g/m2for ketoprofen and benzoic acid in starch microspheres. After impregnation, drugs were in the amorphous state in the Aerogel microspheres. Release behavior was evaluated in different pH media (pH 1.2 and 6.8). Controlled drug release from pectin and alginate Aerogel microspheres fitted Gallagher-Corrigan release model (R2> 0.99 in both cases), with different relative contribution of erosion and diffusion mechanisms depending on the matrix composition. Release from starch Aerogel microspheres was driven by dissolution, fitting the first-order kinetics due to the rigid starch Aerogel structure, and showed different release rate constant (k1) depending on the drug (0.075 and 0.160 min-1for ketoprofen and benzoic acid, respectively). Overall, the results point out the possibilities of tuning drug loading and release by carefully choosing the polysaccharide used to prepare the Aerogels.
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a novel process for coating of silica Aerogel microspheres for controlled drug release applications
Microporous and Mesoporous Materials, 2012Co-Authors: Mohammad Alnaief, Sergiy Antonyuk, C M Hentzschel, Stefan Heinrich, Claudia S. Leopold, Irina SmirnovaAbstract:Abstract Aerogels are nanoporous materials with an open-pore structure and high specific surface area. Because of their outstanding properties they have been investigated in immense fields of applications like novel insulation materials, catalysts and catalysts carrier, optics, waste treatment and drug delivery systems. However, the limitation of Aerogels (specially hydrophilic ones) in a number of applications is their open-pore structure, allowing the penetration of liquids therein resulting in destruction of their textural properties. Applying a polymeric coating layer on Aerogels surface can be a solution for this problem and can open a wide window of new applications for Aerogels, especially in pharmaceutical industry. This work suggests a novel process for coating of Aerogels with polymeric materials using spouted bed technology. Firstly, spherical silica Aerogel particles with a high surface area up to 1100 m 2 /g and particles diameter ranging from 200 μm to few millimetres were produced. Then, the Aerogel particles were loaded with a model drug (Ibuprofen) by adsorption from supercritical CO 2 phase. The loaded Aerogel particles were coated with different polymeric materials in a slit-shaped spouted fluidized bed with two horizontal gas inlets and adjustable gas supply. The corresponding polymers were sprayed as an aqueous suspension or as melts. The process conditions for coating (coating material, fluidization air flow rate, temperature, etc.) were optimized accordingly. The physical, mechanical, structural and release properties of the resulting formulations were evaluated. This technology allows to provide a specific release mechanism of pharmaceuticals (thermal, pH-sensitive or enzyme triggered release) from Aerogels and to broaden Aerogel applications in pharmaceutical technology.
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dissolution rate enhancement by adsorption of poorly soluble drugs on hydrophilic silica Aerogels
Pharmaceutical Development and Technology, 2005Co-Authors: Irina Smirnova, Matthias Seiler, Supakij Suttiruengwong, Wolfgang ArltAbstract:The aim of this work is to evaluate the feasibility of hydrophilic silica Aerogels as drug carriers and to investigate the influence of the Aerogels properties on the release rate of poorly water-soluble drugs. Hydrophilic silica Aerogels of different densities were loaded with two model drugs, ketoprofen and griseofulvin, by adsorption from their solution in supercritical CO2. It is demonstrated that up to 30 wt% of ketoprofen and 5.4 wt% of griseofulvin can be deposited on hydrophilic Aerogels through physical adsorption. The obtained drug-Aerogel formulations were characterized by IR- and UV-spectroscopy, X-ray diffraction and scanning electron microscopy. Release kinetics of both drugs were studied in vitro. The release rate of ketoprofen from the drug-Aerogel formulation is much faster than that of the corresponding crystalline drugs. The release rate of ketoprofen increases in 500% and that of griseofulvin in 450%, respectively. The reasons for the release enhancement are the enlarged specific surface area of drugs by adsorption on Aerogels compared to their crystalline form and the immediate collapse of Aerogel network in aqueous media. The dissolution rate of poorly water soluble drugs can be significantly enhanced by adsorption on highly porous hydrophilic silica Aerogels.
Siqun Wang - One of the best experts on this subject based on the ideXlab platform.
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a thermally stable and hydrophobic composite Aerogel made from cellulose nanofibril Aerogel impregnated with silica particles
Journal of Materials Science, 2018Co-Authors: Siqun Wang, Yongsheng ChenAbstract:A thermally stable and hydrophobic cellulose nanofibril (CNF)–silica composite Aerogel was prepared by simply immersing the CNF Aerogel into the silica sol with different tetraethyl orthosilicate (TEOS) concentration and shaping it by means of low-risk ambient pressure drying. After the introduction of the mesoporous silica particles into the cellulose network structure, the BET surface area was found to have sharply increased from 11.3 to 497.8 m2 g−1. All composite Aerogels displayed good thermal stability and super-hydrophobicity compared with pure cellulose Aerogel. The onset temperature of pyrolysis rose from 317 to 348 °C, and the contact angle reached 152.1°. The TEOS concentration was found to have a great influence on the silica content and the dispersion of silica particles in the cellulose scaffold. Good chemical compatibility at the nanoscale level was present, which indicates that a continuous and homogeneous CNF–silica interface would yield great improvement in thermal properties and water resistance. The results show that a composite Aerogel prepared at 2.5 mol L−1 TEOS concentration has better comprehensive performance with only a slightly decrease in mechanical properties compared to CNF Aerogel. Thus, this study details a new direction for the synthesis of a cellulose–silica composite Aerogel with tailored properties achieved by controlling the silica content and silica dispersion in the cellulose scaffold. Thermally stable, water-resistant, and environmentally friendly cellulose–silica composite Aerogels may provide a promising development for designing new functional Aerogels that can be applied in various fields.
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facilitated fabrication of high strength silica Aerogels using cellulose nanofibrils as scaffold
Carbohydrate Polymers, 2016Co-Authors: Siqun Wang, Jingda Huang, Zhilin ChenAbstract:Monolithic cellulose nanofibrils (CNF)-silica composite Aerogels were successfully prepared by immersing CNF Aerogels into a silica solution in a two-step sol-gel process (initial hydrolysis of tetraethyl orthosilicate (TEOS) followed by condensation of silica particles). Aerogels were characterized by SEM, BET surface area test, bulk density and silica content analysis, FTIR spectroscopy, and compression test. The form of SiO2 existing in the composite Aerogel was the spherical individual particles coated on CNF fibrils. The pH value of condensation solution was found to have great influence on the properties of the composite Aerogels. By varying the pH value of condensation atmosphere from 8 to 12, the bulk densities of composite Aerogels were able to be linearly increased from 0.059gcm(-3) to 0.29gcm(-3)，and the silica content in the matrix sharply jumped from 3wt% to 79wt%. The porosities of the Aerogels remained very high, between 85 and 96%, and the surface area of the composite Aerogel reached up to 700.1m(2)g(-1). The compression properties of the composite Aerogel improved greatly compared with those of the silica Aerogel, about 8-30 times higher. Moreover, the compressive strength of the composite Aerogel prepared in this work greatly exceeded the conventional insulation materials found in the recent commercial market, and without substantial increases in thermal conductivity. Hence, the findings of this research offer a promising application for composite Aerogels and give a theoretical basis for developing new advanced materials.
Feng Jiang - One of the best experts on this subject based on the ideXlab platform.
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dual wet and dry resilient cellulose ii fibrous Aerogel for hydrocarbon water separation and energy storage applications
ACS omega, 2018Co-Authors: Feng Jiang, Youlo HsiehAbstract:Cellulose fibrous Aerogels have been fabricated by a facile and aqueous process that disintegrated electrospun cellulose fibers (ECFs) and reassembled via freezing/freeze-drying with significantly improved dry resiliency and spontaneous 89% shape recovery from ca. 70% compressive strain. Owing to the resilient and 200-300 nm wide ECFs, the cellulose fibrous Aerogels exhibited excellent dual dry and wet resiliency as well as improved pore accessibility. The fibrous cellular walls interconnect the Aerogel pore structure to allow extraordinary liquid absorption capacity up to 373 g/g, accounting for 95% of the theoretical absorption capacity. Both highly dry resilient and absorbent properties of the ECF Aerogel are highly advantageous for hydrocarbon/oil contamination removal and for hydrocarbon/water separation applications. In addition, the ECF Aerogel could be carbonized into carbon Aerogel in supercapacitors for energy storage.
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adsorption and desorption of cationic malachite green dye on cellulose nanofibril Aerogels
Carbohydrate Polymers, 2017Co-Authors: Feng Jiang, Darren M Dinh, Youlo HsiehAbstract:Ultra-light Aerogels have been assembled from cellulose nanofibrils into hierarchically macroporous (several hundred μm) honeycomb cellular structure surrounded with mesoporous (8-60nm) thin walls. The high specific surface (193m2/g) and surface carboxyl content (1.29mmol/g) of these Aerogels were demonstrated to be highly capable of removing cationic malachite green (MG) dye from aqueous media. The rapid MG adsorption was driven by electrostatic interactions and followed a pseudo-second-order adsorption kinetic and monolayer Langmuir adsorption isotherm. At a low 1:5mg/mL Aerogel/MG ratio, both initial MG adsorption rate (2.3-59.8mgg-1min-1) and equilibrium adsorption capacity (53.0-203.7mgg-1) increased with increasing initial MG concentrations from 10 to 200mg/L, reaching a maximum adsorption of 212.7mgg-1. The excellent dye removal efficiency was demonstrated by complete MG removal through four repetitive adsorptions at a low 1:5mg/mL Aerogel/MG ratio and 10mg/L dye concentration as well as 92% MG adsorption in a single batch at one order of magnitude higher10:5mg/mL Aerogel/MG ratio and 100mg/L dye concentration. The adsorbed MG in Aerogels could be desorbed in aqueous media by increasing ionic strength, demonstrating facile recovery of both dye and Aerogel as well as the robust capability of this Aerogel for repetitive applications.
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cellulose nanofibril Aerogels synergistic improvement of hydrophobicity strength and thermal stability via cross linking with diisocyanate
ACS Applied Materials & Interfaces, 2017Co-Authors: Feng Jiang, Youlo HsiehAbstract:A facile gelation cross-linking approach was devised to fabricate meso- and macroporous cellulose nanofibril (CNF) Aerogels with multiple improved properties. CNF hydrogels made using a freezing–thawing method with a 94 kPa modulus were solvent exchanged with acetone and then cross-linked with methylene diphenyl diisocyanate (MDI) to produce Aerogels with significantly improved compressive properties that follow a power law increment against Aerogel density with impressive 1.69, 2.49, and 1.43 scaling factors for Young’s modulus, yield stress, and ultimate stress, respectively. The optimally cross-linked Aerogels had nearly tripled specific surface area (228 m2/g) and doubled pore volume (1 m3/g) from numerous new 9–12 nm wide mesopores as well as significantly improved thermal stability (43% char residue at 500 C vs 9.1% for un-cross-linked Aerogel). Cross-linking also made the amphiphilic CNF Aerogel highly hydrophobic and capable of completely separating chloroform from water via simple filtration. The...
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amphiphilic superabsorbent cellulose nanofibril Aerogels
Journal of Materials Chemistry, 2014Co-Authors: Feng Jiang, Youlo HsiehAbstract:Ultra-light (1.7 to 8.1 mg cm−3) and ultra-porous (99.5 to 99.9%) Aerogels have been assembled from cellulose nanofibrils (CNFs) that were defibrillated from rice straw cellulose at 96.8% yield. The as-prepared Aerogels, amphiphilic super-absorbents, absorbing 210 and 375 times water and chloroform, respectively, are far superior to any previously reported cellulose Aerogel. Vapor deposition with triethoxyl(octyl) silane turned the amphiphilic Aerogel more hydrophobic and oleophilic, capable of absorbing 139–356 times non-polar hydrocarbons, polar aprotic solvents and oils, surpassing all previously reported polymeric, cellulosic and carbonaceous Aerogels by 2 to nearly 20 times. These Aerogels are excellent amphiphilic super-absorbents for selective oil removal and recovery.
Huaihe Song - One of the best experts on this subject based on the ideXlab platform.
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enhancements of thermal insulation and mechanical property of silica Aerogel monoliths by mixing graphene oxide
Materials Chemistry and Physics, 2017Co-Authors: Zijun Hu, Xiaohong Chen, Huaihe SongAbstract:Abstract In order to improve the thermal insulation and mechanical property of silica (SiO2) Aerogels, the graphene oxide (GO), as nanofillers, was added into SiO2 matrix to prepare the SiO2/GO composite Aerogel monoliths on the basis of sol-gel technology and submitted to supercritical drying. The results showed that the monoliths were maintained and GO was well-distributed in the Aerogel, due to the interfacial interaction between GO nanosheets and SiO2 matrix. The thermal insulation property of composite Aerogels was improved in contrast with that of pure Aerogel. The experimental results suggested that the thermal conductivity was lowered from 0.0089 W/mK to 0.0072 W/mK. A possible mechanism was analyzed to explain this result in virtue of GO loadings. The mechanical strength of Aerogels was enhanced. It was found that with the loading of GO from 0.0 wt% to 5.0 wt%, the compressive modulus was enhanced from 0.238 MPa to 0.394 MPa, which was a significant improvement for low-solid-content silica Aerogels. Moreover, the composite Aerogels exhibited some toughness compared to the fragility of pure Aerogel.