The Experts below are selected from a list of 6645 Experts worldwide ranked by ideXlab platform
Andrew G Livingston - One of the best experts on this subject based on the ideXlab platform.
-
Controlling Crystallization via Organic Solvent Nanofiltration: The Influence of Flux on Griseofulvin Crystallization
Crystal Growth & Design, 2014Co-Authors: J.r. Campbell, Ludmila G. Peeva, Andrew G LivingstonAbstract:Organic Solvent nanofiltration (OSN) is suggested as a method for enhancing crystallization in the pharmaceutical industry. OSN crystallization has the potential to reduce energy and/or chemical inputs and allows for control of process conditions and crystal morphology. This work focuses on the crystallization of the pharmaceutical compound griseofulvin using OSN membranes to concentrate solutions via Solvent removal. Griseofulvin solutions were concentrated in a pressure-driven dead-end nanofiltration cell, and crystals were allowed to spontaneously nucleate. The process was carried out using a range of different pressures to manipulate the Solvent Flux through the membrane. It was found that two distinct crystal types could be produced by altering the process Solvent Flux. At high Flux, large crystals (≈1 mm) were produced, whereas, at low Flux, small crystals (2–25 μm), which grew in clustered formations, were observed. The large crystals produced a previously unreported X-ray powder diffraction patter...
-
high Flux hydrophobic membranes for organic Solvent nanofiltration osn interfacial polymerization surface modification and Solvent activation
Journal of Membrane Science, 2013Co-Authors: Maria Fernanda Jimenez Solomon, Y S Bhole, Andrew G LivingstonAbstract:Abstract This paper describes the formation of a new generation of hydrophobic organic Solvent nanofiltration (OSN) membranes: high Flux hydrophobic thin film composite (TFC) membranes via interfacial polymerization. These are the first reported hydrophobic TFC membranes which are stable in DMF. They exhibit significantly higher permeabilities for nonpolar Solvents, including toluene and ethyl acetate, than commercial OSN hydrophobic integrally skinned asymmetric and rubber coated membranes and yet have comparable or better selectivity. Solvent stable crosslinked polyimide ultrafiltration membranes were used as supports for the formation of these TFC membranes. For some membranes, a mixture of acyl chlorides (trimesoyl chloride blended with a monoacyl chloride containing fluorine) was used during the interfacial polymerization to manipulate molecular weight cut off and to make the membranes more hydrophobic. Measured by the rejection curves, the loosest membrane was prepared when the mixture of acyl chlorides was used, and the tightest when trimesoyl chloride was used alone. To increase nonpolar Solvent Flux the free acyl chloride groups on the TFC membrane surface were capped with different monomers containing hydrophobic groups. Comparison of TFC membranes formed with and without capping suggests that the chemistry of the membrane surface plays an important role in Solvent permeation. As reported previously by our group, in order to “activate” Solvent Flux we post-treated the TFC membranes with DMF. Incorporation of F and Si to the polyamide top layer resulted in dramatically improved permeabilities for non-polar Solvents. Such hydrophobic TFC membranes prepared via interfacial polymerization and treated with an activating Solvent may lead to the next generation of high performance hydrophobic OSN membranes.
-
Solvent transport in organic Solvent nanofiltration membranes
Journal of Membrane Science, 2005Co-Authors: Pedro Silva, Shejiao Han, Andrew G LivingstonAbstract:Abstract Solvent transport in organic Solvent nanofiltration membranes has been studied in a lab-scale cross-flow nanofiltration rig over extended periods using the common Solvents methanol, toluene, ethyl acetate and their mixtures. The organic Solvent nanofiltration membranes STARMEM™ 122 1 (W.R. Grace and Co.) and MPF50 (Koch Membrane Systems) were investigated. It was found that it took a few days to obtain stable Solvent Flux using STARMEM™ 122, and that the Solvent Flux in this membrane showed good repeatability between different sample discs. MPF50 did not provide reproducible results, therefore, no modelling/data analysis was performed for this membrane. Our experimental data shows that both solution-diffusion and pore-flow models can be used to predict permeation of Solvent mixtures, using only the permeabilities of the pure Solvents to obtain input parameters to each model. The solution-diffusion model gave more accurate predictions. Our conclusion is that for the Solvents studied, it is possible for reasonable predictions of Solvent mixture Flux to be made over the whole concentration range, based on the data for pure Solvents.
-
effect of concentration polarisation and osmotic pressure on Flux in organic Solvent nanofiltration
Journal of Membrane Science, 2004Co-Authors: Ludmila G. Peeva, Satinder S Luthra, Lloyd S White, Emma J. Gibbins, Roumiana P Stateva, Andrew G LivingstonAbstract:Abstract The separation of molecules present in organic Solvents by nanofiltration has potential application in several industries, and organic Solvent stable nanofiltration (NF) membranes have recently become available. There is a rapidly growing body of information available on the processes controlling Solvent Fluxes and solute rejections in Solvent nanofiltration. However, previous work has mainly been carried out with dilute solutions ( 5 wt.%) and phenomena such as concentration polarisation and osmotic pressure may contribute to the Solvent Flux, as in aqueous systems. In order to improve our understanding of organic Solvent nanofiltration phenomena, experiments were performed in a cross-flow rig in which NF was carried out in a continuous mode. Solutions of different concentrations (up to 20 wt.%) of tetraoctylammonium bromide and docosane in toluene were used. Description of the experimental data, including prediction of solute rejection, was performed using the solution diffusion model for membrane transport and the film theory for liquid mass transfer effects. The results show that the organic systems cannot always be described by a simple osmotic pressure model. The Flux through the membrane is affected by the cross-flow velocity, indicating that concentration polarisation induces mass transfer limitations. The fit between the model and the experimental data is markedly improved by allowing the activities of the solution components to vary, indicating that these systems are non-ideal.
-
homogeneous phase transfer catalyst recovery and re use using Solvent resistant membranes
Journal of Membrane Science, 2002Co-Authors: Satinder S Luthra, Xiaojin Yang, Luisa Freitas Dos M Santos, Lloyd S White, Andrew G LivingstonAbstract:Abstract This paper explores the use of nanofiltration (NF) membranes in phase transfer catalysis for separating the catalyst and product present in the post-reaction mixture and recycling the catalyst. The conversion of bromoheptane into iodoheptane with toluene as Solvent, using an aqueous solution of potassium iodide, and catalysed by tetraoctylammonium bromide as the phase transfer catalyst, was employed as a model reaction. A range of NF membranes from commercial manufacturers were evaluated in terms of membrane stability, Solvent and product permeation rates, and catalyst rejection. The best performance resulted in a catalyst rejection of >99% and a Solvent Flux of >10 l m −2 h −1 , with negligible product rejection. The catalyst was 100% recycled and re-used in subsequent reactions. No loss in catalyst activity was observed over a cycle of three consecutive reactions.
Tai-shung Chung - One of the best experts on this subject based on the ideXlab platform.
-
Solvent Recovery via Organic Solvent Pressure Assisted Osmosis
Industrial & Engineering Chemistry Research, 2019Co-Authors: Yue Cui, Tai-shung ChungAbstract:The organic Solvent forward osmosis (OSFO) process suffers from certain drawbacks, such as relatively low Solvent Flux. One strategy to overcome the relatively low Solvent Flux of OSFO is to utilize an external hydraulic pressure, on top of the osmotic pressure difference across a membrane, to enhance the Solvent transport through the membrane. Thus, organic Solvent pressure assisted osmosis (OSPAO) has been proposed and demonstrated in this study to effectively recover organic Solvents from pharmaceutical products. The OSPAO process was conducted using various Solvents including ethanol, IPA, and hexane, with different draw solutes, such as lithium chloride (LiCl) and methyl palmitate. Experimental results show that the Solvent Flux can be significantly enhanced, while the reverse solute Flux (RSF) is slightly reduced with an increase in applied hydraulic pressure from 0 to 1 bar. However, the enhancement in Solvent Flux by the external hydraulic pressure reduces as the draw solution concentration increa...
-
Pharmaceutical concentration using organic Solvent forward osmosis for Solvent recovery.
Nature Communications, 2018Co-Authors: Yue Cui, Tai-shung ChungAbstract:The organic Solvent forward osmosis (OSFO) process can simultaneously concentrate the active pharmaceutical ingredients (APIs) and recover the organic Solvents. Here we demonstrate and evaluate an OSFO process for Solvent recovery. In this demonstration, OSFO was conducted in different Solvents with different draw solutes. The OSFO process shows rejections >98% when recovering organic Solvents from different feed solutions, even when the feed concentration is as high as 20 wt%. More importantly, all systems exhibit relatively low ratios of reverse solute Flux to Solvent Flux, indicating that the adverse effects of using hazardous draw solutions could be minimized. Nevertheless, the use of non-hazardous draw solutes such as citric acid is highly recommended to remove any potential risk, and it has been demonstrated. Herein, the OSFO process is a promising technology for Solvent recovery as it possesses a reasonable Solvent Flux, low reverse solute Flux and requires no external pressure. Solvent recovery is an important process in the pharmaceutical industry, but organic Solvent nanofiltration membranes operate under high pressures. Here the authors demonstrate organic Solvent forward osmosis — an alternative process that does not require application of external pressure and may prove to be economically favorable.
-
a slow fast phase separation sfps process to fabricate dual layer hollow fiber substrates for thin film composite tfc organic Solvent nanofiltration osn membranes
Chemical Engineering Science, 2015Co-Authors: Shipeng Sun, Sui Yung Chan, Tai-shung ChungAbstract:Abstract A novel slow–fast phase separation (SFPS) process is proposed to fabricate the desirable ultrafiltration dual-layer hollow fiber substrate for effective interfacial polymerization. By controlling the ratios of non-Solvents to volatile co-Solvents in both the outer- and inner-layer dopes, the outer and inner layers undergo slow and fast coagulation, respectively, in the dry-jet wet-spinning co-extrusion process. The inner layer is highly porous for high Solvent Flux permeation, while the outer layer possesses a surface with nano-sized pores that have a sharp size distribution for effective thin film polymerization. The addition of polyvinylpyrrolidone in the outer dope further reduces the pore size, and enhances surface hydrophilicity as well as mechanical strength. The substrate was cross-linked and subjected to interfacial polymerization for fabricating thin-film composite (TFC) membranes. The effects of the substrate properties of various hollow fiber membranes from the SFPS process on the TFC membrane were systematically investigated in terms of morphology and organic Solvent nanofiltration (OSN) performance. The membrane shows a 99.3% rejection of ramazol brilliant blue (MW: 626.54 g mol −1 ) and a methanol Flux of 14.4 l m −2 h −1 at 16 bar.
-
enhancement of Flux and Solvent stability of matrimid thin film composite membranes for organic Solvent nanofiltration
Aiche Journal, 2014Co-Authors: Shipeng Sun, Tai-shung Chung, Sui Yung ChanAbstract:The development of high Flux and Solvent-stable thin-film composite (TFC) organic Solvent nanofiltration (OSN) membranes was reported. A novel cross-linked polyimide substrate, consisting of a thin skin layer with minimum Solvent transport resistance and a sponge-like sublayer structure that could withstand membrane compaction under high-pressure was first fabricated. Then the Solvent Flux was significantly enhanced without compromising the solute rejection by the coupling effects of (1) the addition of triethylamine/camphorsulfonic acid into the monomer solution, and (2) the combined post-treatments of glycerol/sodium dodecyl sulphate immersion and dimethyl sulfoxide (DMSO) filtration. Finally, the long-term stability of the TFC membrane in aprotic Solvents such as DMSO was improved by post-crosslink thermal annealing. The novel TFC OSN membrane developed was found to have superior rejection to tetracycline (MW: 444 g/mol) but was very permeable to alcohols such as methanol (5.12 lm−2h−1bar−1) and aprotic Solvents such as dimethylformamide (3.92 lm−2h−1bar−1) and DMSO (3.34 lm−2h−1bar−1). © 2014 American Institute of Chemical Engineers AIChE J, 60: 3623–3633, 2014
Sui Yung Chan - One of the best experts on this subject based on the ideXlab platform.
-
a slow fast phase separation sfps process to fabricate dual layer hollow fiber substrates for thin film composite tfc organic Solvent nanofiltration osn membranes
Chemical Engineering Science, 2015Co-Authors: Shipeng Sun, Sui Yung Chan, Tai-shung ChungAbstract:Abstract A novel slow–fast phase separation (SFPS) process is proposed to fabricate the desirable ultrafiltration dual-layer hollow fiber substrate for effective interfacial polymerization. By controlling the ratios of non-Solvents to volatile co-Solvents in both the outer- and inner-layer dopes, the outer and inner layers undergo slow and fast coagulation, respectively, in the dry-jet wet-spinning co-extrusion process. The inner layer is highly porous for high Solvent Flux permeation, while the outer layer possesses a surface with nano-sized pores that have a sharp size distribution for effective thin film polymerization. The addition of polyvinylpyrrolidone in the outer dope further reduces the pore size, and enhances surface hydrophilicity as well as mechanical strength. The substrate was cross-linked and subjected to interfacial polymerization for fabricating thin-film composite (TFC) membranes. The effects of the substrate properties of various hollow fiber membranes from the SFPS process on the TFC membrane were systematically investigated in terms of morphology and organic Solvent nanofiltration (OSN) performance. The membrane shows a 99.3% rejection of ramazol brilliant blue (MW: 626.54 g mol −1 ) and a methanol Flux of 14.4 l m −2 h −1 at 16 bar.
-
enhancement of Flux and Solvent stability of matrimid thin film composite membranes for organic Solvent nanofiltration
Aiche Journal, 2014Co-Authors: Shipeng Sun, Tai-shung Chung, Sui Yung ChanAbstract:The development of high Flux and Solvent-stable thin-film composite (TFC) organic Solvent nanofiltration (OSN) membranes was reported. A novel cross-linked polyimide substrate, consisting of a thin skin layer with minimum Solvent transport resistance and a sponge-like sublayer structure that could withstand membrane compaction under high-pressure was first fabricated. Then the Solvent Flux was significantly enhanced without compromising the solute rejection by the coupling effects of (1) the addition of triethylamine/camphorsulfonic acid into the monomer solution, and (2) the combined post-treatments of glycerol/sodium dodecyl sulphate immersion and dimethyl sulfoxide (DMSO) filtration. Finally, the long-term stability of the TFC membrane in aprotic Solvents such as DMSO was improved by post-crosslink thermal annealing. The novel TFC OSN membrane developed was found to have superior rejection to tetracycline (MW: 444 g/mol) but was very permeable to alcohols such as methanol (5.12 lm−2h−1bar−1) and aprotic Solvents such as dimethylformamide (3.92 lm−2h−1bar−1) and DMSO (3.34 lm−2h−1bar−1). © 2014 American Institute of Chemical Engineers AIChE J, 60: 3623–3633, 2014
Kamalesh K. Sirkar - One of the best experts on this subject based on the ideXlab platform.
-
Interfacially polymerized thin film composite membranes on microporous polypropylene supports for Solvent-resistant nanofiltration
Journal of Membrane Science, 2008Co-Authors: Praveen B. Kosaraju, Kamalesh K. SirkarAbstract:Abstract Interfacial polymerization (IP) is a powerful technique for fabrication of thin film composite (TFC) membranes. The polymers used most often as support are polysulfone (PS) or polyethersulfone (PES). These supports have limited stability in organic Solvents. In this work, microporous polypropylene (PP) flat film and hollow fiber membranes were used as a support to fabricate TFC membranes for nanofiltration by the IP technique. Porous polypropylene membranes can provide substantial chemical, pH, and Solvent resistance and are therefore suitable as supports for fabricating TFC membranes functioning as Solvent-stable nanofiltration membranes. The surface and the pore interior of polypropylene flat sheet and hollow fiber membranes were hydrophilized first by pre-wetting with acetone followed by oxidation with chromic acid solution. A standard procedure to successfully coat the hydrophilized flat film and hollow fiber membranes was developed next. The monomeric system chosen for IP was poly(ethyleneimine) and isophthaloyl dichloride. The TFC hollow fiber membranes were characterized by nanofiltration of safranin O (MW 351) and brilliant blue R (MW 826) dyes in methanol. Rejection values of 88% and 43% were achieved for brilliant blue R and safranin O, respectively at a transmembrane pressure of 413 kPa in the TFC hollow fiber membranes. Pressure dependences of the Solvent Flux and solute rejection of the TFC membranes were studied using the modified flat sheet membranes up to a pressure of 965–1241 kPa. Solvent Flux increased linearly with an increase in the transmembrane pressure. Solute rejection also increased with an increase in the transmembrane pressure. All modified membranes were also characterized using scanning electron microscopy. Extended-term Solvent stability of the fabricated membranes was studied in toluene; the membranes demonstrated substantial Solvent stability in toluene.
-
Nanofiltration studies of larger organic microsolutes in methanol solutions
Journal of Membrane Science, 2000Co-Authors: J.a. Whu, B. C. Baltzis, Kamalesh K. SirkarAbstract:Abstract Multistep organic Solvent-based pharmaceutical syntheses of larger organic microsolutes having molecular weights (MW) in the range of 300–1000 generally require athermal separation processes because the active molecules and the intermediates are thermally labile. To that end, nanofiltration (NF) of methanol solutions of three selected solutes, safranin O (MW 351), brilliant blue R (MW 826) and vitamin B12 (MW 1355) has been studied in a batch stirred cell for a dilute solution of each individual solute at 3034 kPa (440 psig). The Solvent-resistant membranes investigated and their manufacturer-specified molecular weight cut-offs (MWCO) are MPF-44 (250), MPF-50 (700) and MPF-60 (400). During an initial transient period, the Solvent Flux decreased with time and the solute rejection increased with time for every membrane reaching a steady state after about 12 h. This behavior resulting from membrane compaction and pore size reduction was partially reversible. Additional studies using higher feed solute concentrations (1 and 3 wt.%) show considerable reduction in Solvent Flux and increase in solute rejection; the effect appears to be far more than that due to an increase in osmotic pressure and possible reasons for such a behavior have been suggested. The observed solute rejection values are generally significantly lower than the manufacturer-specified MWCO values. Additional studies varying the feed solution pressure through the membrane MPF-60 indicate that the variation of the percent rejection of solutes safranin O and brilliant blue R with the Solvent Flux tends to follow the relation suggested by the Finely Porous Model.
Shipeng Sun - One of the best experts on this subject based on the ideXlab platform.
-
a slow fast phase separation sfps process to fabricate dual layer hollow fiber substrates for thin film composite tfc organic Solvent nanofiltration osn membranes
Chemical Engineering Science, 2015Co-Authors: Shipeng Sun, Sui Yung Chan, Tai-shung ChungAbstract:Abstract A novel slow–fast phase separation (SFPS) process is proposed to fabricate the desirable ultrafiltration dual-layer hollow fiber substrate for effective interfacial polymerization. By controlling the ratios of non-Solvents to volatile co-Solvents in both the outer- and inner-layer dopes, the outer and inner layers undergo slow and fast coagulation, respectively, in the dry-jet wet-spinning co-extrusion process. The inner layer is highly porous for high Solvent Flux permeation, while the outer layer possesses a surface with nano-sized pores that have a sharp size distribution for effective thin film polymerization. The addition of polyvinylpyrrolidone in the outer dope further reduces the pore size, and enhances surface hydrophilicity as well as mechanical strength. The substrate was cross-linked and subjected to interfacial polymerization for fabricating thin-film composite (TFC) membranes. The effects of the substrate properties of various hollow fiber membranes from the SFPS process on the TFC membrane were systematically investigated in terms of morphology and organic Solvent nanofiltration (OSN) performance. The membrane shows a 99.3% rejection of ramazol brilliant blue (MW: 626.54 g mol −1 ) and a methanol Flux of 14.4 l m −2 h −1 at 16 bar.
-
enhancement of Flux and Solvent stability of matrimid thin film composite membranes for organic Solvent nanofiltration
Aiche Journal, 2014Co-Authors: Shipeng Sun, Tai-shung Chung, Sui Yung ChanAbstract:The development of high Flux and Solvent-stable thin-film composite (TFC) organic Solvent nanofiltration (OSN) membranes was reported. A novel cross-linked polyimide substrate, consisting of a thin skin layer with minimum Solvent transport resistance and a sponge-like sublayer structure that could withstand membrane compaction under high-pressure was first fabricated. Then the Solvent Flux was significantly enhanced without compromising the solute rejection by the coupling effects of (1) the addition of triethylamine/camphorsulfonic acid into the monomer solution, and (2) the combined post-treatments of glycerol/sodium dodecyl sulphate immersion and dimethyl sulfoxide (DMSO) filtration. Finally, the long-term stability of the TFC membrane in aprotic Solvents such as DMSO was improved by post-crosslink thermal annealing. The novel TFC OSN membrane developed was found to have superior rejection to tetracycline (MW: 444 g/mol) but was very permeable to alcohols such as methanol (5.12 lm−2h−1bar−1) and aprotic Solvents such as dimethylformamide (3.92 lm−2h−1bar−1) and DMSO (3.34 lm−2h−1bar−1). © 2014 American Institute of Chemical Engineers AIChE J, 60: 3623–3633, 2014
