Co-reporter:Baishali Kanjilal, Iman Noshadi, Jeffrey R. McCutcheon, Alexandru D. Asandei, Richard S. Parnas
Journal of Membrane Science 2015 Volume 486() pp:59-70
Publication Date(Web):15 July 2015
DOI:10.1016/j.memsci.2015.03.025
•Novel allylcyclohexylamine functionalized siloxane and phase separated blend.•Superior cost-performance trade off with excellent mechanical integrity.•High 1,3-propanediol flux of 5.5–5.8 g/m2 h.•Solution diffusion modeling indicated minimal concentration polarization.•Hansens parameter estimates indicated polar interactions dominated.This work reports the synthesis of a novel allylcyclohexylamine functionalized siloxane and its phase separated blend with styrene-butyl acrylate copolymer and their application for pervaporative enrichment of 1,3-propanediol from dilute aqueous solutions. The phase separated blend allowed for the recovery of mechanical strength lost due to functionalization without loss in separation performance. Separation factors of 9–15 were achieved with functionalization levels of 50–90%, while 1,3-propanediol flux was 1.5×10−3–1.6×10−3 g/m2-s (5.5–5.8 g/m2-h). Separation efficiency increased with functionalization and decreased with increasing temperature and feed concentration. Solution diffusion model was used to compute the overall mass transfer coefficients, concentration polarization and intrinsic material mass transport properties. The overall mass transfer coefficient for 1,3-propanediol was between 1.0×10−7–1.4×10−7 m/s while the boundary layer mass transfer coefficient ranged from 5×10−7 m/s to 18×10−7 m/s indicating the dominance of the membrane on the transport resistance. A computation of Hansens solubility parameters by a group contribution method was carried out to underscore the results. The membrane, with its good cost/performance tradeoff and excellent mechanical integrity, offers the possibility of fabrication into modules and scale up.
Co-reporter:Baishali Kanjilal;Iman Noshadi;Eddy J. Bautista
Applied Microbiology and Biotechnology 2015 Volume 99( Issue 5) pp:2105-2117
Publication Date(Web):2015 March
DOI:10.1007/s00253-014-6259-5
1,3-propanediol (1,3-PD) was produced with a robust fermentation process using waste glycerol feedstock from biodiesel production and a soil-based bacterial inoculum. An iterative inoculation method was developed to achieve independence from soil and selectively breed bacterial populations capable of glycerol metabolism to 1,3-PD. The inoculum showed high resistance to impurities in the feedstock. 1,3-PD selectivity and yield in batch fermentations was optimized by appropriate nutrient compositions and pH control. The batch yield of 1,3-PD was maximized to ~0.7 mol/mol for industrial glycerol which was higher than that for pure glycerin. 16S rDNA sequencing results show a systematic selective enrichment of 1,3-PD producing bacteria with iterative inoculation and subsequent process control. A statistical design of experiments was carried out on industrial glycerol batches to optimize conditions, which were used to run two continuous flow stirred-tank reactor (CSTR) experiments over a period of >500 h each. A detailed analysis of steady states at three dilution rates is presented. Enhanced specific 1,3-PD productivity was observed with faster dilution rates due to lower levels of solvent degeneration. 1,3-PD productivity, specific productivity, and yield of 1.1 g/l hr, 1.5 g/g hr, and 0.6 mol/mol of glycerol were obtained at a dilution rate of 0.1 h−1which is bettered only by pure strains in pure glycerin feeds.
Co-reporter:Cheng Diao, Hongwei Xia, Iman Noshadi, Baishali Kanjilal, and Richard S. Parnas
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 11) pp:2554
Publication Date(Web):October 9, 2014
DOI:10.1021/sc500425h
Wheat gluten (WG) is reactively blended with a macromolecular cross-linker, polyethylene-alt- maleic anhydride (PEMA), to simultaneously improve strength, stiffness, strain, and reduce water absorption for the first time. FTIR illustrates the cross-linking reaction. An increase in Tg measured by DSC and a decrease in protein extractability measured by SE-HPLC demonstrates an increase in cross-linking as PEMA content increases. The modified WG is thermo-molded into solid bars and tested for flexural properties. The flexural testing results indicate that the maximum strain and stress of the modified WG can be improved by as much as 95% and 120%, respectively. Addition of PEMA to WG lowers the water absorption by as much as a factor of 4 at the same time as improving the mechanical properties. The results are consistent with a single phase, intermolecular, cross-linked morphology. The improvements attained make these blends approach the properties of polystyrene and aerospace grade epoxies.Keywords: Intermolecular cross-linking; Mechanical properties; Polyethylene-alt-maleic anhydride; Water absorption; Wheat gluten
Co-reporter:Cheng Diao, Timothy Dowding, Sudsiri Hemsri, Richard S. Parnas
Composites Part A: Applied Science and Manufacturing 2014 Volume 58() pp:90-97
Publication Date(Web):March 2014
DOI:10.1016/j.compositesa.2013.12.005
The aim of the present work is to fabricate a biodegradable composite with improved mechanical properties and high work to failure by combining toughened wheat gluten matrix with 15 mass% surface treated, highly ductile coconut fiber. Matrix cracking at a flexural stress of 46 MPa in wheat gluten was delayed until nearly 71 MPa in the composite, with ultimate stress greater than 105 MPa. Flexural stiffness was improved from roughly 4 GPa in the wheat gluten to 5.4 GPa in the composite. The work to failure was improved from 0.26 MJ/m3 in wheat gluten to 1.45 MJ/m3 with the toughened wheat gluten, and finally to 4.94 MJ/m3 for the composite. The toughening additive for the wheat gluten was shown to “erase” aging effects in the wheat gluten but also appeared to change the interfacial characteristics.
Co-reporter:Michael Pomykala, James D. Stuart, Iman Noshadi, Richard S. Parnas
Fuel 2013 Volume 107() pp:623-632
Publication Date(Web):May 2013
DOI:10.1016/j.fuel.2012.12.017
A countercurrent liquid/liquid phase biodiesel reactor achieved 99% triglyceride to methyl ester conversion at the same time as separating 90% of the produced glycerin. However, a low inverse sensitivity of the conversion to the glycerin separation efficiency led to biodiesel that did not meet ASTM quality standards in previous work. A distributed methanol injection strategy is demonstrated herein to improve reactor performance, yielding ASTM quality biodiesel and 90% separation efficiencies. Preliminary data on feed rate changes yields counterintuitive results where conversion increases as feed rate increases. A model that assumes equilibrium between the reacting oil phase and the settling glycerol phase simulates the experimental results and provides insight into the reactor behavior.Highlights• Countercurrent liquid/liquid phase biodiesel reactor. • Distributed methanol injection strategy. • Improve reactor performance, yielding ASTM quality biodiesel and 90% separation efficiencies. • A model that simulates the experimental results and provides insight into the reactor behavior.
Co-reporter:Sudsiri Hemsri, Kasia Grieco, Alexandru D. Asandei, Richard S. Parnas
Composites Part A: Applied Science and Manufacturing 2012 Volume 43(Issue 7) pp:1160-1168
Publication Date(Web):July 2012
DOI:10.1016/j.compositesa.2012.02.011
Coconut fiber-reinforced wheat gluten (WG) biocomposites were fabricated. The coconut fibers (CCFs) were chemically modified by either sodium hydroxide or silane treatment, as well as following the alkali surface treatment with a silane treatment. (3-triethoxysilylpropyl)-t-butylcarbamate (carbamate silane), which is a masked isocyanate functional silane, was used for the first time to improve interfacial adhesion between WG and natural fibers. X-ray photoelectron spectroscopy (XPS) and gas chromatography/mass spectroscopy (GC/MS) analyses were employed to prove the presence of the silane on silane-treated coconut fiber (SCCF) and alkali-followed by silane-treated fiber (ASCCF). It was found that ASCCF has more silane content on the fiber surface than SCCF. The mechanical properties of composites with 15 mass% fiber loading were assessed by three-point bending tests. Moreover, scanning electron microscopy (SEM) was used to investigate fracture surface characteristics of composites. The WG/ASCCF composite provided an 80% increase in strength, and showed superior fiber–matrix interfacial adhesion.
Co-reporter:Sudsiri Hemsri, Alexandru D. Asandei, Kasia Grieco, Richard S. Parnas
Composites Part A: Applied Science and Manufacturing 2011 Volume 42(Issue 11) pp:1764-1773
Publication Date(Web):November 2011
DOI:10.1016/j.compositesa.2011.07.032
Two composite systems were explored to assess the effect of particle dispersion on the properties of filled wheat gluten composites. Nanosilica particles and micro-alumina particles were combined with several silane coupling agents by various methods to perform a broad brush survey of chemical and physical interactions. Thermo-gravimetric analysis (TGA) was used to assess surface coverage on coated particles. Electron microscopy (scanning and transmission) techniques were used to assess particle dispersion and surface interactions. Producing the silica particles in the wheat gluten matrix led to better physical properties, as measured by 3-point bending, than producing the silica particles first, and then mixing them into the wheat gluten. Similarly, coating the alumina particles with silane coupling agents in the wheat gluten matrix led to better mechanical properties than first coating the alumina with silane and then mixing the coated particles into the wheat gluten.
Co-reporter:Si-Yu Li, Ranjan Srivastava, Richard S. Parnas
Journal of Membrane Science 2010 Volume 363(1–2) pp:287-294
Publication Date(Web):1 November 2010
DOI:10.1016/j.memsci.2010.07.042
A novel tri-layer composite membrane consisting of the active layer polydimethylsiloxane (PDMS, Sylgard® 184) and dual support layers of high porosity polyethylene (PE) and high mechanical stiffness perforated metal was investigated for the separation of 1-butanol from aqueous solution by means of pervaporation. The experimental data show that total flux and separation factor are both increased by placing a layer of hydrophobic PE between the PDMS and the metal support. The enhancement is especially obvious at low temperatures. With the feed solution of 2% 1-butanol at 37 °C, the PDMS/PE/Brass support composite membrane confers a total flux of 132 g/h/m2 and a separation factor of 32. With the increase of the PDMS thickness, the separation factor increases as the total flux declines. It is suggested that while the water flux remains stable, the 1-butanol flux has linear relationship with respect to the feed concentration of 1-butanol. The overall mass transfer coefficient for butanol was determined to be 6.9E−7 m/s using the resistance-in-series model. Using a semi-empirical Sherwood number correlation, the mass transfer coefficient of 1-butanol through the liquid side boundary layer was estimated to be 25.5E−7 m/s. This is more than 3 times higher than the overall mass transfer coefficient, indicating that the membrane dominates the mass transfer of the pervaporation process.Research highlights▶ Porous polyethylene support improves PDMS membrane performance in pervaporation. ▶ Separation and flux for 1-butanol removal from water both improved over 100% at room temperature. ▶ Enhancement effect of the porous polyethylene increases with decreasing temperature.
Co-reporter:Jing Dong, Alexandru D. Asandei, Richard S. Parnas
Polymer 2010 Volume 51(Issue 14) pp:3164-3172
Publication Date(Web):24 June 2010
DOI:10.1016/j.polymer.2010.04.058
The molecular weight distribution (MWD), rheology and electrospinning of a series of wheat gluten (WG) mixtures with poly(vinyl alcohol) (PVA), dithiothreitol (DTT), and thiolated poly(vinyl alcohol) (TPVA) in water/1-propanol (1/1) were investigated by size-exclusion chromatography, steady-shear viscosity measurements and scanning electron microscopy. Thiolated additives reduce disulfide bonds between protein subunits and thus increase WG solubility. Accordingly, Newtonian behavior is observed for pure components and PVA/WG, and shear-thinning for DTT/WG and TPVA/WG. Concentration, viscosity and additive type affect WG electrospinnability. At higher concentrations, PVA/WG fibers are thicker than WG ones, whereas DTT/WG and TPVA/WG fibers are thinner and beadless. While at low concentrations both DTT/WG and TPVA/WG generate poor fibers, lowering TPVA thiolation level results in better fibers, unobtainable with DTT. Thus, although using only the lower end of the WG MWD, reasonably good fibers can nonetheless be obtained with an inexpensive aqueous system and very low additive amounts.
Co-reporter:Matthew B. Boucher, Clifford Weed, Nicholas E. Leadbeater, Benjamin A. Wilhite, James D. Stuart and Richard S. Parnas
Energy & Fuels 2009 Volume 23(Issue 5) pp:2750
Publication Date(Web):March 27, 2009
DOI:10.1021/ef9000049
The following study presents the first quantitative performance data for a novel laminar flow biodiesel reactor/separator. The reactor ideally achieves high conversion of vegetable oil triglycerides to biodiesel while simultaneously allowing glycerol to phase separate and settle from the reacting flow. The reactor was operated using pretreated waste canola oil as a feedstock; potassium hydroxide dissolved in methanol was used as a catalyst. Reactor performance was assessed by computing conversion of vegetable oil triglycerides to biodiesel as well as subsequent separation of the coproduct glycerol stream. At slightly elevated temperatures (40−50 °C), an overall feed of 1.2 L/min, a 6:1 molar ratio of methanol to vegetable oil triglycerides, and a 1.3 weight % catalyst loading, the reactor was able to achieve greater than 99% conversion of pretreated waste canola oil to biodiesel and remove 70−99% of glycerol produced.
Co-reporter:Matthew B. Boucher, Steven A. Unker, Kyle R. Hawley, Benjamin A. Wilhite, James D. Stuart and Richard S. Parnas
Green Chemistry 2008 vol. 10(Issue 12) pp:1331-1336
Publication Date(Web):04 Nov 2008
DOI:10.1039/B810225B
Global concerns regarding greenhouse gas emissions combined with soaring oil prices have driven the search for renewable diesel fuels derived from either virgin or waste vegetable oils, dubbed “bio-diesels”. A key challenge in the emerging bio-diesel industry is cost-effective pre-treatment of waste vegetable oils to reduce free-fatty acid content prior to transesterification. This article reports, for the first time, recoverability and reusability of hydrochloric and sulfuric acid catalysts for efficient pre-treatment of waste cooking oils for subsequent conversion to bio-diesels. Esterification of omega-9 polyunsaturated fatty acids, particularly 18:2,18:3 linoleic acid with methanol and a homogenous acid catalyst was investigated over a range of fatty acid concentrations. It was determined that greater than 95% by weight of each catalyst was recovered after esterification under all conditions investigated. When recovered methanol was used, containing recovered catalyst and water, it was determined that hydrochloric acid catalyzed esterification exhibits a higher tolerance to water accumulation. After sulfuric acid was recovered and re-used, the observed rate constant decreased more than 50% to a value comparable to that observed for hydrochloric acid at more than three times the water concentration.
Co-reporter:Jing Dong, Rebecca Dicharry, Eleanor Waxman, Richard S. Parnas and Alexandru D. Asandei
Biomacromolecules 2008 Volume 9(Issue 2) pp:
Publication Date(Web):January 16, 2008
DOI:10.1021/bm7011136
The morphology of wheat protein (WG) blends with polyvinyl alcohol (PVA) and respectively with thiolated polyvinyl alcohol (TPVA) was investigated by atomic force (AFM) and transmission electron microscopy (TEM) as well as by modulated dynamic scanning calorimetry (MDSC). Thiolated additives based on PVA and other substrates were previously presented as effective means of improving the strength and toughness of compression molded native WG bars via disulfide−sulfhydryl exchange reactions. Consistent with our earlier results, AFM and TEM imaging clearly indicate that the addition of just a few mole percent of thiol to PVA was sufficient to dramatically change its compatibility with wheat protein. Thus, TPVA is much more compatible with WG and phase separates into much smaller domains than in the case of PVA, although there are still two phases in the blend: one WG-rich phase and another TPVA-rich phase. The WG/TPVA blend has phase domains ranging in size from 0.01 to 0.1 μm, which are roughly 10 times smaller than those of the WG/PVA blend. MDSC further illustrates the compatibilization of the protein with TPVA via the dependence of the transition temperatures on composition.
Co-reporter:Qiang Liu, Richard S. Parnas, Hermione S. Giffard
Composites Part A: Applied Science and Manufacturing 2007 Volume 38(Issue 3) pp:954-962
Publication Date(Web):March 2007
DOI:10.1016/j.compositesa.2006.06.024
The determination of accurate permeability values is critical to process simulations for Resin Transfer Molding (RTM). New instrumentation is presented in this paper for high throughput permeability measurements. The design extends the original work of Hoes [Hoes K. Development of a new sensor-based set-up for experimental permeability identification of fibrous media, PhD thesis, Vrije Universiteit Brussels, Brussels, 2003] with a new sensor design, a much larger sensor pattern, and new analysis software. For example, the new analysis software is more robust than previous versions in that it will compute the flow front orientation angle rather than assume the angle as given by the user. The new set-up was used to measure the permeability of a basalt woven 3/1 twill fabric. When compared with previous work on 2/2 twill and plain woven fabrics, a relationship was observed between the breadth of the anisotropy distribution, the correlation between the principle components of the permeability tensor, and the fabric structure. Such a relationship has implications for manufacturing reliability, and may help explain why some fabrics process much more consistently than others.
Co-reporter:Qiang Liu;Montgomery T. Shaw;Anne-Marie McDonnell
Polymer Composites 2006 Volume 27(Issue 5) pp:475-483
Publication Date(Web):8 AUG 2006
DOI:10.1002/pc.20215
New materials such as basalt fiber offer the promise of innovative applications in transportation because of documented strengths (V. Ramakrishnan, N.S. Tolmare, and V. Brik, “NCHRP-IDEA Program Project Final Report, ” Transportation Research Board, Washington, DC, (1998)). Previously, we found that mechanical properties of basalt twill fabric-reinforced polymer composites were comparable to composites reinforced with glass fabrics of similar structures [Q. Liu, M.T. Shaw, R.S. Parnas, and A.M. McDonnell, Polymer Composites, 27(1), 41 (2006)]. Use in transportation also requires knowledge of environmental durability. This study reports the tolerance of basalt-fiber-reinforced polymer composites to salt water immersion, moisture absorption, temperature, and moisture cycling. Parallel tests were conducted for the corresponding glass-reinforced polymer composites. Aging for 240 days in salt water or water decreased the Young's modulus and tensile strength of basalt composites slightly but significantly (p < 0.05). Freeze-thaw cycling up to 199 cycles did not change the shear strength significantly, but aging in hot (40°C) salt water or water did decrease the shear strength of basalt composites (p < 0.05). The aging results indicate that the interfacial region in basalt composites may be more vulnerable to damage than that in glass composites. POLYM. COMPOS., 27:475–483, 2006. © 2006 Society of Plastics Engineers
Co-reporter:Qiang Liu;Montgomery T. Shaw;Anne-Marie McDonnell
Polymer Composites 2006 Volume 27(Issue 1) pp:41-48
Publication Date(Web):23 DEC 2005
DOI:10.1002/pc.20162
New materials offer the promise of innovative applications in transportation. One such new material is basalt fiber, which is used in other industries because of documented strengths [Ramakrishnan et al., “Performance Evaluation of 3-D Basalt Fiber Reinforced Concrete and Basalt Rod Reinforced Concrete,” NCHRP-IDEA Program Project Final Report, Transportation Research Board, Washington, DC, 1998]. Use in transportation, however, requires a better knowledge of many properties. This article discusses initial work with basalt-reinforced polymer composites. Polymer composites reinforced by basalt fabric and glass fabrics were produced for these tests. Void content below 3% were measured for all the composites produced for the testing program. No significant differences in Young's modulus, tensile strength, flexure strength, shear strength, and compression strength were found between basalt composites and glass composites. Environmental durability testing of basalt composites is ongoing. POLYM. COMPOS. 27:41–48, 2006. © 2005 Society of Plastics Engineers
Co-reporter:Richard S. Parnas;Shawn M. Walsh
Polymer Composites 2005 Volume 26(Issue 4) pp:477-485
Publication Date(Web):30 MAR 2005
DOI:10.1002/pc.20121
A model of the vacuum-assisted resin transfer molding (VARTM) process is developed that includes the most important aspects of the processing physics. The model consists of several submodels, such as preform mechanics, Darcy flow, wicking flow, and void formation. The preform mechanics model treats the preform as a linearly elastic, one-dimensional (1D) solid. However, the key physical process is the lubrication of the preform due to fluid wetting, and this is modeled as a reduction in preform modulus, an easily measurable parameter. Residual stress, three-dimensional (3D) structural behavior, and nonlinearity are neglected, but can all be included. The fluid flow model of capillary wicking is not tacked onto the Darcy equation as a modified boundary condition, as was previously done. The wicking is treated simply, but more realistically, by performing a force balance on the fluid in a pore. Balancing the capillary pressure and the viscous drag allows the development of a wicking front that precedes the main Darcy flow front to an extent that depends on several easily measurable factors. It is this wicking front that is responsible for the small void formation that reduces the quality of VARTM parts, relative to resin transfer molding (RTM) parts. POLYM. COMPOS. 26:477–485, 2005. © 2005 Society of Plastics Engineers
Co-reporter:Richard S. Parnas;Martine Wevers;Ignaas Verpoest
Polymer Composites 2003 Volume 24(Issue 2) pp:212-220
Publication Date(Web):15 APR 2004
DOI:10.1002/pc.10022
The 3-dimensional yarn architecture in a 2-dimensional woven fabric reinforced composite is nonuniform. Many structural features appear that are not obvious from consideration only of the yarn architecture in the single layer textile fabric. A complete set of 3-dimensional image data was acquired for a representative volume of the composite using X-ray micro-computed tomography. Extensive image analysis was, however, necessary to reveal the yarn architecture due to relatively low signal-to-noise ratio and contrast levels relative to optical microscopy of polished cross sections.
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