Equilibrium Isotherms of Water and Ethanol Vapors on Starch Sorbents and Zeolite 3A

Wang, Kuan-Shyang; Liao, Chien-Chih; Chu, Richard Q.; Chung, Tsair-Wang

doi:10.1021/je100118p

Cited by 12 publications

(8 citation statements)

References 18 publications

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“…These factors contribute to the swelling and solvent selectivity of starch biopolymers, however, a detailed understanding of the role of cross-linking on the structure and function of these materials is the subject of ongoing and future work. The greater R selectivity observed herein for starch and its modified forms finds additional support reported elsewhere. , Physicochemical properties of the solvent such as the relative size and polarity of water and ethanol are key factors that influence the uptake of water over ethanol observed for starch-based materials. The offset in molar volume ( V m ) of water ( V m = 18 cm 3 /mol) and ethanol ( V m = 58.0 cm 3 /mol) and the difference in relative polarity (H 2 O, 16 D; and C 2 H 5 OH, 8.8 D) contribute to the observed fractionation properties and provide insight into the kinetic and thermodynamic adsorption properties of starch materials.…”

Section: Resultssupporting

confidence: 86%

“…The greater R selectivity observed herein for starch and its modified forms finds additional support reported elsewhere. 43,44 Physicochemical properties of the In general, starch shows greater uptake selectivity toward water over ethanol according to the greater accessibility of polar (−OH) groups of starch. Cellulose materials have reduced accessibility of polar groups due to more extensive intra-and intermolecular hydrogen bonding, owing to its fibril morphology and lower water solubility.…”

Section: Energy and Fuelsmentioning

confidence: 99%

“…The variable R selectivity values for starch materials at different cross-linker content account for the variation in hydrophobic character inferred for such materials. 44 Cross-linkers alter the relative hydrophobicity of starch biopolymers by decreasing the net number of hydroxyl groups and presence of chain branching. 45 The stabilizing effect of hydrogen bonding with water and ethanol differ according to the level of cooperative interactions due to the structured nature of each solvent.…”

Section: Energy and Fuelsmentioning

confidence: 99%

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NMR Investigation of the Fractionation of Water–Ethanol Mixtures with Starch and Its Cross-Linked Forms

Dehabadi

Wilson

2016

Energy Fuels

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The development of low-cost materials and efficient methods for the fractionation of water and ethanol in binary mixtures is of great interest for food processing and biofuels production. Herein, we report a systematic study of a series of linear and branched starch-based biopolymers along with their modified forms via cross-linking with epichlorohydrin (EPI) at variable EPI composition. The fractionation properties of these adsorbent materials were studied in binary ethanol−water solutions and compared against those of neat solvents. 1 H NMR spectroscopy was used to assess the binary solvent composition for the study of isotherms for the respective solvent components. The monolayer adsorption capacity (Q m ) for starch and its cross-linked forms varied from 0.01 to 2.70 g•g −1 for water and ethanol in binary mixtures according to the Sips isotherm model. The fractionation selectivity [R selectivity ; Q m (W)/Q m (E)] of starch-EPI adsorbents for water (W) and ethanol (E) in binary mixtures ranges from 3.8 to 80. At saturative conditions in binary W−E mixtures, the R selectivity isotherm parameter reveals unique solventselective uptake that depends on the amylose versus amylopectin composition and the EPI content of these cross-linked materials. The unique water uptake properties of starch and its cross-linked forms illustrate the role of textural properties and relative hydrophobic character of the polymer network based on the selective adsorption properties. Starch and its modified forms represent a promising class of adsorbent materials and a sustainable technology for the adsorptive-based fractionation of W−E binary mixtures.

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Section: Resultssupporting

confidence: 86%

Section: Energy and Fuelsmentioning

confidence: 99%

Section: Energy and Fuelsmentioning

confidence: 99%

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NMR Investigation of the Fractionation of Water–Ethanol Mixtures with Starch and Its Cross-Linked Forms

Dehabadi

Wilson

2016

Energy Fuels

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“…Only a few water adsorption isotherm data sets for 3A are reported in the literature. − Most well accepted data are published by commercial manufacturers such as Union Carbide and Grace Davison for their products. Recently Lin et al measured water adsorption on the UOP 3A beads at 25, 40, 60, and 80 °C using a continuous-flow adsorption system.…”

Section: Introductionmentioning

confidence: 99%

Measurements and Modeling of Water Adsorption Isotherms of Zeolite Linde-Type A Crystals

Wang

2020

Ind. Eng. Chem. Res.

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A systematic study of water adsorption isotherms of zeolite 3A and 4A crystals over a pressure range of 10 −5 to 10 −1 bar and temperatures from 25 to 250 °C was carried out. This work focuses on water isotherms of 3A and 4A zeolite crystals, not pelletized zeolites containing binders. Zeolite 3A crystals show approximately 12% less swing working capacity for partial pressure swing processes at room temperature for deep dehydration, when compared to 4A crystals. However, the 3A crystal can be regenerated at a lower temperature than the 4A crystal. The 4A crystal has a steeper water isotherm and higher heat of adsorption at zero coverage than 3A. Our results on 3A and 4A crystals are compared to literature data for pelletized 3A and 4A zeolites which contain binders. A new triple-site Langmuir model has been proposed and provides a satisfactory description when compared to other models, such as the Toth model and dual-site Langmuir model. The triple-site Langmuir model is consistent with the Linde-Type A crystal having three different sites for water adsorption. The improvement in fitting is significant in the region where water loadings approach a maximum. This new model was also successfully applied to existing literature data sets for the water isotherm at multiple temperatures for 3A and 4A beads. These results provide fundamental water isotherms and a simple model to evaluate 3A and 4A in deep dehydration with temperature-swing, or partial pressure-swing adsorption processes, or their combination using nontraditional monolith contactors.

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“…Sowerby and Crittenden investigated the effect of type A zeolites, such as 3A, 4A, 5A, and 10A, which are used for bioethanol purification adsorption [17]. Meanwhile, Wang et al compared type 3A zeolites with bio-based adsorbents [18]. In addition, some researchers conducted an investigation using NaZSM-5 type zeolites [19], silicalite [20], natural clinoptilolite [21], and several types of Linde type A (LTA), faujasite (FAU), and mordenite (MOR) [14].…”

Section: Introductionmentioning

confidence: 99%

Structured Polyvinyl Alcohol/Zeolite/Carbon Composites Prepared Using Supercritical Fluid Extraction Techniques as Adsorbent for Bioethanol Dehydration

Laksmono

Sudibandriyo

Saputra

et al. 2019

International Journal of Chemical Engineering

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Introduction. Adsorption is a purification process with a more efficient energy level than others. Adsorption performance is strongly influenced by the ability of the adsorbent to be used; therefore, the modification of the adsorbent becomes a very important key for the purification process that occurs. Methods. In this study, the preparation of composite adsorbents was carried out by combining polyvinyl alcohol (PVA), zeolite (Zeo), and activated carbon (AC) as precursors. The crosslinking process was fulfilled by adding glutaraldehyde to the precursor mixtures followed by a supercritical fluid CO2 extraction (SFE) technique to create conditions for the crosslinking process. The composites were analyzed using Braunner–Emmet–Teller (BET) surface area analysis, Fourier-transform infrared (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy with energy dispersive X-ray (SEM/EDX-mapping), while individual and composite adsorbents were evaluated for their ability in bioethanol dehydration at various initial concentrations of ethanol and temperature. Results. The BET characterization shows that composite preparation under supercritical CO2 conditions provides reasonable surface areas, which are proportional to the content of activated carbon. The crosslinking process has been described by FTIR data interpretation, showing that PVA and glutaraldehyde were properly distributed on Zeo and AC precursors. The DSC characterization results give information that PVA successfully forms hydrophilic composites within Zeo and AC. The SEM micrograph analysis shows the formation of pores on the surface and cross section in structured adsorbents. The experimental adsorption shows that an increasing amount of AC in the composites increases the capacity of water adsorption (i.e., 0.80 gram of water/gram of adsorbent for PVA/Zeo/AC = 1 : 1 : 1 at 22°C). However, the effect is not significant when the ratio of AC is less than 0.5. As expected, the lower temperature increases the adsorption capacity. Further, by using approximately 4.5 gram adsorbents composite in 30 ml of water-ethanol mixtures, high concentration of bioethanol (>99%) can be achieved at various temperatures from 22°C to 40°C and bioethanol initial concentration from 88% to 96%. Conclusion. The SFE technique provides distinguished adsorbents composite properties. Further, the new composites provide about four times better adsorption capacity than that showed in the individual adsorbents test. The addition of AC influences on increasing the capacity and adsorption kinetics value.

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Equilibrium Isotherms of Water and Ethanol Vapors on Starch Sorbents and Zeolite 3A

Cited by 12 publications

References 18 publications

NMR Investigation of the Fractionation of Water–Ethanol Mixtures with Starch and Its Cross-Linked Forms

NMR Investigation of the Fractionation of Water–Ethanol Mixtures with Starch and Its Cross-Linked Forms

Measurements and Modeling of Water Adsorption Isotherms of Zeolite Linde-Type A Crystals

Structured Polyvinyl Alcohol/Zeolite/Carbon Composites Prepared Using Supercritical Fluid Extraction Techniques as Adsorbent for Bioethanol Dehydration

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