Article

Ethoxylated polyethylenimine gel‐coated on textile‐grade acrylic fiber. A thermally regenerable superfast sorbent for water desalination

Journal of Applied Polymer Science (Impact Factor: 1.4). 07/2004; 93(2):883 - 893.

ABSTRACT A commercial acrylic fiber containing 92 wt % acrylonitrile was hydrolyzed to convert a part of its nitrile (CN) groups to carboxylic acid (COOH) groups and then was coated chemically with 80% ethoxylated polyethylenimine (EPEI) resin, followed by crosslinking with glutaraldehyde. The resulting sorbent, PAN(CO2H)(EPEI.XG), containing carboxylic acid groups and weakly basic tertiary amine groups in close proximity on the same fiber is found to simulate the well-known Sirotherm™ resins used for partial desalination of brine solution by adsorbing the salt at ambient temperature and desorbing it at an elevated temperature in the same solution. The sorption behavior of the new sorbent was evaluated for solutes NaCl and MgCl2, showing saturation capacities of 0.797 and 0.877 meq/g (dry) sorbent fiber, respectively, at 30°C. The equilibrium sorption data show good agreement with both Langmuir and Freundlich isotherms for sorption from single-component solutions and with Butler–Ockrent and LeVan–Vermeulen models for bicomponent sorption. Although the equilibrium uptake of NaCl reaches maximum in neutral solutions (pH ∼ 6.5), falling at both lower and higher pH, that of MgCl2 is augmented in alkaline pH due to additional sorption by cation exchange at the ionic sites formed at higher pH. The initial uptake of the salt, which is nearly instantaneous, exceeds the sorption value attainable at equilibrium. The high initial rate of salt uptake fits a shell-core kinetic model for sorption on fiber of cylindrical geometry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 883–893, 2004

0 Bookmarks
 · 
172 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Interpenetrating polymer networks (IPNs) comprising weakly acidic and weakly basic cross-linked polymers, namely, poly(acrylic acid-co-ethyleneglycol dimethacrylate) (XPAA) and 80% ethoxylated polyethyleneimine (EPEI) cross-linked with glutaraldehyde, were prepared by the copolymerization of acrylic acid (AA) and ethyleneglycol dimethacrylate by a free-radical method, in the presence of calculated amounts of EPEI in methanol solution, followed by cross-linking with glutaraldehyde. The resulting IPNs, containing carboxylic acid groups and weakly basic tertiary amine groups in close proximity in the same resin bead, exhibited thermally regenerable desalination properties [e.g., sorption of salt at 30 °C and desorption at higher temperatures (80 °C)], simulating the behavior of the well-known Sirotherm resins. For NaCl and MgCl2, the maximum equilibrium sorption (0.5 mmol/g of dry resin in 0.1 M salt solution) was exhibited by an IPN with a carboxylic-to-amine (C/A) mole ratio in the range of 3−5. The equilibrium sorption at 30 °C for NaCl and MgCl2 on an IPN sorbent with a C/A mole ratio of 4.2 (referred to as Sirosorb) fitted well to both the Langmuir and Freundlich isotherms for single-component sorption and the Butler−Ockrent and Jain−Snoeyink models for bicomponent sorption. Containing both carboxylic and amine groups largely in a free state, Sirosorb exhibited buffer action over a wide range of feed solution pH values (3−8) to give nearly constant sorption of NaCl, although the sorption of MgCl2 increased with increasing pH because of additional sorption by ion exchange at the ionic sites formed by neutralization of the carboxylic acid groups. The sorption rate data showed characteristics of particle diffusion control with a NaCl and MgCl2 diffusivity ratio of 2:1, yielding diffusivity values of (2.5−3.9) × 10−7cm2/s for NaCl and (1.2−1.7) × 10−7cm2/s for MgCl2 in the initial period at 30 °C, with the diffusivity falling abruptly in both cases at higher conversion. Continuous column operation performed with Sirosorb showed that the quantity of potable water with a NaCl content of less than 1500 mg/L that can be produced is about 4 times the weight (dry) of the resin, when the influent brackish water has a NaCl content of 3000 mg/L. The used resin was regenerated with 1 M NaCl solution at 90 °C and used repeatedly with no apparent loss of capacity, as demonstrated in the present work for up to 10 cycles of operation.
    Industrial & Engineering Chemistry Research 07/2010; 49(16). · 2.24 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Ion exchange processes are widely used in the food, bioprocessing and related industries for the isolation of proteins and other ionic species. Traditional ion exchange resins require salts, acids or bases for releasing adsorbed molecules creating a strong saline waste stream with negative environmental and economic impact. Stimuli responsive polymers (SRPs) with ion exchange functional groups can be used to selectively capture and release charged molecules from a complex mixture using physical stimuli to trigger conformational transitions in the polymer. The structural change of the polymers in response to a stimulus may lead to reduced ligand-target molecule interaction resulting in the release of the captured molecule without the use of chemical reagents, thereby reducing the environmental burden associated with ion exchange processes. The use of temperature responsive polymers has already been demonstrated for such applications at analytical scale. However, little progress has been made to extend these discoveries to the development of materials and methods amenable to industrial scale processing. So far, other SRPs such as, electric, magnetic and light responsive polymers remain largely unexplored for such application. This article discusses the potential of temperature responsive and other SRPs for developing sustainable ion exchange processes. It also highlights the material science and engineering challenges that need to be overcome to bring such processes to industrial application.
    Food and Bioproducts Processing 04/2014; · 2.29 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Polymer-supported Schiff base complexes of metal ions show high catalytic activity in comparison to their unsupported analogues. The catalytic activity of metal complexes of different types of Schiff base was analyzed and presented in this review. The manganese(III) Schiff base complexes exhibited high catalytic activity in the oxidation of alkenes and alkanes both in homogeneous and heterogeneous conditions. Similarly, the Schiff base complexes of iron(III), cobalt(II), nickel(II), copper(II) and zinc(II) ions have been used as catalysts in the epoxidation of cyclohexene and oxidation of phenol. Polymer-supported iron(III) Schiff base complexes have demonstrated higher activity than unsupported and polymer-supported Schiff base complexes of other metal ions. Similarly, the polymer-supported salen complexes of ruthenium(III), iron(III) and Schiff base complexes of molybdenum carbonyls have been used successfully as catalysts in the oxidation of cyclo-octene. The oxidation of styrene, limonene, stilbene, benzene and its alkyl derivatives, adamantane, benzyl alcohol, etc. was catalyzed significantly by polymer-supported Schiff base complexes of different metal ions. The recyclability of polymer-supported Schiff base complexes has also been evaluated and presented in this review. The thermal and moisture stability of polymer-supported Schiff base complexes is responsible for their high activities in reactions involving high temperatures.
    Coordination Chemistry Reviews 07/2009; 253(13):1926-1946. · 12.10 Impact Factor

Full-text (2 Sources)

Download
9 Downloads
Available from
Sep 2, 2014