Functionalized PU Foam for Water Filtration

Authors: Nidal H. Abu-Zahra, Subhashini Gunashekar

Abstract:

Polyurethane foam is functionalized with Sulfonic acid groups to remove lead ions (Pb²⁺) from drinking water through a cation exchange process. The synthesis is based on addition polymerization of the -NCO groups of an isocyanate with the –OH groups of a polyol to form the urethane. Toluene-diisocyanateis reacted with Polypropylene glycol to form a linear pre-polymer, which is further polymerized using a chain extender, N, N-bis(2-hydorxyethyl)-2-aminoethane-sulfonic acid (BES). BES acts as a functional group site to exchange Pb²⁺ ions. A set of experiments was designed to study the effect of various processing parameters on the performance of the synthesized foam. The maximum Pb²⁺ ion exchange capacity of the foam was found to be 47ppb/g from a 100ppb Pb²⁺ solution over a period of 60 minutes. A multistage batch filtration process increased the lead removal to 50-54ppb/3g of foam over a period of 90 minutes.

Keywords: Adsorption, Functionalized, Ion exchange, Polyurethane, Sulfonic.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1091890

References:

[1] R L MacBrayer, D C Wysocki, Polyurethane Foams Formulation and Manufacture, Program Division, Technomic Publishing Company, Incorporated, 1998, 347 pages.
[2] T Braun and A B Farag, "Polyurethane foams and microspheres in analytical chemistry: Improved Liquid–Solid, Gas-Solid and Liquid-Liquid contact via a new geometry for the solid phase”, Anal chemacta, 1978, 99(1), 1-36
[3] J.G.A. Terlingen, Introduction of functional groups at polymer surfaces by Glow discharge techniques, Europlasma tech paper, Ch 2
[4] K H Yeon, J W Lee, J S Lee, S H Moon, "Preparation and characterization of cation-exchange media based on flexible polyurethane foams”, J ApplPolymSci, 2002, 86, 1773–1781
[5] Lemos VA, Santos LN, Alves AP, David GT, "Chromotropic acid-functionalized polyurethane foam: A new sorbent for on-line preconcentration and determination of cobalt and nickel in lettuce samples”, J Sep Sci. 2006 Jun;29(9):1197-204
[6] David Fournier, Bruno G. De Geest, Filip E. Du Prez, "On-demand click functionalization of polyurethane films and foams”, Polymer, Vol. 50, Issue 23, 3 November 2009, Pages 5362-5367,
[7] Krupadam RJ, Khan MS, Das S, "Adsorption of fluoride from water by surface-functionalized polyurethane foam”, Water Sci Technol. 2010;62(4):759-65. doi: 10.2166/wst.2010.190
[8] E. A. Moawed, M. A. A. Zaid, M. F. El-Shahat, "Analytical application of polyurethane foam functionalized with quinolin-8-ol for preconcentration and determination of trace metal ions in wastewater”, J of Anal Chem, September 2006, Volume 61, Issue 5, pp 458-464
[9] E. A. Moawed, M. A. A. Zaid, M. F. El-Shahat, "Preparation, characterization and applications of polyurethane foam functionalized with resorcinol for quantitative separation and determination of silver(I) and mercury(II) from tap and wastewater”, Intl J of Envi Anal Chem, Volume 84, Issue 12, 2004
[10] G A Meligi, "Removal of Some Heavy Metal Ions Using Grafted Polyurethane Foam”, Polym-PlastTechnol, 2008, 47: 106–113
[11] S H Jang, B G Min, Y G Jeong, W S Lyoo, S C Lee, "Removal of lead ions in aqueous solution by hydroxyapatite/polyurethane composite foams”, J Hazard Mater, 2008, 152(3), 1285-92
[12] H Sone, B Fugetsu, S Tanaka, "Selective elimination of lead(II) ions by alginate/polyurethane composite foams”, J Hazard Mater, 2009, 162(1), 423-9
[13] Understanding Chain Extenders and Crosslinkers, SpecialChem - Jul 21, 2004
[14] M Szycher, Szycher's Handbook of Polyurethanes, CRC Press, 1999, 1126 pages.
[15] G Saunders and B MacCreath, Application Note, "Materials Testing and Research”, Polymers, http://www.chem.agilent.com/Library/brochures/ 5990-7994-GPCorganics-Apr11-9lo.pdf (accessed April 2013)
[16] C E Harland, Ion exchange: theory and practice, 2nd Ed. Royal Society of Chemistry, 1994, 285 pages.
[17] C S P Sung, N S Schneider, "Infrared studies of hydrogen bonding in toluene diisocyanate based polyurethanes”, Macromolecules, 1975, 8, 68-73
[18] AAneja, G L Wilkes, "On the issue of urea phase connectivity in formulations based on molded flexible polyurethane foams”, J ApplPolymSci, 2002, 85, 2956-2967.