Membrane, made from commercially-available hollow fibers, is used in reverse osmosis, or dialysis. Fiber has skin layers which pass only small molecules. Macromolecules cannot penetrate skin. Fibers can also be used to remove other undesirable anions, such as phosphate, sulfate, carbonate, and uranium in form of uranium-sulfate complex

Klein, E.

Rembaum, A.

Yen, S. P. S.

English

NASA Technical Reports Server

lime 1975	 B75-10117 
NASA TECH BRIEF 
NASA Pasadena Office 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Improved Ion Exchange Membrane 
.
The problem: 
Existing ion exchange membranes have low 
exchange capacities, are not homogeneous, and have 
relatively-small surface areas. 
The solution: 
An improved ion exchange membrane has been 
made from ion exchange fibers. The new membrane is 
homogeneous and presents a relatively-large surface 
area. 
How it's done: 
The membrane is made from commercially-
available hollow fibers which are used in reverse 
osmosis, or dialysis. A cross section of this fiber is 
shown in the illustration. The fiber has outside and 
inside skin layers which pass only small molecules. 
Macromolecules cannot penetrate the skin.
The fibers are simply impregnated with two 
monomers. The process consists of the spontaneous 
polymerization of 4-vinyl pyridine and similar 
monomers with dihalides. The polymerization pro-
ceeds without the aid of a catalyst or initiator, and the 
resulting polymer is therefore unusually pure. At the 
end of the polymerization, an insoluble cross-linked 
ion exchange resin exists in the walls of the fibers. The 
finished fibers have a high ion exchange capacity, a 
practical wall permeability, and good mechanical 
strength. This principle of polymerization inside of 
small pores can be extended to other materials, such 
as porous ceramic tubes and many types of porous 
membranes. 
The ion exchange capability of the new membranes 
has been demonstrated by utilizing fibers with a 
300-gm outside diameter and a 200-m inside 
diameter. A bundle of 150 fibers 8 in. (20 cm) long 
Outer Skin
Inner kin 
50 prin	 200im
Hollow 
Interstices 
(Holes of the, 
Order of 100 A) 
Ion Exchange Hollow Fiber
(continued overleaf) 
This document was prepared under the Sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
	
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19750000117 2020-03-19T20:05:37+00:00Z
was, assembled. When a K 2Cr04 solution of 10 ppm 
was fed through the core of the above fibers (at the 
rate of 16 cm 3/min) and when the outside of the fiber 
bundle was bathed with a 2 N NaCl solution, the exit 
concentration of dichromate ion was found to be as 
low as 0.7 ppm. In another test with the same 
solutions, 15 liters of a solution containing 10 ppm of 
potassium chromate were passed through the fibers at 
a rate of 3 cm 3/min. The existing solution contained 
0.02 ppm of the chromate. 
The fibers can also be used to remove other 
undesirable anions, such as phosphate, sulfate, 
carbonate, and uranium in the form of a uranium-
sulfate complex. In addition, by the application of 
suitable monomers (e.g., acrylic acid,salts of acrylic 
acid, or monomers containing sulfonic groups), cation 
hollow fibers can also be produced.
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: TSP75-101 17 
Patent status: 
Title to this invention has been waived under the 
provisions of the National Aeronautics and Space Act 
[42 U.S.C. 2457(f)], to the California Institute of 
Technology, Pasadena, California 91109. 
Source: Alan Rembaum, Shiao Ping S. Yen, 
and Elias Klein of
Caltech/JPL
under contract to
NASA Pasadena Office
(NPO-13309)
. 
B 75-10117	
Categories: 04 (Materials) 
05 (Life Sciences)


Improved ion exchange membrane

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