Claims
- 1. A method for preparing polymeric membranes of high urea and salt rejection characteristics, which comprises:
- generating a plasma of ethylene and nitrogen in an RF field having a power within the range of about 15 to about 35 watts;
- forming a polymeric membrane by depositing a polymer of ethylene from said plasma onto a substrate, such that nitrogen from the nitrogen gas is incorporated within the polymer in a chemically combined form.
- 2. The method of claim 1, wherein said unsaturated hydrocarbon monomer is an alkene, an alkyne, a cyclic or heterocyclic compound.
- 3. The method of claim 1, wherein the flow rate of nitrogen into said plasma ranges from 1 to 2 cc (STP)/min.
- 4. The method of claim 1, wherein the flow rate of said unsaturated monomer into said plasma ranges from 1 to 2 cc (STP)/min.
- 5. The method of claim 1, wherein the power of the RF field which generates said plasma is 15 watts.
- 6. The method of claim 1, wherein the pressure of said unsaturated monomer ranges from 0.1 to 0.4 torr and the pressure of said nitrogen ranges from 0.1 to 0.4 torr.
- 7. The method of claim 1, wherein said nitrogen and unsaturated monomer are mixed prior to entry into said plasma.
- 8. The membrane of claim 7, wherein said polymeric material contains 15 to 22 wt % nitrogen.
- 9. The method of claim 1, wherein said plasma is created by an internal capactively coupled discharge at a radio frequency of 13.56 MHz.
- 10. A reverse osmosis membrane containing nitrogen in chemically combined form prepared by the process of claim 1.
- 11. A process for purifying aqueous wastes containing salt and urea, which comprises:
- subjecting said aqueous waste to reverse osmosis over a membrane prepared by the process of claim 1.
- 12. An apparatus for the plasma activated polymerization of unsaturated monomers in the presence of nitrogen, which comprises:
- a glass cross reactor comprising four glass tubes, wherein an open end of each tube is joined to form a common center for all four tubes;
- a pair of electrodes disposed within said reactor each through one of the four tubes of the reactor and sealed from the external environment of the reactor and coupled to a radio frequency source so as to generate a plasma within the reactor;
- means for introducing and controlling the inflow of a gaseous mixture of an unsaturated monomer and nitrogen into the reactor through an unoccupied sealed tube of the reactor;
- means for evacuating the glass cross reactor; and
- means for controlling the pressure of the gaseous mixture within the reactor, wherein said evacuating and controlling means are attached to said reactor through the remaining tube of the reactor.
- 13. The apparatus of claim 12, wherein one of said electrodes functions as a support within the reactor for collecting said polymerized material and is at ground potential.
- 14. The apparatus of claim 12, wherein said plasma is created by a radio frequency of 13.56 MHz.
- 15. The apparatus of claim 12, wherein said pressure control means is a throttling valve.
- 16. The apparatus of claim 12, wherein each of said electrodes is a 9 cm O.D. copper electrode.
- 17. The apparatus of claim 12, wherein said means for introducing and controlling a gaseous mixture into said reactor is a sequence of a shut off valve, a mass flow tranducer and flow control valve each in a line from a source of nitrogen and unsaturated monomer which lines are joined together prior to entry into said reactor to mix said nitrogen and unsaturated monomer.
ORIGIN OF THE INVENTION
The invention described herein was made by employees of the U.S. Government and may be manufactured and used by or for the Government for Governmental purposes without the payment of any royalties thereon or therefor.
US Referenced Citations (6)