Method for preparation of water-treatment separation membrane and water-treatment separation membrane prepared thereby
Provided is a method for manufacturing a water-treatment membrane, the method including bringing an aqueous solution including free chlorine and a halogen ion into contact with a polyamide active layer, wherein the free chlorine is present in an amount from 150 ppm to 400 ppm and the halogen ion is present in an amount from 150 ppm to 400 ppm based on the aqueous solution, and a water-treatment membrane manufactured using the same.
1. A method for manufacturing a water-treatment membrane, comprising:
bringing an aqueous solution including free chlorine and one or a combination of sodium bromide, potassium bromide, calcium bromide, magnesium bromide, ammonium bromide, lithium bromide, germanium bromide, cobalt bromide, strontium bromide, cesium bromide, tungsten bromide, copper(II) bromide, barium bromide or hydrogen bromide to yield a bromine ion into contact with a polyamide active layer on a porous polysulfone support for a contact time of from 15 seconds to 30 seconds, wherein an amount of the free chlorine is from 150 ppm to 400 ppm and an amount of the bromine ion is from 150 ppm to 400 ppm based on the aqueous solution;
wherein the water-treatment membrane has a bromine element content of greater than 0 at % and less than or equal to 5 at %, a chlorine element content of greater than 0 at % and less than or equal to 1 at %, and a ratio of the bromine element to the chlorine element (Br/Cl) is from 5:1 to 10:1 when measured using an electron spectroscopy for chemical analysis (ESCA) elemental analysis on a surface of the water-treatment membrane using X-ray photoelectron spectroscopy.
2. The method of claim 1 , wherein the aqueous solution including free chlorine and the bromine ion has a pH of 4 to 11.
3. A water-treatment membrane having a bromine element content of greater than 0 at % and less than or equal to 5 at % when measured using an electron spectroscopy for chemical analysis (ESCA) elemental analysis on a surface of the water-treatment membrane using X-ray photoelectron spectroscopy,
wherein:
the membrane has boron rejection of 93.7% to 96.9% and a salt rejection of 99.90% to 99.96%;
a chlorine element content is greater than 0 at % and less than or equal to 1 at %, and a ratio of the bromine element to the chlorine element (Br/Cl) is from 5:1 to 10:1.
4. A water-treatment module comprising one or more of the water-treatment membranes of claim 3 .
5. A water-treatment system comprising one or more of the water-treatment modules of claim 4 .
6. The method of claim 1 , wherein the membrane has a salt rejection of 99.90% to 99.96%.
7. The method of claim 1 , further comprising drying a surface of the polyamide active layer after the polyamide active layer is brought into contact with the aqueous solution containing free chlorine and a bromine ion to produce a dried polyamide active layer.
8. The method of claim 7 , further comprising forming a protective layer by coating a protective layer composition comprising a hydrophilic material onto the dried polyamide layer.