DOWEX Resins for Separation of Nitrogen from Liquid or Vapor

 
Nitrogen - N
Elemental Nitrogen, as the gas, makes up more than 78% of the Earth's atmosphere. Nitrogen is also the primary building block for several classes of chemical compounds that can be manipulated with ion exchange resins. In industry, nitrogen plays its largest role in the form of ammonia, which is the feedstock for the production of many useful compounds such as nitric acid, the nitrates, and thiocyanates.

Applications

Potable Water: Nitrate and nitrite are the more common nitrogen contaminants of drinking water. Since anion exchange resins are generally more selective for sulfate over nitrate, the capacity of a resin for nitrate removal will be limited by the concentration of sulfate. If the ratio of sulfate to nitrate is low, a high capacity resin like DOWEX™ 1 is recommended. If the ratio of sulfate to nitrate is high, a nitrate selective resin should be considered like DOWEX NSR-1 resin. The highest affinity for nitrate is achieved with DOWEX PSR-3, a Tributylamine, strong base, macroporous anion exchange resin. This high affinity comes at the cost of requiring more regenerant chemicals.

DOWEX resins, coupled with Dow's exclusive UPCORE™ process technology to minimize regenerant brine waste, provide an excellent way to address today's nitrate removal challenges.

If you have a commercial nitrate removal application, please Contact Us via the link on this page. Please include information about your particular nitrate removal application.

Waste Water: The common ionic forms of Nitrogen are the oxidized species of nitrate (NO3-) and nitrite (NO2-) and the reduced species of ammonia (NH4+). Other Nitrogen compounds such as amines, amino acids, and heterocyclic amines can be removed with ion exchange resins.

Nitrate and Nitrite are anions that can be removed with an anion exchange resin. When these anions are present as acids, they can be most efficiently removed from solution with a weak base anion exchange resin like DOWEX M-43 resin, an acid absorber. When nitrate and nitrite are present as salts, they can be removed with a strong base Type I anion exchange resins like DOWEX 21K XLT and DOWEX 1 resins or strong base Type II anion exchange resins like DOWEX MARATHON™ A2 or DOWEX SAR resins according to their selectivity coefficients. Both Type I and II anion resins can strip nitrates from a stream, but the Type II resin is easier to elute and regenerate than the Type I resin. Regeneration for a Type II resin in this application can be accomplished using a brine solution.

Ammonia acts like a cation when it is protonated so it can be removed from air and liquids with a strong acid cation exchange resin or a weak acid cation exchange resin. A weak acid cation exchange resin like DOWEX MAC-3 cation exchange resin will only work when the ammonia is present as the free base, not a salt. Under these conditions, DOWEX MAC-3 resin is preferred due to its higher capacity and higher regeneration efficiency. When ammonia is present as a salt, a strong acid cation resin is needed to split the salt. Our product recommendation here is DOWEX G-26 (H) resin as a tough and versatile cation exchanger.

Primary, secondary and tertiary amines can be protonated to become cations which can be removed with a strong acid cation exchange resin like DOWEX G-26 (H) resin but it must be used in the H form.

Quaternary amines are already cationic and readily removed with DOWEX G-26 (H) resin. Heterocyclic amines can be similarly treated.

Amino Acids and Peptides are a special focus for Dow so a section is devoted to this topic in the Biotech / Pharma and Fine Chemicals.

Gas: Since N2 gas is often used in a compressed form, it is often contaminated with compressor lubricants. DOWEX OPTIPORE™ Polymeric Adsorbents have been shown to work well to remove these compressor lubricants from compressed gas streams. For more information, please go to VOC Control with Polymeric Adsorbents.

DOWEX Ion Exchange Resins

Product Description Type Matrix Total
Exchange
Capacity*
eq/l (kgr/ft3)		 Available
Forms
DOWEX 1 High capacity strong base anion exchange resin. Type I Strong Base Anion Styrene-DVB, Gel 1.4 (30.6) Cl-
DOWEX NSR-1 A strong base, nitrate selective, anion exchange resin. Triethylamine Strong Base Anion Styrene-DVB, Macroporous 0.9 (19.7) Cl-
DOWEX PSR-3 A strong base anion exchange resin designed for the selective removal of trace contaminants from potable water. Tri-n-butyl Amine Styrene-DVB, Macroporous 0.6 (13.1) Cl-
DOWEX M-43 Corrosion control with DOWEX M-43 ion exchange resin. Weak Base Anion Styrene-DVB, Macroporous 1.55 FB (Free Base) form
DOWEX 21K XLT Uniform particle size, high capacity, strong base anion exchange resin for mineral processing applications. Type I Strong Base Anion Styrene-DVB, Gel 1.4 Cl-
DOWEX MARATHON A2 An efficient, uniform particle size, high capacity, Type II strong base anion exchange resin for demineralization applications. Type II Strong Base Anion Styrene-DVB, Gel 1.2 (26.2) Cl-
DOWEX SAR A high capacity, type II strong base anion exchange resin for potable water applications. Type II Strong Base Anion Styrene-DVB, Gel 1.4
DOWEX MAC-3 A macroporous weak acid cation exchange resin used for water softening, dealkalization, and demineralization applications. Weak Acid Cation Polyacrylic, Macroporous 3.8 (83.0) H+
DOWEX G-26 (H) Uniform particle size strong acid cation exchange resin for specialty demineralization and catalyst applications. Strong Acid Cation Styrene-DVB, Gel 2.0 H+


References

"Removal of oil from compressed gas with macroporous polymeric adsorbents" Bowman, R.H. and Goltz, H.R. US Patent 5,700,310 December 23, 1997.


®™* Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow