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United States Department of Agriculture

Agricultural Research Service

Title: Stability of Ion Exchange Resin under Freeze Thaw Or Dry-Wet Environment

Authors
item Mamo, Martha - UNIV OF NE/LINCOLN
item Ginting, Daniel - UNIV OF NE/LINCOLN
item Renken, Roger - UNIV OF NE/LINCOLN
item Eghball, Bahman

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 1, 2003
Publication Date: March 1, 2004
Citation: MAMO, M., GINTING, D., RENKEN, R., EGHBALL, B. STABILITY OF ION EXCHANGE RESIN UNDER FREEZE- THAW OR DRY-WET ENVIRONMENT. SOIL SCIENCE SOCIETY OF AMERICA JOURNAL 68:677-681. 2004.

Interpretive Summary: Ion exchange resins have been used to measure nitrogen (N) mineralization of organic materials in the soil. Nitrogen mineralization is an indicator of how much soil N is becoming plant available. However, the stability of resins that are used to measure nitrate, ammonium, or phosphate ions under changing physical environmental conditions is not well known. Our objective was to evaluate N and P adsorption or desorption (release) characteristics of resins exposed to freeze-thaw or dry-wet cycles. Resins were subjected to 0, 1, and 30 freeze-thaw or dry-wet cycles. To accomplish the dry-wet cycles, fresh resin was kept in forced-air oven at 81 oF for 28 hours and rewetted to initial moisture condition for 20 hours. To accomplish freeze-thaw cycle, fresh resin was frozen for 16 hours and thawed to room temperature for 8 hours daily. At the end of the freeze-thaw or dry-wet cycles, resin was equilibrated with 45 ppm ammonium, 45 ppm nitrate, or 30 ppm phosphate solutions for a period of one hour. Under each dry-wet cycle or freeze-thaw cycle, nitrate was four to five times more adsorbed to the resin than phosphate. Dry-wet cycles induced desorption of N and P associated with shrinkage of resins and expulsion of interstitial liquid. The desorption of phosphate, ammonium, and nitrate at the highest dry-wet cycle were 2.7%, 0.2%, and 0.1%, respectively. Freeze-thaw cycles had no effects on N and P adsorption or desorption characteristics of resins. Dry-wet cycles did not affect the N and P adsorption, but increased N and P desorption.

Technical Abstract: Ion exchange resins have widely been used in mineralization studies of organic materials. However, the stability of resin (anionic and cationic) under changing physical environmental conditions is not well known. Our objective was to evaluate N and P adsorption or desorption characteristics of resins exposed to freeze-thaw or dry-wet cycles. Mixed bed resins (1:1 strong base anion A464-D and strong acid cation C-249) were subjected to 0, 1, and 30 freeze-thaw or dry-wet cycles. To accomplish the dry-wet cycles, fresh resin was kept in forced-air oven at 27 oC for 28 h and rewetted to initial moisture condition for 20 h. To accomplish freeze-thaw cycle, fresh resin was frozen for 16 h and thawed to room temperature for 8 h daily. At the end of the freeze-thaw or dry-wet cycles, resin was equilibrated with 45-mg L-1 NH4, 45-mg L-1 NO3, or 30- mg L-1 PO4 for a period of one h. Under each dry-wet cycle or freeze-thaw cycle, NO3 was four to five times more adsorbed to the resin than PO4. Dry-wet cycles induced desorption of N and P associated with shrinkage of resins and expulsion of interstitial liquid. The desorbed PO4, NH4, and NO3 at the highest dry-wet cycle were 2.7%, 0.2%, and 0.1%, respectively. Scanning electron microscopy revealed that the dry-wet or freeze-thaw cycles did not alter the physical integrity of these resins. Freeze-thaw cycles had no effects on N and P adsorption or desorption characteristics of resins. Dry-wet cycles did not affect the N and P adsorption, but increased N and P desorption.

Last Modified: 12/18/2014
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