Comparative ease of separation of mixtures of selected nuisance anions (nitrate, nitrite, sulfate, phosphate) using Octolig®

Abstract

Mixtures of sodium salts of nitrate, nitrite, sulfate, and phosphate were prepared in relative amounts present in atomic waste containers with a view to effect removal by chromatography over Octolig®, commercially available material with polyethylenediamine moieties covalently attached to high-surface area silica gel. Separation was attempted using aqueous solutions and column chromatography with Octolig®. It is presumed that this material is capable of removing the anions by means of encapsulation. Matrix effects were tested by varying the relative concentrations. Rates of elution were varied 5-fold without adverse effect. The order of selectivity was found to be phosphate > sulfate > nitrite > nitrate through experiments altering the volume and relative concentrations. Quantitative removal of all anions (375 ppm of each) could be achieved given reasonable volumes of Octolig®. An effort at regeneration by altering the pH of the eluant indicated the stability of the encapsulated anions.

Keywords:

• Nuclear wastes
• nitrite
• nitrate
• sulfate
• phosphate
• Octolig®
• separation

Acknowledgments

The authors acknowledge the cooperation of the Department of Chemistry REU Program, Dr. Patricia Muisener, Director. We are grateful for the support of Dr. Naomi Yavneh, Director, Undergraduate Research Office, USF Honors College. We thank the reviewers for helpful comments.

Notes

*Analyzed value. Calculated values (ppm) were SO₄ ⁼, 30; PO₄ ^{3 −}, 135; NO₃ ⁻, 18; NO₂ ⁻, 123.

**Calculated values (ppm) were SO₄ ⁼, 30; PO₄ ^{3 −},135; NO₃ ⁻, 12; NO₂ ⁻, 150; TDS (obs) = 351.

^†BDL = Below detection limit.

*Trial 1. Calculated values (ppm) were SO₄ ⁼, 30; PO₄ ^{3 −}, 135; NO₃ ⁻, 18; NO₂ ⁻, 405.

**Trial 2. Calculated values (ppm) were SO₄ ⁼, 30; PO₄ ^{3 −}, 135; NO₃ ⁻, 18; NO₂ ⁻, 150.