Selenium release in buffer solutions with the use of pellets made with different types of agglomerates

Abstract

THE PRESENT STUDY WAS MADE TO DETERMINE IN VITRO RELEASE OF SELENIUM FROM MINERAL PELLETS OF 1 G OF WEIGHT, WITH 5 AND 10% OF SELENIUM AND MADE WITH THREE DIFFERENT AGGLOMERATES (PLASTER, CONCRETE-CEMENT AND TILE- CEMENT), WITH OR WITHOUT COPPER SULFATE. THEY WERE KEPT IN FOUR BUFFER SOLUTIONS WITH PH 7.0, 6.5, 6.0 AND 5.5. THE CONCENTRATION OF RELEASED SE (MG/PELLETS/DAY) WAS MEASURED BY ATOMIC ABSORPTION SPECTROSCOPY ON DAYS 1, 4, 8, 16, 32 AND 64. AT DAY 4, THE PLASTER PELLETS WERE DISINTEGRATED IN EVERY BUFFER SOLUTION. THERE WAS NO RELEASE OF SELENIUM AFTER DAY 32 IN THE CONCRETE-CEMENT PELLETS, WITH OR WITHOUT COPPER SULFATE. THE AVERAGE RELEASE OF SE WAS GREATER FOR THE PELLETS CONTAINING BOTH TILE-CEMENT, AND COPPER SULFATE, THAN THEPELLETS CONTAINING ONLY TILE-CEMENT WITHOUT COPPER SULFATE. THIS WAS HIGHER FOR PELLETS CONTAINING 10% OF SE THAN THE ONES CONTAINING 5% SE. THROUGHOUT TIME, A COMPLEX INTERACTION WAS OBSERVED BETWEEN THE SE CONTENT, THE PRESENCE OR ABSENCE OF COPPER SULFATE AND PH LEVELS, WITHOUT SHOWING ANY PREDOMINANT PATTERN. IN CONCLUSION, THE BEST AGGLOMERATE IS THE TILE- CEMENT BECAUSE THE RELEASE OF SE IS MORE CONSTANT AND LASTS LONGER.