Cation Exchange Processes Involving the Agricultural Antibiotic Tylosin in Soil and Soil Minerals

Author

Jaime Jacinda Call, University of Tennessee, KnoxvilleFollow

Date of Award

5-2017

Degree Type

Thesis

Degree Name

Master of Science

Major

Environmental and Soil Sciences

Major Professor

Michael E. Essington

Committee Members

Jaehoon Lee, Jennifer M. DeBruyn

Abstract

Tylosin (TYL) is a veterinary antibiotic that is used as a feed additive in swine production. Concentrations as high as 4.0 mg L^-1 have been found in swine manure leachates. Tylosin is predominately a cationic species, due to the protonation of a dimethylamine moiety in pH < 7.5 solutions. The soil adsorption of TYL is influenced by pH, background electrolyte, and ionic strength, suggesting that ion exchange is an important retention mechanism. The objective of this study was to examine the exchange selectivity of TYL in competition with sodium and calcium in montmorillonite and vermiculite reference clays and in the Bt2 horizons of a west Tennessee Loring soil. Binary exchange studies were performed and exchange isotherms were developed to establish preference, to determine the Vanselow selectivity coefficient (K_V) as a function of exchange phase composition, and to determine the exchangeable and nonexchangeable forms of TYL. X-ray diffraction was used to evaluate TYL intercalation into reference and soil clay minerals. For TYLX-NaX exchange, the exchange isotherms indicated that TYL⁺ was preferred over Na⁺ by montmorillonite, but not by the Loring soil. For TYLX-CaX exchange, the exchange isotherms indicated that TYL⁺ was preferred over Ca²⁺ by montmorillonite and the Loring soil. The K_V values were generally invariant with exchange phase composition for NaX to TYLX exchange on montmorillonite and soil clay minerals. However, the K_V values were variable with exchange phase composition for CaX to TYLX exchange. Tylosin adsorption was described by the Freundlich and partition models, with exchangeable TYL dominating in Na systems and nonexchangeable TYL in Ca systems. X-ray diffraction revealed TYL intercalation of the reference and soil clay minerals. The STx^-1 expanded to 3 nm with TYL intercalation, while the Libby vermiculite had no TYL intercalation. The d-value of TYL intercalated soil clay ranged from 1.7 nm to > 2 nm for the Ca and Na systems. The intercalation of TYL into soil and reference smectite suggests that this compound may be protected from microbial degradation. Conversely, the competition of TYL with common soil cations for exchange sites may result in enhance environmental mobility.

Recommended Citation

Call, Jaime Jacinda, "Cation Exchange Processes Involving the Agricultural Antibiotic Tylosin in Soil and Soil Minerals. " Master's Thesis, University of Tennessee, 2017.
https://trace.tennessee.edu/utk_gradthes/4728