Sulfamethoxazole sorption by cattail and switchgrass roots

Abstract

Sorption to roots is one of several mechanisms by which plant-assisted attenuation of antibiotics can be achieved. The objectives of this study were to (1) evaluate the sorption of sulfamethoxazole (SMX) by cattail and switchgrass roots, (2) determine the kinetics of SMX sorption by cattail and switchgrass roots, and (3) characterize the temperature-dependency of SMX sorption. A batch sorption experiment was conducted to measure SMX sorption by roots of the two plant species using five initial antibiotic concentrations (2.5, 5, 10, 15, and 20 µg L⁻¹) and eight sampling times (0, 0.5, 1, 2, 4, 8, 12, and 24 h). Another batch experiment was conducted at three temperatures (5, 15, and 25 °C) to determine the effect of temperature on sorption kinetics. SMX sorption followed pseudo-second-order kinetics. The pseudo-second-order rate constant ($k_2)$ decreased with increasing temperature for both plant species. The rate constant followed the order: 5 °C = 15 °C > 25 °C for cattail and 5 °C > 15 °C = 25 °C for switchgrass. Results from this study show that switchgrass roots are more effective than cattail roots in the removal of SMX. Therefore, the use of switchgrass in systems designed for phytoremediation of contaminants might also provide an efficient removal of some antibiotics.

Keywords:

• Phytoremediation
• batch sorption
• sorption kinetics
• thermodynamics
• antibiotics

Acknowledgments

The authors also acknowledge Rob Ellis for technical assistance, Dr. Ike Agomoh for help with statistical analysis, and Dr. Nicholson Jeke for helping with biosolids collection.

Author contributions

The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

Additional information

Funding

The authors acknowledge funding support from NSERC (Discovery Grants and CREATE H2O programs) and the University of Manitoba Graduate Fellowship (UMGF) program, which provided a stipend for Theresa Adesanya.