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.

摘要

吸附到根部是几种机制的一种，通过这种机制可以实现植物对抗生素的减毒。这项研究的目的是（1）评价香蒲和柳枝switch对磺胺甲恶唑（SMX）的吸附;（2）确定香蒲和柳枝root对SMX的吸附动力学;（3）表征SMX的温度依赖性吸附。使用五个初始抗生素浓度（2.5、5、10、15和20 µg L ^-1）进行了分批吸附实验，以测量两种植物的根对SMX的吸附。）和八个采样时间（0、0.5、1、2、4、8、12和24小时）。在三个温度（5、15和25°C）下进行了另一批实验，以确定温度对吸附动力学的影响。SMX吸附遵循伪二级动力学。伪二阶速率常数（${ķ}_2）$两种植物的温度都随着温度的升高而降低。速率常数遵循以下顺序：香蒲5°C = 15°C> 25°C，柳枝switch 5°C> 15°C = 25°C。这项研究的结果表明，柳枝root的根部比香蒲根在去除SMX方面更有效。因此，在设计用于污染物的植物修复的系统中使用柳枝might还可以有效去除某些抗生素。