State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai, China.
Biomed Environ Sci. 2011 Jun;24(3):255-60. doi: 10.3967/0895-3988.2011.03.008.
To investigate the kinetic rate constants ozone and hydroxyl radicals towards two groups of antimicrobials -sulfadiazine (SD) and sulfamethoxazole (SMX).
The solute consumption method was used to detect the rate constants of ozone alone with sulfadiazine and sulfamethoxazole, and tertiary butanol was selected as a scavenging agent and pH was adjusted to 2.5 by adding orthophosphate buffers (OB); and the competition kinetics studying methodwith nitrobenzene as a reference was applied to measure the rate constants of hydroxyl radicals towards sulfadiazine and sulfamethoxazole, and pH was adjusted to 7.0 by adding OB.
The rate constants of SD and SMX with ozone alone were 261 mol(-1) · dm(3) · s(-1) and 303 mol(-1) · dm3 · s(-1) by calculating in low reaction system. The rate constants of hydroxyl radicals with SD and SMX were 2.2×1010 mol(-1) · dm(3) · s(-1) and 2.7×1010 mol(-1) · dm(3) · s(-1), respectively. Moreover, the rate constants of hydroxyl radicals with SMX were found to have increased from 3.6×109 mol(-1) · dm(3) · s(-1) to 2.8×1010 mol(-1) · dm(3) · s(-1) with pH value rising from 5.0 to 7.8.
SMX and SD are both refractory to ozone oxidation alone, and are liable to be degraded by hydroxyl radicals, and the rate constants of SMX with the hydroxyl radical slightly increases with pH rise.
研究动力学速率常数臭氧和羟基自由基对两组抗菌药物 - 磺胺嘧啶（SD）和磺胺甲恶唑（SMX）。
采用溶质消耗法检测臭氧单独与磺胺嘧啶和磺胺甲恶唑的速率常数，选择叔丁醇作为清除剂，并通过添加正磷酸盐缓冲液（OB）将 pH 值调节至 2.5；并应用竞争动力学研究法，以硝基苯为参照，测量羟基自由基对磺胺嘧啶和磺胺甲恶唑的速率常数，并通过添加 OB 将 pH 值调节至 7.0。
在低反应体系中计算，SD 和 SMX 与臭氧单独作用的速率常数分别为 261 mol(-1) · dm(3) · s(-1) 和 303 mol(-1) · dm(3) · s(-1)。SD 和 SMX 与羟基自由基的速率常数分别为 2.2×1010 mol(-1) · dm(3) · s(-1) 和 2.7×1010 mol(-1) · dm(3) · s(-1)。此外，发现 SMX 与羟基自由基的速率常数从 3.6×109 mol(-1) · dm(3) · s(-1)增加到 2.8×1010 mol(-1) · dm(3) · s(-1)，随着 pH 值从 5.0 增加到 7.8。
SMX 和 SD 均不易被单独的臭氧氧化，容易被羟基自由基降解，且 SMX 与羟基自由基的速率常数随 pH 值升高略有增加。
