López-López Alberto, Flores-Payán Valentín, León-Becerril Elizabeth, Hernández-Mena Leonel, Vallejo-Rodríguez Ramiro
Department of Environmental Technology, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, A. C., Av. Normalistas 800, Colinas de la Normal, 44270 Guadalajara, Jalisco Mexico.
Springerplus. 2016 Jul 18;5(1):1105. doi: 10.1186/s40064-016-2782-4. eCollection 2016.
Steroids are classified as endocrine disrupting chemicals; they are persistent with low biodegradability and are hardly degraded by conventional methods. Ozonation process has been effective for steroids degradation and the determination of the kinetics is a fundamental aspect for the design and operation of the reactor. This study assessed two methods: competitive kinetics and stopped flow, for determining the degradation kinetics of two steroids, estradiol (E2) and ethinylestradiol (EE2) in spiked water. Experiments were performed at pH 6, 21 °C, and using tertbutyl alcohol as scavenger of hydroxyl radicals; competitive kinetics method used sodium phenolate as reference compound. For the stopped flow, the experiments were performed in a BioLogic SFM-3000/S equipment. For both methods, the second order rate constants were in the order of 10(6) and 10(5) M(-1) s(-1) for E2 and EE2 respectively. The competitive kinetics can be applied with assurance and reliability but needing an additional analysis method to measure the residual concentrations. Stopped flow method allows the evaluation of the degradation kinetics in milliseconds and avoids the use of additional analytical methodologies; this method allows determining the reaction times on line. The methods are applicable for degradation of other emerging contaminants or other steroids and could be applied in water treatment at industrial level. Finally, it is important to consider the resources available to implement the most appropriate method, either competitive kinetics or the stopped-flow method.
类固醇被归类为内分泌干扰化学物质；它们具有持久性且生物降解性低，难以通过传统方法降解。臭氧化工艺对类固醇的降解有效，而动力学的测定是反应器设计和运行的一个基本方面。本研究评估了两种方法：竞争动力学法和停流法，用于测定加标水中两种类固醇，即雌二醇（E2）和炔雌醇（EE2）的降解动力学。实验在pH值为6、21℃的条件下进行，并使用叔丁醇作为羟基自由基清除剂；竞争动力学法使用酚钠作为参考化合物。对于停流法，实验在BioLogic SFM - 3000/S设备中进行。对于这两种方法，E2和EE2的二级速率常数分别约为10(6)和10(5) M(-1) s(-1)。竞争动力学法可以可靠地应用，但需要额外的分析方法来测量残留浓度。停流法能够在毫秒级评估降解动力学，并且无需使用额外的分析方法；该方法允许在线测定反应时间。这些方法适用于其他新兴污染物或其他类固醇的降解，可应用于工业级水处理。最后，重要的是要考虑可用于实施最合适方法（竞争动力学法或停流法）的资源。
