次氯酸钠氧化分解污水中美托洛尔的反应动力学及影响因素

Reaction dynamics and effect factors of metoprolol oxidative decomposition in municipal wastewater by sodium hypochlorite

降压药美托洛尔经病人服用后由尿液排出,并经由市政管网进入城市污水处理厂但去除率不高,排入天然水体后成为一种新型微量污染物,在环境中持久存在,并具有潜在危害。研究讨论了污水处理厂中常用的氯消毒剂——次氯酸钠对美托洛尔的氧化分解情况,分别考察了温度、pH和水中常见有机物等对分解效果的影响。结果表明:次氯酸钠氧化分解美托洛尔的过程符合伪一级动力学反应特征;温度因素对反应速率的影响符合范特霍夫规则,在15～45℃范围内,提高反应温度,有利于美托洛尔的氧化分解;当pH为3～8时,反应速率随pH的降低而增大。同时,水体中0.1～1.0 mg·L^(-1)的腐殖酸和5～20 mg·L^(-1)的表面活性剂的存在均会促进美托洛尔的去除效果,且促进作用随着含量的升高逐渐趋于稳定。由此可知,次氯酸钠可以氧化去除美托洛尔,为污水处理厂消除美托洛尔提供科学依据。

After taken by the patients, antihypertensive drug metoprolol can be excreted with urine into municipal wastewater treatment plants through the sewers and ultimately enters into natural water due to its low removal efficiency. As an emerging pollutant, it is persistent in the environment and can cause potential hazards. The decomposition of metoprolol with sodium hypochlorite, a chlorine disinfectant, under environmental factors such as temperature, pH and common organic compounds in wastewater was investigated. The results revealed that the elimination of metoprolol by sodium hypochlorite followed pseudo-first order kinetics. Temperature played a significant role in the reaction as the removal rate of metoprolol increased with the temperature rising between15 and 45 degrees Celsius, which followed Van＇t Hoff rule. As p H increased from 3 to 8, the reaction rate decreased accordingly. In addition, the presence of 0.1～1.0 mg·L（-1） humic acid or 5～20 mg·L（-1） surfactant in the water environment also promoted the oxidative decomposition reaction, but the acceleration gradually stabilized as the content of these organics increased. These results provide a scientific basis for the elimination of metoprolol in wastewater treatment plants by sodium hypochlorite.