谷振超 邬东 陈莉荣

摘   要：含氮杂环化合物随着化工行业的发展不断进入环境中，增加了对生态环境的威胁.考察了UV/H2O2对化工废水中含氮杂环化合物2，6-二氯吡啶（2，6-DCLPY）的降解特征，降解过程中的2，6-DCLPY浓度通过紫外分光光度法测定;并对2，6-DCLPY降解反应的影响因素包括初始2，6-DCLPY浓度、H2O2浓度、pH和共存阴离子等进行了研究. 结果表明：2，6-DCLPY 在UV/H2O2体系下的降解符合准一级反应动力学，该体系中羟基自由基（·OH）是降解2，6-DCLPY的主要活性物质，UV起协同作用;随着H2O2用量的提高，2，6-DCLPY的降解效率也逐渐提高，当H2O2和2，6-DCLPY的投加摩尔比为37 ∶ 1，pH为7.2时达到最高降解率77.3%. 共存阴离子HCO-3和NO-3因能与·OH直接发生反应，对降解反应有显著的抑制作用.吡啶环上存在氨基等给电子基团有利于吡啶类污染物的降解，而氯等吸电子基团会抑制吡啶类污染物的降解.

关键词：光催化;UV/H2O2;2，6-二氯吡啶;含氮杂环化合物;羟基自由基

Abstract：With the development of the chemical industry， nitrogen-containing heterocyclic compounds constantly enters the environment， which increases the threat to the ecological environment. The degradation characteristics of the nitrogen-containing heterocyclic compounds 2，6-dichloropyridine（2，6-DCLPY） in chemical wastewater by UV/H2O2 were investigated， and the concentration of 2，6-DCLPY in the degradation process was determined by ultraviolet spectrophotometry. The influencing factors of 2，6-DCLPY degradation reaction including initial 2，6-DCLPY concentration，H2O2 concentration， pH and coexisting anions were studied. The results showed that the degradation of 2，6-DCLPY under UV/H2O2 system accorded with quasi-first-order reaction kinetics.  Hydroxyl radical（·OH） was the main active substance for degradation of 2，6-DCLPY， while UV played a synergistic effect. The degradation efficiency of 2，6-DCLPY gradually increased with the increasing H2O2 dosage， and the highest degradation rate could reach 77.3% when the molar ratio of H2O2 and 2，6-DCLPY was 37 ∶ 1 and the pH was 7.2. The coexisting anions HCO3- and NO3- can directly react with ·OH， which leaded to significant inhibitory effect on the degradation reaction. The presence of electron-donating groups such as amino groups on the pyridine ring is conducive to the degradation of pyridine pollutants，while electron-withdrawing groups such as chlorine inhibits the degradation of pyridine pollutants.

Key words：photocatalysis;UV/H2O2;2，6-dichloropyridinr;nitrogen-containing heterocyclic compound;hydroxyl radicals

2，6-二氯吡啶（2，6-DCLPY）是一種应用广泛的含氮杂环化合物，不仅是许多杀菌剂、香料和特定农医药物的基本原料[1]，还经常作为染料、树脂和部分精细化学品生产过程中的溶剂使用[2]. 因此，它普遍存在于焦化废水、医药废水和精细化工等工业废水中[3-7]. 这些化工废水中的2，6-DCLPY因结构中含有难降解的吡啶环结构并具有较强的生物毒性，难以被一般物化处理工艺或生化手段去除[8-9]. 此外，它具有较强的水溶性和生物活性，可以在土壤、水体和沉积物中迁移和富集，对生态安全构成直接威胁[10]. 已经从包括北海（0.07 ng/L）、英国沿海（0.13 ng/L）、易北河（8.76 ng/L）等……