Co掺杂δ-MnO2活化PMS高效降解水中有机污染物的性能及机理
- Activation of peroxymonosulfate by Co doped δ-MnO2 for the degradation of organic pollutants in water: Catalytic performance and mechanism
- 摘要：锰氧化物在活化过一硫酸盐(PMS)降解去除水中有机污染物方面具有明显优势，但仍存在PMS活化效率低的问题。为此，采用一种简单的低温还原方法制备了Co掺杂δ-MnO2的层状钴锰氧化物(0.5Co/δ-MnO2), 并对其进行了系统的表征和活化PMS性能研究，同时探究了影响因素. 结果表明，Co的引入诱导了Mn的价态转变和氧空位(Ov)的形成，促进了CoMn双金属的价态循环，提高了δ-MnO2对PMS的活化效率并增强了有机污染物的降解. 在催化剂用量0.2 g·L-1、PMS浓度为1 mmol·L-1、pH为9的条件下，15 min内对苯酚(PhOH)、环丙沙星(CIP)、双氯芬酸(DCP)、磺胺甲恶唑(SMX)和阿特拉津(ATZ)的降解去除率为100%，其中CIP的总有机碳去除率高达90%. 淬灭实验和电子顺磁共振(EPR)测试确定了0.5Co/δ-MnO2/PMS体系的主要活性物种是SO4?-和1O2, 明晰了催化活化机制. 此外，0.5Co/δ-MnO2对水中共存阴离子展现出良好的耐受性, 循环使用4次后仍然保持着较高的催化活性. 本研究为水中难降解有机污染物的无害化去除和过硫酸盐高级氧化技术的实际应用提供了理论依据.
- Abstract：Manganese oxides have many advantages in activating peroxymonosulfate(PMS)towards degradation of organic pollutants in water, but there is still a problem of low PMS activation efficiency. Here, Co doped layered δ-MnO2 (0.5Co/δ-MnO2) was prepared by a simple low-temperature reduction method. The obtained catalyst was extensive-ly characterized, its catalytic performance for PMS activation was systematically investigated, and the influencing factors on the catalytic activity were further explored. The results showed that the introduction of Co element facili-tated the conversion of Mn valence states and the formation of oxygen vacancies(Ov), promoting the re-dox cycle between different valence states for Co or Mn ions, thereby significantly enhancing the PMS activation for organic pollutants degradation. Under the conditions of 0.2 g·L-1 catalyst dosage, PMS addition of 1 mmol·L-1 and pH=9, the degradation removal efficiency of phenol (PhOH), ciprofloxacin(CIP), diclofenac (DCP), sulfamethox-azole (SMX) and atrazine (ATZ) was 100% within 15 min, and the total organic carbon (TOC) removal rate of CIP was as high as 90%. The quenching experiments and electron paramagnetic resonance (EPR)tests confirmed that the main active species in the 0.5Co/δ-MnO2/PMS system were SO4?- and 1O2, and the corresponding catalytic activation mechanism was clarified. In addition, 0.5Co/δ-MnO2 showed good tolerance to coexisting anions in water. Moreover, the catalyst still maintained high catalytic activity after four runs of recycling. This study provides a theoretical guid-ance for the harmless removal of refractory organic pollutants and the practical application of PMS-based advanced oxidation technology in water.
