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锰氧化物是一类环境友好型材料,可以有效活化过一硫酸盐(PMS)降解水中难降解有机污染物.但是锰氧化物在单独使用时容易出现严重的团聚现象,进而降低其对PMS的催化活性,不利于水中污染物的降解.因此,人们通常将锰氧化物负载于多孔的载体材料上.金属有机骨架材料(MOFs)因具有巨大的比表面积和温和的制备条件而广受关注.本文采用温和的溶剂热法首次成功制备了Mn_3O_4与MOF的复合材料Mn_3O_4/ZIF-8,并通过X射线衍射、扫描电镜、透射电镜、X射线光电子能谱和红外光谱等手段对其进行了表征,探究了Mn_3O_4/ZIF-8的形成机理.考察了Mn_3O_4负载量对Mn_3O_4/ZIF-8催化性能的影响,以及Mn_3O_4/ZIF-8投加量、PMS投加量、初始罗丹明B(RhB)浓度和反应温度对RhB去除效果的影响,同时探究了Mn_3O_4/ZIF-8的重复使用性能,分析了RhB的降解途径、去除机理以及最终的降解副产物.结果表明,边长为50-150 nm的片状Mn_3O_4均匀分散在粒径为250 nm的六边形ZIF-8的外表面;当Mn_3O_4负载量为0.5时,所制备的复合材料0.5-Mn/ZIF-120活化PMS对RhB的降解效果最好,反应60 min时RhB降解率可达到99.4%,且Mn的浸出量可以忽略不计.在该体系中,RhB的降解过程符合一级动力学反应方程,其降解速率常数随催化剂和PMS投加量的增加、反应温度的提高和初始RhB浓度的减小而增大.在0.5-Mn/ZIF-120催化剂投加量为0.4 g/L、PMS投加量为0.3 g/L、初始RhB浓度为10 mg/L、初始溶液pH为5.18及室温(23oC)条件下,水中RhB的降解率在40 min时即可达到98%.淬灭实验表明,该体系中HO·起主导作用,而其主要来源于活化PMS所产生的SO_4–·.此外,通过简单的二次水冲洗方式对0.5-Mn/ZIF-120催化剂进行回收使用,在连续5次循环使用后仍然可见较高的催化活性和稳定性,RhB的去除率保持在96%以上,且Mn的浸出百分率始终低于5%.
Manganese oxide is an environmentally friendly material that can effectively activate permonosulfate (PMS) to degrade refractory organic pollutants in water, but manganese oxides are prone to severe agglomeration when used alone, Catalytic activity is not conducive to the degradation of water pollutants.Therefore, the manganese oxide is usually supported on the porous carrier material.Metalorganoskeleton materials (MOFs) due to the huge surface area and mild preparation conditions and widespread concern. In this paper, Mn_3O_4 / ZIF-8, a composite of Mn_3O_4 and MOF, was successfully prepared by mild solvothermal method and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and infrared spectroscopy , The formation mechanism of Mn_3O_4 / ZIF-8 was explored.The effects of Mn_3O_4 loading on the catalytic performance of Mn_3O_4 / ZIF-8 and the addition of Mn_3O_4 / ZIF-8, PMS dosage, initial Rhodamine B (RhB) Concentration and reaction temperature on the removal efficiency of RhB, the reusability of Mn_3O_4 / ZIF-8 was explored, and the degradation pathway, the removal mechanism and the degradation by-products of RhB were analyzed.The results showed that, The flaky Mn_3O_4 with a length of 50-150 nm was uniformly dispersed on the outer surface of a hexagonal ZIF-8 with a diameter of 250 nm. When the Mn_3O_4 loading was 0.5, the prepared 0.5-Mn / ZIF-120 composite was activated The degradation of RhB by PMS was the best, and the degradation rate of RhB reached 99.4% at 60 min, and the leaching amount of Mn was negligible.In this system, the degradation process of RhB accorded with the first-order kinetic equation and its degradation rate The constant increases with the dosage of catalyst and PMS, the increase of reaction temperature and the decrease of initial RhB concentration.When the dosage of 0.5-Mn / ZIF-120 catalyst is 0.4 g / L and the dosage of PMS is 0.3 The initial RhB concentration of 10 mg / L, the initial pH of 5.18 and room temperature (23oC), the degradation rate of RhB in water can reach 98% at 40 min. The quenching experiments show that the system of HO · The leading role comes from SO_4- · generated by activated PMS In addition, the 0.5-Mn / ZIF-120 catalyst is recycled by a simple secondary water rinse method, and after 5 consecutive cycles of use High catalytic activity and stability can be seen with RhB removal above 96% and Mn leaching consistently below 5%.