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由于硫酸根自由基(SO·-4)的强氧化性,基于SO·-4的高级氧化技术受到人们的高度关注.采用过渡金属活化过一硫酸盐(PMS)产生SO·-4用以分解有机物,反应体系简单,反应条件温和,且不需要额外的能量供给,因此,成为人们优先选用的方法,其中,采用高效、环境友好的非均相过渡金属催化剂活化PMS处理难降解有机物成为研究热点.本文研究了非均相CoFe/SBA-15-PMS体系对水中难降解染料罗丹明B(RhB)的降解.以SBA-15为载体,Co(NO3)2·6H2O和Fe(NO3)3·9H2O为前驱物,采用一步等体积浸渍法制备了CoFe/SBA-15,通过X射线衍射(XRD)、N2吸附-脱附、扫描电镜(SEM)、能谱(EDS)、透射电镜(TEM)和振动样品磁强计(VSM)等对其进行了表征.考察了焙烧温度、Co与Fe的负载量对CoFe/SBA-15催化性能的影响和该催化剂的重复使用性能,还考察了RhB降解动力学及催化剂CoF e/SBA-15投加量、氧化剂PMS投加量和反应物(Rh B和PMS)初始浓度对其性能的影响,探讨了Rh B的降解机理.结果表明:对于催化剂CoFe/SBA-15,合成焙烧后在SBA-15上负载的Fe、Co化合物主要是CoFe2O4复合物,它作为催化剂的活性中心负载在SBA-15的孔道内外.制备的焙烧温度对Co Fe/SBA-15催化性能几乎无影响,但对Co浸出影响显著.与SBA-15相比,催化剂10Co9.5Fe/SBA-15-700(Co和Fe负载量分别为10 wt%和9.5 wt%,焙烧温度700 oC)的比表面积、孔体积和孔径均减小,分别为506.1 m2/g,0.669 cm3/g和7.4 nm,但仍然保持SBA-15的有序六方介孔结构.该催化剂以棒状体的聚集态存在,聚集体直径大于0.25μm,其磁化强度为8.3 emu/g,因此,可通过外磁铁容易地从水中分离.相比之下,10Co9.5Fe/SBA-15-700具有最佳的催化性能和稳定性,可使Rh B的降解率达到96%以上,Co的浸出量小于32.4μg/L.在CoFe/SBA-15和PMS共存下,RhB的降解符合一级动力学方程,Rh B降解速率随CoFe/SBA-15和PMS投加量的增加和初始反应物浓度的减小而提高.淬灭实验结果表明,在Co Fe/SBA-15,PMS和RhB水溶液体系中,存在的主要活性自由基为SO·-4,它是由CoFe/SBA-15活化PMS产生的,对RhB的降解起决定性的作用.RhB降解过程的UV-vis结果表明,RhB的降解途径主要是蒽环打开,SO·-4优先攻击RhB的有色芳香烃环,然后RhB进一步分解为小分子有机物.CoF e/SBA-15循环使用10次仍能保持高催化活性和稳定性,在每次反应中RhB的降解率均大于84%,Co和Fe的浸出量均分别小于72.1和35μg/L.CoFe/SBA-15作为高效、环境友好的非均相催化剂可有效地活化PMS产生SO·-4降解水中RhB,具有实际应用的潜力.
Due to the strong oxidation of sulfate radical (SO · -4), advanced oxidation technology based on SO · -4 has drawn great attention.Using transition metal activated monopersulfate (PMS) to produce SO · -4 for decomposition Organic matter, simple reaction system, mild reaction conditions and no additional energy supply make it a preferred method. Among them, the use of highly efficient and environment-friendly heterogeneous transition metal catalysts to activate PMS to treat refractory organic compounds has become a research hotspot In this paper, we investigated the degradation of RhB in Heterogeneous CoFe / SBA-15-PMS system by using SBA-15 as support, Co (NO3) 2 · 6H2O and Fe (NO3) 3 · 9H2O was used as precursor to prepare CoFe / SBA-15 by one-step volume impregnation method. The structure of CoFe / SBA-15 was characterized by XRD, N2 adsorption- desorption, SEM, EDS and TEM. And vibrating sample magnetometer (VSM), etc. The effects of calcination temperature, the loading of Co and Fe on the catalytic performance of CoFe / SBA-15 and the reusability of the catalyst were investigated. The effects of RhB degradation Kinetics and catalyst CoF e / SBA-15 dosage, oxidant PMS dosage and reactants (Rh B and P MS), the degradation mechanism of Rh B was explored.The results showed that for the catalyst CoFe / SBA-15, the Fe and Co compounds supported on SBA-15 after calcination were mainly CoFe2O4 compounds The catalytic activity was almost the same as that of SBA-15, but the influence of the calcination temperature on the catalytic performance of CoFe / SBA-15 was not significant.Compared with SBA-15, the catalyst 10Co9.5Fe / The specific surface area, pore volume and pore size of SBA-15-700 (10wt% and 9.5wt% Co and Fe loadings, respectively) were reduced to 506.1 m2 / g and 0.669 cm3 / g, respectively 7.4 nm, while still maintaining the ordered hexagonal mesoporous structure of SBA-15. The catalyst exists in the aggregated state of the rod-like bodies with an aggregate diameter of more than 0.25 μm and a magnetization of 8.3 emu / g, In contrast, 10Co9.5Fe / SBA-15-700 has the best catalytic performance and stability, can RhB degradation rate of 96% or more, Co leaching less than 32.4μg / L Under the coexistence of CoFe / SBA-15 and PMS, the degradation of RhB conforms to the first-order kinetic equation, and the degradation rate of Rh B increases with the addition of CoFe / SBA-15 and PMS The results of quenching experiments showed that the main active radical existed in Co Fe / SBA-15, PMS and RhB aqueous solution was SO · -4, which was composed of CoFe / SBA- 15 produced by activated PMS played a decisive role in the degradation of RhB.The UV-vis results of RhB degradative process showed that the degradation pathway of RhB was mainly anthracene ring opening, and SO · 4 preferentially attacked the colored aromatic hydrocarbon ring of RhB and then RhB Further decomposed into small organic molecules.CoF e / SBA-15 can still maintain high catalytic activity and stability after being reused for 10 times, and the degradation rate of RhB is greater than 84% and the leaching amounts of Co and Fe are less than 72.1 and 35μg / L.CoFe / SBA-15 as efficient and environment-friendly heterogeneous catalysts can effectively activate PMS to produce SO · -4 to degrade RhB in water, which has the potential of practical application.