新型Fe3O4@α-MnO2活化过一硫酸盐降解水中偶氮染料

采用两步水热法制备了新型磁性纳米Fe₃O₄@α-MnO₂复合材料作为催化剂，用于活化过一硫酸盐（PMS）产生强氧化性的硫酸根自由基（SO₄^-·）氧化降解偶氮染料活性黑5（RBK5）.采用透射电子显微镜（TEM），X射线粉末衍射仪（XRD）和振动样品磁强计（VSM）对制备的催化剂进行表征，证明成功合成了纳米α-MnO₂包覆Fe₃O₄形态的Fe₃O₄@α-MnO₂催化剂，催化剂的饱和磁化强度为39.89emu/g.Fe₃O₄@α-MnO₂催化剂活化PMS与单一的Fe₃O₄和α-MnO₂活化PMS相比，具有更高的催化效率，说明铁锰双金属存在协同作用.同时研究了催化剂的投加量、PMS的浓度和初始pH值等各种因素对RBK5的降解效率以及反应动力学的影响.实验结果表明，Fe₃O₄@α-MnO₂催化剂活化PMS降解RBK5的过程符合准一级反应动力学，在催化剂投加量为1.2g/L，PMS的浓度为4mmol/L，初始pH值为7.0，反应时间为60min的情况下，浓度为30mg/L的RBK5的降解效率可达到91%，此时RBK5的降解速率常数也达到最高值0.023min^-1.此外，通过加入自由基淬灭剂甲醇、叔丁醇和硝基苯判断了Fe₃O₄@α-MnO₂/PMS体系中起主要氧化降解作用的活性物种为SO₄^-·.

Novel Fe3O4@α-MnO2 activated peroxymonosulfate degradation of azo dyes in aqueous solution

The degradation of reactive black 5, an azo dye, in aqueous solutions was investigated using novel magnetic nano-Fe₃O₄@α-MnO₂catalyst, which prepared by two step hydrothermal method. The catalyst was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and vibration sample magnetometer (VSM). TEM and XRD results of as-synthesized catalyst showed the nano-α-MnO₂ coated Fe₃O₄ was successfully prepared. VSM indicated the saturation magnetization of nano-Fe₃O₄@α-MnO₂ was reach up to 39.89emu/g. As all the Fe₃O₄, α-MnO₂ and nano-Fe₃O₄@α-MnO₂ was applied to assess the individual and interaction effects of metals, the higher catalytic efficiency of nano-Fe₃O₄@α-MnO₂ implied the synergistic effect between Fe and Mn. Several operating parameters (catalyst dosage, PMS concentration and initial pH value) on the treatment efficiency and reaction kinetics of RBK5were also studied. As results, the RBK5degradation process via Fe₃O₄@α-MnO₂ activated PMS is consistent with the pseudo-first-order reaction. The degradation efficiency of RBK5 (30mg/L) could reach 91% within 60min under the condition of the catalyst dosage was 1.2g/L, the PMS concentration was 4mmol/L, and the initial pH value was 7.0. Under this situation, the degradation rate constant of RBK5also reached the highest value of 0.023min^-1. Moreover, the main active species in RBK5degradation in Fe₃O₄@α-MnO₂/PMS system was identified as SO₄^-· by adding radical quencher such as methanol, tert-butanol and nitrobenzene.