ZnFe/BC活化过硫酸盐降解金橙Ⅱ

Degradation of Orange Ⅱ by ZnFe/BC catalyzed persulfate

为了研究ZnFe/BC在常温下活化过硫酸盐(PS)产生硫酸根自由基(SO_4^(·-))降解酸性偶氮染料金橙Ⅱ(AOⅡ)的效能,采用水热合成法制备了ZnFe/BC催化剂,并用X射线衍射(XRD)和扫描电子显微镜-能谱分析(SEM-EDS)对其形貌与负载成分进行了表征,结果显示生物炭上负载的球状颗粒物为ZnFe_2O_4和Fe_3O_4.考察了ZnFe/BC投加量、PS投加量、AOⅡ初始浓度以及初始pH对ZnFe/BC/PS体系降解AOⅡ效果的影响.结果显示,ZnFe/BC和PS投量的增加对AOⅡ的去除率均有提升效果,而随着AOⅡ初始浓度的增加,金橙Ⅱ的去除率逐渐降低,在初始pH值在3—10范围内,ZnFe/BC对PS均有较高的催化活性.ZnFe/BC催化剂投加量为0.5 g·L^(-1),PS投加量为5 mmol·L^(-1),溶液pH为初始值为6,反应90 min后,50 mg·L^(-1)金橙Ⅱ的脱色率可达到93.7%,而且其降解速率符合拟一级反应动力学.延长反应时间至180 min,TOC去除率达到39.7%.通过对催化剂ZnFe/BC稳定性研究,发现经4次连续循环使用后,金橙Ⅱ脱色率仍然可保持在85%以上,说明该催化剂具有良好的循环使用性能.通过投加对苯醌、乙醇和叔丁醇等3种不同种类的猝灭剂,证实了ZnFe/BC/PS体系中具有SO_4^(·-)、·OH和O_2^(·-)活性物种.发芽实验证明,在反应时间为180 min内,金橙Ⅱ降解出水对小麦发芽的抑制率随反应时间的进行而先升高而逐渐降低,最后基本无抑制.

In order to study the effect of sulfate radical (SO4^·-) on the degradation of acid azo dye orange Ⅱ (AOⅡ) by ZnFe/BC activated sulfate persulfate (PS) at room temperature, ZnFe/BC catalyst was prepared by hydrothermal synthesis method. The structure of ZnFe/BC was characterized by X ray diffraction (XRD) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). The results showed that spherical particle loaded on biochar (BC) was ZnFe2O4 and Fe3O4. The effect of ZnFe/BC dosage, PS concentration, initial AOⅡ concentration and initial pH on the degradation of AOⅡ in ZnFe/BC/PS system was investigated. The results showed that the removal rate of AOⅡ increased with the increase of ZnFe/BC dosage and PS concentration while it decreased when the initial AOⅡ concentration increased. When the initial pH was in range of 3-10, ZnFe/BC has high catalytic activity for PS. When ZnFe/BC addition was 0.5 g·L^-1, PS concentration was 5 mmol·L-1, the initial pH was 6, and the initial AOⅡ concentration was 50 mg·L^-1, the AOⅡ decolorization could reach 93.7% after reaction 90 min, and the degradation rate was accorded with the pseudo first order reaction kinetics. Extending the reaction time to 180min, the TOC removal rate reached 39.7%. The AOⅡ decolorization rate could still remain above 85% when ZnFe/BC was used for 4 continuous cycles in ZnFe/BC/PS system, which indicating that the catalyst had a good recycling performance. Three different kinds of quenching agents (p-benzoquinone, ethanol and tert-butyl alcohol) were added to the ZnFe/BC/PS system for AOⅡ degradation, respectively, and the result confirmed that active species SO4^·-,·OH and O2^·- consisted in ZnFe/BC/PS system. The germination experiment showed that among 180 min of the AOⅡ degradation reaction time, the inhibition rate of the effluent from AOⅡ degradation to wheat germination increased first, and then gradually decreased. Finally, the inhibition rate dropped down to near 0.