粉煤灰掺杂MnO2催化处理高盐废水中的化学需氧量研究
Catalytic ozonation of chemical oxygen demaud in high-salt coal chemical waste water by fly ash doped with MnO2
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摘要: 为实现煤化工高盐废水的有效处理,各种高级氧化技术均得到深入研究,非均相催化氧化技术有效且前景广阔,因此臭氧氧化的非均相氧化技术得到长足发展,而高效催化剂的开发至关重要。采用水热合成法制备了活性组分MnO2,通过掺杂成型技术制备了颗粒状固体催化剂,通过X射线荧光光谱(XRF)、扫描式电子显微镜-X光微区分析(SEM-EDS)、X射线光电子能谱(XPS)、Zeta电位分析等表征技术对催化剂进行分析。结果显示,催化剂以硅、铝、钙的氧化物为主体,以二氧化锰为主要活性组分的混合型多层催化剂,催化剂表面形态较好且具有较好的孔道结构。催化臭氧氧化高盐水中化学需氧量降解试验中,探讨了臭氧投加量、催化剂投加量、初始pH等因素,结果表明,在臭氧投加量为10 mg/L、催化剂投加量为100 g的条件下反应60 min后,高盐水的COD去除率为60%左右,反应体系最优的酸碱度在催化剂等电点附近。反应机理研究中,通过添加PO3-4证明了表面的酸性位点为有机物降解的活性位点;加入对苯醌体系的化学需氧量降解率仅45%左右而加入叔丁醇反应体系可实现55%的化学需氧量降解率,因此通过添加不同种类的自由基抑制剂证明了·O2-2对化学需氧量降解的贡献远大于·OH;无机阴离子的加入对反应效果的影响结果不一致,Cl-、HCO-3的加入浓度为1 000 mg/L时催化效果会下降5%以上,说明自由基捕获剂类的阴离子会显著降低COD的降解率。Abstract: In order to realize the effective treatment of high-salt wastewater from coal chemical industry,various advanced oxidation technologies have been studied in depth. Heterogeneous catalytic oxidation technology is an effective and promising technology,which is essential for the development of high-efficiency catalysts. Therefore,the heterogeneous oxidation technology for ozonation has been developed by leaps and bounds. The active component manganese dioxide was prepared by hydrothermal synthesis,and the granular solid catalyst was prepared by JP3doping molding technology. The catalyst was analyzed by X-ray fluorescence spectroscopy(XRF),Scanning electron microscopy-X-ray microanalysis(SEM-EDS),X-ray photoelectron spectroscopy(XPS),Zeta potential analysis and other characterization techniques. The results show that the catalyst is a mixed multi-layer catalyst with silicon,aluminum,and calcium oxides as the main body and manganese dioxide as the main active component. And the surface of the catalyst has good morphology and has a good pore structure. Catalytic ozonation of organics in high salt water degradation experiments discussed factors such as ozone dosage,catalyst dosage,initial pH and other factors. The results showed that the reaction was carried out for 60 minutes under the conditions JP4of ozone dosage of 10 mg/L and catalyst dosage of 100 g. Afterwards,the COD (chemical oxygen demand) removal rate of high brine is about 60%,and the optimal initial pH of the reaction system is near the isoelectric point of the catalyst. In the study of the reaction mechanism,the addition of PO3- 4proved that the acidic sites on the surface are the active sites for organic degradation; the COD degradation rate of the p-benzoquinone system is only about 45%,while the addition of tert-butanol reaction system can achieve 55% COD degradation rate,so it is proved by adding different kinds of free radical inhibitors that ·O2-2 contributes far more to the degradation of COD than ·OH,and the effect of the addition of inorganic anions on the reaction effect is inconsistent. The concentration of Cl- and HCO-3 When it is 1 000 mg/L,the catalytic effect will decrease by more than 5%,indicating that the anions of free radical trapping agents will significantly reduce the degradation rate of COD.