Kang Ya-ning, Li Hua-nan, Xu Bing-bing, Qi Fei, Zhao Lun
Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
Huan Jing Ke Xue. 2013 May;34(5):1790-6.
Red mud as one kind of aluminum industrial wastes was used as raw material for catalyst preparation. It was activated by acidification in order to enhance its catalytic activity in the system of catalytic ozonation. Furthermore, removal performance and reaction mechanism in degradation of organic pollutants were discussed. Results showed that acid modified red mud had more significant catalytic activity than the raw red mud. The removal efficiency of nitrobenzene by catalytic ozonation with acidified red mud (RM6.0) increased with the increasing ozone concentration. When the ozone concentration was increased from 0.4 mg x L(-1) to 1.7 mg x L(-1), the removal efficiency of nitrobenzene increased from 45% to 92%. There was a consistent effect of water pH on the removal efficiency and the ozone concentration variation. The variation of the removal efficiency depended on the initial water pH. This was because the concentration of OH(-) led to ozone decomposition to generate hydroxyl radicals. The higher water pH value led to the quenching of hydroxyl radicals, resulting in the reduction of catalytic activity of RM6.0. The experimental results of aqueous ozone concentration variation in the presence of RM6.0 and inhibition by hydroxyl radicals indicated that the main reaction mechanism was catalytic ozonation of NB. Firstly, aqueous ozone was absorbed onto the surface of RM6.0, and then the concentrated ozone oxidized NB in water which was with a combination of direct and indirect oxidation. In catalytic reaction, hydroxyl radicals were present, which were generated during the oxidation of NB on the surface of RM6.0.
赤泥作为一种铝工业废弃物，被用作制备催化剂的原料。通过酸化对其进行活化，以增强其在催化臭氧化体系中的催化活性。此外，还探讨了有机污染物降解中的去除性能和反应机理。结果表明，酸改性赤泥比原始赤泥具有更显著的催化活性。用酸化赤泥（RM6.0）催化臭氧化去除硝基苯的效率随臭氧浓度的增加而提高。当臭氧浓度从0.4 mg·L⁻¹增加到1.7 mg·L⁻¹时，硝基苯的去除效率从45%提高到92%。水的pH值对去除效率和臭氧浓度变化有一致的影响。去除效率的变化取决于初始水的pH值。这是因为OH⁻的浓度导致臭氧分解产生羟基自由基。水的pH值越高，羟基自由基淬灭，导致RM6.0的催化活性降低。在RM6.0存在下的水相臭氧浓度变化及羟基自由基抑制的实验结果表明，主要反应机理是硝基苯的催化臭氧化。首先，水相臭氧被吸附到RM6.0的表面，然后浓缩的臭氧在水中氧化硝基苯，这是直接氧化和间接氧化的结合。在催化反应中，存在羟基自由基，它们是在RM6.0表面硝基苯氧化过程中产生的。
