硝酸氧化和负载铁氧化物改性活性炭催化臭氧化性能

Performance of catalytic ozonation by activated carbon modified with nitric acid oxidation and Fe oxides loaded

采用硝酸氧化与硝酸铁负载对颗粒活性炭进行改性处理,研究了活性炭样品表面官能团的变化,分析了活性炭样品对酸性大红3R吸附和催化臭氧化能力,探讨了p H值与·OH捕获剂对催化臭氧化效果的影响。结果表明,硝酸改性后活性炭表面羧基、内酯基、酚羟基以及总官能团的含量均明显增加,其中羧基增幅最大;负载铁氧化物后,活性炭表面官能团数量有所降低。活性炭样品化学吸附性能随官能团含量的增加而增强。催化臭氧化对酸性大红3R的氧化降解效果明显优于单独臭氧化。增加表面官能团含量可以加速催化臭氧化反应,但反应速率随着表面官能团消耗而降低;负载金属组分具有更为稳定和有效的催化臭氧化活性。活性炭催化臭氧化性能在碱性条件下明显优于酸性条件,且随着p H值升高而提高。投加·OH捕获剂(Na2CO3)后,其对·OH的消耗使得催化臭氧化效果显著下降。

The adsorption and catalytic ozonation of Acid Red 3R by the granular activated carbon modified with nitric acid oxidation and Fe oxides loaded were investigated in this study. The variation of surface functional groups of treated activated carbon samples was determined. The influences of p H and ·OH scavenger on catalytic ozonation were discussed. The results showed that the total surface functional groups of activated carbon,including carboxyl group,lactone group and phenolic hydroxyl group,increased significantly after nitric acid modification,especially for carboxyl group. However,the amount of surface functional groups of activated carbon was reduced after Fe oxides loaded. The larger amount of surface functional groups could improve the adsorption capacity of activated carbon samples. The catalytic ozonation of Acid Red 3R by activated carbon samples was more efficient than ozonation alone. An increase in the surface functional groups of activated carbon could accelerate catalytic ozonation,but consumption of the surface functional groups during catalytic ozonation resulted in reduced reaction rate. Comparatively,the Fe oxides loaded activated carbon showed more stable and effective catalytic ozonation activity. The catalytic ozonation seemed more efficient under alkaline condition rather than acidic condition,and higher p H value was favorable for catalytic ozonation. The performance of catalytic ozonation by activated carbon samples decreased significantly in the presence of ·OH scavenger( Na2CO3),due to ·OH consumption by Na2CO3.