Abstract:

In this study, ferrous sulfide(FeS) was used to catalyze the degradation of p-nitrophenol(PNP) by ozone. The effects of catalyst dosage, ozone concentration, reaction temperature and solution pH on the degradation efficiency of PNP in FeS/O₃ system were obtained by single factor experiments. The results showed that the degradation efficiency of PNP increased with the increase of catalyst dosage and ozone concentration. Between 15 ℃ and 35 ℃,the degradation efficiency of PNP first increased and then decreased with the increase of temperature, and the degradation efficiency was the highest at 25 ℃. When the pH was in the range of 3 to 11, the greater the pH, the higher the degradation efficiency. Considering the economy of engineering application and the limit of Fe²⁺ ion emission, the optimal processing parameters were obtained as follows:FeS dosage of 0.5 g/L, ozone concentration of 40 mg/L,temperature of 25 ℃, pH of 7. Under the optimal reaction parameters, the degradation rate of PNP by FeS/O₃ system reached 90.04% within 3 min, which was 10.1% higher than that by ozone alone. The surface morphology and crystal structure of FeS before and after the reaction were analyzed by SEM,and it was found that it had good stability. In 5 consecutive cycles, the removal rate of PNP remained above 93% after 6 min of reaction. Possible intermediates and degradation pathways of PNP degradation were investigated by gas chromatography mass spectrometry. Hydroxyl radical(·OH) as an important role in improving the reaction rate during the degradation of PNP by FeS/O₃ system was confirmed by radical quenching experiments.

Key words: catalytic oxidation, p-nitrophenol, ozone, ferrous sulfide

摘要：

利用硫化亚铁（FeS）催化臭氧降解对硝基苯酚（PNP），通过单因素实验，考察催化剂投加量、臭氧浓度、反应温度、溶液pH等因素对FeS/O₃体系降解PNP效率的影响规律。结果表明，PNP降解效率随催化剂投加量和臭氧浓度的增加而增加；15~35 ℃时，PNP降解效率随温度的增加先升高后降低，在25 ℃时降解效率最高；pH在3~11范围时，pH越大，降解效率越高。考虑到工程应用经济性及Fe²⁺排放限值，得出最佳处理工艺参数：FeS投加量为0.5 g/L，臭氧质量浓度为40 mg/L，温度为25 ℃，pH为7。最佳反应参数下，3 min内FeS/O₃体系对PNP的降解率达到90.04%，较单独臭氧降解提高了10.1%。通过SEM分析了反应前后FeS的表面形貌和晶体结构，发现其具有良好的稳定性，在连续5次循环实验中，反应6 min时PNP的去除率均能保持在93%以上。通过气相色谱-质谱探究了PNP降解可能存在的中间产物和降解途径，利用自由基猝灭实验证实了FeS/O₃体系降解PNP过程中羟基自由基（·OH）对提升反应速率具有重要作用。

关键词: 催化氧化, 对硝基苯酚, 臭氧, 硫化亚铁

CLC Number: 

• X703.1