过氧化氢/磷钼酸体系的催化机制及对苯胺的降解效果

以苯胺为目标污染物，通过苯胺的降解实验从3类6种过氧化氢催化剂中筛选出催化效果较好的杂多酸催化剂磷钼酸(PMA)。利用氧化还原电位测定法、电子顺磁共振波谱法、化学发光法以及拉曼光谱法分析了H₂O₂/PMA催化体系的催化机制，初步推测PMA催化H₂O₂生成高活性的[Mo(OO)₂]*和[Mo(OOH)₂]*中间体。同时，考察了PMA用量、pH以及苯胺与活性氧的摩尔比对苯胺降解效果的影响，获得了H₂O₂/PMA体系最佳反应条件。当H₂O₂和PMA质量分数分别为1%和0.365‰、溶液pH为4，在1 min内对4 mg·mL⁻¹苯胺的降解率可达98%以上。通过气相色谱质谱联用仪(GC/MS)、液相色谱质谱联用仪(LC/MS)和离子色谱(IC)等仪器分析方法检测确定苯胺的降解产物，推测其在H₂O₂/PMA催化体系的降解途径主要以N、C原子的氧化和聚合反应为主。

Catalytic mechanism and performance of the hydrogen peroxide/phosphomolybdic acid system on aniline degradation

In this study, aniline was taken as a pollutant object, a heteropolyacid catalyst of phosphomolybdic acid(PMA) with better catalytic effect was screened out among six kinds of catalysts combined with hydrogen peroxide solution which could be divided as three types. The catalysis mechanism of H2O2/PMA system was anayzed through redox potential measurement, electron paramagnetic resonance, chemiluminescence and Raman spectroscopy. The experimental results indicated that H2O2 was catalyzed by PMA to produce highly active [Mo(OO)2]* and [Mo(OOH)2]* intermediate species. Meanwhile, the effects of PMA dosage, pH value and the molar ratio of aniline to reactive oxygen species on aniline degradation efficiency were studied to determine the optimum degradation conditions of H2O2/PMA system. When the mass concentrations of H2O2 and PMA were 1% and 0.365‰, respectively, over 98% aniline could be degraded within 1min for the solution with pH=4 and initial concentration of 4 mg·mL-1. The degradation products of aniline were determined by gas chromatography-mass spectrometry(GC/MS), liquid chromatography-mass spectrometry(LC/MS) and ion chromatography(IC), then it can be predicted that the main pathway of aniline degradation was oxidation and polymerization of N and C atom in H2O2/PMA oxidation system.