金属离子对NaNO_2催化氧化降解酸性蓝129的影响

Effects of metal ions on the NaNO_2-catalyzed wet oxidation of Acid Blue 129

选取蒽醌染料酸性蓝129(AB129)为研究对象,采用催化湿式氧化技术,在以NaNO_2为催化剂的基础上,详细考察了Cu^(2+)、Ni^(2+)、Mn^(2+)、Co^(2+)、Cr^(3+)、Fe^(3+)6种金属离子助催化剂对AB129降解的影响.染料溶液初始浓度固定为100mg/L,初始pH值为2.5,氧气压力为0.5MPa,温度为150℃,当助催化剂;NaNO_2:AB129的物质的量之比为0.2:0.6:1时,在相同的反应时间内6种金属离子的催化活性大小依次为Fe^(3+)>Cu^(2+)>Cr^(3+)>Co^(2+)>Mn^(2+)≈Ni^(2+),并且在NaNO_2/FeCl_3体系下,反应2h后,AB129的脱色率达到了100%.在此基础上进一步考察了NaNO_2/FeCl_3体系中COD的变化情况,结果显示,反应4h后,NaNO_2和FeCl_3联合使用相对于单独使用FeCl_3和NaNO_2时,体系COD去除率分别提高了21%和45%,达到了68%.结合UV-vis光谱图可知,AB129分子最终矿化为CO_2和小分子有机物.可能的催化循环机理为反应过程中M^((n+1)+)/M^(n+)、NO、NO_2和ONOOH之间发生循环转化对体系产生催化作用,其中ONOOH和助催化剂离子被认为是起氧化作用的活性物质.

To investigate the promoting catalysis of metal ions（Cu^（2＋）,Ni^（2＋）,Mn^（2＋）,Co^（2＋）,Cr^（3＋）,Fe^（3＋）） on the NaNO_2-catalyzed wet oxidation of the anthraquinone dye,the Acid Blue 129（AB129） was taken as the research substrate,and the initial AB129 concentration of 100 mg/L coupled with the molar ratio of NaNO_2 to AB129 at 0.6：1 in acid aqueous media（pH 2.5） under moderate conditions（T=150℃;oxygen pressure=0.5 MPa） was used.The promoting catalysis of the different metal ions was sort by the order of Fe^（3＋）Cu^（2＋）Cr^（3＋）Co^（2＋）Mn^（2＋）≈Ni^（2＋） based on the catalytic activity detection when the molar ratio of cocatalysts,NaNO_2 and AB129 was 0.2：0.6：1.In addition,the decoloration rate reached 100%after 2 h of catalytic wet oxidation in the NaNO_2/FeCl_3 system.The variation of COD of the solution showed that the NaNO_2/FeCl_3 coupling system was better than the Fe^（3＋） or NaNO_2 catalysis alone.After 4 h of catalytic wet oxidation,the COD removal rate reached 68%in the presence of NaNO_2/FeCl_3,and the increment of COD removal rates compared with the Fe^（3＋） and NaNO_2 alone were 21%and 45%,respectively.The UV-visible spectrum analysis as well as the COD determination indicated that the final products of the AB129 degradation were CO_2 and small molecule organic compounds.As a result, a probable mechanism of the stimulative catalytic oxidation was proposed by the cycle and transformation of M^（（n＋1）＋）/M^（n＋）、NO、NO_2 and ONOOH,while ONOOH and cocatalysts were considered as the most important active oxidants.