高铁酸盐溶液氧化直接耐晒黑G的效果及机理

Degradation and mechanism of direct fast black G with ferrate solution

研究了高铁酸盐溶液(FS)降解直接耐晒黑G(DB19)的效果,并采用UV-Vis、GC/MS等方法对降解机理进行了分析.结果表明,FS对DB19的脱色效果较好,pH<7.7时,5min的脱色率达到94%以上,最佳范围为pH<10.7.FS的最佳投加量为20mg/L,反应60min时,对DB19色度和COD的去除率分别为95%和60%.FS对DB19废水TOC的去除率为5%,表明染料大分子难以被完全矿化.UV-Vis扫描、GC/MS分析和体系pH值的变化结果表明,染料分子的偶氮键能被迅速攻击破坏,使染料消色,染料大分子被氧化为有机小分子中间产物,提高了染料废水的可生化性,同时产生大量的酸性有机中间物质,导致体系的pH值显著降低.

The degradation of direct fast black G （DB 19） with ferrate solution （FS） was studied, and the mechanism was analyzed by UV-Vis and GC/MS methods. The decolorization ratio was above 94% after 5min in the presence of FS at pH〈7.7, and the optimal range ofpH was lower than 10.7. The decolorization ratio and COD removal ratio were 95% and 60% after 60min, respectively, in the case of FS which dosage was 20mg/L. TOC removal ratio of DBI9 was only 5% when ferrate was supplied to reaction system, which indicated that it was difficult for FS to mineralize dye macromolecule. The results of UV-Vis, GC/MS and pH change showed that the azo bonds of dye molecule were attracted and cleaved, causing decolorization of DB19. The dye macromolecule could be oxidized to small molecule, which increased the biodegradability of the dye wastewater. Furthermore, a large number of acidic organic intermediates were detected, which obviously caused the decrease ofpH.