Abstract

Degradation of a dye in water alone or as part of a mixture was studied under different advanced oxidation processes in order to elucidate possible competition or interference between dyes. For this purpose, color degradation of aqueous solutions of Rhodamine B alone or mixed with Indigo Carmine was evaluated under ultrasound, ultraviolet radiation and under their combined effect, in the presence or absence of catalyst, which was either TiO₂ (Degussa P-25) or a mixed catalyst TiO₂-ZrO₂ prepared by sol gel method.

Regardless of the oxidation process used, results suggest that Rhodamine B discoloration was negatively affected by the presence of Indigo Carmine, which was degraded preferentially. Concerning the oxidation processes, synergy was observed for the combined operation of ultrasound and ultraviolet radiation in the presence of TiO₂ catalyst, for both dyes when treated individually, however, for a mixture of dyes synergetic degradation was observed only for Indigo Carmine. It appears that competition exists between individual components in a mixture for the access to catalyst reaction sites and interaction with hydroxyl radicals, and which seem to ease the degradation of some components in detriment of others.

Photosonocatalytic degradation of these dyes was not improved by the presence of mixed TiO₂:ZrO₂ catalysts as compared with Degussa P-25 catalyst. However, for the case of Rodamine B, the yield of decolorized dye converted into mineralized products appears to be enhanced for the mixed catalyst.

摘要

在不同的高级氧化工艺下研究了染料在水中单独或作为混合物的一部分的降解，以阐明染料之间可能的竞争或干扰。为此，在存在或不存在催化剂（TiO ₂ (Degussa P-25)）的情况下，在超声波、紫外线辐射和它们的组合作用下评估单独的罗丹明 B 水溶液或与靛蓝胭脂红混合的水溶液的颜色降解。或溶胶凝胶法制备的混合催化剂TiO ₂ -ZrO _{2 。}

无论使用何种氧化过程，结果表明，若丹明 B 变色受到靛蓝胭脂红的存在的负面影响，靛蓝胭脂红优先降解。关于氧化过程，在 TiO ₂催化剂的存在下，对于两种染料单独处理时，观察到超声波和紫外线辐射的联合操作的协同作用，然而，对于染料混合物，仅对靛蓝胭脂红观察到协同降解。似乎混合物中的各个组分之间存在竞争，以接近催化剂反应位点和与羟基自由基的相互作用，这似乎减轻了某些组分的降解而损害了其他组分。

与 Degussa P-25 催化剂相比，混合 TiO ₂ :ZrO ₂催化剂的存在并未改善这些染料的光催化降解。然而，对于罗丹明 B，混合催化剂似乎提高了脱色染料转化为矿化产物的产率。