Cervantes Francisco J, Enríquez Javier E, Galindo-Petatán Eden, Arvayo Héctor, Razo-Flores Elías, Field Jim A
Departamento de Ciencias del Agua y del Medio Ambiente, Instituto Tecnológico de Sonora, Av. 5 de Febrero 818 Sur, Cd. Obregón, Sonora 85000, Mexico.
Chemosphere. 2007 Jun;68(6):1082-9. doi: 10.1016/j.chemosphere.2007.01.071. Epub 2007 Mar 9.
The effect of high concentrations of sulphate on the reductive decolourisation of different azo dyes by anaerobic sludge was studied in batch cultures. Sludge cultures were pre-incubated under sulphate-reducing conditions prior addition of dyes. Little or no effects of sulphate (5-10 g sulphate l(-1)) on the rate of decolourisation of Reactive Orange 14 (RO14), Direct Blue 53 (DB53) and Direct Blue 71 (DB71) were observed when no external redox mediator was provided. However, an increase in sulphate concentration, in the presence of riboflavin (20 microM), enhanced the decolourisation of all dyes. The first-rate constant of decolourisation (k) was increased up to 2-, 3.6- and 2-fold for RO14, DB53 and DB71, respectively, by supplying high sulphate concentrations, compared to the controls lacking sulphate, in the presence of the redox mediator. Sulphate reduction did not take place during the course of azo reductions, but was only evident before dye addition and after complete decolourisation, suggesting azo dyes reduction out-competed sulphate reduction for the available reducing equivalents. The experimental data suggest that reduction of azo dyes by riboflavin, which had been reduced by biogenic sulphide, was the major mechanism implicated during decolourisations, which was corroborated by abiotic incubations. Riboflavin greatly accelerated the abiotic reduction of RO14, so that the k value was increased up to 44-fold compared to the control lacking riboflavin.
在分批培养中研究了高浓度硫酸盐对厌氧污泥还原不同偶氮染料脱色的影响。在添加染料之前，污泥培养物在硫酸盐还原条件下进行预培养。当不提供外部氧化还原介质时，观察到硫酸盐（5-10 g硫酸盐l(-1)）对活性橙14（RO14）、直接蓝53（DB53）和直接蓝71（DB71）的脱色速率几乎没有影响。然而，在核黄素（20 microM）存在下，硫酸盐浓度的增加增强了所有染料的脱色。与缺乏硫酸盐的对照相比，在氧化还原介质存在下，通过提供高硫酸盐浓度，RO14、DB53和DB71的脱色一级速率常数（k）分别提高了2倍、3.6倍和2倍。在偶氮还原过程中没有发生硫酸盐还原，仅在添加染料之前和完全脱色之后才明显，这表明偶氮染料还原在可用还原当量方面比硫酸盐还原更具竞争力。实验数据表明，由生物源硫化物还原的核黄素对偶氮染料的还原是脱色过程中的主要机制，非生物培养证实了这一点。核黄素极大地加速了RO14的非生物还原，因此与缺乏核黄素的对照相比，k值提高了44倍。
