氧气对混合菌群脱色降解偶氮染料效果的影响

【背景】偶氮染料及其中间产物具有一定的环境毒性,利用混合菌群降解偶氮染料是一种环境友好型方法,但降解过程中氧气的存在起到至关重要的作用,可以促进或抑制偶氮染料的微生物降解作用。【目的】探讨氧气对偶氮染料微生物脱色液的影响,分析氧气对混合菌群脱色降解偶氮染料效果的影响。【方法】利用混合菌群DDMY1在3种培养条件(好氧、厌氧、兼氧)下,对7种偶氮染料进行脱色降解,探讨偶氮染料脱色液对氧气的响应情况,利用紫外可见分光光度法(ultraviolet visible spectrophotometry,UV-vis)和傅里叶变换红外光谱法(Fourier transform infrared spectroscopy,FTIR)对脱色产物进行分析。【结果】在兼氧和厌氧条件下反应48 h后的染料脱色液,与氧气充分接触后,部分偶氮染料微生物脱色液发生较为明显的复色现象,如活性黑5、直接黑38;UV-vis分析结果表明,这种复色现象是由于脱色液与氧气接触之后产生新物质所致;FTIR分析结果表明,混合菌群对发生复色反应的偶氮染料仍然具有一定脱色降解效果,但是脱色尚不够完全。【结论】兼氧和厌氧条件下,氧气对部分偶氮染料微生物脱色液具有较为明显的影响,从而影响混合菌群对偶氮染料的整体脱色效果,这可为今后研究偶氮染料彻底生物降解提供理论基础。

Effect of oxygen on decolorization and degradation of azo dyes by mixed flora

[Background] Azo dyes and their degradation intermediates have certain environmental toxicity. The application of mixed flora to degrade azo dyes is environmentally friendly, whereas the presence of oxygen plays a vital role in the degradation process, which can promote or suppress the biodegradation of azo dyes. [Objective] The effect of oxygen on the azo dye decolorizing solutions were explored, and the influence of oxygen on the decolorization and degradation of azo dyes by mixed flora were investigated. [Methods] Through the decolorization and degradation of seven azo dyes by mixed flora DDMY1 under three culture conditions (aerobic, anaerobic and facultative), the response of their decolorizing solutions to oxygen were discussed. Meanwhile, the degradation products were detected by ultraviolet visible spectrophotometry (UV-vis) and Fourier transform infrared spectroscopy (FTIR). [Results] After 48 h reaction under facultative and anaerobic conditions, several azo dye decolorizing solutions were captured to have the remarkable color restoration after exposure to oxygen, such as Reactive Black 5 and Direct Black 38. The results of UV-Vis analysis showed that the phenomenon of color restoration was derived from the generation of the new substances produced after decolorizing solutions contact with oxygen. In addition, the outcome of FTIR analysis indicated that the mixed flora DDMY1 still had the decolorization and degradation effect on azo dyes despite of color restoration, but the decolorization was not complete. [Conclusion] Under facultative and anaerobic conditions, oxygen had obvious influence on partial azo dye decolorizing solutions, affecting the overall decolorization performance of mixed flora DDMY1 on azo dyes. The study provides a theoretical basis for further research on the complete biodegradation of azo dyes.