白腐真菌对酸性橙7的脱色降解

Decolorization and biodegradation of acid orange 7 by white-rot fungi

摘要:

偶氮染料广泛应用于纺织、造纸和包装等行业，因其具有三致性、结构稳定且难降解，已成为染料废水处理的研究热点之一。本研究以白腐真菌作为脱色菌株，考察了不同白腐真菌对偶氮类染料酸性橙7(acid orange 7,AO7)的脱色降解，探讨了AO7染料的浓度、pH、温度以及脱色时间对染料脱色率的影响，同时应用紫外-可见光谱吸收法、红外光谱吸收法、高效液相色谱法和气相色谱-质谱法对AO7的降解产物进行分析，并对其产物进行植物毒性实验，以推断AO7可能的降解途径及其降解产物的毒性。结果表明：在pH 4.5、28℃条件下，刺芹侧耳(Pleurotus eryngii)和杂色云芝(Trametes versicolor)的混合菌丝脱色降解100 mg/L AO7，24 h脱色率可达93.46%。推测AO7可能的生物降解途径：AO7偶氮键断裂生成对氨基苯磺酸和1-氨基-2-萘酚；接着对氨基苯磺酸脱去磺酸基，生成对苯二酚；同时1-氨基-2-萘酚开环生成邻苯二甲酸和对羟基苯甲醛，之后进一步降解生成苯甲酸；最后对苯二酚和苯甲酸继续氧化成其他小分子中间体、H₂O和CO₂。植物毒性实验表明，P.eryngii和T.versicolor混合菌丝对AO7脱毒效果较好。以上研究为探究白腐真菌在工业废水中降解偶氮类染料的应用奠定基础。

关键词:白腐真菌;酸性橙7;生物降解路径;植物毒性

Abstract:

Azo dyes are widely used in textile, paper and packing industries, and have become one of the research hot spots in dye wastewater treatment because of their carcinogenicity, teratogenic mutagenicity, stable structure and degradation difficulty. In this study, the biodecolorization of acid orange 7 (AO7), an azo dye, by different white rot fungi was investigated, and the effect of different conditions on the decolorization rate of the dye was analyzed. At the same time, the degradation liquor was analyzed and the phytotoxicity experiment was performed to deduce the possible degradation pathway of AO7 and assess the toxicity of its degradation products. The results showed that the decolorization rate reached 93.46% in 24 h at pH 4.5, 28 ℃ by Pleurotus eryngii and Trametes versicolor when AO7 concentration was 100 mg/L. The biodegradation pathway of AO7 was initiated by the cleavage of the azo bond of AO7, generating p-aminobenzenesulfonic acid and 1-amino-2-naphthol. Subsequently, the sulfonic acid group of p-aminobenzene sulfonic acid was removed to generate hydroquinone. Moreover, the 1-amino-2-naphthol was de-ringed to generate phthalic acid and p-hydroxybenzaldehyde, and then further degraded into benzoic acid. Finally, hydroquinone and benzoic acid may be further oxidized into other small molecules, carbon dioxide and water. Phytotoxicity experiment showed that the toxicity of AO7 could be reduced by P. eryngii and T. versicolor.

Key words:white-rot fungi;acid orange 7;biodegradation pathway;phytotoxicity