黑曲霉吸附弱酸性艳蓝RAWL的机理

Mechanism of Adsorption of Weakly Acidic Brilliant Blue RAWL on Aspergillus niger

为了研究黑曲霉吸附弱酸性艳蓝RAWL(简称染料)的机理,通过红外光谱和化学修饰的方法,考察了黑曲霉对染料吸附性能的pH响应模式,表征了黑曲霉干粉菌体表面的主要官能团组成及不同官能团对吸附染料的贡献。实验结果表明:在强酸性(pH不大于2)条件下黑曲霉对染料的吸附效果最好;黑曲霉干粉菌体表面含有氨基、羧基和磷酸根;经脂质脱除、磷酸根酯化修饰、羧基酯化修饰、氨基甲基化修饰后对染料的吸附性能不变,而乙酰化氨基在酸性体系中失去质子化能力,对染料的吸附性能下降51.6%,说明低pH条件下氨基质子化导致带正电的黑曲霉干粉菌体与带负电的染料之间的静电引力是吸附染料的重要原因。

For the research on the mechanism of adsorption of weakly acidic brilliant blue RAWL on Aspergillus niger, the response model of pH on RAWL adsorption was investigated, and the main functional groups on the surface of the dry powder of AspergiUus niger and the contribution of different functional groups on adsorption were studied by means of IR spectrum and chemical modification. The results show that the adsorption effect of RAWL on Aspergillus niger is the best under strongly acidic condition（pH is lower than 2 ） ;The surface of the dry powder of Aspergillus niger contains amino, carboxyl and phosphatic groups;There is no change of the adsorption capability after modification of amino, carboxyl and phosphatic groups on the surface of Aspergillus niger by extraction of lipid, esterification of phosphatic and carboxyl groups, and methylation of amino group, whereas the adsorption capability is reduced by 51.6% after acetylated amino groups lost their protonation capabilities in acidic system. This result indicates that the important reason for dye adsorption is the electrostatic attraction between positive dry powder of AspergiUus niger and negative dye molecule because of the protonation of amino groups under the condition of low pH.