黑曲霉吸附弱酸性艳蓝RAWL机理研究

考察了黑曲霉对染料吸附性能的pH响应模式,红外光谱表征了菌体表面的主要官能团组成,化学修饰定量研究了不同官能团的染料吸附贡献.结果显示,在低pH条件下,菌体表现出最优的染料吸附特性:随着pH值由2.0升至6.0,染料吸附量由39.6mg/g降至9.3mg/g.菌体表面含有氨基、羧基和磷酸根.高pH下,羧基和磷酸根电离导致菌体表面带负电并与染料发生静电斥力,使得染料吸附量下降;低pH下,氨基的质子化使得菌体带正电并通过静电吸引提高染料吸附.甲基化氨基在酸性条件下仍然可以质子化,故氨基甲基化修饰后染料吸附性能不变;乙酰化氨基在酸性体系中失去质子化能力,乙酰化修饰菌体染料吸附性能下降51.6%.氨基质子化引起的菌体正电性和染料负电性之间的静电引力是染料吸附的重要机制.图6参10

Mechanism of Biosorption of Weak Acid Brilliant Blue RAWL by Biosorbent Derived from Aspergillus niger

The effect of pH on dye biosorption by a biosorbent derived from Aspergillus niger was investigated. The important functional groups in the surface of biomass were analyzed using IR. The contributions of different functional groups to dye biosorption were quantitatively studied with chemical modification method. The results showed that the biomass exhibited efficient dye biosorption at low pH and the capacity of dye biosorption decreased from 39.6 mg/g to 9.3 mg/g with pH increasing from 2.0 to 6.0. The surface of biomass contained amino group, carboxyl group and phosphate group. The repulsion between negative charged dye molecule and negative charged carboxyl & phosphate groups dissociated at high pH caused decrease in capacity of dye biosorption; the electrostatic attraction between negative charged dye molecule and positive charged amino group protonated at low pH caused increase in capacity of dye biosorption. The methylated amidogen still held protonation at low pH. Therefore, the adsorption ability of biomass was almost unchangeable through methylation of amidogen in biomass. The acetylated amidogen lost protonation at low pH, and the capacity of dye adsorption of biomass decreased by 51.6% after acetylation of amidogen in biomass. It was concluded that the electrostatic attraction between negative dye molecule and positive biomass due to amidogen protonation was the important mechanism of dye biosorption by biomass. Fig 6, Ref 10