Study on the adsorption effect and mechanism of modified Aspergillus flavus A5P1 for dye acid blue 25

Abstract

Aspergillus flavus A5P1 was used as raw material to prepare biosorbent A5P1acid by hydrochloric acid modification，which was used to adsorb acid blue 25（AB25） dyes. Batch experiments were used to explore different influencing factors. The results showed that the optimum amount of adsorbent and pH for dye adsorption was 0.5 g/L and 2，and the adsorption reached equilibrium in 60 min. Compared with unmodified adsorbents，the adsorption capacity of acid modified adsorbents increased from 137 mg/g to 182 mg/g，and the dye removal rate increased to 32%. The thermodynamics，kinetics and adsorption isotherm of AB25 removed by A5P1acid adsorption were studied. The adsorption process met the quasi-second-order kinetic model，and the adsorption rate was controlled by chemical adsorption. Moreover， it met the Freundlich adsorption isotherm，and the adsorption belonged to multi-layer heterogeneous adsorption. The thermodynamic results showed that it was an endothermic spontaneous adsorption process. The results of Zeta potential and FTIR showed that the adsorption was assigned to the electrostatic adsorption and hydrogen bonding of various functional groups. The adsorbent still retained 50.6% of the initial adsorption capacity after cyclic adsorption-desorption for 7 times. The experimental results showed that A5P1acid was a green and effective biological adsorbent material which could be used to remove anionic dyes.

Keywords

• aspergillus flavus
• adsorption
• acid modification
• dye decolorization