Biosorption Behavior and Reuse Potential of Waste Biomass of Aspergillus fumigatus, previously Used in Humic Acid Biosorption, in Removal of Reactive Blue 49

摘要

This study focuses on the reuse of waste biomass after biosorption. The effect of pH on the removal of reactive blue 49 from solution by the waste biomass of Aspergillus fumigatus, already used for humic acid biosorption, is studied for the first time in this paper. It is shown that the optimal initial pH was 2.0. The biosorption equilibrium experiment revealed that Langmuir isotherm fits well the biosorption equilibrium data. The theory maximum biosorption capacity was 60.6 mg/g. Kinetic studies indicated that the biosorption process followed the pseudo-second-order kinetics, and that chemisorption might be the rate-limiting step that controlled the biosorption of dye. Thermodynamic studies revealed that the biosorption was a spontaneous exothermic process and that an increased randomness occurred at the solid-solution interface during the fixation of the reactive dyes onto the active sites of the biosorbent. Through chemical modification experiments, it was found that the lipid extraction process for reduction of biosorption capacity was the greatest (17.7 %) compared with the respective 7.1 % and 6.9 % reductions by carboxyl and phosphate groups modified biomass biosorption. This result combined with Fourier transform infrared (FTIR) studies could deduce that lipid took part in the biosorption of reactive blue 49 and occupied a larger proportion among all the biosorption sites. In addition, carboxyl and phosphate groups were the main biosorption functional groups. Thus, it can be proved that the biosorbents can be reused, and still have a good adsorption performance for another adsorbate only if the main biosorption sites in the biosorbent are different.