Performance assessment and characterization of the biosorption of the azo dye reactive Red 2 on thermally inactivated biomass of Trichoderma reesei

Abstract

The present study evaluated and characterized the performance in the biosorption of the dye azo Reactive Red 2 (RR2) on thermally sterilized biomass of the fungus Trichoderma reesei. An FTIR analysis of unloaded and loaded biomass with RR2 confirmed the interactions between dye molecules and functional groups on the fungal biomass surface. The decrease in the initial pH of 9 to 3 with an increase in the temperature of 20 to 40 °C improved the biosorption, reaching for RR2 a higher removal efficiency of 76.88% at pH 3 and 40 °C. A pseudo-second-order model explained the biosorption kinetics of RR2 (R2≥0.9869), and the intraparticle diffusion model showed that the biosorption process was initially controlled by diffusion rate and later by biomass surface saturation with the dye molecules. The Langmuir isotherm explained the biosorption equilibrium well (R2 ≥ 0.9241), achieving the maximum biomass biosorption capacity (qmax ) value at 61.72 mg g−1. The dimensionless separation factor values (0.0632 ≤ RL ≤ 0.0973) and the thermodynamic evaluation of the process (ΔG° ≤ −24.09 kJ mol−1, ΔH° ≥ 12.39 kJ mol−1, ΔS° ≥ 0.1265 kJ mol−1 K−1) demonstrate that the biosorption was favorable, reversible, spontaneous, and endothermic. The findings in the present study allow it to consider the biomass of Trichoderma reesei thermally sterilized as a biosorbent biomaterial that can be used for bioprocess design in removing the azo reactive dyes from textile wastewater.