Porous heat-treated fungal biomass: preparation, characterization and application for removal of textile dyes from aqueous solutions

Fermentation process waste was used as an ideal alternative, with low cost and high efficiency, to the expensive methods of removing dyes from wastewater. In this study, granular particles of heat treated-lyophilized biomass of the fungi Neonectria radicicola were tested to remove the three acid dyes Acid Orange 51 (AO 51), Reactive Red 75 (RR 75) and Direct Blue 86 (DB 86) from aqueous solutions and their adsorption was characterized in terms of adsorption isotherms and kinetics. Biosorption was investigated under different conditions of pH, contact time, temperature, adsorbent dosage and dye concentrations. The obtained results showed that optimum pH for dye adsorption was 2.0, the maximum uptake between 30 and 60 min of contact time and the equilibrium was reached within 60 min. The adsorption kinetics of the three dyes followed a pseudo-first-order rate model and Redlich–Peterson model fitted well the adsorption isotherms. The maximum adsorption capacities determined from the Redlich–Peterson equation were 120.6, 75.37 and 200.5 L g−1 for AO 51, RR 75 and DB 86, respectively. FT-IR analysis indicates the involvement of various functional groups and SEM images showed morphological changes.