In this study, white-rot fungus, Rigidoporus vinctus, collected from an unidentified fallen twig from Pathankot, Punjab, India, was used for biosorption of anionic Congo red and cationic Methylene blue dyes from an aqueous medium. The biosorption efficiency of the live biomass of Rigidoporus vinctus was investigated to optimize biosorbent dosage, process time, concentrations of dyes, and pH of solutions. The results indicated that Rigidoporus vinctus is more efficient than other reported bio-adsorbents for Congo red and Methylene blue dyes. The maximum biosorption activity of Rigidoporus vinctus for Congo red was found at pH 2, and that for Methylene blue was at pH 10, after 24 h of the reaction period. The process followed pseudo-second-order kinetics, which indicated that the interaction of both dyes to the adsorption sites on the surface of Rigidoporus vinctus was responsive to biosorption. The biosorption process could be well explained by the Langmuir isotherm for both dyes. The maximum monolayer biosorption capacity of Rigidoporus vinctus for Congo red and Methylene blue was observed to be 54.0 mg/g and 80.6 mg/g, respectively. The seed germination test was carried out, and it was assessed that the toxicity of dyes was reduced up to significant levels. Based on the present experimental findings, it can be concluded that biosorption using the live biomass of Rigidoporus vinctus can effectively decolorize dye-containing wastewater, thus reducing the hazardous effects of dyes on human beings.
Keywords: Congo red; Rigidoporus vinctus; biosorption; fungi; methylene blue.