Biosorptive uptake of cationic dyes from aqueous phase using immobilised dead macro fungal biomass

Present study deals with possible utilisation of immobilised biomass of a wood rotting dead macro fungus Fomitopsis carnea for the removal of cationic dyes from aqueous solution. The results indicated that biosorbent showed the highest affinity (Langmuir monolayer saturation capacity) for Safranin O (62.9 mg/g), followed by Neutral red (45.5 mg/g), Pyronin Y (30.6 mg/g), Malachite Green (29.9 mg/g), Thioflavine T (21.9 mg/g) and the lowest for Acriflavine (17.4 mg/g). The uptake of Safranin O was increased from 52.8 mg/g to 70.9 mg/g when temperature was increased from 20°C to 40°C. Increased uptake at high temperature suggests predomination of chemi-sorption and/or ion-exchange process. Safranin O uptake capacity of the biosorbent was decreased (from 87% to 74%) with increased in salt concentration (from 0 mM to 100 mM) indicating an ion-exchange type of dye-biosorption interaction could be possible. However, in case of increase in initial pH from 2 to 11, dye sorption also increased from 25% to 75%. This suggests possibility of electrostatic attraction between dye cation and biosorbent particle. Hydrochloric acid (0.1 M) could be used to regenerate the spent biosorbent.