BIOSORPTION OF ACID BLACK 52, AN AZO DYE FROM AQUEOUS SOLUTION USING PRE-TREATED BIOMASS OF ASPERGILLUS FUMIGATUS A23

摘要

Up to 50% of the dyes are lost during the dyeing process and about 10-15% of them are discharged in the effluents. Dyes are mutagenic /carcinogenic and also cannot be completely removed by conventional wastewater treatment systems thereby causing serious environmental and health concerns. In this study, pre-treated biomass of Aspergillus fumigatus A23 was used as a sorbent for biosorption of a commercial textile azo dye, Acid Black 52 from aqueous solution. A comparison of pre-treatment methods showed that autoclaved biomass could decolorize dye maximally (86%) followed by acid (78%) and alkali (74%) treatment. The batch sorption parameters were optimized with respect to pH, initial dye concentration, adsorbent dose and equilibrium time; biosorption kinetic parameters were also determined. The optimum conditions for biosorption were found to be initial pH (6.0), initial dye concentration (25 ppm) and biomass concentration (0.5 mg/50 mL) at 30±22C. The R2 values for Langmuir and Freundlich isotherms were calculated to be 0.993 and 0.971 respectively, which indicated that the biosorption of Acid Black 52 on autoclaved biomass of A. fumigatus A23 dye could be explained better by Langmuir as compared to Freundlich isotherm equilibrium. Scanning electron microscopic image and Infra-red spectra showed modifications in dead fungal cell as compared to untreated biomass. The autoclaved biomass of A. fumigatus A 23 efficiently removed dye Acid Black 52 and since it is dead biomass it can be used to decolorize composite, toxic raw industrial effluent generated from leather, pharmaceutical and dye manufacturing company.