Biosorption of an azo dye Reactive Blue 4 from aqueous solution using dead and CMC immobilized biomass of Rhizopus oryzae (MTCC 262)

Abstract

In this current investigation, the adsorption of an extensively used azo dye Reactive Blue 4 (RB4) was carried out using dead and carboxy-methyl cellulose (CMC) immobilized Rhizopus oryzae (MTCC 262) as biosorbent in batch scale from the aqueous solution having dye concentration: 200–500 mg L⁻¹ in 50 mL dye solution taken in a 250 mL Erlenmeyer flask. It was found that RB4 adsorption capacity was maximum (97.44%) under following conditions, pH: 3.0, Temp: 30 °C, dye concentration initially was: 200 mg L⁻¹ and contact time: 6 h. CMC matrix was found to be the most effective among all the matrices tested as carrier for immobilization of R. oryzae biomass. The uptake of dye was very fast initially. Within 6 h the equilibrium was attained using both dead and CMC immobilized R. oryzae (MTCC 262). The pseudo 2nd order kinetic model can best explain the overall process of biosorption using both dead and immobilized biomass. The adsorption isotherm data of dead and immobilized biomass conformed well to Langmuir and Redlich-Peterson isotherm model respectively. Immobilized biomass can be competently recycled up to five consecutive cycles of biosorption where as a desorption medium 0.1 (N) NaOH solutions was used. FTIR spectroscopic studies indicate that in the dye adsorption process the functional groups existing on the exterior of dead biomass were more effectively involved in comparison to the other pretreated fungal biomass of R. oryzae (MTCC 262). SEM photograph confirmed some surface morphology changes of the immobilized and dead biomass of R. oryzae due to dye adsorption.

Keywords:

• Adsorption isotherm
• biosorption and desorption
• dead and immobilized biomass
• kinetic model
• reactive blue 4
• Rhizopus oryzae (MTCC 262)

Acknowledgement

The authors also gratefully acknowledge the guidance and support given by Late Prof. Lalitagauri Ray, Department of Food Technology and Biochemical Engineering, J.U.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

The authors gratefully acknowledge Department of Science and Technology, Government of India for financial support to pursue the research work.