Biosorption of Malachite Green from Aqueous Solution Using Resting and Immobilised Biomass of Bacillus cereus M¹₁₆ (MTCC 5521)

Abstract

Biosorption of Malachite green, a hazardous environmentally persistent textile dye by resting and immobilised cells of mutant Bacillus cereus M¹₁₆ was standardised. Calcium alginate (3%) was found to be the most suitable and effective matrix for immobilisation of the biomass. Malachite green adsorption up to 91% and 83% was possible using resting and immobilised cells of B. cereus M¹₁₆ at pH 5.0, temperature 30°C, biomass concentration 0.5 g L⁻¹, initial dye concentration 100 mg L⁻¹ and contact time 360 min. Redlich–Peterson isotherm model fitted best to the experimental results and pseudo-second-order kinetic model described the process best. Immobilised biomass was efficiently reused up to four consecutive cycles of biosorption. UV-visible spectra analysis of growth media containing the organism in presence of Malachite green showed that the dye was not metabolised by bacterial species. Scanning electron microscopy confirmed the phenomenon of adsorption onto cell surface as the underlying mechanism of dye removal.

Keywords:

• Malachite green
• Biosorption
• Bacillus cereus
• Resting and immobilised biomass
• Adsorption isotherm

Disclosure statement

No potential conflict of interest was reported by the authors.

Nomenclature

C_i = initial dye concentration in solution

C_f = final dye concentration in solution

C_e = equilibrium dye concentration

V = volume of sample used for batch dye removal

M = dry weight of biosorbent used for batch dye removal

q = dye uptake capacity of biosorbent

q_e = dye uptake capacity of biosorbent at equilibrium

q_t = dye uptake capacity of biosorbent at time t

K_L = Langmuir constant

K_F = Freundlich constant

A, B, g = Redlich–Peterson constants

n = Freundlich exponent

q₀ = monolayer sorption capacity of biosorbent

K₁ = rate constant of pseudo-first-order kinetic model

K₂ = rate constant of pseudo-second-order kinetic model

R² = linear regression correlation coefficient

Additional information

Funding

The authors gratefully acknowledge University Grants Commission (CAS Program), Government of India [Grant number: F4-1/2006(BSR)/5-46/2007(BSR)] Dated: March 31^st 2010, for financial support to carry out the research work.