Biosorption of Malachite green from aqueous solution by dry cells of Bacillus cereus M116 (MTCC 5521)

• Malachite green biosorption with dry cells of Bacillus cereus M116.
• Optimum physicochemical conditions, isotherm and kinetic parameters were studied.
• FTIR analysis and functional group modification suggested COO− as adsorption site.
• AFM analysis showed structural changes of Bacillus sp. after interaction with dye.
• Biosorbent found feasible in Malachite green removal from simulated effluent.

Malachite green is a commonly used textile dye. Bacillus cereus M116 was found to be an efficient adsorbent for Malachite green removal from dye solutions. Optimum biosorption of Malachite green by B. cereus M116 was obtained at pH 5.0, biomass concentration 0.5 g/L, initial dye concentration 400 mg/L and contact time 360 min. The kinetics of the overall adsorption process was best described by pseudo-second order kinetic model and sorption data fit best to both Langmuir and Redlich–Peterson isotherm model indicating a hybrid and not an ideal monolayer adsorption behavior. Maximum biosorption (saturation) capacity was found to be 485 mg/g of biomass. FTIR spectroscopic analysis and chemical modification of the functional groups of B. cereus M116 suggested the major involvement of carboxylate groups of B. cereus M116 in Malachite green adsorption. Study of cell morphology of B. cereus M116 using atomic force microscopy showed structural changes of B. cereus M116 after interaction with dye. B. cereus M116 dry biomass was also found capable of removing Malachite green from dye solutions containing ingredients that may normally be present in actual industrial effluent efficiently up to 400 mg/L dye concentration.