Burkholderia cepacia immobilized on eucalyptus leaves used to simultaneously remove malachite green (MG) and Cr(VI)

A multifunctional biomaterial capable of simultaneously removing malachite green (MG) and Cr(VI) was prepared by immobilizing Burkholderia cepacia (B. cepacia) on eucalyptus leaves (EL). The maximum uptake of MG (60 mg/L) and Cr(VI) (20 mg/L) were 94.8% and 71.9% respectively, which was more efficient than when using EL or free cells alone. SEM-EDS demonstrated that B. cepacia was attached to EL and that Cr(VI) was biosorbed into the immobilized cells. FTIR showed that the degradation by functional groups of immobilized cells was in keeping with the products, detected by GC-MS, which suggested that MG could be degraded to 4-dimethylamino benzophenone and 4-dimethylamino phenol. The removal of both MG and Cr(VI) by EL immobilized cells fit the pseudo-second order adsorption kinetic model well (with both R2>0.983). The equilibrium adsorption capacity of MG was 9.59, 18.67 and 28.64 mg/g for initial MG concentrations of from 30, 60, 90 mg/L, respectively when the concentration of Cr(VI) was held constant at 20 mg/L. The adsorption capacity of Cr(VI) increased from 3.49, 7.68 to 9.79 mg/g as the initial Cr(VI) concentrations increased (10, 20, 30 mg/L) while the MG concentration was kept constant at 60 mg/L. The results showed that eucalyptus leaves as a low cost and eco-friendly material have some potential to be an effective immobilization for environmental applications.