Effect of rhamnolipids on cadmium adsorption by Penicillium simplicissimum

Abstract

The effect of rhamnolipids (RL) on Cd 2+ adsorption by Penicillium simplicissimum (P. simplicissimum) was studied. The maximum adsorption capacities of Cd 2+ were obtained at pH 6.0 for the intact P. simplicissimum and at pH 5.0 for the RL-pretreated P. simplicissimum, respectively. The adsorption equilibrium was reached after about 4 h. The experimental adsorption isotherms were in good agreement with the Langmuir model. The maximum adsorption capacities (q max) for the intact P. simplicissimum and for the RL-pretreated P. simplicissimum were 51.6 and 70.4 mg/g, respectively. The interactions between Cd 2+ and functional groups on the cell wall surface of the P. simplicissimum were identified by SEM, EDAX and FTIR analysis. It is indicated that carboxyl, amino and hydroxyl groups play major roles in the Cd 2+ adsorption. The results suggest that the RL-pretreated P. simplicissimum is a promising candidate for the removal of Cd 2+ from aqueous solutions. © 2012 Central South University Press and Springer-Verlag Berlin Heidelberg.