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.