Assessment of Cadmium (II) biosorption by mucilaginous seeds of Ocimum americanum

The adsorption behavior of boiled mucilaginous seeds of Ocimum americanum for cadmium (II) ions from aqueous solutions was investigated in this study. Batch adsorption experiments were carried out to study the effects of contact time, initial concentration of cadmium, pH on the kinetics of cadmium adsorption. Cadmium ion removal increased significantly as the pH of the solution increased from 4 to 9. At the range of pH 7, the cadmium ion removal reached a maximum value with contact time 80 minutes and initial concentration of 50 mg/L. The biosorption data fitted well with Langmuir isotherm. The biosorption capacity calculated from the Langmuir isotherm was q = 34.2 mg of cadmium (II)/g of dry seeds. The continuous column study was also carried out at the flow rate of 27 mL/hr with the initial concentration of 50 mg/L of cadmium (II) feed solution using a packed bed column filled with boiled mucilaginous seeds. The maximum removal of cadmium (II) in the packed bed was more than 80%. These results show that boiled mucilaginous seeds of Ocimum americanum are an effective biosorbent for the removal of cadmium ions from aqueous solution compared to other biosorbents. This material can be employed potentially in waste water technology for remediation of heavy metal contamination.