Biosorption of Th(IV) in a fixed-bed column by Ca-pretreated Cystoseira indica

Th(IV) biosorption from aqueous solutions by Ca-pretreated Cystoseira indica alga was studied by variations of bed height (3.5, 5.25 and 7 cm) and flow rate (1,2 and 4 ml/min) in a fixed-bed column. Favorable conditions were observed with the highest bed height and lowest flow rate. The maximum breakthrough time was 1450 min at flow rate 1 ml/min and bed height 3.5 cm. The experimental data were accurately described with the Belter model with R2 0.99. In addition, the results obtained agreed entirely with the bed depth service time (BDST) model. The flow rate study and the BDST model led to the conclusion that the mass transfer in continuous mode of Th(IV) biosorption onto C. indica is governed by intra-particle diffusion. FTIR analysis confirmed that hydroxyl, carboxyl and amine are the main groups for Th(IV) biosorption. Calcium ion concentration measurement in the effluent solution and XRF analysis performed due to investigation on ion exchange process in biosorption.