Adsorption of Th¬(IV) From Aqueous Solutions Using Bi-Functionalized Algae-Yeast Biosorbent

Immobilized Cystoseira indica algae and Saccharomyces Cerevisiae on the silica gel were used for the biosorption of Th (IV) from aqueous solutions. Ability and capacity of bi-functionalized algae- yeast biosorbent for adsorption of thorium (IV) from aqueous solutions were investigated in a batch method. The response surface methodology (RSM) based on the central composite design (CCD) was used to investigate the effect of pH (2-6), time (10-180 min), initial thorium(IV) concentration (50-300 mg/l) and adsorbent dosage (0.5-5 g/l) on the sorption of thorium (IV) from aqueous solutions, and to optimize the biosorption of Th (IV). Variance analysis showed that the adsorbent dosage, initial Th(IV) concentration, time and pH were respectively, the most effective factors in the biosorption of thorium(IV). Under optimal conditions (pH 5, contact time 137.5 min, initial Th(IV) concentration 237.5 mg/l, and adsorbent dosage 1.63 g/l ) the capacity of the biosorbent for Th(IV) was estimated to be 128.82 mg/g. The kinetic data were fitted well the pseudo-second-order rate equation. The biosorption data could be well described by Langmuir isotherm in comparison to Freundlich and Temkin isotherms. The maximum sorption capacity of the biosorbent for Th (IV), by Langmuir isotherm was estimated to be 142.86 mg/g. The thermodynamic parameters indicated that the biosorption of Th(IV) on the biomass was a spontaneous, and endothermic process, at the studied temperatures and would occur via physical adsorption.