Abstract:The adsorption characteristics and mechanisms of spirulina powder were investigated when it was used as adsorbent to recover ytterbium(III) from wastewater solution. Surface structure and element valence of the adsorbent were analyzed by SEM and XPS for the exploring of its adsorption mechanism for ytterbium(III). The adsorption characteristics of ytterbium(III) on spirulina powder was analyzed through assessing adsorption isotherm, kinetics and thermodynamic models. The adsorption isotherm data were best explained by Langmuir model, and the adsorption capacity of spirulina powder for ytterbium(III) was 72.46 mg/g when adsorption temperature was 318 K. The kinetic experiment results showed that the pseudo-second order kinetic model can better simulate the adsorption process of spirulina powder to ytterbium(III), indicating that the rate-controlling step was chemical adsorption. Spirulina can be an efficient and economical ytterbium(III) recycling material, because it showed good adsorption stability and reusability from the adsorption-desorption cycle experiment results.

Key words: spirulina; ytterbium(III); adsorption; thermodynamics; kinetics