Adsorption characteristics of spirulina to rare earth erbium ions

In this study, the adsorption characteristics of spirulina to rare earth erbium ions (Er3+) in simulated mine wastewater were studied. The effects of different parameters on the adsorption process were investigated: including pH value of the treated solution, dose of spirulina, initial concentration of erbium ion, adsorption time, and so on. The adsorption kinetics and thermodynamic laws were discussed in detail with different adsorption models, such as Freundlich, Langmuir and Redlich-Peterson, Dubin-Radushkevich andpseudo first-order, pseudo-second-orderand elovich, intra-particle diffusion model. The mechanisms governing the adsorption process were more comprehensively understood. The results indicated that the adsorption rate of spirulinato rare earth erbium ions in simulated mine wastewater was 90.73% when the pH value of treated liquid was 5, dosage of spirulina was 2.0g/L, temperature of adsorption was 298K and initial Er3+ concentration was 100mg/L. Rate of desorption of Yb3+ from spirulina reached to 97.12% when it was eluted with 5mL of 0.5mol/L HNO3 solution after 60min. The results showed that the adsorption rate of spirulina was fast, and the adsorption and recovery of Yb3+ were ideal. At the same time, the results indicated that the adsorption kinetics of this processis in good agreement with the pseudo-second-order kinetic model (R2>0.99); the adsorption process was mainly controlled by chemical adsorption;a better adsorption isotherm can be simulated by the Langmuir equation (R2>0.9);the adsorption is a spontaneous endothermic process. © 2019, Editorial Board of China Environmental Science. All right reserved.