Studies of Niobium Sorption from Chloride Solutions with the Use of Anion-Exchange Resins

This paper presents the results of studies for niobium sorption from chloride solutions with the use of anion-exchange organic sorbents: Amberlite IRA-67, Purolite A-100, AB-17-8, and AN-2FN. Niobium sorption was performed from model niobium-containing solutions. Data on comparative sorption characteristics of the studied sorbents were obtained, and the static exchange capacity of the sorbents, values of distribution coefficients, and extraction degree during the niobium sorption from chloride solutions were calculated. The Purolite A-100 anion-exchange resin exhibited the highest affinity for niobium ions under the conditions studied. Its distribution coefficient was 184 mL/g; the niobium extraction degree was 41.5%. To study the equilibrium sorption of niobium from solution on the Purolite A-100 anionite, three well-known models of isotherms were applied: Langmuir, Freundlich, and Dubinin-Radushkevich. The data obtained confirm the good agreement of the Langmuir model with the results of experiments and indicate that the process takes place in a monomolecular layer on the adsorbent having homogeneous adsorption centers. The optimum conditions of niobium sorption by the Purolite A-100 anion-exchange resin were determined as follows: hydrochloric acid concentration-5-10 wt.%, process temperature-35-40 degrees C, and duration-40-50 min. The calculated activation energy values for niobium sorption from hydrochloric acid solution in the temperature range of 20-50 degrees C were 25.32 kJ/mol, which corresponds to the intermediate region corresponding to the transition from the diffusion to the kinetic mode.

Automated summary

This study investigated the sorption of niobium from chloride solutions using various anion-exchange organic sorbents. The Purolite A-100 resin showed the highest affinity for niobium ions, with a distribution coefficient of 184 mL/g and an extraction degree of 41.5%. The Langmuir model was found to be in good agreement with the experimental results, indicating monomolecular layer adsorption on the homogeneous adsorption centers of the resin. The optimal conditions for niobium sorption by the Purolite A-100 resin were determined as hydrochloric acid concentration of 5-10 wt.%, process temperature of 35-40 degrees C, and duration of 40-50 min. The activation energy for niobium sorption from hydrochloric acid solution was calculated to be 25.32 kJ/mol, suggesting a transition from diffusion to kinetic mode.