Adsorption characteristics of strontium onto K2Ti4O9 and PP-g-AA nonwoven fabric

Abstract

This study investigated the possibility of using potassium titanate oxide (K2Ti4O9) and acrylic acid-grafted polypropylene fabric (PP-g-AA) as adsorbents capable of removing strontium from aqueous solutions. K2Ti4O9 showed the highest rate of strontium removal in the weak alkaline range, while the PP-g-AA increased strontium removal in the neutral range. Moreover, the adsorption capacity of the K2Ti4O9 was not affected by the coexistence of K and Na ions, while the adsorption capacity decreased when Ca and Mg ions were present at the same concentration as that of strontium. When coexisted at the same concentration as strontium, Na, K, Ca, and Mg ions strongly reduced the adsorption capacity of the PP-g-AA. The results also indicated that the adsorption of strontium on K2Ti4O9 was consistent with both the Langmuir and Freundlich adsorption isotherms. In contrast, the adsorption of strontium on the PP-g-AA was more consistent with the Langmuir isotherm model. Moreover, the adsorption equilibrium time of K2Ti4O9 was generally 12 h, while that of the PP-g-AA was 5 h, indicating that the adsorption rates were consistent with the pseudo-second order kinetics model. K2Ti4O9 and the PP-g-AA could be regenerated by simple washing with 0.5 N HCl.