Highly effective K-Merlinoite adsorbent for removal of Cs+ and Sr2+ in aqueous solution. Issue 49 (15th June 2017)

• Record Type: Journal Article
• Authors: Kakutani, Yuki; Weerachawanasak, Patcharaporn; Hirata, Yoshiya; Sano, Makoto; Suzuki, Toshimitsu; Miyake, Takanori
• Is Part Of: RSC advances. Volume 7:Issue 49(2017)
• Page Start: 30919
• Page End: 30928
• Publication Date: 2017-06-15
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c7ra03867d
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Cs + and Sr 2+ removal using K-MER adsorbent. Abstract : K-Merlinoite or "K-MER" was successfully synthesized and firstly employed as an adsorbent for the removal of Cs + and Sr 2+ cations in aqueous solution by batch operation. The optimum conditions to synthesize K-MER were hydrothermal temperature of 250 °C and a hydrothermal time of 8 h. As revealed by XPS, TG, NMR, and ICP analyses, the composition of K-MER synthesized under optimum conditions was "K10.9 Al11.2 Si20.9 O61.6 ·17.8H2 O", which corresponded with the typical formula of Merlinoite zeolite. 27 Al MAS NMR indicated that no octahedrally coordinated aluminum existed suggesting very high purity of K-MER. The calculated theoretical ion-exchange capacity was 4.2 mmol g −1, assuming exchange of the total amount of potassium. In aqueous solution, K-MER exhibited an excellent Cs + (≥90%) and Sr 2+ (≥65%) removal performance with the maximum exchange capacity of 3.08 meq. g −1 for Cs + and 2.01 meq. g −1 for Sr 2+ . K-MER showed higher adsorption for Cs + than Sr 2+ when performed using the same adsorption conditions. Coexisting monovalent cations, Na + and K +, significantly influenced Cs + removal more than divalent cations, Ca 2+ and Mg 2+, and they were in the order of K + > Na + > Ca 2+ > Mg 2+ . The most important factor for competitive adsorption between Cs + and the coexisting cation was the hydrated ionic size. Cs + became more difficult to adsorb when Cs + was interfered by a coexisting cation of close size. Although the efficiency of Cs + removal by K-MER decreased around 50% in artificial seawater compared with that in the aqueous solution, K-MER was a promising material for Cs + and Sr 2+ removal.