Author’s personal webpage: : http://www.asdn.net/asdn/chemistry/silicates.shtml
Applied Clay Science, Volume 87, January 2014, Pages 205-211.
Department of Material Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 4-217, Cambridge, MA 02139, USA.
Ion exchange properties of pure potassium-based geopolymer (pure K-GP) formulated with Si/Al = 2.1 and K/Al = 1.0 ± 0.02 atomic ratios have been studied. For pure K-GP, the maximum ion-exchange level of K+with respect to Na+ and Cs+ is 77 and 61%, respectively, as determined by exhausted exchange with 1 M solutions of appropriate nitrates at 22 ± 2 °C. The geopolymer shows a slight preference for K+ over Cs+ as indicated by the normalized Cs/K-GP isotherm obtained under noncompetitive exchange. Parent geopolymer yields a pure geopolymer when it is extensively washed with deionized water until neutral pH is obtained and equilibrated with aqueous solution of KNO3 resulting in changing in composition and textural properties. As calculated from N2 sorption–desorption isotherms, surface specific area and cumulative pore volume for parent K-GP are 5.5 m2 g− 1 and 0.01 cm3 g− 1, respectively, whereas for pure K-GP surface specific area and cumulative pore volume are 270 m2 g− 1 and 0.4 cm3 g− 1, respectively.