Metakaolin-Based Geopolymers for Targeted Adsorbents to Heavy Metal Ion Separation

Abstract

Geopolymer adsorbents were prepared from silica and metakaolin in different Al and Si compo-nents and applied for removal of metal ions, Cs + and Pb 2+ , from other heavy metal ions mixture. The geopolymer was optimized at Si/Al = 2 as adsorbent, targeting to Cs + and Pb 2+ separation. The binding behavior was well fitted to Langmuir model, which proved that the metakaolin-based geopolymer had multibinding to adsorb ions. The effective adsorption was also observed inde-pendent of NaCl concentration for the Cs + and Pb 2+ . This meant that the ion adsorption of geopo-lymers occurred under non-electrostatic mechanism.