The Research on Adsorption Behaviors and Mechanisms of Geopolymers on Sr2+, Co2+ and Cs+

The adsorption behaviors and mechanism of geopolymers based on metakaolin-fly ash for Sr2+, Co2+ and Cs+ were investigated in static method. The results showed that the geopolymer has a strong adsorbability for Sr2+, Co2+ and Cs+ and the adsorbances are mainly affected by ion concentration and pH value of the solution. The adsorption dynamic model of the material for Sr2+, Co2+ and Cs+ is confirmed to be the first-order reaction and the adsorption isotherm curves showed that the adsorption behaviors belong to monolayer adsorption which is simulated by the Langmuir model very well. Desorption of Sr2+, Co2+ and Cs+could be carried on by immersing the adsorbents in the solutions with low pH or high ionic strength solution. Desorption experiments and XRD analysis indicate that the adsorption behaviors of geopolymer for the three kinds of ions are mainly chemical adsorption, according to the ion-exchange mechanism.