Effect of silicate content on the mechanical strength of potassium-based geopolymer adsorbent derived from coal fly ash

抄録

Major alumino-silicate content in coal fly ash can be used to form geopolymer, an eco-friendly cement-like product. Geopolymer can be simply produced by reacting alumino-silicate component with metal alkali activator throughout geopolymerization. Potassium silicate and potassium hydroxide were used for the preparation of the fly ash-based porous geopolymer throughout the saponification and peroxide combination method. The synthesized geopolymers were investigated and tested for methylene blue removal.

In this study, the geopolymers were fabricated using different potassium alkali activator ratios with the fixed proportion of fly ash and pore forming agent. The ratios of potassium silicate to potassium hydroxide solution were set at 3.5: 1, 1.5: 1, 0.5: 1, and 0.3: 1 and named as G35, G15, G05, and G03, respectively. The geopolymer with higher silicate content displayed the greater value of durability index and compression strength. The highest durability index and the compression strength can be observed on the G35. The higher soluble silicate content resulted in more polymerization encouragement in the formation stage of the geopolymer. In terms of toxic substance removal, it might also affect removal performances. The display of good physical characteristic onto the geopolymer can assure that the geopolymer can be applied further to practical usage.