Utilization of incineration fly ash from biomass power plants for zeolite synthesis from coal fly ash by hydrothermal treatment

- K-zeolite was synthesized used an extracted solution from biomass incineration ash
- Biomass incineration ash was used as an alkali source and a potassium source
- The synthesized K-zeolite contained phillipsite and chabazite
- The K-zeolite crystal size was dependent on pH and the potassium ion concentration
- K-zeolite exhibited a higher selectivity for cesium ions than Na-zeolite

In Japan, the quantity of incineration fly ash discharged from biomass power plants has increased rapidly due to the feed-in tariff established by the Japanese government. The costs of disposing of this biomass incineration ash are generally high; therefore, a method must be developed to utilize this by-product. In this context, we propose the syntheses of potassium-type zeolites (K-zeolites) from biomass incineration ash and coal fly ash via a hydrothermal route, which represents a novel use for this material. As the aqueous solution extracted from biomass incineration ash contains high concentrations of potassium, it was employed to substitute the KOH solution that is typically used in the synthesis of K-zeolites from coal fly ash. Consequently, we successfully synthesized a K-zeolite, containing phillipsite and chabazite phases, from coal fly ash using the extracted solution obtained from incineration fly ash. The NH4+ adsorption capacity of our synthesized K-zeolite was comparable to that of the K-zeolite synthesized using only KOH. We also confirmed that the prepared K-zeolite exhibited higher cesium adsorption selectivity than sodium-type zeolites, which are commonly produced industrially.

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