Hydrothermal Synthesis of a Novel Tobermorite-Based Porous Material from Municipal Incineration Bottom Ash

A novel tobermorite-based porous material has been synthesized from municipal incineration bottom ash (MIBA), using a hydrothermal processing method under saturated steam pressure (1.0 MPa) at 453 K for 12 h. Without additional vesicants, NaOH solution that is incorporated into the starting material acts as both a reaction solvent and a vesicant. As a reaction solvent, the NaOH solution first promoted tobermorite formation to form a huge number of small pores during hydrothermal processing; then, as a vesicant, it was released as vapor from the solidified specimens to form large pores after drying. The porous material possessed a pore diameter distribution of 0.01−10 μm, a BET specific surface area of 60 000 m2/kg, and a bulk density of 500−700 kg/m3. Moreover, the leaching tests showed that the concentration of heavy metals dissolved from the solidified specimen became very low after hydrothermal processing.