Interferences of carbonate quantification in municipal solid waste incinerator bottom ash: evaluation of different methods

Quantification of carbonate contents in fresh and weathered municipal solid waste incinerator (MSWI) bottom ash was performed using volumetric and gravimetric methods, Fourier Transform Infrared (FT-IR) spectroscopy and thermal analysis. Results differ considerably depending on the method applied. Volumetric measurement and thermogravimetry (TG) are based on the determination of CO₂ release by acid or thermal treatment, respectively. Interactions of CO₂ with the mineral matrix and de novo synthesis of carbonates during thermal analysis were observed. In order to find out the contribution of CO₂ released from residual organic matter, an additional experiment was carried out to demonstrate how the material is affected by the heating process in the course of thermal analysis. FT-IR spectroscopy as a non-destructive method seems to provide the most reliable quantitative results.