Abstract

Thermal desorption spectrometry (TDS) and Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS) have been used in combination to analyze the water and hydroxyl groups associated with four coal fly ashes. Measurements using the former technique on these ashes resulted in identification of three water desorption regions in the temperature range from 25° to 1100°C. The regions consisted of a small desorption peak at 50°, a broad band from 180° to 400°, and an intense peak from 400° to 590°. No additional water desorption was observed up to 1100°. A fourth ash gave a similar spectrum except that it lacked the intense last peak. The TDS spectra together with FT-IR/PAS spectra taken on samples exposed to pre- and post-desorption peak temperatures allowed the first TDS peak to be assigned to the desorption of physically adsorbed water, the broad band to desorption of hydrogen-bonded surface hydroxyls, and the intense last peak to the decomposition of Ca(OH)₂.

Photoacoustic phase-controlled Fourier-transform infrared spectroscopy

Santeri Larnimaa, Mikhail Roiz, and Markku Vainio
Opt. Continuum 2(3) 564-578 (2023)

Optimal boiler control through real-time monitoring of unburned carbon in fly ash by laser-induced breakdown spectroscopy

Miki Kurihara, Koji Ikeda, Yoshinori Izawa, Yoshihiro Deguchi, and Hitoshi Tarui
Appl. Opt. 42(30) 6159-6165 (2003)

High temperature Fourier transform photoacoustic spectroscopy: sample emission effects

S. McGovern, B. S. H. Royce, and J. Benziger
Appl. Opt. 24(10) 1512-1514 (1985)

Model of the diffuse reflectivity of fly ash and its application to an optical sensor system for the determination of carbon in fly ash

Alexander Schneider
Appl. Opt. 38(27) 5710-5723 (1999)

Quantitative Fourier transform IR photoacoustic spectroscopy of condensed phases

Y. C. Teng and B. S. H. Royce
Appl. Opt. 21(1) 77-80 (1982)