Thermal desorption of creosote remaining in used railroad ties: Investigation by TGA (thermogravimetric analysis) and Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry)

A two-step thermal process, an initial thermal treatment at mild temperature followed by a fast pyrolysis step, was investigated to recover wood preservatives and produce preservatives-free wood for production of high quality bio-oil from used creosote-treated railroad ties. During the initial thermal treatment at temperature of 280 degrees C for 10-30 min, the treated wood ties underwent a 20-25% weight loss with energy yield (77-83%). Energy yield at 280 degrees C was lower than that at 200 and 250 degrees C (92-97%) but higher than that at the 300 degrees C (64-74%). Recovery level of creosote at 280 degrees C was comparable to that at 300 degrees C. Fast pyrolysis at 450 degrees C of the 280 degrees C-treated wood ties produced high amount of levoglucosan and phenolic compounds with a traceable amount (1.7-1.9% of the total peak area) of creosote compounds. (C) 2015 Elsevier Ltd. All rights reserved.