Application of TGA and EDX analysis to evaluate the process of preservative-treated woods

This study investigated the use of TGA under different thermal decomposition conditions (nitrogen or air, and 5 or 40 degrees C/min) to evaluate preservative-treated woods and their preservatives. It also analyzed the residual elements in the char using EDX. Two types of preservative-treated woods were investigated. One impregnated with CCA-3 and the other one treated with ACQ-1 using a full-cell treatment. The results of the TGA showed that the thermal properties of CCA- or ACQ-treated wood were similar to that of untreated wood in either a nitrogen or an air atmosphere, but the pyrolysis temperature for the heating rate of 5 degrees C/min was lower than that of 40 degrees C/min. Regardless of different atmosphere or heating rate, the char of the CCA specimens and the CCA-3 was more than that of the ACQ ones and the ACQ-1. The results of the EDX analysis of both preservative-treated woods show that the main element is C (CCA: 47.96%; ACQ: 50.24%), and that the relative proportion of C (CCA: 60.42%; ACQ: 77.89%) is higher after thermal decomposition. Cr from the char of CCA-3 is a stable element, and the amount of Cr (34.99%) is obviously more than that of As (11.89%) and Cu (16.69%). The char of ACQ-1 left a high amount of inorganic metal elements, such as Cu (50.14%). This suggests that by using EDX to analyze the residual elements in char, the results can provide experimental data for referencing the disposal-end practices (char) of both preservative-treated woods.