Volatile fatty acids from oxidation liquefaction of the end-of-life wind turbine blades - GC analysis
The oxidative liquefaction method was used to get the chromatographic data shown here. This method has been used to break down the polymer matrix of wind turbine blades and measure the resin degradation yield. In this experiment, the effects of five different parameters, such as reaction temperature, residence time, pressure, waste-to-liquid ratio, and oxidant concentration, on resin degradation were studied in detail. Experiments were performed in the temperature range of 250°C to 350°C with a residence time of 30 to 90 minutes, at a pressure of 20 to 40 bar, a waste-to-liquid ratio of 5-25%, and oxidant concentrations of 15-45% by weight. The GC method was used to analyse an achive liquid sample after the oxidative liquefaction process.
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The raw data obtained during chromatographic analysis were exported using OpenChrom software, and then the signals in TIC form were placed in an Excel file together with a description of the process conditions. Sample names were written in the following form: Process temperature [°C]|Pressure [bar]|Oxidant addition [%]|Process time [min]|Waste-Liquid ratio [%]|Sample number. For example, 250|20|15|30|25_1 - sample obtained at 250 °C at 20 bar pressure with an oxidant addition of 15% to the amount of solution used in the liquefaction process, the liquefaction process carried out for 30 minutes, sample number 25 according to the experimental plan (DOE), 1 repetition per GC. Samples additionally marked with R are those for which the entire liquefaction process was repeated. We used a gas chromatograph from Perkin Elmer (USA) that was a Clarus 500 and had a flame ionisation detector (FID). A 30 m × 0.25 mm × 0.25 μm DB-FAT WAX UI capillary column (Agilent Technologies, USA) was used to separate the sample components. The flow rate of the carrier gas, i.e., helium, was 1.5 cm^3/min. Samples were introduced into a split/splitless injector. The initial temperature in the GC oven was 40 °C and maintained for 4 min, then increased by 5 °C/min until 240 °C was reached, after which it was held constant for 15 min. The total analysis time was 59 minutes. Hydrogen (45 cm^3/min) and air (450 cm^3/min) were supplied to the detector. Quantitative analysis was carried out based on calibration curves prepared for selected fatty acids (FATs), as well as the use of an internal standard. Peak area and FAT concentrations in the range 10-130 ng/l had a linear correlation (correlation coefficients > 0.99). The recovery of the standards used ranged from 91% to 115%. Due to the presence of strong acids and water in the samples from the WTB oxidative liquefaction process, the extraction of saturated fatty acids with chloroform was performed to protect the column phase. Analyses of these extracts were then carried out.
Narodowe Centrum Nauki