SUBCRITICAL AND SUPERCRITICAL EXTRACTION OF OIL FROM USED AUTOMOTIVE TIRE SAMPLES

Samples from a used automotive tire were subjected to sub- and supercritical extraction with w-pentane, toluene and nitrogen. Solvent effectiveness for extraction was greatest for toluene and least for nitrogen. When the extraction with toluene was completed at temperature 653 K and pressure 5.2 MPa, for instance, 57 % (by weight) of the sample was converted to liquid oils and 40 % remained as solid residue. Rate constants for extraction with n-pentane, assuming that the process is first-order, increase with both temperature and pressure. Scanning electron microscope pictures show that many cavities are produced inside the solid during extraction with toluene and n-pentane. From this evidence a qualitative explanation of the process is suggested.