the process developer and other published information this result was most unexpected at five years of age doubling the water injection rate for two weeks produced the same beneficial effects as in year four the recovery and purity decreased while the water injection was at 400 wt ppm when the water injection rate was returned to 200 wt ppm the purity and recovery improved to almost start of run performance thus once again the unexpected result of increasing both recovery and purity was seen when non linear water injection rates were used at six years of age based on laboratory tests a polar organic compound was added to the water injection tank in the particular set of tests run the polar organic compound selected for use was tetrahydrothiophene 1 1 dioxide commonly called sulfolane at 300 wt ppm water plus sulfolane the improvement in the performance of the solid adsorbent was faster and the temporary loss of purity and recovery was not as severe it appeared that about half the time was needed for the adsorbent to produce higher recovery once the sulfolane was removed from the injection water and the rate was returned to 200 wt ppm the performance of the adsorbent returned to start of run performance it has further been established through empirical testing that the method will provide improved extraction when applied for a period of time equaling a complete cycle of a controller for the bed of solid adsorbent to be rejuvenated in plant b after several years of operation the recovery of paraxylene had declined.