after treatment with the acid acting substance the invention will now be illustrated with reference to the following examples a sample of sulfolane solvent which had been used in service for extracting benzene from a petroleum stream and containing triethanolamine inhibitor was found to have a ph of 9 0 a chloride ion content of about 1045 parts per million by weight ppmw a total nitrogen content of about 0 63 per cent by weight w and when measured by immersion of a carbon steel coupon in the sulfolane liquid at 400 degrees f for about 24 hours was found to exhibit a calculated corrosion rate of 74 mils year this sulfolane was combined with orthophosphoric acid 85 h 3 po 4 to lower the ph of the combined material to about 7 0 about 1 5 grams of acid per 100 grams of sulfolane was required and resulted in formation of a dark tarry solid phase the liquid was separated by vacuum filtration through a 541 whatman filter paper the separated liquid was found to have a chloride content of about 400 ppmw a total nitrogen content of 0 27 w and to exhibit a carbon steel corrosion rate of about 2 mils year for comparison purposes the sulfolane of example i was combined with a highly acidic ion exchange resin.